GTM roll cage modifications and race car build log

[kabacj]

Hi Mike

Thanks. Yep we had a great time. The top gear drill was one of the training tools I learned when racing motorcycles. I think it was keith code that said that you have a dollar of attention to spend on driving around the track. Each thing you do subtracts from the dollar. Driving the racing line. -10cents. Avoiding traffic -10 cents. Braking -20 cents. Shifting -20 cents - matching revs -10 cents.

Each thing you add diminishes your ability to concentrate on any of the other things that you need to get done at the moment.

When you stop shifting if feels like you have eons of time and attention to spend on carrying the highest corner speed possible. It really works.

Of course its very hard for me to follow these drills when there are lots of other cars on the track . Because two cars makes a race and I just cant help myself.

John

[crash]

We actually practice this regularly in the FFR PDG GTM. We use 4th, but practice go karting to see what we can do for lap times. So far, the difference is only about 2 seconds a lap between shifting and not shifting. Of course, over a 25 hour race, 2 seconds a lap results in about 15 minutes of total time, or about 5 laps.

[kabacj]

We actually practice this regularly in the FFR PDG GTM. We use 4th, but practice go karting to see what we can do for lap times. So far, the difference is only about 2 seconds a lap between shifting and not shifting. Of course, over a 25 hour race, 2 seconds a lap results in about 15 minutes of total time, or about 5 laps.

Yep nothing like a car that can carry corner speed and a good torquey V8.

Speaking of shifting gears not getting you around faster. Here my buddy accidentally dropped into 2nd instead of 4th. Exiting a high G corner and locking the rear tires you really don't have much time to save it. This spin started at 90mph. Lucky for him all he did was trim the grass for a few thousand feet. This is how it happened.



John

[Edgeman]

Thanks for sharing, this is great to see and I hope that one day I will be able to have a few laps on the track.

[fastthings]

Wow, what a rush. Man you guys are haveng fun.

[longislandwrx]

Hope to see her on the road very soon.

[kabacj]

Hope to see her on the road very soon.

Yep I am looking forward to driving it on the street too. In the mean time, I am focusing on getting the car sorted on the track before I go ahead and get it setup for the street.
One of the things many builders have said is that it would have been nice to work out the bugs before they had the car all finished/ painted and prettty. Every time I go to the track I drop a few more seconds. Once I stop going faster as i learn the car I will start changing things in order to maximize downforce, reduce drag, optimize the motor tuning, suspension, ride height, corner weights, maybe a rear anti roll bar. As you all know the summer is really hard to get work done on the car as there are so many other time demands.

Wow, what a rush. Man you guys are haveng fun.

We do have a great time. The videos never show how exciting it is to be sideways or out of shape a few feet away from your buddy’s car. Either he is watching me fighting for control or i am watching him. We are always pushing each other to go faster. Its also very nice to have an extra set of hands when something needs to be fixed quickly.

Thanks for sharing, this is great to see and I hope that one day I will be able to have a few laps on the track.

The first time out on the track is definitely scary, but you soon get acquainted to the speed and it becomes normal. The GTM is such a capable cars its impossible to explore speed and G forces you see on every lap on the track while driving on the street. You have to get out on the track. My buddy who drives the corvette that you see in the videos in prior posts went out on the track for the first time ever last year. One time and he was totally hooked. Now we go once or twice a month.

John

[kabacj]

GTM at lime rock park.

Tuesday was a rare unmuffeled day at lime rock park.

My GTM with a kooks exhaust is not super loud at full song like a cobra or coupe with side pipes. However its louder then a production stock sports car. Even stock cars have difficulty meeting the sound restrictions at lime rock.

I have worked most of the bugs out of the car at this point, but one thing i learned this trip out. . The upper cv boots need shielding.


It was 15 min into our 30 min session and a Miata had its engine blow right at the entrance to turn one directly in front of me.



I did not realize that he had coated the outside turn 1 breaking area with oil. I was off line anticipating an unexpected jibe as his car spun to a stop. Since i was well inside the normal I missed the oil. That was lucky.

I did not see the oil and continued around the track expecting a local yellow in that corner at worst. Unfortunately our session was black flagged at the last turn before pit in. During the black flag we wait on pit road for the safety workers to do their thing. Since I only got the flag on the last corner I entered the pits with a very hot car.


The upper cv boot is 3 inches below the kooks catalytic converter. The rubber boot started to smoke from the radiant heat. you can see in the picture below how the outside edge of the CV toward the bottom of the picture was permanently deformed.



I shut down the engine and a kind official kept rolling the car every few min to keep the smoking down while we waited for the miata to be towed off the track and the oil slick cleaned up.

I know the PDG team had a similar issue with burnt cv boots getting hot and failing however I don't think they have a kooks exhaust.

I doubt that folks driving on the street would experience this issue commonly, but given the right conditions it could be a problem.

I thought it odd that I've driven the car on hotter days on a different tracks without issue.

I drove the remainder of the day without any smoking running a good cool down lap. It's possible that simply running the car for 1 min at part throttle cools the cats down to avoid a problem.


I see two potential solutions.
Ceramic coat the exhaust. Or wrap it.

I like the look of bare stainless.
I can wrap the cats in with fiberglass or basalt based heat shield or build a metal heat shield.

Has anybody compared the shielding capacity of exhaust wrap vs metal with an air gap?

Thanks
John

[Kempo]

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.

[rev2xs]

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

[kabacj]

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]

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]

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]

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

I really want to see the open bell mouths.



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.



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.





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]

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

Looks good man.

[sk7500]

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]

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

[Fraser D]

John,

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

[kabacj]

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]

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]

Nice, it's got that cool LamborghiniWP_20130706_030.jpg louver look.

[LCD Gauges]

John,

Eat my shorts.



\\sick looking stuff \\

[sk7500]

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

Got a pm waiting for its place in line.

[kabacj]

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.



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.





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



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

John

[Fraser D]

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]

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]

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]

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]

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.



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]

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]

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]

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]

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]

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.




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.




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.





John

[RumRunner]

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]

Awesome news, and info.

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

[fastthings]

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]

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]

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]

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.



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.




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