GTM roll cage modifications and race car build log

[kabacj]

In an attempt prepare the GTM for top speed runs, track duty, and hopefully even SCCA and NASA approval for racing I have made a few modifications to the GTM frame.

The job started with bending and welding in roof bars that cross over the passenger compartment and follow the curve of the fiberglass.

http://drive.google.com/uc?export=view&id=1Xyw5FRIV7UXKRWXM-er3JHvAEPUepYdS
I

these bars allow for the duct that channels air into the engine compartment but maintain the maximum head room possible under the stock bodywork.

Next step was to cut out the 1 inch square tubing that supports the rear hoop and beef it up with 1.5 .095 wall DOM tubing.

After a few versions I was able to get the tubes to just kiss in the center but still place the down tubes very near the stock 1 inch square tubing location. In order to keep them perfectly vertical and aligned, I under bent them by a few degrees and then pulled them into place with ratchet straps.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/barswithstraps_zps489ba9a7.jpeg

Next I welded everything in. Boy it would be nice to have a rotisserie for this job. I was laying on my back feeding rod working the foot pedal and straining to see what I was doing on a few of the welds, but it all worked out.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/framedrvr_zpsf550daff.jpeg

This is what I have so far.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/barstopview_zps0ef331d9.jpeg

With the help of JCHracer we might soon have a plan that folks can follow in order to modify the GTM for NASA and SCCA racing, or just to beef up the frame for full on track duty.

Still lots of structure to add, but its a start.

John

[LCD Gauges]

Pretty good welds for being on your back, and half blind. Wish I had that sort of skill with all of my senses present!

Will the rear glass still be in place, or do you have a modification for that section?

[kabacj]

Yes the rear glass will be kept. Unfortunately in order to fit the roof bars and my air intake I ended up almost cutting through the upper section rear bulkhead. I cut and welded on a strip of aluminum to allow for more clearance.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/rearwindow_zpsbcdd2366.jpeg

I might need to trim the section around the roof tubes just a bit more.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/rearwindow2_zps82c50022.jpeg

Of course now I need to cut the bottom side of the oval opening for the rear glass since I added that half inch strip on the top half. I will fit the window as the last step after everything else works.

I am trying to retain all the aspects of a stock GTM when I make modifications. Only builders will be able to tell what I added and what was built by factory five. That's my goal anyway. We will see how it comes out.

John

[Brian Z]

Wow! Nice job with the mods! The tubing is in just the right spots and the welds look great!

[fastthings]

What a pain in the a**, came out real nice. You have put alot of work into that. Sure does look good.

[Joe Mush]

That is some great looking fab work

[crash]

I am trying to retain all the aspects of a stock GTM when I make modifications. Only builders will be able to tell what I added and what was built by factory five. That's my goal anyway. We will see how it comes out.

John

Me too.:p

[kabacj]

Thanks for the compliments guys.

I still have a ways to go on the additional structure.

Attached is an example of how I want to lay out the bars. You can see this was an earlier version of the left and right uprights. They did not touch in the center like I planned so I binned them and started over. I also changed the location of the radius. I was so excited to use my bender, I did not want to make a template. As they say haste makes waste... I can cut them apart for the other elements of the cage so only time was wasted. Oh well live and learn.

https://drive.google.com/file/d/1R6w6o09GqsuBk2FhCYHs0oXRdJ4uVoCl/view?usp=drivesdk


If everything goes as planned this weekend ill install the bars as shown in blue tape just in time for the wiring to begin and maybe another tweak on the gas tank. If I am REALLY lucky ill have the car in go kart condition for the open house.


John

[Kempo]

Impresive work John. I really like the quality of your welds. You have talent.

[Radkat]

Does anyone have information on installing an electronic LS3 Gas Pedal to the GTM?
Is there a bracket or information available or is it just "Do the best you can to fit it on the pedal box?
Thanks for any feedback.

Radkat

[Kempo]

Does anyone have information on installing an electronic LS3 Gas Pedal to the GTM?
Is there a bracket or information available or is it just "Do the best you can to fit it on the pedal box?
Thanks for any feedback.

Radkat

I'm using the LS3 on mine. You need to install two riv-nuts in the fire wall and use the provided template. Here is a link to what I had to do.

redirecting to that link in order to not hijack John's cage thread.

http://thefactoryfiveforum.com/showthread.php?173-The-build-is-picking-up-some-speed&p=30822&viewfull=1#post30822

[kabacj]

Impresive work John. I really like the quality of your welds.

Thanks Hugo.

One thing i did learn about the stock frame. The stock factory five welds are SOOOO much thicker and stronger then necessary. Thats a good thing.

When I cut off the 1 inch square tubing I had a whole lotta grinding to do in order to remove the stout welds that factory five puts on each and every attachment point.

We surely dont need to worry about cold welds or poor penetration on the stock frame. Each Factory five weld had a 1/4 inch thick bead with perfect penetration every time.

The factory five weld quality is one thing you can only see when you cut the car apart. It sure made this job harder, however it made me feel good about the quality of the welds I did not cut apart.

John

[Radkat]

Thanks Kempo for the information.
It looks like the mounting bracket and gas pedal for the LS3 Erod is different.
I appreciate the quick response and information.
Radkat




I'm using the LS3 on mine. You need to install two riv-nuts in the fire wall and use the provided template. Here is a link to what I had to do.

redirecting to that link in order to not hijack John's cage thread.

http://thefactoryfiveforum.com/showthread.php?173-The-build-is-picking-up-some-speed&p=30822&viewfull=1#post30822

[mikespms]

Hi John,
Outstanding job on your mods.Are you going to make any mods to the front of the frame or the foot box area?I noticed the A/C hose,are you going to register your car for street use or is it going to be a track car? And are you going to be able to use the close out panels behind the seats and center engine cover? I am impressed with your bends using that harbor freight bender
Keep up the good work. Mike

[kabacj]

Hi John,
Outstanding job on your mods.Are you going to make any mods to the front of the frame or the foot box area?I noticed the A/C hose,are you going to register your car for street use or is it going to be a track car? And are you going to be able to use the close out panels behind the seats and center engine cover? I am impressed with your bends using that harbor freight bender
Keep up the good work. Mike


Hi Mike, yes I modified the front of the car and the foot box too. I need to upload a few of those pictures for you.

The footbox mods were done to prevent a very hard side impact from intruding on the foot box. The mods also prevent the tire from swinging back pivoting on the A arms *into the foot box after hitting something very solid at very high speed. The foot box mods provide a six point cage required for racing.

Yep this will be a fully registered street car with heat and AC. Any comfort feature added to the cabin will be installed in a manner that it can be easily removed. Except the AC of course. I am going to have plenty of HP so I am not worried about parasitic losses from the AC compressor.

My dream car is a street car that can go out on the track and compete with pure race cars. A registered car will be nice to just cruise around slowly on a nice sunny day on the street and leave the aggressive driving for the track.

Of course im going to compromise a bit to make it more livable with heat and AC, however, take any production car and make it a street registered race car and there are a ton of compromises that the factory made that I can't change. That was my logic. If I am really lucky I will be able to go out on the track with plates on and compete at the same level as high dollar race cars. Again that's the dream.

All of the close out panels and engine cover can still be used just like the stocker. I will need to trim the aluminum and add tabs on the round tube for the left and right lower aluminum panels behind the seats but that's no big deal.

The roof bars were bent with the harbor freight bender. The cage bends under the hoop were done with a JDsquared bender. the JDsquared is just a wonderful tool. Easy to use, super high quality, American made to last a lifetime. Expensive.. but you get what you pay for.


John

[carbon fiber]

looks good john. getting this done will help out the guys who want to race, knowing what has already been accepted. great work.

[kabacj]

Are you going to make any mods to the front of the frame or the foot box area?

Hi Mike,

Here are the mods for the foot box area

This painted bar that passes through the panel intersects with the square tube mid way down and lands on a perch I made the outside edge of the foot box floor.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/IMG_0899_zps552ffeab.jpg

These supports keep cage elements that surround the windshield from twisting . They clear the stock dash without trimming.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/IMG_0887_zps05b084b3.jpg

I made good progress on the cage mods under the rear hoop. As usual I made it really hard on myself with very complex tubing intersections. Two more solid days and the frame should be compete… unless I think of something else to change.

John

[Kalstar]

Hi Mike,

Here are the mods for the foot box area

This painted bar that passes through the panel intersects with the square tube mid way down and lands on a perch I made the outside edge of the foot box floor.
http://thefactoryfiveforum.com/attachment.php?attachmentid=9837&d=1337567675

These supports keep cage elements that surround the windshield from twisting . They clear the stock dash without trimming.
http://thefactoryfiveforum.com/attachment.php?attachmentid=9835&d=1337567672

I made good progress on the cage mods under the rear hoop. As usual I made it really hard on myself with very complex tubing intersections. Two more solid days and the frame should be compete… unless I think of something else to change.

John


John, Wow, I mean WOW! You are a craftsman!

Question, any guess on how much additional weight added?

[kabacj]

Hey Jim.

Thanks for the compliment.

The tubing weighs 1.426 lbs per foot

I have not been keeping close track of the total length of tubing used so far ,
But I figure 25 or 30 lbs. added when I am done.

Also remember I took some structure out.

I got a light weight racing battery so I'm back to even. Ha just kidding.


John

[mikespms]

Thanks for the compliments guys.

I still have a ways to go on the additional structure.

