GTM roll cage modifications and race car build log [Archive] - Page 2

kabacj

08-06-2013, 07:39 PM

You are really enjoying the summer with the car. You can remove the cats from the system unless you need them for street use. That will take a huge amount of heat from the engine bay.

Yep Hugo im having a great time driving the car. Its just such an awesome package. I didn't think of eliminating the cats completely. That's a great idea. I lose heat and gain a bit of power. Ill ask Shane what the lead time is for a kooks tail pipe setup without cats. I bet that solves my problem.

I did both, heat wrap with FG tape and a home made aluminum heat shield from an old Audi. As we all know, you cant FG wrap a cat, it'll screw it over time.

rev2, that's a nice setup. I was thinking that I could also use that quilted aluminum material as a metal shield with an air gap. When you mean you cant wrap the cat with FG tape , you mean the tape burns up right? I know there is that Lava tape which is basalt based and supposedly can stand up to 2000 degrees direct contact. One way or the other I do need to address the heat. Those CV boots will not last long if I keep cooking them to nearly melting point.

Thanks for the ideas guys.

John

mikespms

08-06-2013, 08:55 PM

Hi John.

The paint on the lizard skin on the panels was blistering I used DEI titanium heat wrap on the pipes and 1/2" armor heat shield on the cat's it cut down the radiant heat about 60%,

Mike

kabacj

08-07-2013, 06:53 PM

Hi John.

The paint on the lizard skin on the panels was blistering I used DEI titanium heat wrap on the pipes and 1/2" armor heat shield on the cat's it cut down the radiant heat about 60%,

Mike

Thanks Mike. Seems like you guys had good results with the wrap and shield combo.

I am taking a month off to work on the car before my next track visit so ill be sure to get this sorted.

John

kabacj

08-22-2013, 07:36 PM

The past couple of weekends I have been mocking up my intake.

I really want to see the open bell mouths.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/0826c5e90604c04444021d13cb93349a.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/0826c5e90604c04444021d13cb93349a.jpg.html)

That of course is impossible if I want to avoid sucking rocks and low flying birds into the engine.

I currently use foam filters I was able to mount up as they are the same OD as the ID of the intake runners and only need a sleeve to act as a union.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/5B738B6E-78D1-447B-A6D6-0C5D7B853A4F-5447-0000064AC8507312_zpsf5eb3b63.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/5B738B6E-78D1-447B-A6D6-0C5D7B853A4F-5447-0000064AC8507312_zpsf5eb3b63.jpg.html)

The only way to accomplish this is build an intake. I'm thinking it will be like a shaker hood scoop.

The pink foam mock up will be a vacuum formed clear polycarbonate bubble sitting in the middle of a clear polycarbonate hatch cover.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps8250b7fd.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps8250b7fd.jpg.html)

http://i1073.photobucket.com/albums/w389/kabacj/null_zps4f2f214e.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps4f2f214e.jpg.html)

All fed through two KN cone filters in a heat shielded box above the trans-axle. The air will enter at the rear most edge of the hatch cover a la Daytona prototype cars.

The setup still needs lots more work but I am starting to get an idea of how it will look.

How hard could it be to make?
( famous last words. )

John

fastthings

08-23-2013, 12:35 PM

Like my dad used to tell me, "I may not know what doing, but I put on a good show."

Looks good man.

sk7500

08-24-2013, 10:48 AM

Cutting edge as usual. Can't wait to see how this turns out.
And what's with taking a month off to work on the car!? That should be illegal or better yet MANDATORY.

claybags

08-24-2013, 01:56 PM

John belongs to a European labor union where everybody gets the month of August off!! LOL
Cheers, Jeff

Fraser D

08-24-2013, 03:13 PM

John,

I think that the design is awesome!
will you be louvering the poly carb hatch cover or leaving in flat?

kabacj

08-26-2013, 04:03 PM

John,

I think that the design is awesome!
will you be louvering the poly carb hatch cover or leaving in flat?

Hey Dave. Thanks. I think louvers are the way to go. I want to make sure there is plenty of air circulation. The louvers and cold air intake will be a design element that I repeat on other areas of the car.

I know taking August off to work on the car instead of running it on the track the way it is was a tough choice. I plan to do the body mods over the winter. The intake and hatch cover will have related design elements to the other aero features on the body. I hope they all will work as I planned but you never know. I don't want to complete the intake only to find a flaw in the design when I use it on the track. Since the intake is the core element and will relate to everything else, I figure I get that right first. Test it on the track to make it works as planned. Then continue on with my other plans over the winter.

Regarding heat. The motor and transaxle run nice and cool with the hatch open and the diffuser off. Now that I have telemetry attached to the ecu. I see that the motor runs at 205-210 ( not 220 like the analog gauge was reporting. ) The mast ecu can drive analog or digital gauges. I have it setup so the ECU drives the analog guages. I can adjust the analog signal so both the ecu and Factory Five gauges are reporting the same temps.
With everything open the transaxle never got above 180 degrees even when it was very hot out. Without all the airflow I doubt the transaxle will run as cool. Maybe a cooler will be required. If so I want to make sure I can duct some air over it so I dont need a full time fan.

John belongs to a European labor union where everybody gets the month of August off!! LOL
Cheers, Jeff

Ha yeah even the F1 teams get a forced 2 weeks off. Talk about a foreign concept. The only way I know how to relax is to work on something I enjoy.

Cutting edge as usual. Can't wait to see how this turns out.
And what's with taking a month off to work on the car!? That should be illegal or better yet MANDATORY.

Steve if only I could take off a month to work on the car. The time off is only from running it on the track. I cant make major changes when I need the car track ready every 2 or three weeks. Ill be lucky to get a day of GTM work during our vacation in August. Now on LABOR day . That will be a full on GTM day.

Like my dad used to tell me, "I may not know what doing, but I put on a good show."

Looks good man.Gene clearly your Dad is/was a wise man. He passed that on to you and you are passing it on to your son. I usually dont know what Im doing as I love to try things I have never done before. I assure you that either ill get it done or go down in a blaze of glory;) I would just rather keep the blazes out of the car as I have not yet installed the fire suppression system.

John

Taz Rules

08-26-2013, 10:02 PM

John, I am looking so forward to seeing that done!
One of the things I love about GTMs is all the different mods that people do. Creativity well executed is a beautiful thing!

longislandwrx

09-06-2013, 02:55 PM

Nice, it's got that cool Lamborghini21261 louver look.

LCD Gauges

09-06-2013, 05:00 PM

John,

Eat my shorts.

;)

\\sick (file://\\sick) looking stuff \\

sk7500

09-10-2013, 03:09 PM

Hi John.
Time for me to say " hey your inbox is full"

Got a pm waiting for its place in line.

kabacj

09-13-2013, 05:00 AM

When i started my build I wanted a street car that I could take out on the track. But as time goes on I am building a track car that is street legal.

Along that line I decided I will swap out my 5 speed H pattern for a 5 speed mendiola sequential.

That means i needed to take the transaxle out without removing the body. I have heard stories about how hard it is. The requirement to remove the x brace. It's actually easy.

Step 1

I raised the car up a few inches just to allow the engine crane legs access under the car. I did not want to use jack stands because they can get in the way as well as lift the car up pretty high. I thought maybe too high. In hindsight I prob could have used the stands.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsd04beefe.jpg

Next unbolt and detach the cables/ sensors / axles and remove the rear sub frame.

I covered the CVs with bags bc the high moly content grease makes such a mess and sticks to everything. Then I zip tied the axles out of the way.

I used the bolt holes in the mendiola sdr as a lift point. Pulling the transaxle back to the x brace. I dropped the transaxle on the frame supported by blocks of wood and the jack

I slid the transaxle back on the blocks by hand as the transaxle is pretty light. Next I re attached the bolts and chain and tilted the transaxle out.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsa2f62725.jpg

http://i1073.photobucket.com/albums/w389/kabacj/null_zps2b485ef4.jpg

Then re attached the crane when the transaxle was out of the car resting on blocks.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps78a41a7c.jpg

Easily done by one person with some 2x4s, a jack, and engine crane.

John

Fraser D

09-13-2013, 07:43 AM

John,

Perfect timing!
I was planning on reading up tonight and pulling my transaxle Saturday along with the engine.
My build and my own realization and acceptance of that are about half way down the road that you are on.
My street car come weekend warrior is now morphing into a track car with number plates.
Thanks for sharing.

fastthings

09-13-2013, 08:23 AM

That should be cool. You must not have a 8 to 12 month wait for the new sequential box. (whoops did I say that?)

LCD Gauges

09-13-2013, 08:40 AM

Good to know if any transaxle work is needed in the future. Love those calipers too! A big-brake kit is on my wish list for next year.

kabacj

09-15-2013, 07:10 PM

Good to know if any transaxle work is needed in the future. Love those calipers too! A big-brake kit is on my wish list for next year.

Hey Tino.

The transaxle flys in and out without issue. The calipers were custom built by stop tech with 6 piston in the front 4 piston in the rear. They sized the pistons to the weight balance of the car as well as the master cylinders that come with the kit. with 14 inch rotors it stops like it has power brakes. Very happy with the setup. All that and I have use used the same set of pads all season. My buddy has replaced his pads in his corvette 3x since we started.

That should be cool. You must not have a 8 to 12 month wait for the new sequential box. (whoops did I say that?)

Yeah not 8/12 months , but still a wait. Its a custom unit so they did not have the gears on the shelf. They needed to cut them so that adds time. I researched the other options and they are silly money. For what you get if you have to wait... its better then paying 2X as much. And Ian and team are always there for me. I sorta doubt I would get that support from Xtrac or Emco. Nobody pays me to put the car on the track. I just cant justify the cost.

John,

Perfect timing!
I was planning on reading up tonight and pulling my transaxle Saturday along with the engine.
My build and my own realization and acceptance of that are about half way down the road that you are on.
My street car come weekend warrior is now morphing into a track car with number plates.
Thanks for sharing.

Hey Dave, I enjoy watching your track videos. Yeah the GTM is such a great track car. Sure it turns heads on the street, but you really cant drive it anywhere near its potential on the street. I don't care how irresponsible you are you are not going to pull 1.5 Gs and go 145mph every min all day long.

Circuit of the Americas in Austin is on my bucket list. Care to join me?

John

kabacj

09-25-2013, 08:18 PM

Next track day is October 5th at New Jersey Motorsports Park its time to start getting ready.

Now that I have the Stack telemetry installed I can see the RPM of my shift points. Turns out I am shifting quite a bit before peak power many places on the track.

The motor revs so quickly and the motor has so much torque I did not realize I was short shifting at around 6k. It seems like I am accelerating very fast so I did not push for more. In fact I have 1200 more rpm to work with. I have a 7200 rpm redline.

At certain points on the track I cant take the time to look down to see where the revs are on the tac and its harder then normal to accurately judge the RPM just by the sound of it bc the intake makes quite a roar.

I needed a shift light.

My current electronics package includes the MAST motorsports ECU which is a wealth of information in itself it can be plugged into a laptop to log every function of the motor in real time. I have my STACK video and data logger that records video and a 15 channel data stream of my choice from the ECU and overlays that in real time with 3 camera feeds.

But neither of these systems easily incorporates a sequential shift light. I did not want to purchase yet another data logger that would support this feature. I did find a great stand alone system.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsd6d4743f.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpsd6d4743f.jpg.html)

This unit just taps off the tach feed and with a simple configuration I have a sequential shift lights at my choice of RPM from green to yellow to red.

Easy to see in your peripheral vision and I will now more easily be able to know how close to the rev limit I am anywhere on the track.

John

Fraser D

09-26-2013, 05:59 AM

Hey Dave, I enjoy watching your track videos. Yeah the GTM is such a great track car. Sure it turns heads on the street, but you really cant drive it anywhere near its potential on the street. I don't care how irresponsible you are you are not going to pull 1.5 Gs and go 145mph every min all day long.

Circuit of the Americas in Austin is on my bucket list. Care to join me?

John

John,

Give me 6-12 months and I will be up for a play in Austin.

crash

09-26-2013, 10:30 AM

You guys do know that they charge by the foot at Austin if you have any off track excursions, right? It is a unique situation, as far as I have seen, here in the U.S. They make you sign a contract before you are allowed on the track that states the prices for things such as tow truck service, and track repairs, including guard rail and GRASS both charged by the foot. Despite my moniker on here, I usually drive race cars a bit conservatively, but after hearing about this policy, the only list Austin is on for me is the "do not race at" list. You might want to research it before making a drive with the expectations of getting some laps in. Although those I know that have raced there say it is a GREAT track.

kabacj

09-26-2013, 01:07 PM

You guys do know that they charge by the foot at Austin if you have any off track excursions, right? .

I did not know that, but I am not surprised. Its not the first time I have heard of or been asked to pay for damage/ towing. I have even heard of charges for speedy dry when you oil the track. Boy times must be tough!

One of the attrative things about austin, besides the cool layout, is the MILES of run off ... paved run off. Sure its painted and covered in fake grass in some areas but its way better then driving out into actual grass or usually bumpy dirt as everybody tends to leave the track at the same points.

John,

Give me 6-12 months and I will be up for a play in Austin.

Dave, that sounds like great timing to me. By that time ill have a much more finished car that is reasonably well dialed in. Crash you and the west coast crew can join us. Austin in the cooler months makes a nice family trip too. Thats how i plan to sell it.

John

Fraser D

09-26-2013, 07:42 PM

The money grab that is "Circuit of the Americas" has bent over the odd racer or two and spectator from what I am told.
Some clubs have been covering any fines but the entry is typically high to average it out.
I have had a couple of friends who have run there and describe it as a "bucket list" experience.
We just need to pick the right club event to get the best value.

kabacj

10-09-2013, 05:04 AM

3 days at the track

I ended up putting the 5 speed H pattern Mendiola SDR back into the car. I had too much fabrication to complete . I wanted to ensure a quick swap of the transaxle without disturbing the support for the wing and body. I want to re make all of the support structure out of aluminum . A winter project.

I put the car back together and ran through my little check list items like hooking up the fuel gauge and shift light loaded her up and off to the track at 3am Friday.

The first session was great. The car was running well but I immediately saw I had a problem with the cats over heating the cv boots. This was a problem at limerock, but never at this track. The boots were mushed down semi melted from the heat. They looked terrible. I figured they were going to fail some time soon under those conditions. I had looked into removing them, but kooks was going to charge Shane 400 bucks to make a pair of pipes to delete the cats. thats more then 2x what i would cost me to make them. It was great of Shane (Thank you again shane) to try to get a better price but looks like either I wait for the next production run or make the cat delete pipes.

Ok what can i do in 30 min. Which is really 20 min bc by the time I get out of the car and the cats cool to 500 degrees when I can start working around them. We were running 30 min on the track and 30 min off. Which is great for track time, but it makes it very hard to work on the car as everything is blazing hot.

Btw it was a super rare 87 degree day in October. Great just what I need heat issues on a hot day.

I knew it was a short term fix but I have exhaust wrap. I'll wrap the cats. That will block the heat.
Wrong. All that did was heat the cats red hot. The radiant heat was slightly less but still way too much.
I actually would not recommend wrapping the cats. Yes it helps them heat up quickly to reduce emissions which is the point for production cars but they REALLY get hot. Glowing red hot.
After two sessions. First with one layer of wrap then with three. I took off the wrap. It was already brittle.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpse7a5221c.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpse7a5221c.jpg.html)

Ok I see I need a heat shield. Dam it I bring so much extra crap to the track but I did not bring sheet metal this time. Iv had it all year but I figured I had worked out the sheet metal type problems.
Anyway I went to the local lowes during the lunch break and bought tin snips and aluminum flashing.
That worked well...until it melted.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpse9e6f9ba.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpse9e6f9ba.jpg.html)

Ok higher melting point metal. No problem. I got a section of 4 inch galvanized duct work. Pre curved and already split. its perfect. I bent some stand offs into it so I had a nice air gap.
Problem solved.

Now I could focus on driving which was the best this season.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsd839b9c4.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpsd839b9c4.jpg.html)

John

RumRunner

10-09-2013, 05:38 AM

John,

I think you top the list of most creative when it comes to getting out of a pinch. The idea to use the galvanized duct-work is brilliant! I suspect many folks will follow your lead. Quick, cheap insurance.
Glad to hear you had best track day so far. Does the track cower in fear when it sees you coming :)?

-Michael

LCD Gauges

10-09-2013, 05:39 AM

Awesome news, and info.

Are you confined to emissions testing? If not, have you considered removing the catalytics?

fastthings

10-09-2013, 08:04 AM

Thanks for the info. I think I may be in line with you for the next Kooks run. I think I'll replace the cats' also.

RF RIDER

10-09-2013, 11:57 AM

Would there be interest for a group buy thru Shane for just the pipes to replace the cats?? I would be in for a set.
Shane any chance you read this, that you could set up a run for just a set of pipes to replace the cats?
Don't want to hi-jack thread, but you might be interested in a group buy if priced right?

kabacj

10-09-2013, 01:12 PM

Thanks for the info. I think I may be in line with you for the next Kooks run. I think I'll replace the cats' also.

On the street unshielded cats might be ok. Mine were fine until I started pushing on the track. For track duty a delete is the best way to go.

Awesome news, and info.

Are you confined to emissions testing? If not, have you considered removing the catalytics?

Just did not have time to fab them up.

John,

I think you top the list of most creative when it comes to getting out of a pinch. The idea to use the galvanized duct-work is brilliant! I suspect many folks will follow your lead. Quick, cheap insurance.
Glad to hear you had best track day so far. Does the track cower in fear when it sees you coming :)?

-Michael

HA. Hey Michael, yeah I use Home Depot both as a source of finsihed parts and raw materials. Many times The Depot has the finshed part offered more cheaply then I can buy the raw materials. So their products are raw materials for my solution.

I dont think the track is scared of the GTM yet, but we get respect from the fellow drivers. I was only passed once in three days. ( I was on my out lap when I was passed :) )

Would there be interest for a group buy thru Shane for just the pipes to replace the cats?? I would be in for a set.
Shane any chance you read this, that you could set up a run for just a set of pipes to replace the cats?
Don't want to hi-jack thread, but you might be interested in a group buy if priced right?

Great idea RF Rider. I would be in for a set. I am sure the price will come down if we have a volume order.

John

kabacj

10-13-2013, 06:15 AM

Once I sorted the issue with the heat shields I was able to focus on ripping off a few good laps. Here is a picture of the heat shield. A little crude, but it works perfectly and I did not touch it again all weekend. You can see how hot it gets based on the discoloration of the zinc. And a little plug for the CV boots that crash sells. After the abuse I have given it, I cant believe its still working. It heats up smoking hot, deforms, then cools back down and looks fine again. Just amazing.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpseac24b31.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpseac24b31.jpg.html)

Even though my toyo ra1 "street tires" are a season old and well past their prime I was able to click off strings of laps at 1.30. My best lap was 1.29.85. It was'nt even a clear no traffic lap!

To put this in context. The fastest time trial lap I have seen at this track in this configuration is 1.25.9.
That's in the unlimited class. So a car running slick tires. Many days the fastest times for any car don't even dip below 1.30. Since I still have quite a bit of setup to work out on the GTM I am very happy with the results so far.

I also hit my highest top speed ever at 152.9. I still have some more there I think.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/152-9_zps4d38f938.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/152-9_zps4d38f938.jpg.html)

I'm pretty happy with the GTM development so far. I got some great feedback from a few of the veterans at the track that really helped the setup. I am still using stock spring rates with some pre load in the front to support the car under hard braking.

The car is still pushing before it breaks rear traction so that's the next thing to sort out.

John

John

GTM RACER

10-14-2013, 12:29 AM

kabacj

10-14-2013, 08:13 PM

I have been using galvanized heat shields for years now on the GTM. Except I took the metal, folded it, added 3 layers of fiberglass cloth inside and hemmed it. Bent the edges for the stand off and hose clamped it to the muffler. Dropped the temp on the CV boot about 120 degrees. A

Yep that's a good idea. I considered doing the layers at the track, but with the limited time I had, I figured I would just try the single metal shield. Seems like it also works with just metal. I have plenty of air circulation right now too. I am sure that helps.

I have one more weekend planned this year Nov 3-4th. I think ill go with the single metal layer for now if I cant delete the cats all together. Over the winter Ill fab up a two layer setup with insulation for street use.

Thanks for the suggestion on installing the wrap.

John

kabacj

10-15-2013, 05:59 PM

A friend of mine captured a sequence of the GTM motoring down the front straight. I like the silhouette of the GTM vs the 911. Everybody likes pictures so I thought I would share.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpse01876f5.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpse01876f5.jpg.html)

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsfc0d04c3.jpg

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsf7c326ef.jpg
http://i1073.photobucket.com/albums/w389/kabacj/revisedfrontstraitlastpic_zpsb86f5020.jpg (http://s1073.photobucket.com/user/kabacj/media/revisedfrontstraitlastpic_zpsb86f5020.jpg.html)
John

LCD Gauges

10-15-2013, 06:47 PM

A friend of mine captured a sequence of the GTM motoring down the front straight. I like the silhouette of the GTM vs the 911. Everybody likes pictures so I thought I would share.

I like how he conveniently waited until you edged out the Porsche in the last photo. :D

RumRunner

10-15-2013, 08:16 PM

John,

Great photos! Definitely calendar material!

-Michael

Kempo

10-15-2013, 08:34 PM

Great sequence. It really shows the speed difference between the other cars and you. In that short distance you managed to catch and pass them.

VD2021

10-16-2013, 06:25 AM

I really love the angle of the first picture. ......keep them coming.....

kabacj

10-24-2013, 08:32 PM

Thanks Tino , Michael, Hugo and Vidal.

The GTM does have such wicked acceleration. I am still not using all of the car but you can see in this quick clip how easily I catch up to the other cars out on the track. Note that these guys are not slow. I was running with the fastest group comprised of racers and instructors.

http://youtu.be/qz_ShsKTYDE

kabacj

11-01-2013, 05:45 PM

Last trip to the track this happened.
http://i1073.photobucket.com/albums/w389/kabacj/null_zps819ec872.jpg

I put a wheel off on the outside of a corner where everybody goes wide. That means after you go over the curb there is a rut where the dirt starts.

Unfortunately with the car so low the splitter hits the deck pretty quickly. A little annoying but I knew it was only a matter of time till I had splitter damage.

Since I'm back on the track tomorrow AM a little duct tape and im good to go. It's sad to put a pretty carbon fiber piece in harms way. But I'll just fix it and recover with a new layer of carbon fiber.

John

LCD Gauges

11-01-2013, 06:36 PM

It wouldn't be a real racecar without some war wounds!

Kinda reminds me of Colin Chapman's famous quote.

kabacj

11-04-2013, 11:22 AM

You are right Tino war wounds are part of going to the track.

I am very happy to report the splitter was the extent of damage for the year.

I did my best to tempt fate this past weekend however.

My toyo ra1s have over 500 laps on them with at least 45 heat cycles. They were still sort of working last weekend but knew they were well past their prime. I just planned to take it easy. Lack of traction would help me tune the suspension for wet/ cold conditions. I'll just take it easy it will be fine. ( I kept telling myself that.)

Sat am was beautiful. 50 degrees and sunny. The track was damp from rain the night before.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps3b5a8682.png

No worries. I'll just do two warm up laps. Out on the track at 9.30.

I was running with the instructors so everybody had the same idea. Make sure you have good tire temps before you start pushing.

I was moving through traffic after a few laps and I see a guy in my rear camera pushing me. No problem buddy. Be my guest. I move off line and lift to let him by.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps76005641.png

Holy crap! It's a c7 corvette. I had heard about this guy. He is a local dealer and a member at the track. I guess he comes down to the track with his demo for a few laps before work.

So much for taking it easy. I gotta see what he has. Yes the c7 has a billion gizmos to keep him out of the fence but I have horsepower! That will work right?

Needless to say I had quite a few hair raising moments. But it was so much fun. I drew the line at attempting to pass him since I did not want to be "that guy"who takes out a c7 on the track.

I'm on my way to the show at SEMA so I'll post some video when I can.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsbd7f0c91.jpg

I'll be looking for ideas (and tires) for the GTM. I'll post anything cool I find.

John

carbon fiber

11-04-2013, 11:42 AM

all I want from that car is the engine!

VD2021

11-04-2013, 02:28 PM

J,

Very Cool. Loving the write-up.

Stage7

11-05-2013, 11:39 AM

Great read John!

kabacj

12-10-2013, 06:33 AM

Great read John!

J, Very Cool. Loving the write-up.

Hey Stage and Vidal. Glad u enjoyed the story.

After my last track day followed immediately by SEMA I had a nice queue of non GTM things to take care of.

Now that I've sorted those things it's back to the GTM. This weekend was wiring the headlights and turn signals. Pretty boring stuff but the DMV thinks its important so I do it.

While at SEMA i had the opportunity to scour over some top level race cars. One of the cool things, for me anyway, was to see the methods and materials used by grand am and other top teams are the same as we can use. It's not like these guys have a multi million dollar F1 budget to develop parts using the best stuff money can buy. These teams just make things that work with what they have available.

One of the items I will focus on over the winter is aero. As a general rule if you copy designs that work it's possible to at least getting the ball park of a good design.

Here is a compilation of pictures of designs that I think I can modify to work on the GTM

Here is a picture of the pikes peak hill climb car developed by Rhys Millen.

http://i1073.photobucket.com/albums/w389/kabacj/SEMA%202013/d50b9ff9f85a9e8244aa515a55db7d1e_zps58412ab5.jpg

Note the rear diffuser.

http://i1073.photobucket.com/albums/w389/kabacj/SEMA%202013/2FD566EC-77D7-43F2-831D-5555CB6F2FC2_zpsmggukhzc.jpg

Here is the diffuser on a racing version of he Lamborghini Gallardo.
http://i1073.photobucket.com/albums/w389/kabacj/SEMA%202013/5CC97B7C-2A3E-445E-8F9D-3562D2A21E06_zpsrojf100m.jpg (http://s1073.photobucket.com/user/kabacj/media/SEMA%202013/5CC97B7C-2A3E-445E-8F9D-3562D2A21E06_zpsrojf100m.jpg.html)

The rear window louvers on a racing audi R8

http://i1073.photobucket.com/albums/w389/kabacj/SEMA%202013/null_zps2abe136b.jpg

Audi also uses a rear camera to see out the back. ( I really like the camera for rear view in my car)

http://i1073.photobucket.com/albums/w389/kabacj/SEMA%202013/null_zpsd7798cf2.jpg

Check this out.

http://i1073.photobucket.com/albums/w389/kabacj/SEMA%202013/9E455F89-66EB-4841-AADC-692EB05787C7_zpsyxuhzetk.jpg

It's ok to use plywood on your car. This part on a Daytona prototype gets sand blasted into oblivion every race so making an expendable part works I guess

BTW I tried to get continental to give me a few sets of racing slicks. No dice. They only supply top teams. Oh well it's not really practical anyway as I would develop a race setup around tires in limited supply. It would be cool to run them however even if it's just for the physiological effect on the other racers.

Finally a cool spoiler idea. It's not going to be as easy to fabricate since the deck lid on the GTM is a little more complex then a DP car.

http://i1073.photobucket.com/albums/w389/kabacj/SEMA%202013/null_zps7a20c250.jpg

I know the air stays attached to the profile if the rear of the car. Using a deck spoiler I think I can run top speed events without a wing at all. Lower drag is a significant advantage over 150 mph.

I got a few other cool ideas. I'll share them as I try to implement them.

John

kabacj

12-23-2013, 05:54 PM

After about 500 laps my toyo RA1s are toast. For my last track day I needed to flip the tires from left to right to extend the tread life one more weekend. That really did not work as well as I had hoped. I only got a day and a half before traction really fell off a cliff. It was surprising how drastic the change was but it's good to know what it feels like. Since I'm not racing it really does not matter how fast I go as long as I can control the car. Every weekend so far I drop a few seconds as I learn the car. New tires have not been a priority.

The front left took a pretty hard beating all year. The front left is most often most heavily loaded as its usually the outside tire on clockwise tracks.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/38B8E90D-EABF-4D9D-9C96-3A7D7D7A6703_zpsogytctsh.jpg

The front right looks a little better as it has an easier life as the inside tire on most corners.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/715F1233-063B-4B4C-98B4-C87D8FAC645D_zpsd5kuwikq.jpg

The right rear inside wore more quickly then the outside. I'm not sure how this will work , but next year I am going to experiment with less negative camber on the rears in general but the right rear I'll have even less camber. As I make right turns the inside rear naturally gets more negative camber. It then wears the inside of the right rear.

See how the inside of the right rear is worn

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/EECF2F01-6684-4DC7-B836-88759CA2D5E9_zpsp0jq2gfn.jpg

The left rear is a little better but still has too much negative camber I think.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/50A57ADE-9DD5-41DC-9EFC-A11DAAA569B4_zpsqkzglk3l.jpg

Next year I'll also have two sets of tires mounted with me at all times. This way I can swap out out the spent ones before I totally run them to nothing.

It's good to know that even when the tires were junk they are still drivable. Example I ran 1.7 g in July. Then 1.3 g in September and could barely pull 1g when the tires were spent . The GTM was very drivable under all conditions. Definitely got my attention when the tires were going off but it did not do anything evil. Once I slowed down to 70% pace the worn tires were fine.

The only comparison I know is running motorcycle racing slicks past their usable life. Most of the time I crashed. Its funny now that I think about it. It's rare that I was able to catch a slide on a spent motorcycle tire. With a car you get so much warning. Even when I over cook the corner in the GTM I have eons to save it.

Bikes are more fun and scary, but now that I have a little sense from old age, I realize there is something to be said for fighting another day without the drama. I'm very happy in the GTM. Only 100 more days till its track time!

John

fastthings

12-23-2013, 07:34 PM

I think it's cool that it held up, and ready for another set. Good job!!!

crash

12-24-2013, 10:10 AM

kabacj

12-24-2013, 10:54 AM

Might I suggest that you use a tire temp gage to fine tune the suspension? I really think you are to the point that wear patterns and tire temps are going to make or break your ability to get some extra life out of your tires. That said, sometimes they just time out or cycle out. I know with the Kumhos we get about 6 hours or about 13 heat cycles(which ever comes first) before they are toast. We haven't found anything that holds up better with good performance. We have seen 1.9 Gs.

Yep agree Crash tire temps and pressures will be important. I got the tires in a happy place where I had reasonably fast even heat up across the contact patch and the tires would not over heat in a half hour session. So many things (mostly me) were changing each session. Its very hard to get good data regarding what actually is faster. I was just going faster each day i went out regardless of if the car felt better or worse. This year i expect ill hit a plateau on my lap times and it will be easier to fine tune the car.

Since the RA1s in the 335 size are way out of production. I will not get them next season. I think im going with the BFG R1s and a set of toyo R888s for the occasional damp track.

I know the Kumho Ecsta V710 is also a good tire. I think they help you guys out which is cool. I figure my choices are the V710, BFG R1, or Hoosier A6/ R6. Im going with a soft slick for the early spring when track temps are low. Ill have the R888 as my street tire/damp/ wet tire. Then go with a hard slick for the summer and switch back to a soft slick for the fall.

You are right that setting up the camber of the car for the track is a step beyond optimizing the temps with pressure. I actually think that since the GTM has more spring now then it did when i started I might get less roll induced camber change.

I am going to add more caster to the front as well as add more tire width in the front. Ill use a 255 for the R888 but not sure how big I should go on the slick. 275 maybe? Not a lot of data from what works for other guys unfortunately.

John

crash

12-24-2013, 11:31 AM

We seem to have trouble getting temperature in the front tires...you obviously do not. I think anywhere between a 275 and 295 would work for you depending upon compound. We are messing with A6/R6 combos and sizes right now to try and find a happy medium.

Fugly_Old_Cowboy

01-03-2014, 03:59 PM

kabacj

01-03-2014, 06:37 PM

I might have missed it somewhere since I was kind of outta pocket for a while.... did you ever get fully cleared to race with your roll cage mods or are you still pushing that freight train up that hill???

Hey Cowboy

I'm just getting a head of steam before I really start getting the train rolling to extend your metaphor.

I needed to tune the car for racing. Far from done there, but I'm getting closer.

I needed to learn to drive fast enough to be in the game come race day. Good progress there.

I need my racing license. That happens this May.

I'm really going to push the next few months.

I don't give up easily. I'll find a way and be sure to let you guys know how I do. Ill ask for help from the group when I hit road blocks.

We will get it done this year.

John

Fugly_Old_Cowboy

01-03-2014, 10:03 PM

just a thought.... I live about a hour away from (pretty much anything) Texas World Speedway in Bryan/Collage Station & a little over a hour in the other direction from Circuit of America track in Austin...
I know for sure the B/CS track is used extensively by NASA for events as well as HPDE... I was thinking of bringing the naked frame down there & having their tech guys tell me exactly what else is needed to pass their tech for racing.....
good idea???

flotowngtm

01-04-2014, 02:08 AM

Just be prepared for a long conversation when they see the frame.

Fugly_Old_Cowboy

01-04-2014, 03:28 AM

Just be prepared for a long conversation when they see the frame.

I have NO problem talking with folks with the same basic mindset.... even if our view differ.... (as long as they don't mind having to figure out my hick-enese speach patterns)...

kabacj

01-04-2014, 07:06 AM

. I was thinking of bringing the naked frame down there & having their tech guys tell me exactly what else is needed to pass their tech for racing.....
good idea???

Sure more feedback is better, however it's the national safety director that needs to sign off. My local NASA guys agree the frame as I have it built is stronger then many approved cars, but it really doesn't matter what they think. They only enforce the rule book. They can't make a judgement on it. Approval of a new frame boils down to liability and insurance.

John

Fugly_Old_Cowboy

01-05-2014, 09:47 PM

Sure more feedback is better, however it's the national safety director that needs to sign off. My local NASA guys agree the frame as I have it built is stronger then many approved cars, but it really doesn't matter what they think. They only enforce the rule book. They can't make a judgement on it. Approval of a new frame boils down to liability and insurance.

John

that's what I'm thinking.... bring the frame to the guys that enforce the rule book & have them tell me exactly what it needs to meet their specs... rather than build my interpretation of the book & hope it fits theirs...

kabacj

01-19-2014, 03:17 PM

Its been a while since I did any fabrication as my recent focus has been on the electrical required to make the car street legal. It was time for some metal work.

I like to extend my track day as long as possible. That means sticking around till the last runs of the day between 5 and 6 o'clock. When I finish that late there is a premium on getting the car loaded and tied down as quickly as possible for the 3-4 hour drive home. There are not any easy front tie down points on my GTM. Some people tie the car down using the suspension or wheels, I don't like doing that as I think its pretty easy to pull one wheel out of alignment. I ended wrapping an axle strap around the front suspension mounting tabs and using that as the best attachment point that had the least chance of changing the alignment.

Problem is this was 10 or 15 min process to get everything tight. When you are tired and in a rush not a good exercise to go through. My buddy on the other hand was finished with his car in 5 min. The corvette has these little pockets that accepts hooks that will not fall out. These points are used for shipping and make it very easy to tie down the car.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/4341E01F-CB55-4090-9312-E730AA761EC1_zpsmrefezdg.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/4341E01F-CB55-4090-9312-E730AA761EC1_zpsmrefezdg.jpg.html)

I figured putting these tie down points right under the front two corners of the frame under the door hinge. I will have both a strong tie down point and an attachment point that is easily accessed in the trailer. The other nice thing is the brackets act like a gusset increasing the strength of the corners of the frame.

I cut two brackets from 3/16 plate steel.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/D326420E-AACB-4444-981B-6C0E6317DC3D_zpswy3cb78u.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/D326420E-AACB-4444-981B-6C0E6317DC3D_zpswy3cb78u.jpg.html)

Verified the fit of the hooks.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/55D917F6-1F00-4A44-93E6-C22C23BC3D9A_zpsz04nuj4g.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/55D917F6-1F00-4A44-93E6-C22C23BC3D9A_zpsz04nuj4g.jpg.html)

Then tig welded them in.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/87F3C4F2-AF80-45F5-9A13-AC41CA67E1B9_zpsuhcxtpwa.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/87F3C4F2-AF80-45F5-9A13-AC41CA67E1B9_zpsuhcxtpwa.jpg.html)

It works! I am going to get tie down straps with the hooks built in so once the straps are attached they can't fall off.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/6A969B53-7132-404B-94A9-164D72E09B7D_zpswtebptlu.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/6A969B53-7132-404B-94A9-164D72E09B7D_zpswtebptlu.jpg.html)

John

Taz Rules

01-19-2014, 03:24 PM

Hey John

I sent you a PM

Taz

fastthings

01-20-2014, 12:15 PM

Awsome, that looks like a good add on.

Fraser D

01-20-2014, 01:30 PM

John,

What are they called or listed as?
Great Idea.

kabacj

01-20-2014, 05:37 PM

John,

What are they called or listed as?
Great Idea.

Thanks Dave.

This style of hook is called a 'T hook'

Corvette sites have the t hook with the strap attached.

John

Roger Reid

01-20-2014, 10:16 PM

Found them the link at Northern Tool is

http://www.northerntool.com/shop/tools/product_43572_43572?isSearch=3309048

Presto51

01-21-2014, 08:55 AM

Hey John,

X10 what Dave and Gene said, plus my .02

MHO is that this not only a must have fabrication/add on for towing but, like was mention on the Northern Tool site, great tie down points when going to the dyno

Thanks for sharing

Ron

Fraser D

01-22-2014, 09:47 AM

I will be paying Northern Tools a visit this weekend.
Thanks guys! This has been an issue lurking in the back of my mind for awhile.

mikespms

01-22-2014, 09:59 AM

http://www.ecklerscorvette.com/corvette-jack-lifting-pads-1997-2012.html

You can use this jacking pads in the same slots but you will need a very low profile jack or have a suspension lift system.

VRaptor SpeedWorks, LLC

01-23-2014, 09:46 AM

VRaptor SpeedWorks, LLC

01-23-2014, 09:58 AM

Out of all of the transport companies and dynos that I've dealt with, I'd say 95% of them used these straps with this style of hook right here:

http://www.lowes.com/pd_329585-50881-61327_4294856653__?productId=3830851&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_product_qty_sales_dollar%7C1&facetInfo=

And the other 5% used straps that go over the tires.

kabacj

01-23-2014, 10:56 AM

Maybe I'm missing something here......but in my experience, nearly every single tie down ratchet strap sold has a big formed "double hook" sewn into the end of the straps. It looks to me like that hook would probably be too wide to work with the T-hook pictured here......and since the strap already has the hook built into it......why the need for the T-hooks at all? Why not just cut the holes in the plates so you can hook the strap directly to the plate and be done with it? Seems like a cheaper, easier, faster, more reliable and simpler solution to me.....with no parts to lose. Cut the hole in the plate so it could accommodate the strap hook, a tow strap hook, a log chain hook....and then you're covered no matter what you have on hand to tie down or tow with.

Hey Shane,

I agree with you the wire hooks are more common. The hooks you link to would be the universal setup. Thats the type I use now. The cool thing about the T hooks is that they dont fall out. If I cut a slot to accept the wire hook they might stay in , might fall out. When im in the enclosed trailer trying to get everything sorted and in a rush they ALWAYS fall out/ fall off. On an open trailer/ dyno would not be such a pain.

Once you put the T hooks in and turn them 90 degrees in the general direction you are going to tighten the straps they can't fall out. I will replace the car side of my tie down straps with sewn in rings/t hooks. The T hook I have pictured was for mock up purposes .

http://www.autohaulersupply.com/catalog/straps-with-hooks-snap-j-cluster-etc/8ft-10ft-or-12ft-option--corvette-straps-t-link--choice-of-color-5206.php
Hope that helps.

John

kabacj

01-25-2014, 01:30 PM

http://www.ecklerscorvette.com/corvette-jack-lifting-pads-1997-2012.html

You can use this jacking pads in the same slots but you will need a very low profile jack or have a suspension lift system.

Hey Mike,

I would definitely need a suspension lift setup to use jacking pads. At my ride height i cant even get a low profile jack under the side sill of the car.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/2A9A1DF4-0FC7-4711-8246-A58C8E2524D0_zpsfmftqxdu.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/2A9A1DF4-0FC7-4711-8246-A58C8E2524D0_zpsfmftqxdu.jpg.html)

It would be cool to get a set of pneumatic jacks to lift the car, but i still have lots to sort out before I get to a project like that.

For those that have a normal street ride height the pads are a good idea.

John

LCD Gauges

01-25-2014, 01:41 PM

Just drive up on some 2" x 8" slabs of wood, then you can fit the jack underneath. I did that for all the low-riders that I used to service, and for the GTM in the garage.

I'll even use a stand-off between the pad to clear the fiberglass under the "rocker" area.
25628

mikespms

01-25-2014, 02:27 PM

Here in Miami beach you need a lift system to get around, most of the residential areas have speed bumps and streets flood at high tide in some areas.Not to mention that I could not get a jack under the car or put it on the lift with out driving on wood ramps.I was surprised to hear the Beiber was drag racing in Pine Tree dr. not to far from me.I don't think there is a stretch long enough with out a speed bump or a traffic light and the short stretches are like washboard with the roots of the pine trees.

LCD Gauges

01-25-2014, 02:59 PM

I totally did not read the post entirely. Ignore my response. :o

mikespms

01-26-2014, 10:14 AM

kabacj

01-26-2014, 03:28 PM

Hey John,

Looking at your picture I see that your ground clearance in the back is about the same as mine. I set my ride height at 4 1/2" and it has settled at about 4 3/8" since I have a 3" lift I am keeping it low but I am concerned about the clearance between the top of the front tire and the hood and wheel well. I was wondering if you have had any rubbing problems with your suspension travel at the track. How much room do you have between the top of the tire and fender? What spring rate do you have up front? Have you had any issues at high speed or when your suspension bottoms out?
Your input on this would be a big help,I don't want to have to make changes after the body is on and painted.
Thanks Mike

Hi Mike. Good questions.

The front ride height on my car measured under the corner of the chassis right under the door hinge is 3.5 inches. The tape measure itself is 3 inches and add a half.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/392E2BEC-8285-41B2-911F-4EA09F9A1CA0_zps30tjybqt.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/392E2BEC-8285-41B2-911F-4EA09F9A1CA0_zps30tjybqt.jpg.html)

The tire sits a little less then 1 inch under the wheel arch at static ride height.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/602FC324-6FCA-4C59-8EEA-5F31A561C4E5_zpswjr6fguw.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/602FC324-6FCA-4C59-8EEA-5F31A561C4E5_zpswjr6fguw.jpg.html)

The other key bit of information is the shock travel. My shocks have about 1.5 inch of compression travel.

I am running a 450 lb spring with 3/8 inch of pre load.

Even under full braking down from 155 to 75 where I travel through a section of the track that undulates and often bottoms peoples suspension and forces brake lock up. I do not have any tire rubbing issues. I can see that I am using the full travel of my suspension but not bottoming it.

One way you can be double sure about wheel rubbing is to measure the length of your shock at full compression without a spring. I made a tool from some threaded rod, nuts, two washers and some tube.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/7C63C4AD-2105-4B2D-93AB-46E33A83AAD8_zpsjjyb8bij.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/7C63C4AD-2105-4B2D-93AB-46E33A83AAD8_zpsjjyb8bij.jpg.html)

If you make two of those and adjust them to the length to the fully compressed shock you can see what the car looks like under full compression. I also used them to set the shock length at ride height. Hell I had the car rolling around on them for a few months while my shocks were being made. As long as you use 1/2 inch threaded rod its strong enough to hold up the car.

Hope that helps.

John

kabacj

02-24-2014, 06:17 AM

Sunday was a beautiful day with spring like temps in the mid fifties. A perfect day to take out the 5 speed H pattern Mendiola.

Since I have done this at least 4 times already I am getting pretty good at it. I learned a trick that I wanted to pass on.

The key to both mounting and dismounting the transaxle is getting it properly aligned so that the input shaft slides onto the motor without binding.

The transaxle is not heavy but you are not putting the thing in without the engine crane.

The best and fastest way to install the transaxle is using ratchet straps to suspend the transaxle under the engine crane.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/B49F8217-EDBD-441B-95AA-734607FDF02C_zpskfhnezvb.jpg

Using three straps you can always have two straps slung under the body of the transaxle while you tip and swing the transaxle out past the X brace and body without issue.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/4E2B18A5-63AA-47AD-8B10-B70269452451_zpspf0rw0ox.jpg

The most important thing is the straps have some give. This allows you to bounce and tip the transaxle and wiggle it in or out . Not something you can do with an engine crane, chains, and load leveler.

I had the car disassembled and transaxle out in an afternoon without any help. This was the fastest yet and by far the easiest single person transaxle removal.

John

mikespms

02-24-2014, 07:49 AM

Hey John,

What are you doing ? Practicing for your pit stops!

fastthings

02-24-2014, 11:38 AM

Great tip, looks like a good way to do that.

kabacj

02-24-2014, 12:45 PM

Hey John,

What are you doing ? Practicing for your pit stops!

HA HA , yeah . Not exactly a quick change transaxle, but its a pretty quick change.

Real race teams can do it in under 5 min. I have a little more speed to learn before I can do it in a pit stop :)

Great tip, looks like a good way to do that.