Attached is an example of how I want to lay out the bars. You can see this was an earlier version of the left and right uprights. They did not touch in the center like I planned so I binned them and started over. I also changed the location of the radius. I was so excited to use my bender, I did not want to make a template. As they say haste makes waste... I can cut them apart for the other elements of the cage so only time was wasted. Oh well live and learn.

http://thefactoryfiveforum.com/attachment.php?attachmentid=9784&d=1337215304


If everything goes as planned this weekend ill install the bars as shown in blue tape just in time for the wiring to begin and maybe another tweak on the gas tank. If I am REALLY lucky ill have the car in go kart condition for the open house.


John

Hi John,
I like that foot box mod. I think it adds the extra strength needed in that area, for added safety. I already closed up that area in my car but if I build another one, ill do something similar.

Looking at the blue tape going across the center, I think it will interfere with the front of the engine did you take a reference measurement form your motor mounts foward. In my car the top of the engine is about a 1/2 inch from the bottom of the rear window frame and water pump and top of the idler pulley is foward of the window bulkhead.

Mike

[kabacj]

Hi John,

Looking at the blue tape going across the center, I think it will interfere with the front of the engine did you take a reference measurement form your motor mounts forward. In my car the top of the engine is about a 1/2 inch from the bottom of the rear window frame and water pump and top of the idler pulley is forward of the window bulkhead.

Mike

Hi Mike,

Yep you are right the cross bar is pretty close to the idler pulley. Since the photo, I actually had a forum member with an installed LS3 verify the distance from the top of the pulley which is the highest point on the motor to the bottom of the roll bar hoop. He measured 8 1/4 from the bottom of the roll bar hoop to the top of the idler pulley.

My bar is 7.5 inches from the bottom of the hoop to the bottom of the cross bar. Yes its very close. I figure 3/4 inch is miles of clearance.

I have also installed the window bulkhead to make sure that the cross bar is reasonably in line with the bend in the bulkhead that allows for the water pump and idler pulley.

I may drop in the motor before I do my final welds .... or just roll the dice and hope for the best. Whats the worst thing that can happen? ill just lower the motor, trans axle, and install a dry sump system HA! that's in the plan anyway, just not before I get the car running down the road.

Thanks for the heads up however. I must admit I am a bit concerned about welding it all up without my motor in place to verify clearance. I am famous for attempting to get too tight tolerances. Lets hope this one I get lucky or my motor shows up soon.


Thanks again for pointing it out.

Here is a shot of what I have so far with the rear cage. This is still under construction and the two left tubes still need a bit of work to fit properly, but the cross bar fits well and is at the height I plan to weld it.

You can see that my plan modified a bit from the tape version to the steel version.

http://thefactoryfiveforum.com/attachment.php?attachmentid=9858&d=1337649302


John

[crash]

John,

I think it would be helpful to others to name what sanctioning body this was approved by and in what region so that others can referrence this thread when building, as well as "discussing" what they have built with other tech inspectors. Just part of the documentation process, and could be very helpful to many of us. :)

[kabacj]

John,

I think it would be helpful to others to name what sanctioning body this was approved by and in what region so that others can referrence this thread when building, as well as "discussing" what they have built with other tech inspectors. Just part of the documentation process, and could be very helpful to many of us. :)

Yep, totally agree. I will share what I have learned as soon as I have a logbook in hand from each organization. I am still working through the approval process. The goal is to satisfy both NASA north east, SCCA new york, and the Loring timing association with this cage.

I know that the PDG team have blazed a trail in this regard with the only GTM that I am aware of that is SCCA and NASA approved.

Ill update both this thread and the other forum with all of the dimensions for folks to reference in the future.

John

[mikespms]

9887

A few pictures that may help you to determine the position of the center tube. there is about a 1/2 inch at the closes point between the top of the intake and the back of the window bulkhead. In the front there is about 2 inches between the back of the idler and the intake and block. There is room but is going to be a very tight fit. And you need to be able to lift and tilt the engine back for the motor monts studs to go in or out.

[kabacj]

9887

A few pictures that may help you to determine the position of the center tube. there is about a 1/2 inch at the closes point between the top of the intake and the back of the window bulkhead. In the front there is about 2 inches between the back of the idler and the intake and block. There is room but is going to be a very tight fit. And you need to be able to lift and tilt the engine back for the motor monts studs to go in or out.

Thanks for the pictures Mike very helpful. I also was worried about tilting the motor in to clear the motor mount studs. I figured worst case I install the mounts then drop the motor on top then bolt the motor to the mounts. Regardless your point is well taken. Worst worst case I make new mounts that bolt to the frame from the bottom instead of using a stud. I could safety wire the bolt so it would never vibrate and fall out. Or remove the parts that interfere before indrop the motor in.

Regarding the intake clearance. I hope I might gain a little there...maybe. I don't know if the stock front intake runner is farther toward the front of the motor then the intake port in the head.

Looks like it is from pictures of the intake viewing from the bottom.

The hillbornes might gain me a little there.

http://thefactoryfiveforum.com/attachment.php?attachmentid=9497&d=1336005680

I think the front most intake runner is at least one half inch more forward then the intake port on the stock manifold. That said I do want the option of running a common plenum intake.

Maybe I'll just tack the cage until i get the motor. :)

Thanks for the help.
John

[kabacj]

Some good progress this weekend.

I was able to get lots of tubing fitted and most of it welded in.

The first thing was to finish the gussets in the windshield opening.

The lower gussets are under the dash pad and in keeping with my stealth race car theme I moved the upper gussets as far up as possible. When I had the gussets lower I found that they start to get near your line of sight out the front. Sure the lower position is the stiffest for a pure track car, but I wanted braces that were less pronounced.

As you can see below these braces are just touching the vertex of the windshield frame allowing me to weld all the way around the tubing.

http://thefactoryfiveforum.com/attachment.php?attachmentid=9927&d=1338341573

Next was fitting the rear structure.

Here are three shots of the cage pre welding. From the pics in my album you can see I changed things slightly from the masking tape mock up, but its pretty close.

http://thefactoryfiveforum.com/attachment.php?attachmentid=9929&d=1338341896

http://thefactoryfiveforum.com/attachment.php?attachmentid=9928&d=1338341575

http://thefactoryfiveforum.com/attachment.php?attachmentid=9926&d=1338341572

A close up of the joints . I got these nice tools to cut fish mouths in tubing which is great except when you are attempting to land one tube on the radius of another. Yep all hand work. As usual much more time consuming then I expected, but it worked out in the end.

http://thefactoryfiveforum.com/attachment.php?attachmentid=9925&d=1338341570

Just need to figure out the door bars and I'm done.

John

[vnmsss]

Nice work, John! It's great to see another competition cage build in progress....We'll be out here following your thread and cheering you on!

Karen
PS...What top speed/bracket will you be competing?

[kabacj]

Nice work, John! It's great to see another competition cage build in progress....We'll be out here following your thread and cheering you on!

Karen
PS...What top speed/bracket will you be competing?

Hey Karen. Great to hear from you!

The target bracket is 200+

I'll need to my qualify my way up to that level but that's the goal.

John

[Hankl]

Hey John,

Karen was at Loring also!! LOL

Hank :cool:

[LS MAN]

John, superior workmanship, very impressive!

[kabacj]

Thanks for all of the encouragement guys.

This weekend I finished welding the cage with exception to the cross bar that goes over the motor. I think it will be fine where it is, but better be safe then sorry. Ill trial fit the motor then weld it in.

I also fit the two aluminum panels back as they were prior to adding the round cage reinforcement.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10043&d=1338947216

I was shocked but both left and right panels fit perfectly using the holes I drilled before cutting the frame apart.

I was very careful to try to minimize the warping that is un avoidable when you cut things apart and re weld them. I was very lucky to get both sides back exactly the way they were prior to welding. All of my 1/8 inch mounting holes drilled in the aluminum still fit into the holes in the re welded square tube! That was a relief because drilling those 1/8 inch holes is not fun.

The rear most edge of each panel was riveted into the 1 inch square tubing that I cut out so I simply trimmed the panel and added a tab near the bottom of the round tube.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10042&d=1338947215

The panel is very sturdy.

NASA rules state that the roll bar behind the driver should have rear supports with a 30 degree included angle.

Of course they also say that you can use back stays that land on the shock towers like the stock GTM has IF you follow all of the other cage requirements.

Here is a picture of how a back stay would look at 35 degrees. It lands on the only strong point of the frame in the proper orientation to the roll bar.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10044&d=1338947374

In order to make a landing area for the tube I would need to add a plate and some gussets to tie into the 1 inch square tube.

I think I am going to try make a case that the stock GTM back stays are sufficient. I personally don't feel that the 30 degree back stays are any more safe on the GTM, actually probably less strong as attachment to the frame is stiffer near the shock towers. But rules are rules..

From what I read SCCA seem to be OK with the stock GTM back stays.

I am working on the door bar design now. I am not sure if you guys noticed the height and size of the McLaren door sills. They are HUGE. I think I can meet the safety requirements but still cover the bars in the GTM for street duty. Ill post my mock up for review.


John

[crash]

The NASA kicker rules are absolutely ridiculous! Ask me how I know!?!

No way a Grand Am DP would meet the requirement.

Good luck to you.

Please let us know how you come out on this detail.

[TheChief]

That looks really great! You are an insperation to us all.

[kabacj]

A quick note on the tools I used to bend up the cage.

I went with a JD squared bender. Everybody that gets one says they are great and I agree. Its just a great tool. Very well made.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10275&d=1339814908

http://thefactoryfiveforum.com/attachment.php?attachmentid=10278&d=1339815041

I could not spend 180 bucks on the base. (after shipping costs) so I welded up some scrap to make a pretty good base.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10276&d=1339814918

I used an old brake drum from my old F150, some scrap 1/4 inch steel plate, some scraps from a lally column I cut apart for some other project a little hammer tone paint and I had a base for free.