So much easier. Turns a job where I would fight to find the right angle to one where it just slides in an out. Also makes it much easier to tip the transaxle as when you are using the load leveler removing one side without supporting the whole transaxle is a no no. This way you use three ratchet straps and the transaxle is always supported. Also the straps dont damage the powder coat on the X brace or paint on the body.

john

kabacj

03-09-2014, 11:39 AM

As it slowly but surely gets warmer here in the northeast its time to get the car ready for the track season.

On the install list is a sequential transaxle Mendiola custom made for me. The sequential will have similar gearing to the SDR, as I was very happy with the gear placement relative to the power band of the motor, but obviously the sequential will be quicker and easier to shift on the track.

After taking out the SDR, the next step was to change the flywheel and clutch. The SDR uses a standard GM flywheel and clutch. I opted for the twin disk ACT clutch. I was very happy with the performance with both. Good torque holding power and reasonably smooth engagement but lighter then stock LS3. Definitely street worthy but heavy duty enough for the track.

The new setup needs a Porsche flywheel to fit inside the bell housing of the sequential transaxle. I opted for the twin disk Kennedy. This setup should be up to the task of track duty but not as friendly for the street. Folks do use it, on the street. I just will not expect to slip it like a standard street clutch. The nice thing is I can just dump the clutch at idle and the car happily motors along. The drive by wire calibration MAST Motorsports put together make the car stall proof.

Since the transaxle and clutch swap is so easy ,its reasonable to have both a street and track setup. I can switch it over in a few hours. The car keeps getting more track focused as time goes on and the stock GTM has FAR FAR more capacity then you could ever use on the street ..... I will start the street registration process in a few weeks. At any rate it will be fun to have a street legal race car.

Here are a few pictures of the two setups.

you can see the new flywheel is smaller

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/98A6C731-BDF4-4162-999C-C294F2E18379_zpsoyjcitpm.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/98A6C731-BDF4-4162-999C-C294F2E18379_zpsoyjcitpm.jpg.html)

The new Kennedy setup is very much like a motorcycle clutch with floating friction and steel disks.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E1351736-EAE7-4859-A636-60A863DED558_zpsfnevmlbu.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/E1351736-EAE7-4859-A636-60A863DED558_zpsfnevmlbu.jpg.html)

One other thing. the Kennedy clutch and flywheel is only 34.5 lbs that is almost 10 lbs lighter then the ACT twin disk. The light setup will have less inertia. It will make for a better track setup. Ill let you all know how it works on the street.

John

carbon fiber

03-09-2014, 03:28 PM

interested to see how it does on the street and the track with the new trans and clutch/flywheel. how's the hatch project going? looking forward to more vids this year. thanks for the motivation!

kabacj

03-10-2014, 07:29 AM

interested to see how it does on the street and the track with the new trans and clutch/flywheel. how's the hatch project going? looking forward to more vids this year. thanks for the motivation!

Hey Jason. Yeah I also am interested to see how everything works out. This territory is not well charted.

Regarding the hatch. I have made good progress with the foam models. I'm still working out the final design in my head. As you know every part has some interaction with every other part. My solution needs to look cool but also be track worthy. It's hard enough to make things that look cool, but the requirement to work under extreme conditions is a whole other ball game. I'll be sure to call you for some pointers when I get to the CF construction phase.

I made a downdraft table so I could make dust without coating the whole garage in dust. The table connects to my woodworking dust collector. 99% of the dust is captured with this solution.

Now I am at he point where I need to start fitting parts to the car. I don't have a car sized down draft table sadly. I don't want to coat the whole garage with fiberglass dust. I'm focusing on getting the driveline done till I can work outside. I still need to fabricate a transaxle hanger and sort out the new shifter and cables. Ideally I will be able to quickly swap the H pattern and sequential shifter.

Once that's done I'm focusing on the bodywork. I am adding wider front tires. The car is setup to push from the factory. That's a much safer street setup. The new tires and rims will require a little front end rework. Since I don't have enough time to finish all this work I better get started :)

John

carbon fiber

03-10-2014, 08:28 AM

i'll pm you with contact info. if you need any advice on the cf stuff, no prob. maybe you could frame up a temporary "room" inside the garage with 2x4s and plastic to contain the dust. then just take it down when you're finished, like some people do with homemade spray booths. i'm doing tons of mods to the gtm body myself, but i'm trying to keep the mods from creating too much drag or disrupting laminar airflow. I WISH I had the money to do wind tunnel testing, but I think i'm gonna be ok, as the mods i'm doing aren't completely reinventing the wheel. i'm mostly gonna be on the street, but I want to track the car in a similar fashion as you're doing now. at this point i'm mostly focused on 0-180 mph and handling braking vs top speed. are you gonna be able to fit larger front without flares? no big deal if you have make some anyway. keep it up, when I get disgusted I watch some of your vids and i'm ready to go back in the garage!

fastthings

03-10-2014, 05:56 PM

Looks like the ACT was rubbing a little. How much clearence did you have. It gave you no problems though.

kabacj

03-10-2014, 07:56 PM

Looks like the ACT was rubbing a little. How much clearence did you have. It gave you no problems though.

Hi Gene,

Well I had enough clearance when when the engine and transaxle were cool and even when it was warm from tooling around the neighborhood. But after a few hot laps and getting the motor up to peak temperature on the track, I guess everything expanded just enough to make contact with the part of the bell housing that holds the clutch fork mechanism.

After a few weekends i pulled it all apart and I saw that there was a small area on the machined surface that looks like it was a few thou higher. It only ended up taking off the paint on the clutch housing. In some spots it just made a mark on the paint.

I cleaned it up with a bur in 20 seconds.

The tight clearance did not cause any issue. It actually looks worse then it is. Here is a close up of the clutch housing.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/64C16875-2054-44DA-87B5-EC8F1DA283ED_zpsmegg8hfm.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/64C16875-2054-44DA-87B5-EC8F1DA283ED_zpsmegg8hfm.jpg.html)

John

Cobra 61

03-11-2014, 01:25 AM

kabacj

03-11-2014, 06:31 AM

I think Mike(crash) may have mentioned about tires. Adding wider tires on the GTM is probably not the ticket for you right now. The car is notorious for not getting heat in the front tires in race conditions. With 275/17's it took about three years to figure out how to get the correct heat. Went to 295's and lost 30 degrees. The GTM is pretty light in the front and deals with a mid range push. Even using big canards, it still develops a mid entry push. Notice on some more recent photos of the PDG car with open cut fenders and the stock holes in the nose have been moved as far back as the stock frame and accessories allow. Last outing the driver reported no push and tire temps were perfect along with wear. However, the openings in the nose made the rear a little too loose and now they are looking to widen the rear tires from 315 to 335/345.

cheers

Hi Richard.

Thanks for the info.

I am running the stock setup with 245/18 fronts and 335/18 rears.

Yes Mike did mention that you guys needed to tweek your setup to get heat in the fronts.

With my setup I don't seem to have issues getting heat in the front tires. I was able to dial out some of the mid corner push with stiffer front springs. I think I solved some of the push by limiting the weight transfer. I also adjusted the shock damping to limit weight transfer.

Even with those changes , I can actually over heat the fronts and ended up raising the front pressures to keep the heat down. This is what the tire looks like after a weekend where the peak air temp was 55 degrees.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/38B8E90D-EABF-4D9D-9C96-3A7D7D7A6703_zpsogytctsh.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/38B8E90D-EABF-4D9D-9C96-3A7D7D7A6703_zpsogytctsh.jpg.html)

I have played with getting the car to turn in by trail breaking into the corner and using rear brake bias to start the car rotating. That was not faster also not ideal in traffic. I could probably add a rear bar and remove rear grip but that is a last resort.

I am also running lots of caster. And plan on adding more.

I figure I'll try 275s and 310s in the front. Maybe the 310s are too big, but I'm pretty sure the 275s will be better.

I can always push the fronts harder to get more heat into them. Now I need to ease up on them or they get greasy.

Right now I think I can gain the most time if I could get on the gas from the apex. Now I'm waiting a few clicks for the car to get pointed before rolling into it.

I'm not surprised our cars act differently. As you know the GTM is very sensitive to chassis changes.

The final big variable. Actually maybe the biggest variable as I think about why our cars are not behaving the same way is the diff lockup. The SDR had a pretty tight diff according to Ian at Mendiola. Like everything with this car, at the limits we are in uncharted territory. Factory Five sell a street car not a race car.

Ian was happy to hear that the car with the SDR was neutral even in the rain on the race track. Very good balance on and off throttle.

Maybe the S5r diff is stiffer then the SDR. It could be stiff enough that it is fighting the rotation of the car.

We will have a closer setup this year. Happy to share race notes.

Thanks again
John

fastthings

03-11-2014, 06:48 AM

Good to know, I'm running the ACT. Thanks for posting your results.

Stage7

03-11-2014, 12:34 PM

Looks good Kabacj. My SLC is going to the interior shop this week. Let's meet up at a track day this spring, but before then we should schedule another lunch.

kabacj

03-11-2014, 04:40 PM

Looks good Kabacj. My SLC is going to the interior shop this week. Let's meet up at a track day this spring, but before then we should schedule another lunch.

That's great news Stage7. Absolutely. I'll send you a PM

John

Cobra 61

03-12-2014, 12:53 AM

I forgot you were running the 245's. Stepping to a 275 would be a good effort in the front. Are you running sway bar in the rear?

kabacj

03-12-2014, 05:02 AM

I forgot you were running the 245's. Stepping to a 275 would be a good effort in the front. Are you running sway bar in the rear?

Thanks Richard. That's good to hear.

I am not running a rear sway bar yet. I am evaluating using the stock c5 19mm corvette rear bar vs building my own.

John

Presto51

03-12-2014, 05:52 AM

Thanks Richard. That's good to hear.

I am not running a rear sway bar yet. I am evaluating using the stock c5 19mm corvette rear bar vs building my own.

John

Hi John,

If you build your own sway bars, is there a certain formula that you would use to figure out size, shape etc.?

Ron

mikespms

03-12-2014, 08:55 AM

Kempo

03-12-2014, 09:06 AM

VD2021

03-12-2014, 09:45 AM

I really like that set up Mike. Can you please post some more pictures of it?

Hugo,
Here's Mike's original thread while you wait for his reply. http://www.ffcars.com/forums/42-factory-five-gtm-forum/284049-front-rear-sway-bars.html

Kempo

03-12-2014, 09:51 AM

Thanks for the link Vidal.

mikespms

03-12-2014, 09:58 AM

26875http://mikespms.weebly.com/uploads/8/5/1/8/8518788/306054_orig.jpg

Hey Hugo,

I don't have to many pictures,I think I deleted them accidentally.This is What I could find,I have templates for the brackets I can send you or make you the brackets if you want. Pm me or call me ,my father is here with me and I will be taking him back to P.R. in a few weeks.

longislandwrx

03-12-2014, 09:59 AM

Your car is looking fantastic, I enjoy following your build, it's a good to take a break from the 818 threads.

How goes the registration process?

Looking forward to seeing it one day.

Jeff

Kempo

03-12-2014, 10:59 AM

kabacj

03-12-2014, 07:23 PM

26874

Hi John,

I opted for the corvette bars since is just about a direct bolt on, the mounting is basically the same as in the corvette and it can be changed in minutes. Jim from factory five recommend a a 24mm but since you have change your shocks and springs, starting with a 19mm may be the way to go. I have seen the bars on ebay from $50.00 with the links at that price you could get a few different bars and change them at the track for fine tuning.

I agree with Hugo, This is a great setup Mike. Since its almost a direct bolt on and since there are many sizes you can use it takes lots of work to do much better. The aftermarket even has adjustable rear sway bars for the Corvette that we can use on the GTM. Since my shocks are adjustable and I actually want the car to be stiffer in the back I could keep my current springs. I assume Jim suggested you soften your rear springs by 50 or 100 lbs as the stiff rear springs are as much about roll control as they are about supporting the car. I ended up going with more spring preload and more shock damping in the rear to simulate some of the effects of a rear bar. There are a few left right transitions where I know a rear bar would help.

Hi John,

If you build your own sway bars, is there a certain formula that you would use to figure out size, shape etc.?
Ron

Hey Ron,

If I decide to go with the build my own bar solution i will use resources like this http://www.1speedway.com/sb_rates.htm to figure out the bar I should use to gain the amount of roll resistance I want to have. Then i will figure out how long the lever arms are and make a guess at the bar rate I should use. The key points 1) many bar choices that fit my setup as well as 2) packaging up the solution in the space in the rear of the car. Ideally with each bar should have lever arms with a few adjustments so I can increase or decrease the amount of anti roll in small steps.
http://thefactoryfiveforum.com/attachment.php?attachmentid=3945&d=1315230767
It really boils down to the fact that I can fine tune a bar I make my self and I a little more limited if I go with a corvette bar. But if i can find a corvette bar that works with my setup its the obvious choice. My friend is replacing his stock c5 19mm rear bar so I get that one for free. That makes the corvette bar an easy choice to start.

Your car is looking fantastic, I enjoy following your build, it's a good to take a break from the 818 threads.

How goes the registration process?

Looking forward to seeing it one day.

Jeff

Hey Jeff. I also check out what you guys are doing with the 818. I was able to spend time with Wane from Very cool Parts and the quality you can get with the 818 build is awesome.

Regarding registration, I was waiting to swap the transaxle before I bother making the car road worthy again. The first step will be getting the car weighed on a certified scale. I will do that in the next 2 weeks. From then on the registration process should only take about a month. I think you are near by so ill drive over and check out your 818 build and you can check out the GTM.

kabacj

03-13-2014, 09:40 PM

I was looking for some inspiration to get out in the garage and get the GTM ready for the track and I was reviewing videos. I thought I would share this one.

http://youtu.be/tOvqqEmCujE

John

mikespms

03-13-2014, 10:15 PM

Awesome! That engine sounds great,is like music to my ears.

Great video, Thanks

fastthings

03-13-2014, 11:16 PM

Oh man, I love it. Lots of fun.

kabacj

03-14-2014, 12:39 PM

Awesome! That engine sounds great,is like music to my ears.

Great video, Thanks

I need to work on the sound pickup a bit as its clipping, but yes I really enjoy the sound of the car. I even like to listen to the vid without watching it :) its like background music.

Oh man, I love it. Lots of fun.

Gene I wish I was as close to the track as you are. You will be out there all the time. The GTM is so silly fast you cant get anywhere near the limit on the road.

John

KeithBoden

03-14-2014, 04:29 PM

Awesome video! The Octopus makes me pay when I can't get in to the curb tight on turn 8, although it looks like you do it far less frequently than I do (1st time looked like it was definitely because of traffic.) Even so, looking at 7:30, it looks like you can take about any line you want and the car is still fast as hell through there. For anyone that wants to see a slow comparison, here is 145 on the straight, and 20-40 mph slower .5G less everywhere else:

https://www.youtube.com/watch?v=RyPulMFQSrk

Again...awesome car and video kabacj!

kabacj

03-14-2014, 06:39 PM

Thanks for the Video reply Keith! Great to see other guys out on the track.

Yep I was taking all sorts of lines during that session. Its not like when you are racing you barge your way through and often you setup the pass a lap earlier. With these events you pass people in every corner even the corners that its really should never pass in so I end up in the wrong place for the next turn but that adds to the fun.

Ill be at the NASA event at NJMP in May. Maybe ill see you there?

John

kabacj

03-16-2014, 10:20 AM

For the new season I decided to try out a sequential trans-axle. Mendiola made me a setup that is geared much like the SDR so I will have a 60mph first gear and a 215mph 5th gear with the ability to easily swap out gears to optimize the gearing for the track I plan to visit.

Its impossible to buy a setup like you get from mendiola for less then 25k. When you get an Emco transaxle you are also paying for the semi that attends the races to provide you with what ever parts fail or need to be optimized. I sorta doubt Emco will show up to any event I frequent.

The box arrived with the transaxle and an the shifter mechanism.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E656146B-46C3-4BED-BDD1-276268AC81E6_zpsochtlmn8.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/E656146B-46C3-4BED-BDD1-276268AC81E6_zpsochtlmn8.jpg.html)

Using the engine crane and ratchet strap sling method to install the transaxle I had it in the car and bolted in 30 min.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/31789148-F170-4D4C-85B6-059E3285F988_zpsqubj6n1b.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/31789148-F170-4D4C-85B6-059E3285F988_zpsqubj6n1b.jpg.html)

The only trick was to twist the transaxle 45 degrees to fit it between the x brace and lower frame. The S4 does not have a two piece bell housing like the SDR, but it still fits without any fab work.

That is when the easy part ended.

The carrier that works for the SDR and Porsche boxes does not work with the S4. I will need to make a new one of these. The two down legs are not wide enough to fit the transaxle housing or shift actuators.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/8791626C-2CEC-4E2B-AC54-B23F4B3E5D03_zpsvapmauak.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/8791626C-2CEC-4E2B-AC54-B23F4B3E5D03_zpsvapmauak.jpg.html)

I wanted to remake the carrier out of aluminum anyway. I have modified it to work as a wing mount and exhaust mount. I think I can make it both lighter and stronger . We shall see.

John

mikespms

03-17-2014, 07:54 AM

crash

03-17-2014, 09:24 AM

kabacj

03-17-2014, 11:40 AM

Hey John,

Very cool! It will be like riding a 4 wheel motorcycle. What is your first gear and final gear ratio,In your video it looked like you where going 150mph@6000rpm was that in 5th? Did the trans come with a rear mount or you have to make it,looks like the pad with the 4 holes on the side of the trans would line up with your rear frame mount with minor modification.Or is that for the shifter? Is there anything like this available for that trans or do think this may work(dynojet quick shifter)http://www.dragspecialties.com/search/?ci[0]=204&ct1=3071&format=json&q=&offset=282&rows=6
That car is going to be a blast to drive.

Mike

Hey Mike

Ill need to dig up the ratios for you but when using the SDR I am going 150 at 6k in fourth. The motor makes power up to 7k and redlines at 7200.

The pads you see on the side actually are for brackets that hold the shift cables. I took them off in order to try to get the stock subframe to fit on. Unfortunately the tail housing of the S4 is larger then the SDR. The gear actuators are also farther back so the stock hanger is not going to work. I designed a new hanger over the weekend that I will make out of aluminum, but I realized this am i might be able to modify the stock hanger. its going to be heavy, but it might be quick enough to justify.

I am not sure which shifter I am going with, but I was thinking about this one. http://hargettprecision.com/index.php/sequential-shifters/mendeola-single-lever-sequential.html

I was a little sad to take apart all the stuff that was working so well, but at the same time it gets me closer to my dream car.

John

kabacj

03-17-2014, 11:51 AM

As I have mentioned before, Team PDG uses the stock GTM shifter. We just changed the pivot points and U joints to make the entire setup much tighter. It took a little tuning, but it works very well. Just an option.

Good idea Crash. I dont have the factory five setup anymore as I traded most of it in when I got the cable shifted SDR. Since I want to be able to swap the SDR and S4 in and out... not that I will, but I wanted to be able to have a street friendly setup and a track friendly setup if the need arrises. Makes my life a bit more difficult short term, but its also a fun challenge to see if I can do it.

If I am successful I will be able to swap out the transaxle and shifter / cables between the SDR/ a Porsche Box/ and the S4 in an afternoon. Why would I ever want to do that you ask? I dont know :) but maybe I would. I really hate when I could have made somthing easier if planned for it ahead of time. Im doing my best to plan for it !

John

kabacj

03-17-2014, 04:46 PM

As I have mentioned before, Team PDG uses the stock GTM shifter. We just changed the pivot points and U joints to make the entire setup much tighter. It took a little tuning, but it works very well. Just an option.

Crash on second thought. I might be able to rig up somthing using solid rod. That will take lots of brain power however. I want to just get it going with cables first.

I have enough fab work to do just to get the swap going.

I'll call you when I am ready to start that project.

Thanks for the suggestion.
John

mikespms

03-17-2014, 08:41 PM

Hey Mike

Ill need to dig up the ratios for you but when using the SDR I am going 150 at 6k in fourth. The motor makes power up to 7k and redlines at 7200.

The pads you see on the side actually are for brackets that hold the shift cables. I took them off in order to try to get the stock subframe to fit on. Unfortunately the tail housing of the S4 is larger then the SDR. The gear actuators are also farther back so the stock hanger is not going to work. I designed a new hanger over the weekend that I will make out of aluminum, but I realized this am i might be able to modify the stock hanger. its going to be heavy, but it might be quick enough to justify.

I am not sure which shifter I am going with, but I was thinking about this one. http://hargettprecision.com/index.php/sequential-shifters/mendeola-single-lever-sequential.html

I was a little sad to take apart all the stuff that was working so well, but at the same time it gets me closer to my dream car.

John

That's one awesome set up,you need a long straightaway for 5th gear. That Hagertt shifter looks good,the dynojet quick shift and others like it works in conjunction with your shifter. They work with a button shifting and momentarily interrupting the ignition allowing to shift with out the clutch instantly , used on bikes for drag racing and for people that don't know how to use the clutch . Don't know if dynojet makes something for the ls, but if there is a way to momentarily interrupt the ignition it would work like a paddle shifter.
Just an idea:cool:
Mike

kabacj

03-18-2014, 05:14 AM

That's one awesome set up,you need a long straightaway for 5th gear. That Hagertt shifter looks good,the dynojet quick shift and others like it works in conjunction with your shifter. They work with a button shifting and momentarily interrupting the ignition allowing to shift with out the clutch instantly , used on bikes for drag racing and for people that don't know how to use the clutch . Don't know if dynojet makes something for the ls, but if there is a way to momentarily interrupt the ignition it would work like a paddle shifter.
Just an idea:cool:

Mike

Hey Mike. The dynojet kill switch is a good idea. I have something like that on my 125 race bike. The benefit , for me at least, was energy savings over a long race. Just the little bit of mental and physical effort to chop the throttle on up shifts was significant. It allowed more time to relax instead of needing to concentrate on shifting. Sounds like a minor thing, but it was amazing how much of an advantage it offered.

I bet my ecu can take a momentary kill input. It has a boat load of features I have not even started to investigate. I'll find out.

The dynojet kill switch might be a good idea for team PDG. Endurance races were where I found the most benefit.

Re finding a track where I can use fifth gear. I can't wait. 4th pulls hard all the way to redline. You can see on the video I'm pulling longitudinal .3 G under acceleration in 4th. I will need to trim out the wing going much faster, but I figure road America or Daytona will be good places to test out 5th.

Those tracks are on my wish list.

John

KeithBoden

03-18-2014, 05:07 PM

Add VIR to your list if you want to wind the car out in 5th, along with Pocono. Some clubs do run the Long Course, using the North infield, front straight, and turns 1 and 2. Basically the North Course but with the other parts of the tri-oval. Some clubs run the full tri-oval in the afternoon; cars that go less than 140 find it a bit boring... Also, have you done Summit Point Main circuit? I bet you could take turn 11 at 80-85, and then you have 3/4 of a mile before turn 1 at about 50. Here is some old footage of turn 11 to 1:

https://www.youtube.com/watch?v=XB8MaGlpiaU#t=10

kabacj

03-19-2014, 04:57 PM

Hey Keith!