I LOVE making stuff from crap that I have saved over the years. I had those tubing scraps for 10 years! So glad I got to use them! I also like to know that ill have a little bit of my f150 forever.


John

[kabacj]

More solid progress this weekend.

I tell you I must have spent 3 hours staring at this problem over the past two weeks. My goal is to add SCCA and NASA legal door bars to a car that can be street driven. Ideally I should be able to cover the bars and make them look less race car and more street car. Finally I don’t want the bars to make entry or exit any harder.

The ideal way to attach door bars to the stock frame would put the bars right in the same plane as the current window and interior door frame. With this situation the door bars occupy the same space as the stock door frame. If you want working windows and doors this option is out. Several racing bodies also prohibit removal of the stock door framework. In order to install door bars you either need to make a bar that squiggles it way around the obstructions and spans a large distance, or you need to create new landing areas for the door bar structure.

After considering all of the pros and cons I decided new structure to attach the door bars would be easier and stronger.

The first problem was the rear verticals. I did not want to break the plane of the firewall and I also needed to avoid blocking my fuel tank install. The tank is so tight, I have no more then 1/8 clearance at the pinch points. I can just glue some rubber on to the frame to cushion the tank and it does not need any other mounting. (but I will mount it firmly)

Now the verticals. The bottom of the tube lands right where stock corvette seat belts attach. I will not use those seat belt mounts so I cut off the plate. In order to make attaching the tube easier, I used the cut off pieces of seat belt mount to weld up a continuous horizontal plate to attach the vertical bar. It makes it easier to slide the bottom of the bar in from the front. It wedges in when its too long. This way I can sneak up on a tight fit.
http://thefactoryfiveforum.com/attachment.php?attachmentid=10455&d=1340761867

I cut and bent two symmetrical but mirror image vertical bars for the driver and passenger side.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10448&d=1340760317

What’s cool is the vertical clears the stock cross brace but is just touching. I Debated cutting the cross brace out , but there is not much gain and its possible that the frame would pretzel if I took out that support. The frame is jig welded and I found it to be pretty symmetrical, however when its cut apart it will spring to relieve any pent up stresses.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10449&d=1340760318

I ended up using the cross brace as another point to attach and stiffen the rear vertical.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10452&d=1340761428

Next was the front vertical. I attached the bottom to the 2x2 square that runs across the foot box and the top of the tube to my window frame gusset. The gusset was an easier attachment point because I could more easily run a bead around the joint. I think it looks cool there too. With all this new structure the frame is starting to look like a fortress.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10453&d=1340761625

In keeping with my street car/ stealth race car theme I can also hide these supports under the dash .

Finally the whole point of adding the vertical bars is to add the horizontal door bars.

The lower bar is a simple straight bar. It runs just slightly inside the door shell. The top bar is the tricky one. I am going to mock that one up because I think if done properly it might not obstruct the entry into the car at all and yet still meet the safety requirement. I have seen corvette bars where the top bar is an S bend allowing the front half of the door bar to be lower. This is key in the GTM because swinging your feet out is a little tricky. A high set of door bars in this area is going to make it very difficult to get out.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10454&d=1340761718

Getting out with the X style door bars would be very hard. Basically you would need to crawl out or be very good at yoga.

All the vertical elements were welded up. Next weekend is mock up, cutting,and fitting the horizontal elements.


John

[crash]

What are your plans for the main hoop height requirement? Unless you are rather short, this is the other MAJOR problem with the FFR GTM cage.

[kabacj]

What are your plans for the main hoop height requirement? Unless you are rather short, this is the other MAJOR problem with the FFR GTM cage.

Im 5'7. 140 lbs. so that helps with the helmet clearance issue. Helped racing bikes too. Its always nice to automatically have a weight advantage on the race vehicle running down the track.

With the conventional left hand drive GTM seating position, isn't it pretty easy to use a reclined seat to gain the required head room with the racing seat at floor pan height? Keep in mind that the bars that form a V in the roof follow the contour of the roof fiberglass. These curved braces increases the cage height to its maximum. Unless you raise the roof you would not be able to have more helmet clearance under the cage.

Is the roof scoop on the PDG GTM actually a stealth gurney bubble allowing the cage to be even higher then the fiberglass roof?

John

[Hankl]

John,

It looks like you're going towards the SIB's we have in the Coupe, NICE WORK!!

Hank

[crash]

Im 5'7. 140 lbs. so that helps with the helmet clearance issue. Helped racing bikes too. Its always nice to automatically have a weight advantage on the race vehicle running down the track.

With the conventional left hand drive GTM seating position, isn't it pretty easy to use a reclined seat to gain the required head room with the racing seat at floor pan height? Keep in mind that the bars that form a V in the roof follow the contour of the roof fiberglass. These curved braces increases the cage height to its maximum. Unless you raise the roof you would not be able to have more helmet clearance under the cage.

Is the roof scoop on the PDG GTM actually a stealth gurney bubble allowing the cage to be even higher then the fiberglass roof?

John

Yes it does allow for the bars to extend up higher into the roof area for added safety for the taller drivers.

The rule states that the main hoop must be higher than the drivers head, and that there should be "reasonale" clearance for the helmet. I believe some sanctioning bodies specify around 2". This and the kicker placement are THE two main issues that have to be addressed. In a stock GTM there simply isn't enough leg room to lay the driver back without changing the footbox area.

Have you spoken with the official you had look at your setup about this potential issue?

I actually had to raise my roof 1.75 inches to meet this requirement on my new GTMR. That's even with the reclined driver position...but I'm 6' 3".

[kabacj]

Yes it does allow for the bars to extend up higher into the roof area for added safety for the taller drivers.

The rule states that the main hoop must be higher than the drivers head, and that there should be "reasonale" clearance for the helmet. I believe some sanctioning bodies specify around 2". This and the kicker placement are THE two main issues that have to be addressed. In a stock GTM there simply isn't enough leg room to lay the driver back without changing the footbox area.

Have you spoken with the official you had look at your setup about this potential issue?

I actually had to raise my roof 1.75 inches to meet this requirement on my new GTMR. That's even with the reclined driver position...but I'm 6' 3".

Oh see the problem is you are too tall. I don't have any of those problems. Ha just kidding.

I have the required 2 inches as well as have my helmet below the rear hoop, but I can see how it would be nearly impossible to get a 6 foot guy in a comfortable position under the stock cage without altering the foot box or adding the gurney bubble. Of course the GT40 also had the same problem. A 6 foot guy is really stuffed into that car and in some cases will not even fit. Forget about getting helmet clearance. Check out Jeremy Clarkson when he tries to drive an original on YouTube. The door hits the side of his head. He needed to get a modified version in order to fit.

John

[mikespms]

More solid progress this weekend.

I tell you I must have spent 3 hours staring at this problem over the past two weeks. My goal is to add SCCA and NASA legal door bars to a car that can be street driven. Ideally I should be able to cover the bars and make them look less race car and more street car. Finally I don’t want the bars to make entry or exit any harder.

The ideal way to attach door bars to the stock frame would put the bars right in the same plane as the current window and interior door frame. With this situation the door bars occupy the same space as the stock door frame. If you want working windows and doors this option is out. Several racing bodies also prohibit removal of the stock door framework. In order to install door bars you either need to make a bar that squiggles it way around the obstructions and spans a large distance, or you need to create new landing areas for the door bar structure.

After considering all of the pros and cons I decided new structure to attach the door bars would be easier and stronger.

The first problem was the rear verticals. I did not want to break the plane of the firewall and I also needed to avoid blocking my fuel tank install. The tank is so tight, I have no more then 1/8 clearance at the pinch points. I can just glue some rubber on to the frame to cushion the tank and it does not need any other mounting. (but I will mount it firmly)

Now the verticals. The bottom of the tube lands right where stock corvette seat belts attach. I will not use those seat belt mounts so I cut off the plate. In order to make attaching the tube easier, I used the cut off pieces of seat belt mount to weld up a continuous horizontal plate to attach the vertical bar. It makes it easier to slide the bottom of the bar in from the front. It wedges in when its too long. This way I can sneak up on a tight fit.
http://thefactoryfiveforum.com/attachment.php?attachmentid=10455&d=1340761867

I cut and bent two symmetrical but mirror image vertical bars for the driver and passenger side.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10448&d=1340760317

What’s cool is the vertical clears the stock cross brace but is just touching. I Debated cutting the cross brace out , but there is not much gain and its possible that the frame would pretzel if I took out that support. The frame is jig welded and I found it to be pretty symmetrical, however when its cut apart it will spring to relieve any pent up stresses.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10449&d=1340760318

I ended up using the cross brace as another point to attach and stiffen the rear vertical.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10452&d=1340761428

Next was the front vertical. I attached the bottom to the 2x2 square that runs across the foot box and the top of the tube to my window frame gusset. The gusset was an easier attachment point because I could more easily run a bead around the joint. I think it looks cool there too. With all this new structure the frame is starting to look like a fortress.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10453&d=1340761625

In keeping with my street car/ stealth race car theme I can also hide these supports under the dash .

Finally the whole point of adding the vertical bars is to add the horizontal door bars.

The lower bar is a simple straight bar. It runs just slightly inside the door shell. The top bar is the tricky one. I am going to mock that one up because I think if done properly it might not obstruct the entry into the car at all and yet still meet the safety requirement. I have seen corvette bars where the top bar is an S bend allowing the front half of the door bar to be lower. This is key in the GTM because swinging your feet out is a little tricky. A high set of door bars in this area is going to make it very difficult to get out.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10454&d=1340761718

Getting out with the X style door bars would be very hard. Basically you would need to crawl out or be very good at yoga.