I'll run Pocono this year hopefully VIR.

I have heard the same thing about running the trioval. It's only fun above 150. I have only driven an oval once in my life. It's actually fun. Driving up and down the banking as well as taking the turns as fast as possible is harder then it looks.

The turns that look the same on TV have a whole new meaning at speed on the track. Each turn has its own character.

Regarding the build. Parts and raw materials are starting to arrive. A new starter, lots of aluminum, tires, rims and some wiring supplies.

It's going to be a busy weekend.

John

Kempo

03-20-2014, 09:17 AM

I was looking for some inspiration to get out in the garage and get the GTM ready for the track and I was reviewing videos. I thought I would share this one.

http://youtu.be/tOvqqEmCujE

John

That is one cool video John!!!!!! Hadn't had time to see it till now. Just WOW!!!!!!!!!!!!!!!!! The sustained Gs you are pulling are awesome.
How accurate is your telemetry? I noticed that on high G turns and under heavy braking your oil pressure is really dropping. You might want to take a look at that. For example look at 2:56, 3:59, 4:57 under braking and 5:58 at 1.20 Gs. There are more but just wanted to point out a few instances.

crash

03-20-2014, 10:38 AM

kabacj

03-20-2014, 07:43 PM

That is one cool video John!!!!!! Hadn't had time to see it till now. Just WOW!!!!!!!!!!!!!!!!! The sustained Gs you are pulling are awesome.
How accurate is your telemetry? I noticed that on high G turns and under heavy braking your oil pressure is really dropping. You might want to take a look at that. For example look at 2:56, 3:59, 4:57 under braking and 5:58 at 1.20 Gs. There are more but just wanted to point out a few instances.

Hi Hugo. Glad you like the video.

I knew when I posted the video somebody would see the oil pressure fluctuation. Regarding the telemetry. I have confirmed the MPH, the G Meters are accurate. Those readings come from the STACK data logger and I have compared them to another data logger back to back. The Engine signals I record come via the CAN bus on the ECU. Since all the programming on the ECU is custom and the ECU decoding on the stack DVL is also custom, and I did not calibrate the two last year I am not sure that the ECU numbers are perfectly accurate. I was always more worried about car setup rather then camera/ data setup.

Thats a long way of saying I am not sure how accurate the readings are. You can see the throttle never hits 100% even tho I assure you I am flat on the floor. The temp seems a little low to me.... but yes the oil pressure is a concern.

Even if its just a relative number its clear that there i some oil starvation going on in the video. After this run I noticed the same thing and added more oil to the motor. That seemed to lessen the variation in oil pressure on later runs. Its also note worthy that I see negative oil pressure. That's a little weird. Maybe it can happen but seems unlikely.

Mast motorsports have a special extra deep high capacity oil pan they use that they claim solves the oil starvation problem commonly seen in LS3s. It is most likely true that the oil pan solves the issues in most cars but it looks like the GTM develops higher G loads longer then most cars.

For the short term the plan is to put in an accusump. Since I only seem to see the issues under hard braking and the 3 qt accusump is supposed to be able to provide up to 60 seconds of oil pressure. It might be a work around. I hope so anyway.

Thanks for the observation. Im glad people are watching my back.

John

kabacj

03-20-2014, 08:15 PM

You can see that the wing is making some downforce because it flexes downward on the straight. All of ours do that too. Some more than others, but yours indicates that it is building a good amount of downforce.

Is this engine dry sumped?

Crash you made my day. That is the coolest thing EVER! I have never heard about or seen a wing flex under load like that. Its pretty easy to see if you watch the space between the wing edge and the text. The space grows and shrinks as the speed changes. Its interesting that your wings do that too. I know you guys have a super down force configuration with a multi element wing. It would be nice to measure how much down force I am making I am going to work on that. Have you guys done that? I know my data logger has an input for linear potentiometers. Its just an expensive setup to find out facts that are cool but its not like I am racing for money and can justify it.

No unfortunately its not dry sump yet. As I said to Hugo, I am going to try to get by with the accusump and make sure to keep the motor very full of oil to avoid any starvation issues.

It depends on how things go this year, but dry sump is on the short list. I knew I would need one. I just did not think it would be this soon.

Thanks a lot for the observation on the wing I am not kidding that is so damn cool. I am going to put cameras all over that thing and on the rear suspension so I can see what is really happening back there.

John

crash

03-21-2014, 09:33 AM

We have not measured wing down force with an instrument other than the seasoned GM factory test driver we had in the car last year, Paul Edwards, and the rest of us amateur drivers. This is actually a test session where we were doing back to back wing tests. https://www.youtube.com/watch?v=eZ9vIUi7aRY We can change our wing in about 30 seconds, so we went out, ran a few laps to get things warm and get a base line, then came in, did a wing change and saw how the feel and lap times compared. This is why it looks like Paul is up to speed so quickly on the out lap in that video...everything is already warmed up. :)

We are at the point where small changes make a noticeable difference in lap times and with drivers like Paul we can be assured that what he is telling us(besides what the computer is telling us) is indeed what is happening.

EDIT: Almost forgot, that video will also wet your appetite for how the Mendeola S5 will shift. It's a beautiful thing.:)

Presto51

03-21-2014, 11:55 AM

Sheeee-Nikes Crash that is one of the best videos I have seen from you. I think I pulled a 1G in my chair just watching it, and the Mendy is sweet

Thanks

RumRunner

03-21-2014, 08:18 PM

I have to agree with Ron - GREAT video! My wife laughed at me as I'm steering and leaning into turns while I watched it!

Cobra 61

03-23-2014, 01:56 PM

It is truly amazing of the infectious passion this car generates. Who would ever thought of a group of enthusiasts could build a car and attract world class drivers for the sheer enjoyment of the sport of road racing! NOT IN MY WILDEST dreams. There has been over 100 people work on this car and another 100 just offering advise. I might add worldwide! You might also take in the account of operating an a very limited (small) budget! As Mike indicated, having Paul join us, it has been very educational and raises the bar each time we take the car out. If you had not read any of our other stuff before the 25, Paul was runner up in the Red Bull F1 search, then went to GM for 11 years as a test driver and then won a Grand Am championship in a Pontiac GTO. Most of his experience came from the European circuits, winning The Grand Prix of Monaco in a vintage Penske F1. We are so honored to all the talent, behind the wheel and behind the scenes. BUT, let's not forget the PDG regulars that have put this project in the winner's circle time after time!

kabacj

03-24-2014, 05:50 AM

Crash. That video is awesome. Nice editing and multiple camera views. I really can't wait to get out on the track with the new setup.

Richard you have put together a great program. I am looking forward to the day when you guys post a win at the 25 hour. It only a matter of time.

In order for me to get out on the track I need to make a new transaxle support and rear subframe. I could have cut up my old one, but I figured I have some time. Why not start from scratch.

This is the old sub frame. It also functions as my wing mount and rear tow hook receiver.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/8791626C-2CEC-4E2B-AC54-B23F4B3E5D03_zpsvapmauak.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/8791626C-2CEC-4E2B-AC54-B23F4B3E5D03_zpsvapmauak.jpg.html)

After drawing a few sketches. Step one was to make a foam model that allowed me to verify all the pickup points and make sure I would not have any clearance issues

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/8F299547-C88E-4FC8-8265-82D426EE0F7D_zpsqokfoubj.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/8F299547-C88E-4FC8-8265-82D426EE0F7D_zpsqokfoubj.jpg.html)

The next step was to make the mounts that attach to the frame. I could have used a bit of tubing with a half inch hole it and welded that to the frame, but I figured that a solid chunk of aluminum would allow me more welding surface and a much stronger part.

Boy it would be nice to have a mill, but I made due with the bandsaw.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/89493064-D50E-4262-9F99-0DC7009A0BB5_zps6mxfrvps.png (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/89493064-D50E-4262-9F99-0DC7009A0BB5_zps6mxfrvps.png.html)

I drilled a hole in the frame and plug welded the mounting boss into the arm of the frame.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/A28B699E-9E96-4FE4-870C-8AF6E8CF9F32_zpsxa8iucul.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/A28B699E-9E96-4FE4-870C-8AF6E8CF9F32_zpsxa8iucul.jpg.html)

Next I welded the box section tube closed.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/73BBC8E9-F2A1-4597-B7E8-E998004BCA55_zpsvwl809yc.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/73BBC8E9-F2A1-4597-B7E8-E998004BCA55_zpsvwl809yc.jpg.html)

And welded the frame together.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/165618B1-95FC-40CB-BC2B-9FC30912181D_zpstzpoyxs2.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/165618B1-95FC-40CB-BC2B-9FC30912181D_zpstzpoyxs2.jpg.html)

Now for the test fit.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/0C1B8D05-10BF-41B8-A859-5F3A3094284C_zps0h9xzdka.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/0C1B8D05-10BF-41B8-A859-5F3A3094284C_zps0h9xzdka.jpg.html)

It fits!

Of course I put it in the car several times as I was welding to manage the warping as I welded. I basically warped it into shape using each subsequent line of beads to move the frame into the shape I wanted. The subframe drops into the mounting tabs on the frame. Even when using a jig I find that the stress builds up and the part springs out of shape a bit when you take it out of te jig. My method might not be the right way, but it works for me.

The new subframe will also be a rear bumper.

Still need to hang the transaxle. More to follow.

John

Cobra 61

03-24-2014, 07:11 PM

that is some pretty crafty stuff! great work!~

R

carbon fiber

03-25-2014, 07:33 AM

very nice. those welds are super. looks like the right way to me.

kabacj

03-27-2014, 08:08 PM

that is some pretty crafty stuff! great work!~

R

very nice. those welds are super. looks like the right way to me.

Thanks Richard and Jason,

Last weekend I spent most of the time staring, drawing, modeling and measuring. After many mental iterations of the design i decided to make the parts of the design that I was happy with.

It took me two days to make this part even though the actual building only took a few hours.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/165618B1-95FC-40CB-BC2B-9FC30912181D_zpstzpoyxs2.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/165618B1-95FC-40CB-BC2B-9FC30912181D_zpstzpoyxs2.jpg.html)

I have spent the week building the remaining parts of the subframe and transaxle mount in my head. Imagining the stress loads and also the possible difficulty installing or removing the parts.

I hate when you put things together and in order to work on part A you need to take out B, C , D, E and F.

I want to be able to take out any part without messing with the other parts. I also wanted to take the rear subframe out without forcing the body out of the way to clear.

I want this car to be like my two stroke race bikes. you can take the whole thing apart rebuild it and put it back together in an hour.

Requirements

1)light weight but strong
2)stiff but not rigid attachment of the Transaxle to the subframe
3)easy installation and removal
4)transaxle bracket and subframe structure that can stand up to the fatigue loads of the track

I had a hard time with how I would design the attachment point between the transaxle hanger and rear subframe.

Factory five did a nice job with the mendiola SDR mount. You insert the bottom bolts and swing the mount up into position insert the top bolts and drop the transaxle down on the pads.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E12C6C47-033D-47E3-9915-D20BD14F8BDD_zpsmq1zwzxo.png (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/E12C6C47-033D-47E3-9915-D20BD14F8BDD_zpsmq1zwzxo.png.html)

I wanted to carry the same idea, but of I could not rest the transaxle on the subframe like factory five did.

I have come up with this side view of how the bushing will connect with the subframe and transaxle hanger.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/530DF37D-C103-4D9D-9CD3-4B6507BD9474_zpsbwnogsog.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/530DF37D-C103-4D9D-9CD3-4B6507BD9474_zpsbwnogsog.jpg.html)

the bracket will hang from the subframe instead of resting on it. I figure i will weld rings that capture the bushings and that will stabilize the setup as well as limit some of the motion but still allow twist in compression.

here is a top down view of the subframe with bracing and mounts for the transaxle hanger.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/25E7CF82-89FA-4DB8-A0CD-E00447DA2139_zpsrgvzs4wx.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/25E7CF82-89FA-4DB8-A0CD-E00447DA2139_zpsrgvzs4wx.jpg.html)

I have a assortment of polyurethane bushings and hardware. It will be interesting to see how this all works out.

John

kabacj

03-31-2014, 05:32 AM

Good progress this weekend. As usual the I thought I could get more done, but at least the work completed came out well.

I needed to support the rear sub frame with a method that would be strong enough to support the transaxle as well as stabilize the subframe if it were to get a nudge from a car following too closely on the track.

I figure using the design I used for the rear strut supports that make a V over the motor would be both strong and easy to fine tune.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/DA220728-FD30-4F88-9462-FEC9B8913E0E-2661-000006F5671AF553.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/DA220728-FD30-4F88-9462-FEC9B8913E0E-2661-000006F5671AF553.jpg.html)

Now for the time consuming part. I machined 4 ends for the struts that support the rear subframe. One side of the strut has left hand treads and a rod end.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/47BB062B-2E6E-45CD-B5C7-DEBCD27E85F4_zpsbzt02ldp.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/47BB062B-2E6E-45CD-B5C7-DEBCD27E85F4_zpsbzt02ldp.jpg.html)

The other side has right hand threads and a rod end.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/92B0038D-988F-4E3E-A8A6-1C1B4F082526_zps7wtvfjg0.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/92B0038D-988F-4E3E-A8A6-1C1B4F082526_zps7wtvfjg0.jpg.html)

Each end has a press fit into an aluminum tube. This ensures prefect alignment and makes a very strong joint. I'm sure The the ends would stay put even if they weren't welded.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/36C0C690-F49A-4A69-A5E7-47288D6B7D0F_zps24iqsi04.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/36C0C690-F49A-4A69-A5E7-47288D6B7D0F_zps24iqsi04.jpg.html)

Next I made some brackets out of 1/4 inch aluminum plate and welded it all up.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/A3D1DC8A-0CFD-46A8-B0D3-2FC2F30038B3_zpsjkaascby.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/A3D1DC8A-0CFD-46A8-B0D3-2FC2F30038B3_zpsjkaascby.jpg.html)

The solution works well. Plenty of room around the transaxle and very strong.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/5E067A25-987A-43DE-8A9C-F2D8438CD7F7_zpslnrreufs.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/5E067A25-987A-43DE-8A9C-F2D8438CD7F7_zpslnrreufs.jpg.html)

John

kabacj

04-14-2014, 05:16 AM

The family insisted that I attend the family vacation so my other child, the GTM, did not get much attention over the past two weekends. It was great to get some quality family time.
On the other hand I have a deadline to get the GTM back out on the track so I spent a few hours on it this weekend.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E34EFC85-DFE0-4751-B32A-2ACD4DF29B61_zpsbmzj65vo.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/E34EFC85-DFE0-4751-B32A-2ACD4DF29B61_zpsbmzj65vo.jpg.html)

Two major points of progress. I installed an x brace in the rear sub frame. Boy it's stiff! I actually think it will play an active role stiffening the rear shock towers now.

You can also see the plywood template I made to pickup the mounting points on the transaxle and subframe. More refinements needed here but I'm close.

Finally I tipped the whole subframe down so it does not block the holes in the body where the exhaust pipes exit. My original idea was to run the frame perfectly level off the top mounting tabs like factory five does. The problem is my subframe is much wider and more visible from the rear. There is no reason it needs to be level in my application so I decided to tip it down.

Part of the adjustability I get with the left and right hand threaded links are changes like this one. I just made both links a half inch shorter and I am golden.

John

longislandwrx

04-14-2014, 05:53 AM

kabacj

04-15-2014, 04:52 PM

Looks awesome... Your craftsmanship is inspiring.

I ran my front brake lines this weekend, finished up the throttle cable/assembly and started building my custom axles. It was nice to be able to work with the garage door open.

A few neighbors stopped by so that's motivating in itself.

I must agree working with the garage door open is great. Sadly I need to keep it shut when I'm tig welding so the breeze does not blow the shielding gas away and mess up my welds.

Hopefully I'll have the GTM street legal by June. I'll stop over so I can see a 818 under construction.

John

fastthings

04-16-2014, 07:13 AM

kabacj

04-17-2014, 04:51 AM

I learn alot watching guys like you. What is your background, what have you done that makes this stuff such a no brainer for you?

You have a tig welder, you have some kind of band saw, drill press, lathe, or a mill. I'm really thinking I need to open my eyes, I have been building cars off the floor of my garage for so many years. Using crude tools, making a bracket out of some other combination of metal that was in my bin. It all comes out good, but I'm missing the boat., too much work.

You really didn't need much to make that rear brace, did you?

Ha thanks Gene you are too kind.

I have been very impressed with the metal parts you made, like your rear hatch supports. A whole lotta hand work to get them done but they looked GREAT. Of course a black car will highlight the beautiful bodywork you have done. Yes sometime tools make it easier but often they simply make your work faster and more accurate.

What experience do I have?

I sit at a desk all day. I have never built a car. I did'nt tig weld before I got the kit. I have no engineering training I have never raced cars. I just got all these tools in the past 3 years. I really have no idea what I am doing. I simply learn as I go.

I have a talent for building things in my head in 3D and imagining how they will work in the real world. I spend quite a bit of time thinking about how this stuff will work under stress loads before I start building. I test ideas/ prototype them if I can. I second guess myself until I have run out of things to second guess.

I am also a good copy cat. If you dont know what you are doing, copy somebody who does. You will probably end up in a good place. I study how race cars were made in the 60s and 70s and how they are made now. Lots of pictures on the internet to get ideas. Im sure the internet makes this stuff I make look like I just throw it together. But I really work at the design before I build anything.

Tools:

I have a good tig welder. I have a good band saw that is designed to chop angles and retrofitted it with a small table. I have a 1950s lathe and a ton of woodworking tools including the drill press. All of my metal working tools were purchased used for under $1k total so they are very affordable in the context of the GTM expense. I needed all of them to make the rear transaxle sub frame and hanger.

I ended up buying all these metal working tools so I could make the bits that stand between me and a successful custom project. Although I don’t enjoy having to make stuff under pressure of a deadline like I am doing now with this transaxle hanger, I really love making stuff. When I retire that’s all I will do.

I just try to make parts that are functional and pretty. I like to solve problems. I’m glad to share them with you guys. Hopefully my solutions work. If they don't ill be sure to tell you so if you make parts like I have you can learn from my mistakes. Having the right tools for the job makes it a whole lot easier.

I have a little God given talent, TONS of determination and $1000 dollars worth of used tools and a welder. This work is not a "no brainer" for me. It just looks like it is :)

John

Presto51

04-17-2014, 06:45 AM

fastthings

04-17-2014, 08:18 AM

Well, like I said, I'm missing the boat then. I haven't baught a tool in 20 years, I think I will look into some of that stuff when I get the GTM done.
Thanks man

kabacj

04-17-2014, 12:07 PM

"I sit at a desk all day. I have never built a car. I did'nt tig weld before I got the kit. I have no engineering training I have never raced cars. I just got all these tools in the past 3 years. I really have no idea what I am doing. I simply learn as I go"

Sorry John I have to call BS on that statement.

I've seen, worked with rookies, and examples of your work is not that of a rookie. Unless.......

You got a pro doing all the work and then you come in behind and take the pictures, and try to "shine" us forum wingnuts. :rolleyes:

Ron

Very funny Ron and thank you for the compliment.

My mom says im not your average rookie. My wife says im borderline certifiable.

I keep working at something till I get it. Funny one definition of insanity is doing the same thing over and over and expecting a different outcome. Maybe my wife is right!

Scouts honor no BS. My statement is 100% true.

John

kabacj

04-21-2014, 08:25 PM

It was Good Friday. T- 10 days and counting.

I have 10 days till I'm due out on the track for my first event of the season.

On the list for today.

Transaxle hanger bracket:

I have already made a cardboard template then transferred that template on to a piece of 1/4 inch plywood.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/929656be-dbba-4bc5-97f1-72a7610b7244_zps27379d37.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/929656be-dbba-4bc5-97f1-72a7610b7244_zps27379d37.jpg.html)

After cleaning up and mounting the plywood I was able to see that the relationship of the bracket and rear subframe was going to work.

Next was transferring the shapes to aluminum.

Cutting the convoluted section was a real pain. The 1/4 inch 6061 aluminum does not cut well with a hand held air saw. I my only option was nibbling out the inside curves on the bandsaw then cleaning it all up with a die grinder and carbide bur. It was time consuming, but it worked.

After all that work to make the hanger I needed to drill out the mounting holes. I don't like making over sized holes to account for tolerances. I wanted the holes in the bracket to be the same 3/8 inch as the mounting holes in the transaxle. It's very hard to drill 4 properly aligned holes within a few thousandths of tolerance. I need a CNC mill! I reminded myself that in the good ole days before computers machinists did it all the time. It can be done.

I painted on a layer of machinists dye and marked the holes. I drilled a pilot hole with a bit that minimizes runout and wandering and then drilled out to the final 3/8 size. To my relief all 4 holes were perfectly aligned.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/6904D798-3032-4FA8-8D98-D8712740B043_zpsqyv9vibt.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/6904D798-3032-4FA8-8D98-D8712740B043_zpsqyv9vibt.jpg.html)

With the hanger bolted up I was able to see where I needed to install the brackets on the rear subframe that would receive the bushings. Using some of the scrap from the hanger I cut and welded the brackets. Next I drilled a hole to receive the polyurethane bushing.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/C324F605-6071-46A6-81F3-E7A5E6B9A415_zpsyryl7vxb.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/C324F605-6071-46A6-81F3-E7A5E6B9A415_zpsyryl7vxb.jpg.html)

With that done I needed to fabricate some bushings.

I had hoped to find something off the shelf, but it turned out that it was easier to make the needed bushings. I researched buying a cast rod of polyurethane,but it turned out that It was much cheaper to buy a bunch of polyurethane suspension bushings for a total of $20.

Now all I needed to do was mill the suspension bushings to size. Most sources said that I would need to freeze the polyurethane with liquid nitrogen so I could cut them on the lathe. That would be a problem. Because polyurethane is not easy to mill most bushings are cast in the shape needed.

I figured if I made a razor sharp cutter with the right shape I should be able to turn the bushings. Well that might be true but I still needed to hold the bushings in the chuck. That was not working. Once gripped in the chuck the bushings deformed and were not held tightly enough for accurate machining.

No problem. I'll hold them another way. I machined a piece of brass rod, sized so I could just barely press the bushing on by hand. Since the bushing was expanded slightly I would need to account for that when I cut my final outside diameter but at least now I am ready to cut.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/B7DE0760-BD71-42DC-9627-3F6514C87F2B_zpskq65m6jc.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/B7DE0760-BD71-42DC-9627-3F6514C87F2B_zpskq65m6jc.jpg.html)

The system worked perfectly. I was able to turn ribbons of polyurethane off the bushings and both cut and size them as needed.