All the vertical elements were welded up. Next weekend is mock up, cutting,and fitting the horizontal elements.


John
10457
Hi John,
Looking at the strings running along the door, and cant tell how high they are. Did you check if the seat is going to fit in the passenger side? In my car on the passenger side I had less than a 1/4 in. clearance between the seat and the door and the tunel panel. I made a new tunel panel and gained almost 2 in.,it allowed me to move the seat to the center so that I could operate the power seat switch on the side of the seat. It may give you the room you need to run that tube and be able to fit your seat.
Mike

[kabacj]

Talking about a tall guy not fitting in a racing gtm.

A tall guy needs a GT 43

http://m.youtube.com/watch?feature=mhee&v=UzC-mQoY3aI

John

[kabacj]

10457
Hi John,
Looking at the strings running along the door, and cant tell how high they are. Did you check if the seat is going to fit in the passenger side? In my car on the passenger side I had less than a 1/4 in. clearance between the seat and the door and the tunel panel. I made a new tunel panel and gained almost 2 in.,it allowed me to move the seat to the center so that I could operate the power seat switch on the side of the seat. It may give you the room you need to run that tube and be able to fit your seat.
Mike

Good point Mike. I have not tested the passenger seat honestly. The lower bar is under the widest part of the seat so I was guessing that it would be fine. Im surely going to check it out. Thanks for the tip.


John

[kabacj]

John,

It looks like you're going towards the SIB's we have in the Coupe, NICE WORK!!

Hank

Yep Hank, I think your coupe design slightly modified will work well in the gtm. Like what you guys have done, I still want to maintain the stock door function.

Ill post a mock up side view to get everyone's opinion of my plan.

John

[kabacj]

Ok here is my attempt at door bars that are both safe for the track and also easy to exit and enter the car.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10468&d=1341076792

and from the other side

http://thefactoryfiveforum.com/attachment.php?attachmentid=10469&d=1341077038

obviously these are rough mock ups, and i did not adjust the seat for ideal placement, however I was pretty happy with the outcome.

Exit and entry is basically the same as without the bars. Just a little higher to get your first foot out.

I have seen racing corvettes with the same setup as they also have the problem of exit and entry when the front half of the door bars are much higher.

ill add verticals that tie the bars into the lower frame and to each other.

What do you guys think? I am going to run the design by my local safety director as well.

John

[kabacj]

I added the lower door bars on both the passenger and driver side. Both bars are as far outboard as possible while not intersecting with the diagonal square tube.

Here is a view from the top

http://thefactoryfiveforum.com/attachment.php?attachmentid=10476&d=1341104687

here is a view from the side.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10475&d=1341104685

John

[mikespms]

I added the lower door bars on both the passenger and driver side. Both bars are as far outboard as possible while not intersecting with the diagonal square tube.

Here is a view from the top

http://thefactoryfiveforum.com/attachment.php?attachmentid=10476&d=1341104687

here is a view from the side.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10475&d=1341104685

John

Hi Jonh,
Are you going to put the other tubes in also?
Drivers side looks good, where you able to fit the seat on the passenger side with the tunel panel in ?
Mike

[VD2021]

John,
More very impressive work.

How tall is the Gentlemen in the picture?

[kabacj]

Hi John,
Are you going to put the other tubes in also?
Drivers side looks good, where you able to fit the seat on the passenger side with the tunnel panel in ?
Mike
Hey Mike,

Yes I do plan on putting a top tube in. I am experimenting with configurations that sill allow you to enter and exit without lifting your foot so high it would hit the dash. I noticed the issue with the passenger side and the tunnel. I have not tried to fit the seat in. Its on today's list of things to do.





John,
More very impressive work.

How tall is the Gentlemen in the picture?

Hi Vidal.

The driver (me) is 5'7". I am going to have my dad 5' 11' also try out the adjustable seat to see if we can also fit him in with required 2" to the upper roll cage.

John

[kabacj]

After lots of thinking, I realized that the S bend top bar would be less strong then a straight tube. (see post 45 for a picture) Of course the S would bend over instead of pulling the verticals in.
I spoke with "Hank" from the forum here who has much more experience at this than I. He pointed out that the top of the S would be near my helmet and its better to hit your head on a net then a bar.

So change of plans. I decided to go back to basics. I built a cage in tape to see how it would relate to other parts.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10516&d=1341190319

That looked pretty good so i made the top bar out of steel. I decided to go up to .120 wall tubing for the door bars. A few extra lbs here are worth the extra stiffness in my book.


http://thefactoryfiveforum.com/attachment.php?attachmentid=10517&d=1341190321

The front tips down so I can still exit in a dignified manner when driving on the street.

I was thinking of making the passenger bar even lower. I will not have passengers on the track and for street use this bar is easy to get over. The last thing I want to hear is my wife complaining that its hard to get in and out of the car.

note the front of the passenger bar nearly intersects with the lower door bar.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10518&d=1341190323

I am not sure if this is NASA or SCCA legal. If anybody knows I wold be glad to hear it.

I will run both sides by my local scrutineer to make sure he is happy with it before I weld it in.

John

[Hankl]

John,

I think you're pretty safe, they might just comment on the height difference between the driver and passengers side, but you are complying with the intent of the rules, looks GREAT!!

Hank :cool:

[flotowngtm]

John,

Is it possible to make the top door bars removable? Or would it not pass inspection?

And that straight bar looks much stronger!

[crash]

Definitely looks better than the S bar.

I would consider leaving the passanger side upper bar out entirely. You have tons of crush space between you and the passanger door, and including the lower frame rail in the equation, you already have two side bars there. If they say anything, just run a couple of stringers from upper to lower and you are good.

Still not sure if the main hoop flies, but if the scrutoneer says it's good...then it's good!

[kabacj]

John,

I think you're pretty safe, they might just comment on the height difference between the driver and passengers side, but you are complying with the intent of the rules, looks GREAT!!

Hank :cool:


Thanks Hank. I could not have done it without your help.



John,

Is it possible to make the top door bars removable? Or would it not pass inspection?

And that straight bar looks much stronger!

Yes I was originally planning on making the bars removable. Here is the problem. To make the bars removable you compromise strength and I was not able to come up with a mounting method that allowed for a clean removal and be as strong as welded in bars. To make a very strong removable bar you need to have both the horizontal bars and the vertical stringers as one piece. This needs to mount to the uprights around the door frame. I was not able to come up with a solution that was both strong and elegant. I think the door bars actually add to the car. They look no nonsense and hardcore. I like that. They are actually not hard to enter and exit over. Yeah the whole S bend thing was an idea that was given to me by the chief scrutineer. It works well for the corvette, but after seeing both in the GTM I think the straight bars both are strong and look nicer.


Definitely looks better than the S bar.

I would consider leaving the passanger side upper bar out entirely. You have tons of crush space between you and the passanger door, and including the lower frame rail in the equation, you already have two side bars there. If they say anything, just run a couple of stringers from upper to lower and you are good.

Still not sure if the main hoop flies, but if the scrutoneer says it's good...then it's good!


Good idea to leave the passenger bar out. The lower bars sorta form an X and might pass as they are. I agree its not a safety thing.

Ill let you know on the main hoop deal.

Thanks for the feedback guys.


John

[kabacj]

Nearly done.

I finished constructing and welding both the passenger and driver door bars.


My concern on the passenger side was that entry and egress would be nearly as easy as stock. Although I most likely could have gotten away with a less structure on the passenger side, I am a sucker for symmetry. Having door bars on the driver side and nothing on the passenger side would bother me. Since they actually are very easy to get over I was pleased how they looked when added. Regarding entering and exiting. The bars don't actually get in the way. The car is so low the passenger can just sit in the seat then swing their legs in. My grandma could do it.


passenger
http://thefactoryfiveforum.com/attachment.php?attachmentid=10614&d=1341881815


and with the body on.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10613&d=1341881813

The driver side.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10612&d=1341881811

and with the body.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10611&d=1341881809

Funny how these things go. Now that its done I look at it and say of course you would do it that way. Prior to starting I was really unsure how the whole thing would go together.

Since it has been so humid I coated the whole cage with POR 15 metal prep. A great idea I borrowed from the competition coupe build. The metal prep keeps the bare tubes from rusting while the final welding is completed.


John

[Hankl]

SWEET!!

Hank :cool:

[kabacj]

Unfortunately vacation has gotten in the way of the build.

I was able to make a bit of progress today however with the addition of 1 inch square tube that re enforces the area that I needed to remove in order to install my single passenger side fuel tank. This braces the frame and I think reasonably equates to the strength of the structure as designed by factory five.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10788&d=1343011897

My goal with the tank was to get as much capacity as possible with the goal of 18 gallons. Because of that I made the tank as high as I could and still allow filling using the stock filler location. The shape of the tank got in the way of the 1 inch tube I needed to add. I sorta knew this was going to be a problem, however I hoped I was going to come up with some way to re enforce the frame but not notch the tank. I could not think of anything that was as strong as the method I used so I needed to cut the tank.

I bent up a little plate and welded it in.

http://thefactoryfiveforum.com/attachment.php?attachmentid=10789&d=1343011901

Ill loose a few ounces of capacity with that little cut out, but the 18 gallon number was just a target.

I also cut the interior aluminum panels to fit around the new roll cage structure.

John

[flotowngtm]

John,

Looking back in your post I see that you upped that side door bars to .120 tubing. What is the FFR tubing thickness? And did you go with the same size as FFR on all the other bars?

[kabacj]

John,

Looking back in your post I see that you upped that side door bars to .120 tubing. What is the FFR tubing thickness? And did you go with the same size as FFR on all the other bars?