I milled up my bushings. While I was lathing parts I turned sleeves that limit the compression of the poly as well as attached aluminum washers.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/BE04187D-FA80-4AAB-A3BB-C0BAC3F780CF_zps2lxfqzs8.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/BE04187D-FA80-4AAB-A3BB-C0BAC3F780CF_zps2lxfqzs8.jpg.html)

Now the test fit. I used the bushing pressed into the cross brace as a drill guide so the bolt dropped right into the hanger. I tightened it up. Looks like its going to work.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/D23225E5-7358-4991-94D4-44527DC13132_zpsmsgsyy9p.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/D23225E5-7358-4991-94D4-44527DC13132_zpsmsgsyy9p.jpg.html)

Whew. That was a lot of work for one day. Easter weekend is not a great weekend for getting work done so I needed to cram in all the work while I could.

John

Kempo

04-21-2014, 08:40 PM

Impressive work as usual John. Said it once and I'll say it again you really, really, really, have skills.

kabacj

04-23-2014, 05:19 AM

Impressive work as usual John. Said it once and I'll say it again you really, really, really, have skills.

Hey Hugo! Glad to see you are still hanging around the forum. Please keep reporting your adventures with the GTM. I hope one day I can have as many pin up girls around my GTM.

Right now I need to keep my mind off the pretty girls and focus on finishing the GTM in time for my track visit on Monday.

Saturday and Sunday of Easter weekend were mostly dedicated to family visits but I was able to spend a few hours in the garage.

On the task list

Remount the rear wing/ body support:

Since I tipped the rear sub frame down so its not visable from the rear, the rear wing support needs to be a little taller. That ment I needed to move the threads that hold the rod ends down about 3/4 of an inch. I lathed up some aluminum rod and welded it on to the frame extending the threaded section.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/12ED0E66-B903-4B4E-A583-8625EBCAE0A5_zpskzegrnuh.jpg

Next I needed to attach the struts that locate the rear wing body support. More brackets and welding.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/2121E774-26C1-4C0D-9A44-47F5FBACE9C4_zpsgoztrfh9.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/2121E774-26C1-4C0D-9A44-47F5FBACE9C4_zpsgoztrfh9.jpg.html)

Finally the last bit of fabrication is to add the exhaust supports.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/505225BD-6389-4652-B706-4E42C02B552F_zpsbqsd8lhk.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/505225BD-6389-4652-B706-4E42C02B552F_zpsbqsd8lhk.jpg.html)

I had made exhaust suports out of 3 inch clamps. These worked fine over the past year at the track. It seems like the exhaust wrap I installed between the clamps and the muffler tubing (not pictured) was enough to prevent the rubber from melting even under the high heat of track conditions.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/5BED40D5-62B8-439A-8FB1-4DE627809729-12897-000024A95E36AED5.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/5BED40D5-62B8-439A-8FB1-4DE627809729-12897-000024A95E36AED5.jpg.html)

And here is a shot of the sub frame and wing support all ready for installation.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/F5F875A7-CF3C-4EF4-A4E3-D548BCFF8FEC_zpskjxvxent.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/F5F875A7-CF3C-4EF4-A4E3-D548BCFF8FEC_zpskjxvxent.jpg.html)

Now all I need to do is modify the shifter and hook up the cables and I'll be ready to go.

longislandwrx

04-23-2014, 07:09 AM

That is awesome. Good luck finishing it up this week.

kabacj

05-01-2014, 05:06 PM

That is awesome. Good luck finishing it up this week.

Thanks. I finished ! But as you may have guessed. That's not the whole story.

My normal thrash to get all of my planned upgrades complete prior to the first weekend of the year ended 8.00pm Sunday night for Mondays track day.

I finished my punch list that includes new tires I mounted and balanced myself. (Both a first)with bigger 275s up front. New exhaust section from kooks without the cat section that roasts the cv joints at track temps. New sequential transaxle and sequential shifter and dual disk kennedy stage 2 clutch. A re designed, light weight rear sub frame that also acts as a rear bumper.

Testing things out at home I ran the transaxle through the gears on jack stands. I also checked out my modified shifter. It all worked. That was amazing in itself. The reverse setup was heavily modified and that even worked!

I drove it in the driveway in forward and reverse. All seemed great! It was a late night by the time we had packed up. Off to the track at 3am

We arrived at the track at 7am. A little tired I roll the car off the trailer

As usual it attracts some stares

I start it up and that turns heads. It sounds really good without the cats .

The I put it in gear which is still an odd experience pulling directly back for first

Let out the clutch. It barely grabs. Odd

I go back and adjust the slave cylinder till it's barely any travel moving the clutch fork to disengage the clutch. Still nothing.

I knew it was bad. This is not how a new clutch fails. You can't slip it or you can't get it out if there is a problem. Since it's a multi disk dry clutch you can hear when the pressure is off. It sort if rings. When I let out the clutch I hear pressure being applied but no drive.

My gut said call Kennedy. It felt like I had the wrong friction disk or steels. Too thin or something like that. I waited till they got into the shop in California. In about 30 seconds he knew what the problem was. One of the clutch plates needs a small chamfer added to it. A few seconds with a dremel will fix it he said.

Turns out others had the same problem. Without the chamfer there is enough extra metal to keep the friction disk nearest the flywheel from touching the flywheel.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E1351736-EAE7-4859-A636-60A863DED558_zpsfnevmlbu.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/E1351736-EAE7-4859-A636-60A863DED558_zpsfnevmlbu.jpg.html)
I was disappointed that I could not drive the car, but it comes with the territory. Low volume custom parts all mixed together. I expect some "tuning"

I wish i would have done some hard throttle test runs at home, but it was poring rain Saturday and Sunday night blasts at 8pm would not have been popular with the neighbors.

Good news is I'm back at the track on the 16th

I hope to get my nasa racing license. The neighbors are just going to have to deal with a few loud blasts up and down the street while I test out the clutch setup

Out comes the transaxle. Again! It's ok. My new multi part subframe should cut down on the time.

John

crash

05-02-2014, 03:15 PM

kabacj

05-02-2014, 03:38 PM

Good lesson in what happens regularly in racing...just about anything you can think of...and everything you haven't!

I would of had to pull it apart at the track. Even if I ended up towing it home in pieces. I figure I went through that much effort, I may as well add a little bit more.

Don't think I didnt consider going to harbor freight and getting and engine crane and pulling it out. I went to bed at 12.30 after I finished loading up the trailer and doing other odds and ends. I just cant stop working on stuff if I have time. I woke up at 3am to drive to the track so I was working on only a few hours of sleep. The forcast was for heavy rain on Tueday so it was likely to be a wash out. AND altho I had brought enough parts and tools to rebuild almost anything I forgot one key thing. The stupid clutch alignment tool! The barriers kept adding up.

If I had anything like normal energy levels I would have done it, but yeah it was pretty hard to admit failure and go home.

crash

05-02-2014, 04:18 PM

In a pinch you can use a socket and a short extension for an alignment tool. :)

kabacj

05-02-2014, 04:50 PM

In a pinch you can use a socket and a short extension for an alignment tool. :)

Yep that's a good idea. I was going with the plan of going to Home Depot getting a pine dowel and turning it down to size then adding a strip of metal to align the splines on the multi disks. You know something quick and simple.

Course I could always call Ian and ask him what Porsche input shaft the Mendiola s4 uses. Do you happen to know what input shaft the Mendiola s4 uses? Getting that tool at autozone may be a problem tho

Needless to say the engine crane and clutch alignment tool will be in the trailer next time.

crash

05-05-2014, 12:08 PM

I believe the splines on the S5 are of something American made. Can't completely remember, but I'll see if I have a reference. :)

mikespms

05-05-2014, 02:59 PM

Hey John,

http://store.snapon.com/Clutch-Service-Tools-Set-Clutch-Aligner-P635965.aspx
I have one of these it works well when you don't have an old input shaft for alignment

kabacj

05-05-2014, 05:15 PM

I believe the splines on the S5 are of something American made. Can't completely remember, but I'll see if I have a reference. :)

Thanks Crash

Hey John,

http://store.snapon.com/Clutch-Service-Tools-Set-Clutch-Aligner-P635965.aspx
I have one of these it works well when you don't have an old input shaft for alignment

Thanks for the link Mike

Yes this clutch is tricky. I need to align both the plates with the pilot bearing and the splines of the disk.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/3FC9E2EA-8F77-4E8F-BD67-E2E6697CAA38_zps29mcdqe4.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/3FC9E2EA-8F77-4E8F-BD67-E2E6697CAA38_zps29mcdqe4.jpg.html)

Needless to say I will carry the tool at all times now.

kabacj

05-06-2014, 05:38 AM

I had a feeling that I was subject to 3 different custom parts makers having all having tolerances that added up to a problem.

It looks like that is exactly what happened.

My main suspect was the clutch. However after walking through and measuring all of the parts with Kennedy Engineering on the phone. They are all with in spec. When I inspected the clutch it all seemed to be working properly. Each plate and steel surface had scuff marks from engagement. The clutch was clearly clamping when I pulled the transaxle out. My problem was that it was slipping with out fully engaging.

I quickly realized that the problem was not with the clutch function, but rather the relative placement of the clutch between the motor and transaxle.

When the transaxle was installed the throw out bearing was permanently pressing on the diaphragm spring . Even when I adjusted the clutch throw out fork to its max out position, It was still slipping the clutch.

I did not realize this was the case when I installed the clutch and tested for some air gap between the throw out bearing and springs It sounds like there is air gap. You can hear a click as it he throw out bearing hits the diaphragm springs. But in fact the throw out bearing was backed into the bearing guide mounting bolts and I was hearing the click of free play in the assembly that moves the throw out bearing. You can not see the air gap between the clutch and throw out bearing on this transaxle as the bell housing does not have an access window.

I did some careful measurement and confirmed the problem.

There are a few ways I could think of fixing this.

There is quite a bit of material on the back side of the area that the flywheel mounts to the crank shaft. That could be machined to bring the clutch assembly closer to the motor. Or the guide that the throw out bearing rides on in the transaxle could be moved back into bell housing OR I could simply make sure the throw out bearing goes back all the way back on its travel by trimming the bolts behind it.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/A1C26541-2AA5-4584-8EF1-2E05B8829DAC_zpswamburs5.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/A1C26541-2AA5-4584-8EF1-2E05B8829DAC_zpswamburs5.jpg.html)

As I did not really need that much more clearance I opted for the easiest and fastest fix first.

First I removed the lock washers. That got me a few tenths. Then I turned down the heads of button head allen bolts. I was able to make them thin, but I was concerned that I could easily strip out the allen head since I did not have a lot of material left. I decided that I would just turn down a normal hex head as that would be more sturdy and less likely to strip.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/85916380-9A13-4626-BB6F-DFE973798F69_zps8hbi4yw5.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/85916380-9A13-4626-BB6F-DFE973798F69_zps8hbi4yw5.jpg.html)

With everything optimized and adjusted I was able to get a reasonable air gap
If you don’t have one of these I suggest you get one.

It’s a sealed usb camera with a LED lights. I hook this one to a piece of aluminum welding rod. And for 25 bucks I have a GREAT way to trouble shoot things without tearing them apart. For the transaxle I can fish the camera into the bell housing via the opening for the starter.

I was able to inspect the clearances after some creative bending an twisting of the welding rod.

Here is a picture of the back of the throw out bearing. I can confirm its bottoming on the bolt heads I turned down as it travels away from the clutch diaphragm spring.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/Snapshot_20140504_zps813f3c4c.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/Snapshot_20140504_zps813f3c4c.jpg.html)

Here is a view of the air gap. Looks like enough. It looks bigger in the picture as we are super zoomed in.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/Snapshot_20140504_2_zps70eb0171.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/Snapshot_20140504_2_zps70eb0171.jpg.html)

Now that its all sorted im optimizing a few of the cable routes and the position of the slave cylinder, and ill try to do a test run this week. Hopefully that solves my problem

John

Presto51

05-06-2014, 06:23 AM

If you don’t have one of these I suggest you get one.

It’s a sealed usb camera with a LED lights. I hook this one to a piece of aluminum welding rod. And for 25 bucks I have a GREAT way to trouble shoot things without tearing them apart. For the transaxle I can fish the camera into the bell housing via the opening for the starter.

Now we know where MacGyver retired too :cool:

As always thanks for the great tip and for sharing

BTW: You do know that I'm writing down all of your Tips, Tricks, and How To's. So don't be surprised when you see them pop up on a future build, :rolleyes:

Ron

kabacj

05-06-2014, 01:48 PM

[B][ So don't be surprised when you see them pop up on a future build, :rolleyes:

Ron

Hey Ron,

Glad if my "solutions" can be helpful in any way with your build.

here is the camera I use.

http://www.amazon.com/gp/product/B008X13JI8/ref=wms_ohs_product?ie=UTF8&psc=1

Hooked to a laptop and using a bit of welding wire in order to direct the camera to its target, I think its better then a 250 dollar pro tool for ocasional use. The pro units have a flexi shaft that is harder to jamb into really tight spaces.

As it did in this case. For 17 bucks I know what it looks like inside the bell housing at exactly the place I was interested in.

Now lets just hope it works as well as it looks like its going to work.

John

longislandwrx

05-08-2014, 06:08 AM

You can not see the air gap between the clutch and throw out bearing on this transaxle as the bell housing does not have an access window.

Is it possible to add one?

Very impressive diagnostics. Especially on a few hours sleep. Hopefully the rain lets up Sunday and you can test the fix.

mikespms

05-08-2014, 08:07 AM

http://www.mcmaster.com/#94414a583/=rviv86 Hi John, A couple of options for you,How about counter sinking the hole and using a flat head fastener or have you looked into a hydraulic throwout bearing and eliminating the slave cyl.
I had a feeling that I was subject to 3 different custom parts makers having all having tolerances that added up to a problem.

It looks like that is exactly what happened.

My main suspect was the clutch. However after walking through and measuring all of the parts with Kennedy Engineering on the phone. They are all with in spec. When I inspected the clutch it all seemed to be working properly. Each plate and steel surface had scuff marks from engagement. The clutch was clearly clamping when I pulled the transaxle out. My problem was that it was slipping with out fully engaging.

I quickly realized that the problem was not with the clutch function, but rather the relative placement of the clutch between the motor and transaxle.

When the transaxle was installed the throw out bearing was permanently pressing on the diaphragm spring . Even when I adjusted the clutch throw out fork to its max out position, It was still slipping the clutch.

I did not realize this was the case when I installed the clutch and tested for some air gap between the throw out bearing and springs It sounds like there is air gap. You can hear a click as it he throw out bearing hits the diaphragm springs. But in fact the throw out bearing was backed into the bearing guide mounting bolts and I was hearing the click of free play in the assembly that moves the throw out bearing. You can not see the air gap between the clutch and throw out bearing on this transaxle as the bell housing does not have an access window.

I did some careful measurement and confirmed the problem.

There are a few ways I could think of fixing this.

There is quite a bit of material on the back side of the area that the flywheel mounts to the crank shaft. That could be machined to bring the clutch assembly closer to the motor. Or the guide that the throw out bearing rides on in the transaxle could be moved back into bell housing OR I could simply make sure the throw out bearing goes back all the way back on its travel by trimming the bolts behind it.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/A1C26541-2AA5-4584-8EF1-2E05B8829DAC_zpswamburs5.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/A1C26541-2AA5-4584-8EF1-2E05B8829DAC_zpswamburs5.jpg.html)

As I did not really need that much more clearance I opted for the easiest and fastest fix first.

First I removed the lock washers. That got me a few tenths. Then I turned down the heads of button head allen bolts. I was able to make them thin, but I was concerned that I could easily strip out the allen head since I did not have a lot of material left. I decided that I would just turn down a normal hex head as that would be more sturdy and less likely to strip.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/85916380-9A13-4626-BB6F-DFE973798F69_zps8hbi4yw5.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/85916380-9A13-4626-BB6F-DFE973798F69_zps8hbi4yw5.jpg.html)

With everything optimized and adjusted I was able to get a reasonable air gap
If you don’t have one of these I suggest you get one.

It’s a sealed usb camera with a LED lights. I hook this one to a piece of aluminum welding rod. And for 25 bucks I have a GREAT way to trouble shoot things without tearing them apart. For the transaxle I can fish the camera into the bell housing via the opening for the starter.

I was able to inspect the clearances after some creative bending an twisting of the welding rod.

Here is a picture of the back of the throw out bearing. I can confirm its bottoming on the bolt heads I turned down as it travels away from the clutch diaphragm spring.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/Snapshot_20140504_zps813f3c4c.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/Snapshot_20140504_zps813f3c4c.jpg.html)

Here is a view of the air gap. Looks like enough. It looks bigger in the picture as we are super zoomed in.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/Snapshot_20140504_2_zps70eb0171.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/Snapshot_20140504_2_zps70eb0171.jpg.html)

Now that its all sorted im optimizing a few of the cable routes and the position of the slave cylinder, and ill try to do a test run this week. Hopefully that solves my problem

John

crash

05-08-2014, 09:14 AM

http://www.mcmaster.com/#94414a583/=rviv86 Hi John, A couple of options for you,How about counter sinking the hole and using a flat head fastener or have you looked into a hydraulic throwout bearing and eliminating the slave cyl.

Hydraulic throwout will not fit. Wish it would. I've tried all of them starting with the Tilton units and ending with the McCleod units that are ultra short. There's just not enough room, especially with a multidisc.

tachman

05-08-2014, 05:57 PM

http://www.mcmaster.com/#94414a583/=rviv86 Hi John, A couple of options for you,How about counter sinking the hole and using a flat head fastener or have you looked into a hydraulic throwout bearing and eliminating the slave cyl.

I'd keep an eye on the gap as the discs break in and wear; this would reduce the gap as the fingers would move outward with lining wear (and then there's a few thou of crank thrust). You should be able to feel some play by lifting on the arm connected to the slave--that's how I adjust ours. Can anything be gained by machining on the bellhousing or snout? Or perhaps a thin spacer between the bellhousing and engine. Enough to get clearance but not to lose pilot depth. You might have to add spacers to the rear mount also.

Jimh

crash

05-09-2014, 09:09 AM

I'd keep an eye on the gap as the discs break in and wear; this would reduce the gap as the fingers would move outward with lining wear (and then there's a few thou of crank thrust). You should be able to feel some play by lifting on the arm connected to the slave--that's how I adjust ours. Can anything be gained by machining on the bellhousing or snout? Or perhaps a thin spacer between the bellhousing and engine. Enough to get clearance but not to lose pilot depth. You might have to add spacers to the rear mount also.

Jimh

Just an FYI, that will also change starter pinion depth, which we seem to have at a minimum already.

kabacj

05-09-2014, 04:15 PM

http://www.mcmaster.com/#94414a583/=rviv86 Hi John, A couple of options for you,How about counter sinking the hole and using a flat head fastener or have you looked into a hydraulic throwout bearing and eliminating the slave cyl.

Hi Mike,

Your suggestion of counter sinking the hole and using a tapered flat head fastener was plan B. The only down side to that solution that the holes in the throw out bearing carrier have some tollerance when bolted from above. The bearing guide can slide around and seat in the bell housing. If i were to counter sink the bolts my holes would need to be spot on as they now dictate the position of the bearing guide. I was also thinking that I could thin the rear section of the bearing guide to gain a few tenths.

Originally Posted by kabacj

You can not see the air gap between the clutch and throw out bearing on this transaxle as the bell housing does not have an access window.

Originally Posted by longislandwrx
Is it possible to add one?

Yes I was thinking of cutting a hole and adding a brass plug. As suggested its possible to feel the air gap using the linkage, but its easier to tell how big the air gap is when you are looking at it.

I'd keep an eye on the gap as the discs break in and wear; this would reduce the gap as the fingers would move outward with lining wear (and then there's a few thou of crank thrust). You should be able to feel some play by lifting on the arm connected to the slave--that's how I adjust ours. Can anything be gained by machining on the bellhousing or snout? Or perhaps a thin spacer between the bellhousing and engine. Enough to get clearance but not to lose pilot depth. You might have to add spacers to the rear mount also.

Jimh

Good point regarding adjusting for wear. Its possible to gain a little more clearance machining the bell housing so the throw out bearing guide sits slightly deeper. Hower we are limited by the linkage that operates the throw out bearing. The throw out bearing linkage also can be slightly modified.

As you and crash point out shimming the bell housing will also require starter pinion adjustment. Thats actually not very difficult as the IMI 140 starter has a aluminum 1/2 inch thick machined part that mates the starter with the bell housing. I can remove that and turn it to the proper thickness.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/2AF7E4D4-907E-496B-8946-5BD0717F4EB5_zpsttcat8fq.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/2AF7E4D4-907E-496B-8946-5BD0717F4EB5_zpsttcat8fq.jpg.html)

I could shim the bell housing using a strip of aluminum cut to match the outline of where the bellhousing meets the block. Machine down the starter mount by the same amount and then I would need to weld up and re drill the holes in the carrier that hangs the transaxle not a big deal.

I think I could gain 1/4 inch of air gap that way.
Lets hope it does not come to that.

Thanks for all the suggestions guys.

John

Cobra 61

05-09-2014, 07:21 PM

I your spare time, might I suggest getting a plane ticket and coming to Ca. for a track day and drive my GTM. "For your own piece of mind. It will be worth it." eric burden

mikespms

05-09-2014, 08:49 PM

Hi John,

You should not have a problem as long the the thickness of the flange is not less that the taper on the head of the fastener and you use a counter sink to matches the head of the fastener usually 82deg. Make sure that when you counter sink you don't go to deep so that the threads don't bottom out before the taper.

kabacj

05-09-2014, 08:52 PM

I your spare time, might I suggest getting a plane ticket and coming to Ca. for a track day and drive my GTM. "For your own piece of mind. It will be worth it." eric burden

Hey Richard.

I'm in California often. Thanks for the offer. Arrive and drive?!? I would not know what to do with myself. A marathon build session is part of my ritual before going to the track

But I'm sure you are right. Because I don't have experience I'm only guessing. Experience is worth quite a bit and will ultimately save me lots of trial and error

John

kabacj

05-13-2014, 05:29 PM

Thanks all for the suggestions.

I was able to take the car out for a test drive over the weekend and WOW. I can't believe how good the sequential shifts.

Of course I was not driving on the track, but it's amazing how smooth the shifts are. It's a dog box where fingers grab instantly instead of syncros slowly getting everything spinning the same speed. But it's not bone crushing. Pretty cool!

I was instantly transported to my 125 gp bike racing days where with an ignition kill its possible to shift up and down at will. No clutch.

Of course I'm not getting away with that above idle rpm and 30 mph but it's cool none the less.