Hey Jason

FFR use .120 wall tubing on their cage elements. I only used .120 wall on the door bars and foot protection as they obviously will need to resist a side load. Thicker is stronger.

For all other parts I used .095. DOM. Most of the additional structure I added is not side loaded so I did not see much benefit from over sizing the tubing.

095 DOM is the requirement for SCCA and NASA for cars up to 2500 lbs. Many street GTMs come in under this weight so I figure I'm pretty safe from the weight standpoint.

Just to be clear since I left all of the FFR 1.5" round tube and only added tubing to meet SCCA/ NASA spec. I will end up with a cage thats mostly 120 wall with the support structure under the rear hoop in 095.



John

[kabacj]

It was Christmas in August on Friday as my motor arrived. I had ordered a lift gate delivery but when the trucking company called and asked to schedule delivery next week I asked if I could pick it up. Sure they said. So I picked it up after work. Hmm small problem. How Do I get this giant box out of my truck without any help. Well I made like the pharaohs and got the box out of my truck . The engine crane was not high enough and it was too dark to build a gantry outside. Sure I could wait till Saturday when some buddies could help me carry it out of the truck but who has time to wait for that.

After getting the motor out of the crate and installing all the parts needed to check clearance with my rear hoop supports, with the help of my 8 year old son we dropped the motor and tranasxle in.

Boy is that nice to see.

I have been waiting for quite a while for all the parts to arrive and I am pretty happy with how everything turned out.

http://thefactoryfiveforum.com/attachment.php?attachmentid=11085&d=1344215792

http://thefactoryfiveforum.com/attachment.php?attachmentid=11084&d=1344215790

http://thefactoryfiveforum.com/attachment.php?attachmentid=11087&d=1344215796

I had assumed that the motor mounts from my ls1 donor pallet would fit right on to the LS3 block. Nope. The right side hit one of the mounting bosses on the block behind the AC mounts. That was unexpected. So I modified the motor mount to clear the boss on the block and dropped the motor in. Seems to me like the motor is really far forward.

I figured that if i put the transaxle in and if that fit properly the motor was in the right place.

Well the transaxle mount has two sets of holes. One set forward (I used those) and one set about an inch father back. The motor fit perfectly with the mendiola transaxle attached.

See how far forward my motor is? Nothing hits, but it sure is tight.

http://thefactoryfiveforum.com/attachment.php?attachmentid=11086&d=1344215794

Notice how close the top of the thermostat housing is. Sure there is plenty of room, (1/4 inch) but seems pretty close.

Is this normal?

John

[Kempo]

Congrats John. That intake looks amazing.

[VD2021]

Very Nice! A work of art.

[RumRunner]

Notice how close the top of the thermostat housing is. Sure there is plenty of room, (1/4 inch) but seems pretty close.

Is this normal?

John

John,

My LS3 is exactly the same. Just a bit of clearance. I used much stiffer Pfadt motor mounts to minimize motor rocking because the clearance was so small.

-Michael

[flotowngtm]

11122
Dosent even look like you could remove that Thermostat housing without jacking up the motor or something.
Also I noticed that the horizontal bar that you had added to the center of the rear hoop is missing. Is the motor in the way. Or you just going to add it in latter. From the pics it looks like that bar would have to pass through the motor.

It all looks great! Your engine bay is going to look spectacular!

[Hankl]

WOW! WOW! WOW! WOW!!!!

Hank:cool:

[kabacj]

11122
Dosent even look like you could remove that Thermostat housing without jacking up the motor or something.
Also I noticed that the horizontal bar that you had added to the center of the rear hoop is missing. Is the motor in the way. Or you just going to add it in latter. From the pics it looks like that bar would have to pass through the motor.

It all looks great! Your engine bay is going to look spectacular!


With help from folks on the forum here I was pretty sure that the cross bar was going to be close. I was also pretty sure it would fit with a standard intake, but I was concerned that the hillbornes would interfere. Turns out they do. there is a little linkage on the drivers side that would hit that cross bar. I could move the linkage on the intakes move the bar lower or I can move the motor back an 3/4 inch. Right now I am leaning toward moving the motor back a bit. It would most likely take less time then making a new cross bar with the compound cut on each end. I need to think about it for a week and do some more research.

Moving the motor back will change the CG of the car slightly. Dont know if this is a good idea.


Thanks for the compliments on the motor guys. The ITBs are surely more work then the stock GM intake, however I think they will be worth in both on the track and how they sound.. and how they look of course. Mast motorsports sorted them all out and tuned them for great drive ablity both on the street and track. Im going to thrash on this thing as hard as i can to get a first start as soon as possible.

John

[Kempo]

What power was Mast able to get out of that set up?

[kabacj]

What power was Mast able to get out of that set up?

They built the motor to be bullet proof and got a nice power curve

http://i1073.photobucket.com/albums/w389/kabacj/66a57fdc.jpg

[Kempo]

That's a very nice power band. You should have one fast care there. I can only imagine how incredible that intake must sound at WOT.

[kabacj]

That's a very nice power band. You should have one fast care there. I can only imagine how incredible that intake must sound at WOT.

Thanks Hugo.

Yeah I grew up on individual throttle bodies on motorcycles. They were far less sophisticated then the mast/hillborne solution. But I just love how they look, sound, and drive.

I also like the classic throw back.

Of course I could have gone with even bigger hp and torque, but I don't know how much more could be used on a road course. And more importantly I'm pushing the mendiola transaxle power rating as it is.

Sometimes it's easier and more fun to drive a car that has enough hp but is not too much. As if there is such a thing as too much hp.

Can't wait to get out on the track with this setup.

John

[kabacj]

With my motor and transaxle installed I had lots to consider regarding the cross brace under the rear hoop as well as the common ls3 install concerns. AC plug etc

I briefly considered just calling the install good and moving on.. But knowing that a decision to leave things alone would bother me till I'm dead, I decided to move the motor back a bit.

How hard could that be right? I considered my options. Modify the cast section of the mount that connects to the motor. Too time consuming. I considered modifying the rubber elastomer /vibration isolator from the donor. I purchased new ones so I cut the old ones apart.

They are filled with oil! That was a surprise. Too bad because moving the mounting stud would be an easy way to move the motor a small amount. . I love how over engineered parts like this are. I figure its a blob of rubber. Wrong.

The only reasonable option was to change the frame mounting point. The new position is only 7/16ths back and there is almost enough room to fill old hole and reddrill the mount. However the nut that mounts from the bottom would land on the inside corner radius of the cross brace edge.

The easiest way to solve this was to cut a hole in the brace using a 1.5 inch hole saw. Install a 1.5 inch pipe scrap from the cage with a piece of plate welded to the top. Drill the plate and weld it in the cutout.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/ebb65733fccd29ef93e00ef9a3895587.jpg

This was very easy. I installed the new hole plugged the old hole and moved the outer edge of the stock frame outboard in one easy step. I think it's most likely stronger then the old setup.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/0c8ea821f5e939230ed97668644a9b3a.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/fab07a1768e7b90f14e868980d335877.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/008e4300d43fc0aaa50df74c72e2ccaf.jpg

Next was the transaxle mount.

This was easy. Cut some plugs from bar stock and welded the old holes closed.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/58ba0ff318ec57db656a2a3f068dab1d.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/c0bfd52142d40190b3dd4ac7b7c8bdaa.jpg

Re installed the motor and transaxle ( I'm getting good at it now with so much practice.) whew the holes lined up and the motor dropped right in.

With everything in position I checked that the drive line was centered and used the sleeves that hold the transaxle mounting bushings from compressing as the bolts are tightened as drill guides. With this method the holes are perfect.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/f7b3ad9f45a73cb8619988ad80c5a89e.jpg

After a three hours of experimenting the maybe 2 hours of fabrication my motor was 7/16ths more rearward

This will give me clearance for my AC plug but more importantly it gives me more room for my fuel rail plumbing and un shrouds the intake bell mouths a bit. They were pretty close to the cage and might have had a negligible interaction from an airflow standpoint. Trivial you say? Maybe. I like to eliminate problems I don't even have. It's a mental problem .

Next step was the cross brace. I flipped the valve covers from left to right. Took off the drivers side coil packs which are currently mounted with the stock ls3 mount. I mocked up and bent a new cross brace with radius bends at each end. I think I can make it all fit. It was late on Sunday and I was running short on patience. Time to put down the tools and step away from the build

Sitting at a desk for 5 days will allow me to recharge for final sprint to finish of the cage mods.

John

[kabacj]

The before and after shots of my motor relocation explained in the prior post.


Before

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/3b658335ee7c2499d1c76a59a8918510.jpg

After
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/Untitled-1.jpg

John

[Kalstar]

What a work of art. Can't wait for that beast to be on a track.

[kabacj]

The final element of the cage that I needed to finish was the cross bar that spans the motor.

My original plan was to make the bar cross right in front of the intake. Unfortunately my intake is bigger and higher then the stock ls intake. My first attempt made before the motor arrived did not fit.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/c8110cabefc3dc170c9d06904206e908.jpg

I installed the motor and decided to move it back almost 1/2 inch.

Next was fitting the cross bar. Turns out with the motor back 1/2 inch I had plenty of room to install the cross bar. There were still obstructions from the fuel rail plumbing and throttle body linkage, but I was able to put small bends in each end of the cross bar and make it fit with miles of room to spare.


http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/983B3602-B585-4355-8747-747C1A869DB1-8005-0000179655BBEEBC.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/47BDB126-2E3D-43AA-AE8E-C88ACF44B312-8005-000017965D414301.jpg

I resisted my normal urge to make things as tight as possible to make removing and installing the motor easier.