All I need to do is install a fire system, battery cut off, window nets, seat brace, rear tow hook, relocate the manual fire extinguisher and a few odds and ends and I'll be ready to get my NASA racing license on Friday.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/C6A8C4EC-77E9-403F-B6D0-2F3C9FA9ABA3_zpsagumfztx.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/C6A8C4EC-77E9-403F-B6D0-2F3C9FA9ABA3_zpsagumfztx.jpg.html)

Plenty of time!

John

kabacj

05-14-2014, 05:10 AM

Good progress last night.

The rear tow hook is installed. http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/B3886BA9-C131-41AA-82E4-2E5DEDFB5DB0_zpshnpuyrov.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/B3886BA9-C131-41AA-82E4-2E5DEDFB5DB0_zpshnpuyrov.jpg.html)

I welded a bit of 1/4 inch plate and a longitudinal brace to the rear sub frame. Then welded an aluminum coupling nut on to the subframe. This setup should be strong as well as removable. I was thinking that I can also attach a drag chute using the same nut for top speed events.

Here is a view from the inside.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E080AC40-B0CA-4A18-AC8C-9000FD10F144_zpsk8mev1yl.png (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/E080AC40-B0CA-4A18-AC8C-9000FD10F144_zpsk8mev1yl.png.html)

John

fastthings

05-14-2014, 07:38 AM

Lookin good man, curious, where are you towing from the front. Iv'e been looking at that area trying to find a good location for a tow hook.

kabacj

05-14-2014, 02:01 PM

Lookin good man, curious, where are you towing from the front. Iv'e been looking at that area trying to find a good location for a tow hook.

Hey Gene. I did some fab work to install the hook where I wanted it.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/494AFD24-96AC-465B-A38A-E6D8C5935570-12937-000025C0941958D6.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/494AFD24-96AC-465B-A38A-E6D8C5935570-12937-000025C0941958D6.jpg.html)

You can check out more detail on how I did it on this thread.

http://thefactoryfiveforum.com/showthread.php?3603-Does-your-GTM-need-a-tow&referrerid=3030

kabacj

05-14-2014, 09:33 PM

You know how when you are under pressure somthing always goes wrong to compound the problems you need to deal with?

This weekend the kids wanted a ride in the GTM. Because the clutch is very abrupt when it grabs I was trying to feather it but not revving like i would normally. With the almost 10 lb lighter flywheel it's easy to stall. So I stalled it and of course it has a tiny back fire out of one of the cylinders. The foam doesn't like that. The foam burns easily.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/AFE8D96E-3D95-423C-9F74-0609C84C572E_zpstt58nosh.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/AFE8D96E-3D95-423C-9F74-0609C84C572E_zpstt58nosh.jpg.html)

Two day delivery to the rescue

fastthings

05-15-2014, 07:40 AM

kabacj

05-16-2014, 06:34 PM

You could just use some duct tape on that.:)

Very cool on the front tow, I was thinking the same type of thing. I just wasn't sure about clearence with the hood open. I want to be done with mine so bad, but I just can't see finnishing this car without a place to tow it from.

Thanks

Well the good thing is these filters come with pre filters, so I could just put another layer of foam on top of what I have already. Luckily these filters are cheap. Regarding finishing the car, I use the tow hook all the time to pull it into the trailer. I think its a worth while addition.

Regarding being done. You only start driving it, your never really done :)

So after my mad rush to get everything installed in time. I did it. I got my NASA log book today.

my log book.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/7C774529-0CE7-44DA-9520-38E777AC7743_zpskf2x9q54.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/7C774529-0CE7-44DA-9520-38E777AC7743_zpskf2x9q54.jpg.html)

my 2014 tech sticker

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/2EB0A40E-3D7F-4F2F-8F4E-16A312EA10F3_zps3ixgvk60.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/2EB0A40E-3D7F-4F2F-8F4E-16A312EA10F3_zps3ixgvk60.jpg.html)

Boy was it a rainy day today.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/4BDED7DD-498B-47AA-8012-B72B878B3CFC_zpsws2m0pfh.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/4BDED7DD-498B-47AA-8012-B72B878B3CFC_zpsws2m0pfh.jpg.html)

The rain was so heavy at times that they actually canceled the run group, because we couldnt see.

Unfortunately not all of my electronics are rain proof. The isis is fine. But my rear view camera and rear view monitor might be kaput. I am drying them now, maybe they will work, but im not hopeful. Luckily both are cheap.

The biggest downside will be the fact that I dont have a good rear view for tomorrow or Sunday. I purchased a bunch of blind spot mirrors to try to improve my analog viewing capability.

Technology is fun, but good old fashioned mirrors are still better in many ways.

KeithBoden

05-19-2014, 10:02 AM

Looking awesome, standing still, or at speed! I'm still hoping to get to the track when you are there some time to say hi, how did the transaxle operate?
29277

29276

crash

05-19-2014, 11:51 AM

Wow!

That picture of the car at speed is one of the best ones I have seen in a long time. Saved it and it will be in my screen saver portfolio. :)

kabacj

05-19-2014, 04:56 PM

Looking awesome, standing still, or at speed! I'm still hoping to get to the track when you are there some time to say hi, how did the transaxle

That would be great Keith. I would love to see you at the track.

You would not believe how many compliments and questions I get. It's non stop. My car is not even near finished and far from show quality. The whole bodywork and paint took me an afternoon.

Your pictures make it look like a million bucks however. Thanks for posting.

I think I am going to frame this one.

http://i1073.photobucket.com/albums/w389/kabacj/01937E83-9198-4528-8A03-C6B40009183E_zpsrooinjog.jpg (http://s1073.photobucket.com/user/kabacj/media/01937E83-9198-4528-8A03-C6B40009183E_zpsrooinjog.jpg.html)

The new transaxle is awesome. I'll have a track report out tomorow am with the whole story.

Thanks again for the pics.

John

The Stig

05-19-2014, 05:39 PM

Your pictures make it look like a million bucks however. Thanks for posting.

I think I am going to frame this one.

http://i1073.photobucket.com/albums/w389/kabacj/01937E83-9198-4528-8A03-C6B40009183E_zpsrooinjog.jpg (http://s1073.photobucket.com/user/kabacj/media/01937E83-9198-4528-8A03-C6B40009183E_zpsrooinjog.jpg.html)

John

Very cool picture!

Mike

VD2021

05-19-2014, 08:21 PM

That would be great Keith. I would love to see you at the track.

You would not believe how many compliments and questions I get. It's non stop. My car is not even near finished and far from show quality. The whole bodywork and paint took me an afternoon.

Your pictures make it look like a million bucks however. Thanks for posting.

I think I am going to frame this one.

http://i1073.photobucket.com/albums/w389/kabacj/01937E83-9198-4528-8A03-C6B40009183E_zpsrooinjog.jpg (http://s1073.photobucket.com/user/kabacj/media/01937E83-9198-4528-8A03-C6B40009183E_zpsrooinjog.jpg.html)

The new transaxle is awesome. I'll have a track report out tomorow am with the whole story.

Thanks again for the pics.

John

This is just an awesome photograph......:cool:

kabacj

05-20-2014, 09:04 PM

Quite an exciting 3 days at the track.

The culmination of a build idea started in May 2 years ago at the start of this thread. My version of GTM chassis is approved for wheel to wheel racing.

As is everything we do in life , my solution is heavily based on feedback and the experience of other people. Richard , Mike(crash) and Ted (quick racing products), Karen and Hank . As well as Joel who actually did the FEA to make sure this cage design will work. Thank you all for the help.

The racing school started with an over cast day at around 9am. By 9.30 when we were ready to go out on the track the heavens opened. I have not done anything to keep out water on the GTM and lots of water comes in! The windows must be open and at some points the amount of rain coming in the window was as if I was racing in the rain on a motorcycle.

Since I had brand new un scuffed Toyo 888s I had little traction. Well “little” is a bit of an understatement. I barely had any traction. After 3 sessions I still had some of the stickers left on the tires! It definitely made for a interesting drive.

Of course I had planned to have a set of rain tires ready for my first track weekend just in case, but my rim order was delayed over 2 months for various reasons.

I also had lots of new and un tested stuff on the car for this weekend.

-deleted the cats (sounds GREAT)and probably a bit more power and no longer burns the CVs
-added the aluminum rear sub frame / bumper and mendiola sequential with heavily modified shifter using my recycled cables from the SDR (too short so needed to be extended)
-light weight flywheel and twin disk racing clutch
-new tires R888 and increased the front tire size to 275 from 245 RA1 I was running last year.

After my initial issues getting the clutch setup optimized, the sequential is unbelievable. Before I needed to plan my shifts bc I needed enough time to get the shift done. Now I can shift anywhere any time. I tried shifting mid corner. I drove it in pouring rain. Both were uneventful. Major improvement for the track.

The combo of new tires and the sequential made the car much easier to drive when the track finally dried out. When you don’t need to worry about things, it frees up mental resources. Not worrying about shifting allowed me to run right in line with my average lap times from last year the first session out on the track in heavy traffic.

The GTM feels better then it ever has! I am getting closer to a good racing setup.

The only thing that was holding me back was a bit of rear end instability that has cropped up over the last few weekends. I had attributed the cause to way over used tires, but with 4 new tires I still have a serious wiggle when I pop off the throttle after a left hand turn. It almost feels like the passenger tire toes out or brakes when the car does its hard wiggle.

As I went faster the problem started to show.

Both rear wheels are rock solid. Bearings and all suspension points are very tight.
I swapped the rear shocks left to right to make sure it was not a shock setting or broken valving. I checked every nut and bolt in the suspension. All are tight and have not moved since installation. I thought it could be one of the outer corvette CV joints going so I swapped in my new axles and outer CV joints and hubs.

Because the new outer CVs and stub axles are wider then the corvette CVs. I needed to flip the shocks to make clearance. Both shocks are bolted in with nice ARP bolts.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/13F4F7F1-B305-4F7C-964C-FF5281F0EC10_zpskeqtf7d4.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/13F4F7F1-B305-4F7C-964C-FF5281F0EC10_zpskeqtf7d4.jpg.html)

Unfortunately the ARP bolt and stainless fastener galled and the stainless nut cold welded it self on. I tried to break it off, but those stupid ARP fasteners are impossible to break.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/4E9C4A90-0BAD-480D-A5B7-0599391FF17D_zpsgijwytxz.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/4E9C4A90-0BAD-480D-A5B7-0599391FF17D_zpsgijwytxz.jpg.html)

If I had more time I could have cut it off, but only had 35 min before the track closed for the night on Sunday. Just enough time to swap the axle and do a test lap if everything worked as it should. The passenger side is actually more likely to be the problem based on how the car acts but I was only able to replace the drivers side axle. Ill cut off the bolt and add a little anti seize to the replacement ARP bolts.

Next step is a good alignment and corner weight. Unfortunately in order to see the instability problem I need to drive pretty aggressively. Not something I can do on the street. Id hate to go the next event without knowing the problem is fixed.

Any ideas of how I can test the rear end for weird binding or deflection would be appreciated.

John

Hankl

05-21-2014, 12:38 AM

John,

The car has really come into its own! Glad I was able to help.

Hank :cool:

fastthings

05-21-2014, 07:31 AM

Put a camera at the wheel and watch it. I think you will see the toe changing. My buddy had a Vette that did that, bad. He said it was normal, I told him it was scary. Do a search for corvette rear bump steer.

JCHRacer

05-21-2014, 09:13 AM

Great work John....congrats.

I would suspect rear bump steer as well. Do you still have the soft Corvette bushings? Big power, soft bushings and bump steer are a bad combination. I use this to set the bump-steer on my cars:

https://www.pegasusautoracing.com/productdetails.asp?RecID=2598

With your McGiver skills, you can most likely rig up something cheaper but this concept is pretty good.

crash

05-21-2014, 10:06 AM

I would check everything on your rear toe links, including the mounts for any signs of distress. One of the very early things that we did on the FFR PDG GTM for racing was to strengthen the inner mounts with bracing and to go to real rod ends inner and outer. Deflection under moderate loading was the issue. In the second picture you can see the diagnol that we added that goes from the back of the toe link mount down to the frame on the left rear.

2933829339

kabacj

05-22-2014, 05:37 AM

John,

The car has really come into its own! Glad I was able to help.

Hank :cool:

Thanks again Hank. Hopefully I can get out to Cali with the car and run a weekend with you guys.

Put a camera at the wheel and watch it. I think you will see the toe changing. My buddy had a Vette that did that, bad. He said it was normal, I told him it was scary. Do a search for corvette rear bump steer.

Hey Gene. I agree bump steer could be a possibility. I did lots of research on the bump steer problem. I nearly eliminated bump steer on both the front and rear of the car by shimming the toe links to a location that was optimal. I will put a camera on the rear suspension/ wheel to confirm it's working as it should.

Great work John....congrats.

I would suspect rear bump steer as well. Do you still have the soft Corvette bushings? Big power, soft bushings and bump steer are a bad combination. I use this to set the bump-steer on my cars:

https://www.pegasusautoracing.com/productdetails.asp?RecID=2598

With your McGiver skills, you can most likely rig up something cheaper but this concept is pretty good.

Hi Joel. Yes I saw the same problem with the corvette bushings. I replaced them with pfadt poly bushings that are reported to control a slick shod 3300 lb c5. Could still be a problem but this setup is supposed to work. Thanks for the link. I rigged up a similar setup using a laser level with a beam splitter. I projected the beam on to a piece of paper 5 feet away from the wheel. As I ran the suspension through its travel I could mark the bump steer on the paper. I was able to nearly eliminate it front and rear.

I would check everything on your rear toe links, including the mounts for any signs of distress. One of the very early things that we did on the FFR PDG GTM for racing was to strengthen the inner mounts with bracing and to go to real rod ends inner and outer. Deflection under moderate loading was the issue. In the second picture you can see the diagnol that we added that goes from the back of the toe link mount down to the frame on the left rear.

I also saw the rear links as a weak point. I upgraded to much heavier links with rod ends as well

I checked the frame at the track. But I'll do a closer check this weekend.

Here you can see the upgraded links adjusted down at the upright to eliminate bump steer.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/8FB4896E-E095-4C70-9EA3-D60BD1D4064F-10047-000014F912D3D436.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/8FB4896E-E095-4C70-9EA3-D60BD1D4064F-10047-000014F912D3D436.jpg.html)

The weird thing is how this wiggle shows up. After a left hand turn and a full throttle 600 yard short shoot in a straight line. When I lift that's when it wiggles hard right. At worst I move over half a car width. I figure I keep the rear loaded through the corner and down the strait then when I lift it does it's weird thing.

No weird sounds. AND the most maddening thing is it did not happen at all on Saturday. But just started on Sunday. It was happening November when I last drove it.

Even though my stack DVL video/ data logger was literally filled with water after it dried out I kept working! Very surprising. I'll get a clip of what happens posed here this weekend.

My hope is I find something that was binding the passenger side axle or the outer cv is sloppy.

Thanks for the ideas guys. I'm sure we will figure it out.

John

fastthings

05-22-2014, 07:34 AM

I'm sure you checked bump steer as well as possible. Put a camera on it, I think you will be supprized. You will be amazed at how much the suspension will flex under a load. The difference between full throtle/ compressing the rear, to off the throtle/ rebond= movement. It will only have to move slightly to give you a toe out, to toe in situation. There is a whole community of Vettes out there that would love to hear how you fix that, they think it's normal and live with it.

JCHRacer

05-22-2014, 08:41 AM

Given that you have already addressed the rod end and soft bushing issues, If it turns out that deflection steer is still the issue, then stiffening up the rear steering link mounting points would be the first place to start.

After that, if still having issues (or maybe in addition to) you can set up your bump steer to actually help you. Instead of shooting for minimizing bump steer at static ride height (you can’t get zero bump steer through full travel on most suspension layouts….including the GTM) you can actually set up preferential bump steer to help the problem. You can move the bump steer curve to give you some toe-in as the rear wheel goes into compression and slight toe-out as the rear wheel goes into extension. That way, you are essentially steering the rear wheels into the turn as the car rolls…..a very stable feeling. It will also add additional toe-in under power. A fine tuning effect to be sure but maybe worth a try as you get the car dialed in.

crash

05-22-2014, 10:30 AM

kabacj

05-22-2014, 07:10 PM

I do not think a CV will show itself in the manner that you describe. Maybe a bad wheel bearing, but not a CV. In my experience the CVs either work or explode if put into bind. Anything that is causing the car to "shift" a half car width is something major. We have had "wiggles" before when a rear suspension bolt was left loose, but that was about it as far as issues with rear "wiggle". I would double check everything. Also, just an observation, but your rear outer toe link is standing off the upright pretty far for a single shear setup. I hope you have, at least, an AN bolt in there, and an NAS would be advisable.

Dynamic toe is something that is hard to tune on the GTM as the suspension is not really set up for it properly. No doubt it is what you want, and there are some reasons to change some of the pick up points on the GTM, (hint,hint)but it requires a lot of work to get there.

I agree with you the CV was a super long shot. I had checked everything else to the point where only the axle and CV were variables. (didn’t really consider the frame flexing)

Since the last time I had this issue in November. I changed the transaxle. I swapped the shocks side to side this past weekend. I adjusted the damper and spring rates all with no real change in this behavior. I have 4 new tires. Everything in the rear drive line is new except the outer CVs that are known to be robust in the Corvette. I agree if they bind they explode, but I thought maybe the axle was not sliding in and out of the CVs and some how that was jacking up that corner and it would spring out after I let off the gas and I would get my wiggle.

Yeah this is not a lose part wiggle . The first time it happened I thought I broke something. I actually have no problem driving something that is misbehaving as long as its predictable and semi controllable. This is a violent move but then its fine as if nothing happened….thats spooky.

The fact pattern of the toe link flexing the frame changing the toe actually pretty closely matches the behavior I see. Many of my fast laps on Saturday I was held up behind people in the sections of the track where I really load up that corner of the car. Also on Saturday I was not as aggressively driving as I was on Sunday where I had worked out the right gears to be in and modified my timing accordingly. It still does not explain why its only shows this behavior after left turns and not right. Now that I think about it, maybe it happened to a lesser degree after one right turn, but again I need to check the data. Its possible I just load the left side up more on this track.

This all makes me feel pretty good because stiffening up the toe link mounting point is a cheap and easy. I really tried to solve all the corvette related suspension flaws and it was pretty frustrating when I had this problem on the track but could not see any cause. Ill do some research to understand how I would change the geometry to provide dynamic toe.

Given that you have already addressed the rod end and soft bushing issues, If it turns out that deflection steer is still the issue, then stiffening up the rear steering link mounting points would be the first place to start.

After that, if still having issues (or maybe in addition to) you can set up your bump steer to actually help you. Instead of shooting for minimizing bump steer at static ride height (you can’t get zero bump steer through full travel on most suspension layouts….including the GTM) you can actually set up preferential bump steer to help the problem. You can move the bump steer curve to give you some toe-in as the rear wheel goes into compression and slight toe-out as the rear wheel goes into extension. That way, you are essentially steering the rear wheels into the turn as the car rolls…..a very stable feeling. It will also add additional toe-in under power. A fine tuning effect to be sure but maybe worth a try as you get the car dialed in.

Joel
I agree the toe link mounting points are the most likely issue. You could never generate this much side load on the street and unless you are going reasonably fast on the track it actually is not a problem either. with the increased speed and new tires I am probably just pushing the stock frame too far.

The dynamic bump steer is a great idea. I understand the concept, but ill need to learn how to modify the GTM to make it happen.

I'm sure you checked bump steer as well as possible. Put a camera on it, I think you will be supprized. You will be amazed at how much the suspension will flex under a load. The difference between full throtle/ compressing the rear, to off the throtle/ rebond= movement. It will only have to move slightly to give you a toe out, to toe in situation. There is a whole community of Vettes out there that would love to hear how you fix that, they think it's normal and live with it.

Gene

You are right. A camera will show exactly what’s going on. I’m going to work on how I can exaggerate the movements if things are flexing. 1/8 inch would be hard to see but if I say put a length of welding rod on the square tube like a pointer and had some visual reference I could see the toe link flex the frame.

Thanks for the input guys. That really helps. At least now I have a good plan for solving the issue this weekend.

I'll still post a video clip of the "wiggle" I think it's useful to see

John

GTMsomeday

05-27-2014, 04:29 PM

Quite an exciting 3 days at the track.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/13F4F7F1-B305-4F7C-964C-FF5281F0EC10_zpskeqtf7d4.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/13F4F7F1-B305-4F7C-964C-FF5281F0EC10_zpskeqtf7d4.jpg.html)

John

In the picture above the corvette CV does not look right to me. I think it should be seated more. I don't think it should be out like it is. Maybe Crash could comment. I will look at mine and see.

tachman

05-27-2014, 06:56 PM

As Crash noted we have braced the rear toe link mounts on the PDG car. Before that we could apply force to a tire by sitting on the floor and using legs to steer the tire while someone watched the mount and link move.

We are now faced with a similar problem where the car behaves perfectly with a 320 tire on a 12" rim but turns evil with a 355 tire on a 13+ rim that is widened only outside the hub. I'm considering that since the rear uprights are really front uprights with a 'solid' toe link you have to consider scrub radius like you would in the front (we tried front spacers for caliper clearance with evil results). With the widened wheel the tire center is moved more outward of the ball joint axis thus applying more force to the toe link and suspension bushings. In addition the increased track width makes any unequal accel or braking force between the rear tires have more leverage to alter the direction of travel. I want to try either eliminating the 1" spacers which will help the track width issue but really won't address the scrub radius issue--or just reverting to the 12" rims which could solve both issues.

Just thought I'd throw this out there to see what you or the community might think.

Jim H
Team PDG

kabacj

05-28-2014, 04:50 AM

In the picture above the corvette CV does not look right to me. I think it should be seated more. I don't think it should be out like it is. Maybe Crash could comment. I will look at mine and see.

Very good catch. The corvette cv / axle is actually loose in this picture. I was in he process of taking the axle out and then stalled by the gauled arp nut and bolt on the lower shock mount.

The cv should be closer to the upright when everything is installed.

John

kabacj

05-28-2014, 06:26 AM

As Crash noted we have braced the rear toe link mounts on the PDG car. Before that we could apply force to a tire by sitting on the floor and using legs to steer the tire while someone watched the mount and link move.

That's a great idea. This past weekend i spent some time bracing the right rear toe link mount. I can rig up something to apply side load to the rim and measure deflection on the toe link on the braced and un braced side. It would be great to have some measurement of what load is required to deflect the tire and rim.