This weekend I also made an aluminum battery box/ hold down. Welded tabs on to the frame to securely mount the battery. I installed the gas pedal , installed the kooks exhaust (mounts need a bit of modification) installed the engine accessories, and planned out the removable V that goes over the motor.

The key with this V structure above the motor is that I need to leave enough room to install an air box above the intakes as well as make the whole thing as light and strong as possible.

Still lots and lots to do, but getting closer.

John

[mikespms]

Hi John,

Awsome drive line and that roll cage looks to be very strong as is . Is that cross bar needed? It looks like is going to interfere with the window bulkhead and engine cover.

[kabacj]

Hi John,

Awesome drive line and that roll cage looks to be very strong as is . Is that cross bar needed? It looks like is going to interfere with the window bulkhead and engine cover.

Hey Mike.

Thanks for the compliment.

Is the cross bar needed?... well for practical purposes. Probably not. For NASA/SCCA approval it does not hurt.

From stress analysis of the frame with the added parts, the cage is much stronger then needed compared to the SCCA and NASA spec.

The bar just adds a bit more strength and definitely increases the stiffness that prevents the rear hoop from racking sideways. That is the whole point of the SCCA and NASA cross brace that runs diagonally across the car.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/5d118fe98ebc17c95c30c76a21555dfd.jpg

Much of the scrutineers decisions have some subjective element. The more overkill the solution looks the easier time I will have getting this thing approved. Thats my theory anyway.

Regarding the window bulkhead and engine cover. It JUST fits over the bar. The lower bend in the bulkhead sits right on the bar and the engine cover fits on top pretty easily.

That part of the fit is super tight... but since its easy to make it all fit it works.

Good thing you pointed out how tight the first cross bar was. I would have ended cutting that one out if I welded it in.

John

[kabacj]

Spent some quality time with the lathe today. I am working on the v shaped braces that go above the motor between the center of the rear roll hoop and the shock towers. I wanted to make my braces out of aluminum and I could not find aluminum ends that I liked so I decided to make them.

I got some hex bar stock and spent a few hours removing metal.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/F4B2ED45-39DB-473A-8787-14379E9E1B07-12600-00002362A0505713.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/BF18C8A1-73E7-40CE-B371-6754E049F917-12600-00002362A57A8C50.jpg

After quite a while I have 4 ends. Each brace will get one end with a hex and one smooth. The ends have left and right hand threads so I can simply spin the brace and add a bit of preload.

As usual it took much longer then I planned. Tomorrow i will cut the steel tabs in order to attach the braces to the frame.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/DC1C0DC0-B708-4C3D-8CA7-585933079293-12600-00002362AA03718E.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/87F09B4D-09FC-4C72-B754-62890B228C14-12600-00002362ADC951C1.jpg

John

[Kempo]

Awesome job John!!! You really are a fabrication artist. Those are some impressive abilities you have there.

[kabacj]

Thanks Hugo. I just get carried away sometimes.

Wrapping up the welding projects I needed to modify the kooks exhaust mount. The Kooks comes with a bracket that wraps around the polished muffler.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/A368814C-4E1E-4D7D-B658-DF3405ED8D20-12897-000024AA3ACEBB4A.jpg

It hurt me to clamp on to the muffler so I considered other ways.

Turns out that using the 3 inch dynomax auccuseal clamps that come with the setup I could fabricate a mount off the transaxle support.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/4BA10772-A2F3-4CC5-AC3A-A5AF30A6A2BA-12897-000024A9614D83F8.jpg

I took it apart and added a bigger stainless steel block that I could weld a stud onto. Turned out I needed to cut out about a half inch of the clamp band in order to allow it to tighten on the exhaust tubing.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/242EC874-218B-4979-9033-CC66963778CF-12897-000024A951AD77FF.jpg

here it is all ready to install. I was interested in making the mounts somewhat flexable so they don't fatigue and break over time so I found a cool neoprene bushing with a captured stud on one end an a threaded section on the other.


http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E2B58367-89A8-4A77-8377-BFA2FBABC7BD-12897-000024A9597DB4EF.jpg

I added a slotted bracket on to the transaxle support which allows me to move the exhaust left to right for final alignment.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/6FAA4299-08B9-49E6-B5E4-D6B38676033F-12897-000024A9566B6DA3.jpg

And installed everything.

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

I can screw the stud out about 5 threads and or shim the vibration damping mount to raise or lower the exhaust tips.

With both sides attached its very sturdy, but still allows the whole exhaust to flex slightly if pushed hard.

Now back to work...

John

[noother]

Nice solution John!

Can you pass on the source for the neoprene bushing when you get a chance?

Thanks, Mark

[kabacj]

You can find the mounts here.


http://www.mcmaster.com/#catalog/118/1381/=j3c9c6

I got both of these..

http://www.mcmaster.com/#5823K24

http://www.mcmaster.com/#93945K37

Turns out I lied I actually used the rubber ones with the stainless stud. They are both the same durometer or hardness so there was no difference there. you really cant tell them apart unless you look at the stainless stud. The neoprene is a little more heat resistant, but I don't think they will be 300 degrees.

I love stainless steel so I used those.

Jegs has the accuseal clamps.

John

[noother]

Thanks John! I was just getting a McMaster order together, those mounts look quite handy, I'll get some extras.

I totally get the SS love, it's my favorite alloy.

Mark

[kabacj]

Hugo pointed out off line that the both the rubber and neoprene are only rated up to 180 degrees. Somehow I thought they were rated higher. But anyway he has me thinking a better way to do this is to add a strip of heat shielding exhaust wrap between the accuseal clamp and the exhaust tube. This would eliminate the need to trim down the stock 3" clamp and slow the heat transfer between the exhaust pipe and the damper and maybe allow the damper to live next to a very hot exhaust.

Well ill see how hot it gets and just in case Ill get another set of clamps and some heat shielding wrap. All the other stuff will just transfer over.

Thanks for the heads up Hugo

John

[kabacj]

Spent some time mounting the 6 point harness. Boy was that a pain.

I am using Schroth harnesses. They have a DOT legal harness as well as some nice hans specific designs.

They also have very good mounting instructions.

http://www.schrothracing.com/docs/Competition_Instructions.pdf

They want the shoulder belts to be horizontal or at a decline from the shoulders of no more then 20 degrees. Well thats unfortunate because there is nothing to mount to on the stock or my modified GTM that fits that requirement.

The solution i came up with was to mount stubs on the cage that but up against the back of the firewall aluminum. I can then mount a harness bar on the cabin side of the firewall.

This little job took forever.

First I fish mouthed one end of the stub. Then mitered the side that would touch the firewall. Cut out a disk of steel plate that matched the mitered end. Welded a 7/16 fine thread nut on to the plate.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/08D29A47-6CC3-4045-8DBD-9510CFEBF575-12937-00002A3486207445.jpg

Then welded the plate on to the end of the stub. Then mounted the stub on the firewall and welded it to the cage.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/EF187CFA-CF82-41C8-B0B4-1FDC75EB250C-12937-00002A347B9A61F8.jpg

Here is the passenger side done.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/58316059-7E36-40A4-822E-90B9B5811072-12937-00002A347EA281F1.jpg

Then I needed to mount tabs on the passenger side of the firewall because there is not room for nutcerts on the lower firewall since my fuel tank is about 1/8 of an inch away from the steel tab.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/5B6149BF-B4CA-4E7B-8D11-30AACB3C9695-12937-00002A34774C824E.jpg


John

[crash]

There was someone selling harness bar kits awhile ago. Don't know if he is still doing it or not? Too late for you, but maybe this will save someone else some time.

[kabacj]

There was someone selling harness bar kits awhile ago. Don't know if he is still doing it or not? Too late for you, but maybe this will save someone else some time.

That's correct Crash I remember Richard from north race cars was making them a few years ago. http://www.northracecars.com/gtmparts.html

Even if I were to use Richards bar, I still needed to add the stub mounting points following the directions from Schroth.

They want the belts to travel over the top of your shoulders and back from a 0 to 20 degree angle.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/14f4363396cb753c08fc4da5f90b04ea.jpg


Since I have the seat raked back quite a bit to get my helmet down as far as possible, My shoulders are also lower. The harness bar also needs to mount lower down in the car where there is not any support structure in a stock or my modified GTM

Now I am not an expert on what works and or what is required for the harness installation, I'm just following the directions.

John

[kabacj]

The last weekend was a mad dash to get my car finished for my first track day October 6th. I am out of my mind to try to get the car finished that quickly, but I like a challenge. BTW by finished I mean it drives and has a primed body on it.

This past weekend I painted up the chassis. It was kind of sad to cover up the steel, but it must be done. Its nice to see the frame shiny and black again.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/FB926005-7B7D-4B81-99F3-F37F2410C4DD-22287-0000430D11331A6A_zps20271345.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/24889DB4-248D-4DED-917F-5F61F7834F02-22287-0000430D0A89023A_zps02c2b2a0.jpg

I welded up the engine compartment braces, made some double shear tabs welded them in and installed the braces.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E6B81C3A-578B-4220-9471-5FE8C2A4C033-22287-0000430C20581D18_zps51c8bdba.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/0DA69F81-6B5C-4E39-B185-E3F6057B4D0A-22287-0000430C1C13F82A_zps34d7e708.jpg


Installed my motor with Pfadt motor mounts, hooked up the cooling system, installed the belts, and installed the, fly wheel, clutch and starter.

Here is an over head shot of the motor with the braces installed. They have right and left hand threaded rod ends so I can twist them up and preload the chassis. I am interested to see if I can notice the stiffness change by removing and adding them back on the track.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/4D861F75-3ED8-40F4-899E-487A0B618166-22287-0000430C2EFBE9D7_zps6eb0781b.jpg

Transaxle goes in tomorrow night and ill start wiring.