We are now faced with a similar problem where the car behaves perfectly with a 320 tire on a 12" rim but turns evil with a 355 tire on a 13+ rim that is widened only outside the hub. I'm considering that since the rear uprights are really front uprights with a 'solid' toe link you have to consider scrub radius like you would in the front (we tried front spacers for caliper clearance with evil results). With the widened wheel the tire center is moved more outward of the ball joint axis thus applying more force to the toe link and suspension bushings. In addition the increased track width makes any unequal accel or braking force between the rear tires have more leverage to alter the direction of travel. I want to try either eliminating the 1" spacers which will help the track width issue but really won't address the scrub radius issue--or just reverting to the 12" rims which could solve both issues.

Just thought I'd throw this out there to see what you or the community might think.

Jim H
Team PDG

I was wondering why you guys were not running wider rear tires! I have 335s on a 12 inch rim with 51mm offset for clearance of my stop tech big brake kit And 275s on the front. On my car I have the brake balance set so the rear end has a large influence on corner entry. I trail brake right to the apex and I can feel the rear tug on the car but it's nothing bad. That said braking balance is neutral /slightly front biased as the inside front locks before the rear on corner entry.

This past weekend driving with unstuffed 888s in a downpour I was able to confirm the balance as lockup was as simple as braking at all. Hard acceleration was also neutral when I could get traction as the track changed from flooded with standing water to just wet.

My theory is that if the GTM is well behaved with little traction in the rain, my instability might just be the rear toe link mount moving.

Roger Reid

05-28-2014, 08:44 AM

...We are now faced with a similar problem where the car behaves perfectly with a 320 tire on a 12" rim but turns evil with a 355 tire on a 13+ rim that is widened only outside the hub. I'm considering that since the rear uprights are really front uprights with a 'solid' toe link you have to consider scrub radius like you would in the front (we tried front spacers for caliper clearance with evil results). With the widened wheel the tire center is moved more outward of the ball joint axis thus applying more force to the toe link and suspension bushings. In addition the increased track width makes any unequal accel or braking force between the rear tires have more leverage to alter the direction of travel. I want to try either eliminating the 1" spacers which will help the track width issue but really won't address the scrub radius issue--or just reverting to the 12" rims which could solve both issues...

2 solutions to keep the wheel center from moving outward from the ball joint axis. Move upper and lower a arm pivot points outwards or longer custom A arms. Both of these would require a change in wheel offsets or less or no wheel spacer to keep the tire contact patch in the same position.

tachman

05-28-2014, 11:10 AM

I want to try either eliminating the 1" spacers which will help the track width issue but really won't address the scrub radius issue--or just reverting to the 12" rims which could solve both issues.

Oops, I realized I'd contradicted myself right after shutting down the computer to go unload the car--changing the spacer would in fact alter the scrub radius as it did in the front. Richard and I measured the track width with the widened wheel vs the 12" ones and found that we still needed some spacer for caliper clearance but going from the 1" to a 3/8" spacer got the track width much closer and hopefully the SR would get closer to normal.

Admitting mistakes is essential to proper race team operation,
Jim H
Team PDG

crash

05-28-2014, 11:41 AM

kabacj

05-28-2014, 12:28 PM

I'm just going to think out loud here for a minute, so please, if my train of thought is incorrect, then point it out...

2800 LBS car

Roughly 40/60 split front to rear weight distribution.

I'll get conservative and estimate 1400 LBS in rear.

Two tires, so weight is divided by two...700 LBS.

Data shows over 2 Gs of lateral loading.

Therefore back up towards the 1400 LBS in dynamic loading. Probably higher as when side loads increase the inner tire does less work(usually) than the outer tire.

Granted that upper and lower arms take most of this load. Still, one would be "hard pressed" to develop a test rig that will apply 1400 LBS of load to the rear suspension.

Now consider the fact that we used to be able to see it move by using our legs to push on the wheel...

Conclusion? The rear suspension is going to move and flex in a dynamic way under the loads we are now producing.

Also I believe it is imperative to look at the rear suspension system dynamically and to maybe start with something closer to 1/8 toe in, but also to see where it goes when loaded. A 1/16 toe in is pretty light, especially considering that would be 1/32 per side.

In general, the cars I have raced have been very sensitive to toe adjustments. The GTM appears to be no different, and a wider tire just exaggerates the situation because of the distance between the hub and the outer edge of the bigger tire. Moving the upright away from the tire centerline may even exacerbate this issue.

Agree good points.

My idea for side load was to use a bottle jack against the concrete wall and one side of the rim and a dial indicator on the on the edge. All this while the tested wheel was on a turn plate. I can use my friends trailer tongue weight scale to measure the load.

I'm sure I could generate tons of force. Actually break stuff if I'm not careful. The only goal of the exercise was to see if setup A is more stiff then setup B.

But yes it's a dynamic system with lots of variables and a side load test would only be information not a conclusion.

You think adding more rear toe would help? I'm game for that.

I'm thinking stiffer is better to try to limit the dynamic nature of the toe link setup. If it's at all possible to measure. That would be helpful.

My goal is to have a bag of tricks to pull from next weekend at the track.

I'll make the rear as stiff as I can without major surgery. Then I would love to have some tuning tricks to try.

This discussion has been very helpful.

John

crash

05-28-2014, 01:24 PM

Agree good points.

My idea for side load was to use a bottle jack against the concrete wall and one side of the rim and a dial indicator on the on the edge. All this while the tested wheel was on a turn plate. I can use my friends trailer tongue weight scale to measure the load.

I'm sure I could generate tons of force. Actually break stuff if I'm not careful.

I'm sure you will find the limits of tire adhesion to the floor pretty quickly!

tachman

05-28-2014, 01:46 PM

Mike and John,
My concern on the deflection issue was chiefly toe changes (and more offset force moments trying to yaw the car) from accel and decel, not as much from lateral load, that could occur with increased track and scrub radius. Side load would cause toe change (and camber loss) more from aframe bushing deflection since the load is from the tire contact patch and also from bump steer with the vertical movement from roll.

To test for toe change from accel or decel the force could be applied from front or rear, rather than from the side, to the outside of a wheel or test fixture to generate a moment around the ball joint axis. (Ratchet strap to wheel?) This would show if the toe link or the bushings are causing the issue. We also found hub bearing deflection was an issue before going to the Z06 hubs. BTW I repeated the sitting on the floor leg test and noted much less movement than in the test done in '09 before the upgrades.

A test putting side load ahead or behind the hub might better test contact with another object.

JimH

LS MAN

05-28-2014, 02:48 PM

The weird thing is how this wiggle shows up. After a left hand turn and a full throttle 600 yard short shoot in a straight line. When I lift that's when it wiggles hard right. At worst I move over half a car width. I figure I keep the rear loaded through the corner and down the strait then when I lift it does it's weird thing.

John

John, this may not be a rear end problem. Most rear steer instability caused by rear toe, or rear bump steer problems are felt under throttle load, not off throttle.
This may be a problem in the front end. With the throttle applied, the torque reaction of the rear suspension geometry is lifting the front end, when you lift off the throttle, weight is transferred back to the front end. Sounds like your car may be reacting to this forward weight transfer.
It may be possible that there is some static cross weight, more loading on the RF than the LF, (or LF loaded more the RF with toe-in). also could be some preload in the front swaybar causing this.
Have you scaled the car to check your corner weights? make sure you disconnect the sway bar when checking the corner weights. Also a difference in the compression settings of the front shocks, could be a weak shock, (check your gas pressure in shocks too).
Could be a front toe-in problem also, are you running front toe-in or toe-out?
Hope you get her figured out, keep up the good work, very impressive.

kabacj

05-28-2014, 07:47 PM

kabacj

05-28-2014, 07:57 PM

John, this may not be a rear end problem. Most rear steer instability caused by rear toe, or rear bump steer problems are felt under throttle load, not off throttle.
This may be a problem in the front end. With the throttle applied, the torque reaction of the rear suspension geometry is lifting the front end, when you lift off the throttle, weight is transferred back to the front end. Sounds like your car may be reacting to this forward weight transfer.
It may be possible that there is some static cross weight, more loading on the RF than the LF, (or LF loaded more the RF with toe-in). also could be some preload in the front swaybar causing this.
Have you scaled the car to check your corner weights? make sure you disconnect the sway bar when checking the corner weights. Also a difference in the compression settings of the front shocks, could be a weak shock, (check your gas pressure in shocks too).
Could be a front toe-in problem also, are you running front toe-in or toe-out?
Hope you get her figured out, keep up the good work, very impressive.

Hey Ted,

Thanks for the feedback. I tried swapping the rear shocks side to side but ill also try the fronts. I verified that both compression and rebound are the same. I would agree with you that the weight transfer could be a problem, but I also have little wiggles on the exit of the corner as the rear end unloads. It feels just like if you hit a slick spot then it catches and its fine again. This problem could be the front, but I dont get any feedback from the steering wheel and the car rotates from the rear like a slide but does not turn from the front like you would expect if the front was the issue.

Im running toe in on the front 1/16th.

At least I was last time I checked it. After I put the rear back together a full alignment and corner weight will be done.

Your suggestion is a good one. Ill add the front check out to my list of things to verify and also to troubleshoot at the track.

I know the car will do well if I can just run it full out. Thanks for the suggestion.

John

fastthings

05-29-2014, 07:35 AM

I have felt that wiggle in a Vette, I didn't like it. I can't wait till you figure this out.

Fraser D

05-29-2014, 07:52 AM

LS MAN

05-29-2014, 12:16 PM

Hey Ted,

Thanks for the feedback. I tried swapping the rear shocks side to side but ill also try the fronts. I verified that both compression and rebound are the same. I would agree with you that the weight transfer could be a problem, but I also have little wiggles on the exit of the corner as the rear end unloads. It feels just like if you hit a slick spot then it catches and its fine again. This problem could be the front, but I dont get any feedback from the steering wheel and the car rotates from the rear like a slide but does not turn from the front like you would expect if the front was the issue.

Im running toe in on the front 1/16th.

At least I was last time I checked it. After I put the rear back together a full alignment and corner weight will be done.

Your suggestion is a good one. Ill add the front check out to my list of things to verify and also to troubleshoot at the track.

I know the car will do well if I can just run it full out. Thanks for the suggestion.

John

John, how are you setting the rear toe-in? It is critical to understand that rear toe settings are each wheel set to the chassis centerline, not just the total toe in. The fact that the car pulls only to the right may indicate that the rear toe vector is not pointing to the center of the car. We string each rear wheel to the center of each front hub, so that if you want 1/8" rear toe in, each side must have 1/16", and the measurement of the string line at each front hub must be the same, so that the rear end is not dog-tracking.
Also try 1/16" - 3/32" toe-out in the front, surprising how much more stable it is.. Both the PDG GTM & our SLC race with front toe out.
Hope this helps,

kabacj

05-29-2014, 12:23 PM

John, how are you setting the rear toe-in? It is critical to understand that rear toe settings are each wheel set to the chassis centerline, not just the total toe in. The fact that the car pulls only to the right may indicate that the rear toe vector is not pointing to the center of the car. We string each rear wheel to the center of each front hub, so that if you want 1/8" rear toe in, each side must have 1/16", and the measurement of the string line at each front hub must be the same, so that the rear end is not dog-tracking.
Also try 1/16" - 3/32" toe-out in the front, surprising how much more stable it is.. Both the PDG GTM & our SLC race with front toe out.
Hope this helps,

Thanks for the info Ted. I spent a few hours measuring the centerline and marking it on the car for later use. Then stringing the car and setting the wheels to dead zero verifying that measurement and then setting toe from there.

I'll try toe out. I'm actually happy with stability but maybe I don't know what I'm missing :)

Thanks again.

John

kabacj

05-29-2014, 08:55 PM

John,

My setup is stock FF5/Corvette with the exception of poly bushes on the control arms only and aftermarket brake disks.
last Friday I had the car on the local CAT scales for registration purposes and with full stock corvette tanks weighed in at:
Total 2540lbs
Front 960lbs
Rear 1580lbs
Ride height is set at 4 1/2"
Tires are 275 front and 335 rear, (all are 888’s)
I don't have my current alignment figures with me.
When I had my car at the track I was experiencing very similar issues that you are describing with the car becoming unsettled when getting off the gas and on the brakes at over 140mph so I am very interested in this discussion.
I have an appointment with the alignment shop this weekend and a track day next Wednesday and am willing to work with you on some of the suggested setups to see what works.

Hey Dave,

Sounds like fun. What track are you planning on visiting?

As you can see from the experts the GTM is very sensitive to alignment.

here is the setup I used last year that worked well.

Left Front Right front
caster -3 caster -3
camber -2.8 camber -2.7
toe -1/16 toe -1/16

Left Rear Right Rear
camber -1 camber -1
toe -1/16 toe -1/16

for this time I am going to try toe out as Ted suggests.

I will also try a little more rear toe as Mike suggested.

I will also remove .25 degrees of camber from the rear. I found that I was getting a little too much heat and wear on the insides of the rear tires.

Also note that i did not see any ill handling until I started to really carry some G load. On my best lap last year I pulled 1.6 Gs.This past weekend I was pulling 2Gs

Im not saying that you are not having the same problem, just saying that I would first make sure the alignment is good then start chasing other things. Like I said I had a very stable car going faster then all or most all of the guys at the track last year. It was only going up against full on race cars that brought out my current issue.

You are also running a big torquey turbo motor so maybe you are showing the same toe link flex. No sure. I would go with the alignment as the first thing to concentrate on however.

You should try to get some rear suspension video if you can. Im going to rig up several camera angles before I go to the track in case I dont solve the problem.

John

fastthings

05-30-2014, 07:18 AM

Hey Dave,

Sounds like fun. What track are you planning on visiting?

As you can see from the experts the GTM is very sensitive to alignment.

here is the setup I used last year that worked well.

Left Front Right front
caster -3 caster -3
camber -2.8 camber -2.7
toe -1/16 toe -1/16

Left Rear Right Rear
camber -1 camber -1
toe -1/16 toe -1/16

for this time I am going to try toe out as Ted suggests.

I will also try a little more rear toe as Mike suggested.

I will also remove .25 degrees of camber from the rear. I found that I was getting a little too much heat and wear on the insides of the rear tires.

Also note that i did not see any ill handling until I started to really carry some G load. On my best lap last year I pulled 1.6 Gs.This past weekend I was pulling 2Gs

Im not saying that you are not having the same problem, just saying that I would first make sure the alignment is good then start chasing other things. Like I said I had a very stable car going faster then all or most all of the guys at the track last year. It was only going up against full on race cars that brought out my current issue.

You are also running a big torquey turbo motor so maybe you are showing the same toe link flex. No sure. I would go with the alignment as the first thing to concentrate on however.

You should try to get some rear suspension video if you can. Im going to rig up several camera angles before I go to the track in case I dont solve the problem.

John

Can't wait to see the video. The one of the suspensoin, the one showing off your new shifter, the one when your passing cars on the track, the one pulling 2gs. LOL

crash

05-30-2014, 09:46 AM

Left Rear Right Rear
camber -1 camber -1
toe -1/16 toe -1/16

I will also try a little more rear toe as Mike suggested.

John

If you are running an eighth total rear toe in, that is probably good. We were running a sixteenth total and so that was only 1/32 per side when we were having issues. Too much rear toe will also make the car unstable. It is a balancing act. I think you know this, but I would only do one change at a time so that you know what change is having what effect. :)

Fraser D

05-30-2014, 07:51 PM

Hey Dave,

Sounds like fun. What track are you planning on visiting?

As you can see from the experts the GTM is very sensitive to alignment.

here is the setup I used last year that worked well.

Left Front Right front
caster -3 caster -3
camber -2.8 camber -2.7
toe -1/16 toe -1/16

Left Rear Right Rear
camber -1 camber -1
toe -1/16 toe -1/16

for this time I am going to try toe out as Ted suggests.

I will also try a little more rear toe as Mike suggested.

I will also remove .25 degrees of camber from the rear. I found that I was getting a little too much heat and wear on the insides of the rear tires.

Also note that i did not see any ill handling until I started to really carry some G load. On my best lap last year I pulled 1.6 Gs.This past weekend I was pulling 2Gs

Im not saying that you are not having the same problem, just saying that I would first make sure the alignment is good then start chasing other things. Like I said I had a very stable car going faster then all or most all of the guys at the track last year. It was only going up against full on race cars that brought out my current issue.

You are also running a big torquey turbo motor so maybe you are showing the same toe link flex. No sure. I would go with the alignment as the first thing to concentrate on however.

You should try to get some rear suspension video if you can. Im going to rig up several camera angles before I go to the track in case I dont solve the problem.

John

John,

Thanks for the numbers and I will see how close I can get to them but I think that I will be struggling to get 3deg caster on the fronts as I have the stock FF5 control arm pickup points at the moment.
I will be running at MSR Houston for a private event track day.
http://www.msrhouston.com/about/facility-maps
This is the same track that I ran at last year in the rain.
The goal is to run some form of data logging to help understand a bit more of what is happening in regards to my driving as well as the cars handling.
If I can make it happen I will send you the data as well.

kabacj

05-30-2014, 08:18 PM

Can't wait to see the video. The one of the suspensoin, the one showing off your new shifter, the one when your passing cars on the track, the one pulling 2gs. LOL

Ok Gene, ill have cameras running. If i can sort out this handling you will get a good show.

John,

Thanks for the numbers and I will see how close I can get to them but I think that I will be struggling to get 3deg caster on the fronts as I have the stock FF5 control arm pickup points at the moment.
I will be running at MSR Houston for a private event track day.
http://www.msrhouston.com/about/facility-maps
This is the same track that I ran at last year in the rain.
The goal is to run some form of data logging to help understand a bit more of what is happening in regards to my driving as well as the cars handling.
If I can make it happen I will send you the data as well.

If you have an iphone and a good mount, harries lap timer is a great app for gathering video and lap times. It actually has much of the same data logging as much more expensive systems. It really kills the battery on your phone but beyond that its great. I usually run both harries and my stack datalogger just to have a second data source.

John

kabacj

06-02-2014, 08:07 PM

After all of the great advice from folks on the forum I formulated a plan purchased some metal and went to town.

My goal was to weld the toe link mount reinforcement without taking the transaxle out.

Sure it will only take an hour to take it out and re install, but a little inconvenience is worth the hour saved right? More on that later.

The toe link mount is attached to a single diagonal frame tube.

When force is applied to the mount it tends to twist the frame tube. Since
it's steel it's pretty flexible. You will not see a problem on the street, but sticky tires on the track overload the mount.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/d88d7aa0479cc14fe5c7a3bc3635da91_zps5c7c617d.jpg

I figured if I can triangulate the toe link mount that would be ideal. I was also looking to stiffen the lower suspension mounts as the way I figure it they get the majority of the side load from tire and upright and the way the brackets are attached are prone to twist as well.

My solution was to run two pieces of 3/4 square tube.

One between the toe link mount and the forward lower a arm mount. This will cancel one axis of twist at the lower A arm as well as one at the toe link.

Then put a brace between the x brace under the transaxle and the toe link mount.

The x brace under the transaxle is a little weak to take a side load. It's also difficult to. Weld to the x as their is not enough landing area for a tube from either side.

I fabricated up braces from 1/8 inch plate.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/A6CA8D12-AEC8-4B88-ABAA-38A07A9B044B_zpsuyycazvf.jpg

Then welded those then installed the braces.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/43DB0DCD-8F19-4922-80C5-80A0B7166794_zps3u53imxm.jpg

Oh and while I was at it I boxed in the toe link mount and strengthened the attachment to the brace going to the lower a arm mount.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/38D327A4-5109-40EB-9513-BE28B5EA5F3E_zpsjiagqhm0.jpg

What a pain it was to weld this all while the transaxle was installed. I was welding on my back, upside down on the bottom of parts overhead and wedged in the wheel well on others. Of course I'm stubborn as hell and refuse to give up on welding with the transaxle installed.

I actually did one weld hanging over the rear qtr panel head down by the axle with the tig pedal on a shelf. Silly, yes. Should I get a finger operated tig torch. Maybe. But why not just figure out how to make what you have work?

So I proved the point to myself. I can weld in suspension braces with the transaxle installed.

But guess what. Transaxle is coming out next weekend so I can weld the other side in an hour. :)

John

Cobra 61

06-03-2014, 09:16 AM

crash

06-03-2014, 10:17 AM

This weekend, we will revisit this as we are increasing tire size adding a huge increase in grip. I would suspect we will experience some additional movement in this area again.

R

:) :) :)

kabacj

06-03-2014, 09:24 PM

John,
You are right about one thing. The X brace is weak in respect to the lateral load resistance. We did what you are doing 6 years ago. We then found that the X brace was cracking at the welds to the 1.5 box tube chassis. I did it slightly different. Instead of making the gussets that fit in the middle intersection (thinking the gussets were not going to be enough) I used a 4" x 8" plate. The reason I used the plate is because the intersection of the two pieces or "area" seamed to be small and "flexy" looking. My thinking was to increase the load resistance over a larger area. The same as you would look at door bars when crossed. The intersection of the two bars can become a "hinges of sorts and that was the result of changing the door bar rule to diaphragm or gusset the intersection to eliminate this. Also, the interpretation of "two bars required for door protection. The intersection area is still only one bar at that point. Same concept, one vert and other horizontal. This weekend, we will revisit this as we are increasing tire size anss a huge increase in grip. I would suspect we will experience some additional movement in this area again.

R

Thanks for the info Richard. I left a spot to attach the x brace to the beefy 1.5 inch tubes that form the main structure of the rear frame. This way when the toe link mount brace pushes down the other strut will be in tension.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/IMG_20140603_221942_zpsncim2k8r.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/IMG_20140603_221942_zpsncim2k8r.jpg.html)

Grip is good more grip is even better. Do you think we can get 2.5gs?

John

kabacj

06-07-2014, 07:15 AM

I love data. Since everything i post here is relative and not terribly scientific I don't know that we can draw direct correlations, however a car is such a complex system you need to be far beyond my amateur level to really measure this type of stuff. Even the pros make mistakes. So now that my disclaimer is complete, I wanted to share what I think is some very cool data.

I measured the deflection of the rear rim at the 9 o'clock position using my dial indicator.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/64086286-4FA5-4A8C-92FD-797EBA319B0D_zpseberzzmv.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/64086286-4FA5-4A8C-92FD-797EBA319B0D_zpseberzzmv.jpg.html)

The goal was to compare the rim deflection between the modified side of the car and the unmodified.

The car is on jack stands. I repeated all measurements 3x going back and forth between each side of the car and averaged the results and rounded to the nearest tenth. I also measured how much I move the car itself since it is up on jack stands. During this exercise the max i could move the car is 4 thou while twisting the wheel. So assume I have a 4 thou margin of error. I took a measurement with the toe link in compression and tension. To apply force I simply twisted the tire with my arms as hard as I could yanking sightly. (not a lot of force, but its repeatable)

The un modified side of the car.