So much to do so little time.

John

[Kempo]

That is one hell of a challenge but with your talent I'm sure you'll make it. Your GTM is coming along very nice and al those mods really make it unique. Keep up the good work buddy.

[Jacob McCrea]

I really like those engine compartment braces. I would have given serious thought to doing that on 2 removable triangulating tubes, rather than using Ballistic Fabrication connectors, as the latter are extremely tight are will probably be difficult to remove and reinstall when the chassis is stressed. Nice work, as always!

[The Stig]

Beautiful work John! It looks great.

Mike

[kabacj]

Transaxle went in last night. It was not the smoothest install as it just did not want to slip in. After 20 or 30 min of twisting and wiggling it found its way home. I had to swap the hard line to the passenger side of the car since the mendiola slave unit is on the passenger side.

I got a stainless braided flex line with a 90 on one end. This allows me to keep the flex line tight to the side if the transaxle, but not so close that the stainless braid will touch anything.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/05F95556-511C-4211-B26A-F9A185E8EFE3-206-00000091CC3A7311_zpscac29f1c.jpg

I pulled some dot3 fluid through the system with a mity vac and called it a night.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/AE6560AB-7AF4-4776-8E80-E32CC47F3A45-206-0000009199587483_zpsa5ff0003.jpg

John

[Hankl]

John,

Great work, you'll need to do a video of the first engine start!!!

Hank :cool:

[kabacj]

Mike, Jacob, Hugo, and Hank thanks for the support.

Hank I will surely get video of the first start.

I cant belive its almost ready.

John

[kabacj]

Well after a few 17 hour days I think I might have the car ready for the weekend. My wife says its like watching overhauling. I go down to the garage at 5.30am and return at 11.30pm.



This is really the first start note the smoke off the headers. I quickly stopped shooting to check that everything was OK. It was fine :)


http://www.youtube.com/watch?v=_EpEOqJc58w&sns=em



I just need to bleed the rear brakes and install the seats and do an alignment and I'm ready to do a test drive.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/668B5979-4A7E-4219-9183-C7E511CCDFD8-1681-00000661D1B34DFC.jpg


Yesterday I also started the bodywork. The goal is to make the car straight enough to look presentable in flat black epoxy sealer.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/820871BA-3A3F-4D06-94D2-EE7D82E5C5B7-1681-00000661C1A8FFDB.jpg


http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/BE593B10-E405-415B-AE7D-A276376698AC-1681-00000661B77A44A8.jpg


It's going to be close.

John

[Kempo]

Looks great John!!!!! Its impressive how much work you have accomplished in so little time. Looking forward to your track day videos. Just subscribed to your YouTube channel.

[sk7500]

Unbelieveable!!! I can work a whole day and come out the next morning and say, "What did you do all day yesterday"? I know that when a car comes together this quickly it's because of all the time that was spent in preparation. Putting the bolt in for the last time looks easy. Most people don't see the 400 times you put it in and out until it finally fit just right. Your chassis looks awesome. It's almost a shame to cover it with a body. Keep it up. I know you'll make your goal. I'm rowing the same boat. But without deadlines, nothing ever gets done. Right?!

[kabacj]

Unbelieveable!!! I can work a whole day and come out the next morning and say, "What did you do all day yesterday"? I know that when a car comes together this quickly it's because of all the time that was spent in preparation. Putting the bolt in for the last time looks easy. Most people don't see the 400 times you put it in and out until it finally fit just right. Your chassis looks awesome. It's almost a shame to cover it with a body. Keep it up. I know you'll make your goal. I'm rowing the same boat. But without deadlines, nothing ever gets done. Right?!

Thanks Hugo and Steve. Steve I too have had many many of those "where did the time go?' days where I have nothing meaningful to show for my toils. Like the two weekends I spent re furbishing and grinding all the casting marks off the corvette suspension. I was waiting for parts and wanted to work so that's what I did :) And yes most of the car was together quite a few times then taken back apart. My biggest problem has been parts that were not in the car at the same time a few leaks and a few crossed wires that lead me down the wrong trouble shooting path. Yep im a deadline guy. Give me a target and too little time and I don't have the option to 'fix' things that are not broken. Time to get back to work.

John

[Kalstar]

Looks awesome John, like said " what a shame to cover all that beautiful work with a body". YouTube subscribed.

[joe0121]

Nice work man. I bet that thing is a monster around a track.

You need to get these plans the Factory Five so they can incorporate them and have say a "race" model that is legal to race with the major sanctioning bodies.

That way in a few years when I buy mine I wont have to do all this work :)

[kabacj]

Track day

Well it was Thursday night around midnight and I had the final list of things to complete.

I had to re connect all the guages to the Mast Motorsports Ecu which has all the sending units plumbed into the engine control. It's completely stand alone so all I needed to do is make a circuit for the brake lights and I'm done with electrical . Make a bracket for the guages and design and fabricate an intake that would allow for an air filter and the mass air flow sensor.

After bleading the engine cooling, front and rear brakes, and clutch for the final time,I was in no mood to start those projects at midnight.

I went to bed with a strong feeling that I was not going finish everything up and road test the car in time to make new jersery motorsports park (4 hours away)by 7am sat.

I still needed to unload the trailer which is the temporary garage for my next project. Load the trailer with tools,supplies, and the car. Mount all of the tunnel and under car aluminum and finally glue in the windshield.

Over the past 3 weeks I have been working like a madman putting 35 hours a week into the car. I knew I had my work cut out for me especially getting the Hillborne setup ready for the track.

To add to the mix I decided not to use the stock seats (already installed) . I took them out and swapped in Kirkey intermediate road race seats.

I needed to make mounting brackets and weld in tabs for the new seats and weld in tabs for the harnesses that will work for both setups.


http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/5A85DD24-DCBB-433E-963D-77AE9B9D4561-2899-0000040B65B18113.jpg


So basically I just added more work making difficult goal even more difficult.

No time to spare. Friday am I was down in the Garage at 5.00 am. The previous night I was pretty down about my prospects of finishing in time. I felt better with a little rest. Maybe I can make it!

Four and a half hours later my buddy shows up.


http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/0304B6BD-68D9-49F5-80F0-10337E523A39-2899-0000040B1BD8E643.jpg


His car is loaded and his gear packed. We took some time to review the punch list and he asked if I was really going to get all of that done properly and have the car tech inspected by my local race shop by the evening.

I have never cut corners on the build. I was not going to start now. That also meant the I was not going to make it to the track.

To add to the mix. Saturday weather was clear . Sunday was calling for a monsoon.

My buddy said swallow your pride grab your gear and drive my car this weekend. It's nice to have good friends.

So we had a ton of fun. We drove all the way down to southern Delaware to pickup a cool tilt bed trailer.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/861B71B3-E3BD-4A58-95BE-D8A783D09747-2899-0000040B7F598CE2.jpg

We tested out our video and telemetry capture gear. And met some great people.

Funny thing about me building this track version of the GTM is that I have only driven 20 laps around a track in a car. Sure I have done thousands on a motorcycle but clearly it's not the same.

Lucky for me Carl Thomson was assigned my driving instructor. Carl has a long racing history starting before i was born. He currently campaigns a Factory Five Challenge car. Imagine that! I go to a Porsche club event and factory five guys are there.

I was still working out the bugs of the video capture setup but here is a saturday lap of NJMP thunderbolt.

By sunday AM i was able to get down to consistently run low 1.45 lap times. I'm happy with those times in a borrowed stock C5.

Here is a quick video.


http://vimeo.com/50980946



So the deadline has come and gone. I made a pretty good attempt at finishing, but looks like now I can take the time I really wanted to make some more parts for the GTM and make it truly track ready.

John

[sk7500]

Bummer you missed your goal. I respect your unwillingness to compromise. You made some unbelievable progress and you are much further along than you would have been without the goal. And it proves you are only crazy and not stupid. :) I think the first time you drive your well prepared GTM on the track you will look back on your wise decision to wait and go out with your "A Game" car. I also think the seat time you spent on the track in a tame car will prove invaluable. The seat time did little to prepare you for the brute force you will experience with your GTM but it can't hurt.
I can't wait to read your impression of your first track day. I remember my day and it was a true eye opener.

[kabacj]

Bummer you missed your goal. I respect your unwillingness to compromise. You made some unbelievable progress and you are much further along than you would have been without the goal. And it proves you are only crazy and not stupid. :) I think the first time you drive your well prepared GTM on the track you will look back on your wise decision to wait and go out with your "A Game" car. I also think the seat time you spent on the track in a tame car will prove invaluable. The seat time did little to prepare you for the brute force you will experience with your GTM but it can't hurt.
I can't wait to read your impression of your first track day. I remember my day and it was a true eye opener.

Yeah the seat time was very good. But it was a real bummer not to have the GTM. I'll simply take the necessary time to complete the mentioned items as well as add heat shielding, oil and transaxle cooling and do a quality alignment and corner balance.

I'll put together a photo guide of the seat and harness install so folks can see how well the Kirkey seats fit a six point harness setup in the GTM

I'll have the car street legal in the two months it takes for New York State to process the paperwork.

Maybe the dry sump or accusump will go in before the first track day as well. I was pulling 1 G in the corvette with Nitto nt05s. The gtm should hold quite a bit higher g load with dot slicks.

It probably would have been stupid to rush a car on to the track missing the cooling and oiling mods. I just like to hit the goals I set out

John

[RumRunner]

John,

While I feel your pain in the missed deadline (i've missed plenty), I applaud you holding to the "do it once, do it right" mentality. As all of us who are building a GTM can attest, the quick and easy way is rarely the right way. If nothing else, my build has taught me as much about patience as my two kids have!