Toe link in compression -.09 inches of deflection
Toe link in tension .08 inches of deflection

Modified side of the car

Toe link in compression -.04 inches of deflection
Toe link in tension .02 inches of deflection

I was also interested in how much deflection I was getting at the center of the X under the transaxle.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/6CB1DC67-14E8-4EDD-B3CB-ACD7CB79B391_zpsunumoqqt.png (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/6CB1DC67-14E8-4EDD-B3CB-ACD7CB79B391_zpsunumoqqt.png.html)

As a control I tested the deflection when twisting the unmodified side of the car. I expect only the deflection due to me moving the car.

Unmodified side deflection under X

Toe link in compression .0005 inches of deflection
Toe link in tension -.0005 inches of deflection

Modified side of the car

Toe link in compression .03 inches of deflection
Toe link in tension -.025 inches of deflection

So my conclusion is that I can add or remove almost 1/8 inch of toe from the rear wheel while twisting it by hand on the unmodified side.

My modification has decreased that to between a 16th and a 32nd.

The transaxle is coming out and im going to brace it all up even more.

Not sure what all this means for the track , but its cool information.

John

carbon fiber

06-07-2014, 09:02 AM

John, it sure seems like you're onto something, if you can move the toe 1/8" just by pulling on it. I'm sure i'm not the only one interested in seeing how this plays out.

Fugly_Old_Cowboy

06-07-2014, 12:52 PM

stands to reason any reduction in chassis/suspension flex should improve handling...

kabacj

06-11-2014, 11:31 AM

After a few hours of careful fitting and welding I have triangulated the rear toe link mounts

First I added a strut to tie in the toe link mount and the lower forward A arm mount.

This should stiffen both the toe link and the lower A arm mounts.

Next I used that strut to box in the toe link mount.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/777838A6-A608-409D-BAD6-850A5FC3913D_zps30o2ukg8.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/777838A6-A608-409D-BAD6-850A5FC3913D_zps30o2ukg8.jpg.html)

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E2CA571F-B10A-4984-BCE7-6F2A7B908658_zpsuszdlyxx.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/E2CA571F-B10A-4984-BCE7-6F2A7B908658_zpsuszdlyxx.jpg.html)

I used the boxed in section of the toe link mount to land the forward brace.

Here is an overhead shot of the whole layout.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E030AA60-919B-40FE-A53D-6D8C783B8DC3_zpsu56mxghr.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/E030AA60-919B-40FE-A53D-6D8C783B8DC3_zpsu56mxghr.jpg.html)

Now that I'm done for this round of re enforcement. It was time to take some measurements.

What I found shocking was I could feel the rear wheel is stiffer. I guess that's because it is!

I was able to get the toe link itself down to 2 thou of deflection. So the bolt that attaches the toe link to the frame itself is only moving 2 thousands of an inch under load. Thats pretty good.

It's notable however that I was only able to decrease the flex at the wheel to a point. As the frame got stiffer the wheel did as well but flex would only lower the rim deflection to a point.

Since I have the 10 micron runout hubs I'm told were used by Pratt and Miller on the c5r and would last a season on a pro level race car. The toe links have high quality rod ends and tight tolerance attachment to the upright and frame.

I attribute most of the flex to the bushings.

Even though I have pfadt poly bushings I think there is still a bit of give especially in the first few lbs of side load as the frame / suspension takes a set. Then I think the chassis stiffness will shine as the increase in load will not increase the wheel deflection in the same way as it did before the frame upgrade.

Since you would never achieve track level side loads on the street, the stock frame and poly bushings are fine for street use an even occasional track days. As loads increase at race pace the next weakest link is exposed.

I just need to put it all back together this weekend and I'm ready for track testing and my first super unlimited race next week at Thompson Motorsports park in CT. This will be interesting as it's a new track.

Lots of folks will be learning lines. It's too bad I will not have the same track layout to test the car, as I could flex the frame every lap in the same corners time after time.

Actually just realized something. The quick shifting sequential most likely also added to the chassis load.

I could keep the suspension loaded as shifts were so quick I moved my shift points so I could stay on the gas longer.

It's always the same story. The more you improve the more you need to improve.

Sure is fun though!

John

fastthings

06-12-2014, 07:52 AM

Looks good, John.

Couple years ago I took a ride in a buddies Vette. That thing would do such a weird wiggle in the rear when he let off the gas after a hard pull, or going over a bump. I didn't like it, I kept picturing myself in the GTM, when it was done, and thinking no way in hell hell I have a car that does that. I said something to him, and he said, they all do that. Long story short I have been worried about that spot since day one.

It would be way too easy to add a support, to not do it. I'll copie what your doing I susspect, except for the 2 bars going to the rear. How important do you feel those 2 rear bars are.

Pretty cool man,
thank you

kabacj

06-12-2014, 11:58 AM

How important do you feel those 2 rear bars are.

Hey Gene

You will not have any trouble with a wiggle on the street even after a hard pull. I could not generate the instability unless I was at race pace on hot tires. Even if you were totally nuts it almost impossible to drive that hard on the street

I didn't even have it on the track till now.

The rear bars removed two thousands of flex measured under the X brace. I think you only need those on a race car.

John

carbon fiber

06-12-2014, 05:03 PM

You said "almost impossible" right?

kabacj

06-13-2014, 08:15 AM

You said "almost impossible" right?

Ha yep. This is the internet. You gotta caveat everything.

I can say this for sure. I could not duplicate the behavior on the street. When I was trouble shooting the problem I tried. The track has a large network of access roads and parking lots. No one will hastle you if you quickly test somthing.

I could never cause any instability no matter how hard I tried. On the track where there is better grip and triple digit speeds after I got up to race pace. That's where you see this behavior.

Took me a year on the track to even get up to the level where I could make it happen. I was top one or two fastest guys every weekend when the other drivers were not racers. I did not see the problem.

If you are planning a track car then stiffen it up. One or two track days a year on street tires it's optional. If you will never go on the track you are fine.

That's my opinion anyway.

John

carbon fiber

06-13-2014, 08:23 AM

Thanks for the info. I do plan on some track time, and i'll probably get addicted... VIR isn't too far away.

kabacj

06-18-2014, 05:43 PM

While I was welding the rear frame I saw this as the perfect time to weld in some supports for a rear anti roll bar.

I cut some plate and welded it in

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/37988E89-44BB-43D0-B8C7-C8FCD16D79D1_zpsmc66jxew.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/37988E89-44BB-43D0-B8C7-C8FCD16D79D1_zpsmc66jxew.jpg.html)

Then added a little gusset in back. Here it's mostly welded.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/29E5A16D-0E00-4E6D-BD89-FBD9C5B7FEC2_zpsf5tqx9qk.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/29E5A16D-0E00-4E6D-BD89-FBD9C5B7FEC2_zpsf5tqx9qk.jpg.html)

Then you can simply add any stock or after market c5 rear anti roll bar. This is nice because there are quite a few inexpensive options.

I'm starting with the stock corvette rear arb. Since I only have 4 working hours before I need to load up the car and head off to Thompson CT for the inaugural race on a brand new race track. I might not make the bar adjustable just yet.

This is the setup we are carrying over from the c5.

http://i1073.photobucket.com/albums/w389/kabacj/a8307f582b86fffafe34a59667974105_zps4de05764.jpg

3 days at the track with lots to test.

John

mikespms

06-18-2014, 06:26 PM

Hey John,

That mount looks good and strong,you are going to need to space the sway bar mount back about 3/8" to clear the rear cross member.And a mounting tab for the control arm.

kabacj

06-19-2014, 05:33 AM

Hey John,

That mount looks good and strong,you are going to need to space the sway bar mount back about 3/8" to clear the rear cross member.And a mounting tab for the control arm.

Good call Mike. Just last night I was debating on how to address the clearance issue and mounting point on the lower control arm.

One option was to flip the rear ARB over and cut off modify and re align the mounting holes on the arb.

This allows me to make the bar adjustable and spaces the bar away from the frame.

http://i1073.photobucket.com/albums/w389/kabacj/92a86bf8ac79bf31ddb21fa8a121aac0_zps37ac5e30.jpg

I was also considering welding on an aluminum tab directly to the lower A arm. Only problem there is that means pulling the whole thing out and taking the bushings out.

It will take high amperage to weld the thick plate on to the cast A arm. That will heat up the whole A arm very quickly. I think I would roast the bushings.

I'm so used to chopping things apart I imidiately go to that as a solution.

Your idea is better. Retaining the stock bar geometry is a big plus.

Thanks for posting you solution. Now I have a shot of getting the ARB sorted for the track this weekend.

John

JCHRacer

06-19-2014, 07:27 AM

crash

06-19-2014, 09:49 AM

Looking good as always John. I would think twice about welding on the aluminum control arms. I don't know about the corvette stuff in particular but most aluminum control arms are forged and heat treated and actually have much better properties than cast. Welding would reduce the properties significantly.

What he said.

Joel...I'm looking for some serrated plates to use for adjustable mounts. I can't remember if you used those in your suspension setup or not, but I have not been successful in locating a source for them yet. If anyone else might have any ideas, that would be appreciated also. These parts are typically used on panard bar attachment points and such. I have a setup on my brake pedal assembly that I may be able to get a picture of for reference if people don't know what I am talking about, but they are a trick part, and a great solution to allow wide adjustability. Any help in locating a source would be greatly appreciated.

Sorry for the detour, I just don't see Joel posting much anymore and hoped he might check back here. :)

kabacj

06-19-2014, 10:55 AM

Thanks for the feedback Joel and Crash. I have avoided welding the A arms so far with the same concern, but there is so little quality information on the A arm construction available that I was considering it. Your point taken however and I will just make a nice tab.

Crash what about these?

http://www.etrailer.com/Accessories-and-Parts/Reese/58024.html

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/CA96F30C-195A-47CB-B8FE-3E5186B2012F_zps192euezb.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/CA96F30C-195A-47CB-B8FE-3E5186B2012F_zps192euezb.jpg.html)

crash

06-19-2014, 12:19 PM

Yep. That's the idea. I need them in strips though so I can machine them to my specs as far as slots and attachments.

crash

06-19-2014, 01:40 PM

I just did another search and found the Urbine Machine stuff. They are a little course, and I would prefer a 1/8th tooth step.

Would you like me to start another thread John?

kabacj

06-19-2014, 03:51 PM

I just did another search and found the Urbine Machine stuff. They are a little course, and I would prefer a 1/8th tooth step.

Would you like me to start another thread John?

Does not bother me if we go on tangents. It's good race car building info.

KeithBoden

06-23-2014, 04:35 PM

Caught again! I have enough fun posting your pics...maybe I should spend some time in the garage instead of at work!

30485

kabacj

06-23-2014, 08:48 PM

Caught again! I have enough fun posting your pics...maybe I should spend some time in the garage instead of at work!

http://i1073.photobucket.com/albums/w389/kabacj/0b593e4bb40dc7c831af6f69e94171e3_zps79bfe8ae.jpg

Keith yet another great picture! I think you have supplied more great pics then any pros have gotten.

This shot was taken from a giant mound they left when they built Thompson. It does not make any sense till you go up there and view a race. It's a great vantage point. Thanks for the photo. I'll have a race report in the am.

John

kabacj

06-24-2014, 09:33 AM

It's Thompson Raceways inaugural race weekend. An exciting day for track lovers in the north east where we needed some variety. I had a host of changes to test on the GTM including stiffer rear toe link mounts.

Lucky for me I was pitted with the factory five brain trust. . Mark Dougherty (aka the traveling builder) ,John George( FFR challenge series national champion) , Jim Schenck (engineer responsible for the GTM), Pat Maddigan who runs a heavily modified challenge car, Brendan Dougherty who has been working on factory five cars his whole life and Chris Allen who owns a factory five coupe and is racing the spec e-30 class. Talk about a crew of guys who know what they are doing.

Friday am we had a drivers meeting and track walk. The first session was a bit hairy as nobody knew the racing line. The pace of the lap is relatively slow. The track is tight. Several turns where the camber falls off as you exit and and six pavement transitions as we enter and exit the oval.

Friday practice the verdict was good. The car was stable when transitioning from hard G turns to full throttle and off throttle. Seems like I fixed that problem.

Next step was to start tuning the car. I really should have aligned the car after all my welding, but I had marked all the suspension points and mounts to put it all back together with the same settings I started with. I know it was low probability, but work and travel ate up all my garage time in the past two weeks. It's all I had time for.

I had some instability around 120 as I went over some big dips in the front straight.

Thompson has many places where it cycles the suspension through its travel top to bottom. Our theory is that was cycling the rear toe through changes due to bump steer and getting the car into a setting range it did not like.

A toe change and addition of more shock damping and we got the car to settle down over the high speed dips on the front straight.

One thing I learned this weekend is that if you mess up the rear toe/ bump steer on this car you completely change how it handles. It's been said before but it's worth repeating. The car even turns differently when the rear toe is wrong.

The few people who have complained about stability of the car most likely had their rear toe incorrectly setup.

By mid day Saturday I had the car working well enough that I was comfortable pushing. We all had found the fast line around the track and learned where we could pass. The only bad thing was we also started ripping up the new pavement. This made passing a real challenge. Off line was covered with the small stones that make up the track surface. Marbles in the true sense. I think everyone in our group went off the track at least once on Saturday.

I spun for the first time in the GTM and the second time and drove the car sideways like a drifter countless times. One time the car swapped from left to right 5 or 6 times before I caught it. I'll have a hi-lights video soon.

Skip to my rookie race on Saturday afternoon.

Ill admit it was a little scary. Its been 10 years since I have raced anything. I don’t really know the racing protocol. Sure I learned it in the racing school but that’s not the same. We never did rolling starts or standing double yellow restarts on motorcycles… ah hell how hard could it be?

Since the track was super slick. Off line was basically unusable in many corners and nobody wanted to wreck their car on lap one. The first turn was very reasonable. HUGE difference from motorcycles. Turn one is a hairball every time, every race, regardless. You have a bunch of kids 20-30 and a few adults from 40-60 fighting to win the race in turn 1 going 5-10 wide from a standing start. Bumping is normal.

Not so with cars. Much higher dollar investment in the equipment and cooler heads prevailed. . I was the only guy out there on full tread DOT tires. That was not ideal but I did not let that stop me from trying to match corner speed with cars on full slicks. That usually worked. One lap I tried to make a pass in an off camber turn off line. Note to self, don’t do that. I instantly spun on the marbles but luckily was able to get the clutch in and lock the tires and release when I was going forward again. I didn’t need to restart the car. I don’t think I even stopped moving, just down two gears and I was off again. No flat spots . Cool! Dodged that bullet.

I only had one other close call during the race. After I was out of traffic I kept pushing my lines wider to try to carry the most speed through the corners. Of course that got me very close to the slick line. Acutally into it a few times. Its possible to drift a GTM! Not the fast line, but its fun.

I ended my rookie race without further incident. To my surprise I got 3rd place in SU.

The two winners were driving 850+ hp TA1 Trans Am cars. Im not in their league yet, but ill get there :) Lots of folks driving the high horsepower cars spun off including me. I was just lucky enough to limit the time penalty .

My first car racing trophy.

http://i1073.photobucket.com/albums/w389/kabacj/8014DA20-D418-4D80-94B7-B4F097F25B9D_zpsxxluqzfp.jpg (http://s1073.photobucket.com/user/kabacj/media/8014DA20-D418-4D80-94B7-B4F097F25B9D_zpsxxluqzfp.jpg.html)

John

Mark Dougherty

06-24-2014, 10:02 AM

John
It was awesome meeting you. and being able to put a face to the name.
You did great at the track.
Keep tuning and you will find alot more in that car.
Later
Mark D

carbon fiber

06-24-2014, 10:09 AM

Excellent write-up John. I can't wait to see the vids on this one. Glad the frame beef-up helped, I'll be doing the same mods, thanks for pioneering.

kabacj

06-24-2014, 11:08 AM

John
It was awesome meeting you. and being able to put a face to the name.
You did great at the track.
Keep tuning and you will find alot more in that car.
Later
Mark D

Thanks Mark

It was great meeting you as well. Guess what! You know how you were saying I should go full stiff on the shocks. I did that on sunday am and ran a half a second faster!

Thanks so much for your help.

For the group ill spend some time on the suspension setup I used as soon as I have time to measure it at home. Measurements i take at the track are always suspect so I want to verify them all before I post them.

I made at least one mistake with the toe settings and boy was that noticeable. a few turns in the wrong direction on the toe link and the car transformed from good to un driveable. Oops. Oh well. A good learning experience.

John

crash

06-24-2014, 01:30 PM

Great write up. Glad you are having fun.

Fraser D

06-25-2014, 09:53 AM

Congrats John!
I am looking forward to seeing your vids.

fastthings

06-25-2014, 10:26 AM

Good show, can't wait to see some of the video.

kabacj

06-25-2014, 01:30 PM

Thanks guys. Ill have the video done ASAP. I have a few hours of video to watch and edit.

While we are waiting im looking to add the dry sump and a set of wider front rims shod with race slicks.

I need to step up my game now if I plan to be successful in Super Unlimited.

Shopping for the dry sump setup seems like I have quite a few options.

Anybody have an endorsement for a particular system?

Thanks
John

crash

06-25-2014, 02:05 PM

Plebeian

06-26-2014, 12:36 AM

Great report. What was the lap time difference comparing your car to the Trans Am cars?

kabacj

06-26-2014, 05:10 AM

I use ARE stuff, my buddy and my engine builder both swear by the Daley stuff, and the FFR PDG GTM runs the ASA spec engine setup. The ASA stuff is BY FAR the cheapest way to go. Give Richard Migliori a call and he can give you some contacts to help in tracking down the parts. We just set up a complete spare engine so I know he just spoke with the supplier back east. If you need his number PM me.

ARE can be found here...www.drysump.com

I was also leaning to the ARE setup. I have two quotes. One for a 2 stage and one for a 4 stage system. Am I correct in my understating that the 4 stage simply creates more vaccume when compared to a 2 stage?

And with that extra vaccume I'll actually pull the oil through the motor instead of depending on gravity to return the oil to the bottom of the motor?

Thanks for the help

John

kabacj

06-26-2014, 05:34 AM

Great report. What was the lap time difference comparing your car to the Trans Am cars?

Well since I'm not yet up to speed in the GTM I'd say my times are a bad example. I dropped 5 seconds over the weekend and was still making changes on Sunday when I dropped into the 1.19s. John George on the other hand is a very good driver running a well setup car. He was 3 seconds slower then the TA cars running a 1.16 in a challenge car with 1/3 the HP and no aero. My theory is that the GTM is lighter and has better aero and I have more HP. Well setup the GTM will be a good match for the TA1 cars doing 1.13s . At 1/3 the price and far more reliable. We will see how that theory works out :)

The top 10 fastest cars this weekend spanned 1.13 to 1.19.

The good news is the factory five cars made a very good showing this weekend against a field of well funded and well prepped race cars.

John

crash

06-26-2014, 10:55 AM

Not trying to be a Richard, but if JG or you are anywhere near a REAL Trans Am series car then the people running them haven't a clue. Those should be 900 HP with huge tires and great suspensions. I was talking with a friend that used to run the Trans Am series and was saying how we were very happy to be running 148 down a particular straight. His reply was "Let me know when you reach 187". That's a HUGE difference, and challenge cars are no where near our times out here. Again, not trying to be a jerk, and comparing to TA cars is fun(obviously I am doing it also) but they should be 10 seconds faster than a challenge car, easy.

Now the ARE stuff. Really all I use of theirs is the pan. I run a 3 stage Auto Verde pump with a separator. The low profile pans from ARE require a bit of modification for a supply line attachment. I have suggested to Gary that he change/update his castings as it would be very nice to not have to weld on a brand new cast pan to make it work, but last time I checked, he had not done this. You can get one of those long block adapters, but the fitting ends up below the pan and the lowest thing on the engine/trans combo. Not a real good thing for the oil supply line to the engine. Be careful/aware of developing too much vacuum. It can starve a piston of oil. Also, the number of stages does more than create vacuum, it also gets the oil out of the engine better so it helps with crank windage. Segmented pans are another way to go if you want to go with a 4 stage scavange pump. This just makes the pan like four separate little pans and prevents sloshing.

The ASA stuff uses a single stage pump and vacuum is not created in any substantial amount.

I'll look for some pictures of my components.

3060930610

One of the things ARE has that is nice is a multi stage pump that bolts right to the A/C compressor block bosses. In my case I had to make a front engine plate to mount the pump, which was a hassle. ASA pump mounts this way also, and the Daley stuff doesn't need a mount as the pump is part of the pan.

johngeorge

06-26-2014, 01:01 PM

crash

06-26-2014, 01:22 PM

Not trying to be a Richard either, but thanks for the props :) Its 1.7mi with 10 turns and not a long straight thus suiting the Challenge Car on Hoosier A7 extremely well.. ohh and and here is the TransAm guy's incar: http://youtu.be/QC7d4ovEFgA

Video is not loading. Other YT videos are fine. I'll try again later. Anyway, again really not anything against you in that I KNOW you are great at getting everything out of the challenge cars and have enjoyed running with you at the 25. Wish you would continue to make the trek out west but understand why you don't. 10 turns, 1.7 miles? Yeah that sounds pretty tight and with your abilities against a "normal" guy in a Trans Am car I can see how you all may be close. That said, under NORMAL racing conditions with the best TA cars/drivers and you or us, I would still favor the TA car heavily. They are intense...and fast. I was a crew chief for a TA team in the 90s and a fabricator for much longer. Best finish was a podium at Limerock. The TA guys(and gals) are a fast bunch.

tachman

06-26-2014, 01:50 PM

I believe ARE makes a 2 stage setup that has 2 scavenge stages and uses the stock crank driven pressure pump. I think it can be driven by a serp belt with stock AC pulleys. It may even clear the motor mount but I don't know for sure. This is a major upgrade from the circle track pan ASA setup we're using.

One thing we found with our ASA single stage setup is that when the scavenge only pump failed the crank driven pressure pump continued until the tank was emptied. By this time the engine was so full of oil the performance and sound changed alerting the driver to look at the guage (we since have a warning light). Even with no oil pressure, splash lubrication with nearly 2 gallons of oil in the engine avoided major damage (we changed rod bearings but they weren't seriously damaged). This makes it nearly fail safe. A bit down the road from here Team QRP had an ARE 3 stage pulley failure (get the collet mounted one for 3 stage) and even with a bright dash warning by the time Chris shut it down it was seizing and caused major damage to the crank and rods.

If the 2 stage setup is scavenge only I would expect it could be a safer choice and may include an improved pressure pump.

Jim H, PDG

crash

06-26-2014, 03:01 PM

I took a look at this video by the same guy...https://www.youtube.com/watch?v=BAh30jmdd_I

Granted I have not been directly involved in Trans Am stuff in over a decade, but that does not look like a Trans Am car. Looks more like a GT-1 car. Definitely not the required dash and electronics setup we had to run.

kabacj

06-27-2014, 05:03 AM