I've been looking for a tilt-bed trailer as well - where did you get yours?

-Michael

[sk7500]

Yeah the seat time was very good. But it was a real bummer not to have the GTM. I'll simply take the necessary time to complete the mentioned items as well as add heat shielding, oil and transaxle cooling and do a quality alignment and corner balance.

I'll put together a photo guide of the seat and harness install so folks can see how well the Kirkey seats fit a six point harness setup in the GTM

I'll have the car street legal in the two months it takes for New York State to process the paperwork.

Maybe the dry sump or accusump will go in before the first track day as well. I was pulling 1 G in the corvette with Nitto nt05s. The gtm should hold quite a bit higher g load with dot slicks.

It probably would have been stupid to rush a car on to the track missing the cooling and oiling mods. I just like to hit the goals I set out

John

You didn't miss the Goal, you missed the date. The goal remains the same, "the best GTM you can build for both street and track". I have no doubt you'll get there.

[kabacj]

I've been looking for a tilt-bed trailer as well - where did you get yours?
l

Michael

My buddy got his tilt bed from Down to earth trailers who have their factory in Georiga.

He went with the 20 foot steel deck hydraulic tilt model. The goal was to get his stock corvette on the trailer without any blocks or wood at the transition. He just makes it with stock ride height. He will need a scrap of 2/12 to ease the transition when he lowers his car. The gtm will also need a few blocks of wood to ease the transition.

The 20 foot model also allows him to put a pit bike, tool box and tire rack on the trailer with plenty of room to balance the tongue weight

The closest dealer to us in NY was in Laural Delaware, which is on the southern border of the state. Made for a nice road trip.


You didn't miss the Goal, you missed the date.

That's a better way to think about it Steve. Thanks.



You need to get these plans the Factory Five so they can incorporate them and have say a "race" model that is legal to race with the major sanctioning bodies.


Joe I'm going to discuss it with Factory Five. I know they have their hands full with the 818 right now. Maybe an idea for the gen 3 GTM.

John

[kabacj]

There have been a few threads regarding seats in the GTM and although I am happy with the Gen2 seats for street use I needed something stiffer and offering a bit more containment for the track.

I used two methods for mounting the seats. Both used button head bolts and brackets I made from 2x4x.25 6061 aluminum angle.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/CDB35FB2-4209-4E27-9F71-549F7A3AE346-2568-0000063BCB3C4E12.jpg

I cut 4 inch sections and drilled them for two mounting holes into the side of the kirkey seats. The button heads go on the inside of the seat and can barely be felt under the Air knit kirkey seat covers. (which I was surprised how nice look and how comfortable they are) two bolts go down through the rear of the seat in the corners attaching the seat to the floor. I think I might mount the back of the seat to the aluminum firewall for added rigidity. I just need to figure out the best method.

I used the 15 inch wide seat for the drivers side with tons of extra room on either side. I am going to move the steering column slightly more inboard to center it on the new seat position.

I used the 16 inch wide seat for the passenger still fitting between my door bars and the center tunnel without modification. The tunnel will need to be made a bit more narrow before I fit the stock seats.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/8901849E-F60A-4914-B9F5-086C15C0D62F-2107-000005AB6E061F96.jpg

I also welded in plates to mount the harnesses.

Two plates outboard to mount the anti sub straps and the lap belts.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/DC8E3CB0-5561-4C7D-8ADB-E5067C623D38-2107-000005AB688CDC8D.jpg

I used the stock factory five belt mount for inboard lap belt.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/F2083C4A-871F-4BDF-B7C2-A94165D43D3F-2568-0000063BD2BA51AE.jpg

and installed two mounts for the anti sub straps the top left unpainted mount works better for the racing seat and the lower mount works well with the street seat.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/4658598E-EBD8-4D75-8995-9FD6AA259B8E-2107-000005AB5F06A356.jpg

On the drivers side the only difference was welding in plates slightly farther forward to the x brace. These have welded in nuts to receive grade 8 7/16ths -20 bolts. This method of mounting is more rigid then mounting to the sheet metal floor pan. The sheet metal oil cans a bit when you really pull on the seat. I think a third attachment to the aluminum firewall will stiffen up both the passenger and driver method. Seat mounting is something i think its worth spending a little time to over kill.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/5A85DD24-DCBB-433E-963D-77AE9B9D4561-2899-0000040B65B18113.jpg

Also in this picture you can see the smaller nuts that I use to mount the stock seat that rides on tracks for easy adjustment.

John

[kabacj]

This weekends focus was the cooling system. Although the canton tanks work just fine, I wanted to make a custom tank that fits into the nook created by my roll cage additions.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/7256A184-8B28-46D3-9720-4D5709BE52D8-2549-000006540AFAE0EA.jpg

The Corvette tank is 4.5 quarts with 2 quarts to full cold. I figure with the larger volume of water in the GTM an extra quart of expansion area would not hurt. My tank measures 5.5 quarts.

I had temporarily mounted the corvette catch tank. Propped up its higher then the heads and works fine. The hose routing is not ideal with the corvette tank. You cant get the tank all the way up to the top of the hatch like you can with a canton setup.

I mocked up the tank in cardboard. It slots right into the space in the frame but still has enough room for easy removal in the future if necessary.

Since the hookups hang below the tank I wanted to make them first and add them to the mock up to ensure clearance.

I turned the two fittings on the lathe then cut some 1 inch pipe I had laying around .

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/7BEE2A4D-5C20-4427-807A-03B08874DEDE-2549-0000065407A37D5D.jpg

After some fitting and welding I have the part ready to be drilled for the tube that attaches the tank.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/71D435F6-94B1-4918-A0D1-CFF754B5025B-2549-00000654039826CC.jpg

One of the things I like about this setup is I can route the hoses without any major twists and turns. Both hoses have a straight run from the water pump.

This is the connection on the Corvette tank.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/A209C881-9816-43E1-AE4D-352B27194F59-2549-000006540ECE3F79.jpg

John

[kabacj]

Well Hurricane Sandy put the brakes on my GTM build. She even canceled my week long trip to SEMA! The storm itself canceled my flight out on Monday AM. It was a bit windy but I have flown out in worse... On Wed when the storm passed I could not get a flight out because all of the coastal fuel terminals were damaged and without power. The jets did not have enough fuel and airlines were not flying in to NY. Only short haul flights were operating and the airplanes were flying in with enough fuel to fly out... Crazy! Of course we had a gas shortage for cars too, but there was plenty of diesel. It was nice not to deal with 3 hour lines for gas. It reminded me waiting in gas lines in the 70s . I think that scared my for life. I hate waiting.
I was fortunate to only have minor damage at my house but my family was not as lucky. So the past few weeks have been spent helping them recover. Finally this weekend I was able to put a few hours in on the car.

I was in the mood to do some welding so I started with the wing support.

First step was to build a frame to hold the wing.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/3C8B9379-ED66-4828-B2AB-8778C9745761-3799-000009DF82B64768.jpg

I welded in some plate on each side of the frame to accept the through bolts that mount the aluminum wing supports.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/8087F3EF-71E6-4B44-B937-DBA476498181-3799-000009DF7B026D36.jpg

Next I needed to figure out how I was going to support the frame.

I wanted to use struts and rod ends because that will allow me some adjustment.. and i just like them.

The next step was to support the frame in such a way that its rigid and able to support a few hundred lbs. I had a few ideas, but I find that mock up always highlights changes that would be better then my original idea.

I was outside cleaning up the mess from the hurricane and then the nor'easter that dropped 6 inches of very wet snow and did even more damage.... and I had to cut back some of the bamboo. What a great building material that stuff is.

I used it to mock up my struts. The cool part of using this instead of metal is I can see it flex when it takes a load. Was very helpful to optimize the strut placement.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/FF50C65D-C93B-4565-AB28-987B98206307-3799-000009DF7F7B712B.jpg

The metal struts will be slightly different, however I got some good ideas from using the bamboo.

After cutting out a few tabs I ran out of time for this weekend. Its nice to be back in the garage.

John

[vnmsss]

Great that you're back at it John!! We really missed you at SEMA, and all of us were thinking about and praying for our friends back East during our time at the show. Glad you're home didn't sustain too much damage, and very sorry to hear about the damage your relatives sutained. While the hurricane is weeks behind us, I know many folks are still suffering, and we continue to pray and send help where we can.

You made some good progress this weekend, and your story about the bamboo is awesome....I've had the good fortune of talking with some of the greatest racecar designers and engineers over the years, and I think people like Peter Brock and Phil Remmington would appreciate your pragmatic genius. :) I continue to cheer for you over here, and can't wait to see your creation under speed!

Karen

[kabacj]

Hey Karen!

Great to hear from you. I felt bad I let you guys down and could not make the show. From the pictures it was clear that the Factory Five booth was as crowded as ever. When I spoke to Jason his voice was horse from all the talking. That is a great indication of a successful show!

I was also very disappointed that I was unable to see your new coupe and all the beautiful factory five cars at the show.

Thanks for the kind words on the build. Hopefully some of these mods actually work as planned on the track.

Talk to you soon.

John

[kabacj]

In order to support the wing I will make at least 4 struts that support the square frame that acts as the wing mount.

Each mounting point will have two tabs, That means lots and lots of tabs. I don't have a CNC mill or plasma cutter.... yet so I am relegated to the old school methods my a designer / fabricator friend showed me before everybody had cool software that make CAD drawing easy.

Step one mock up the tabs in poster board. Once you have a good design re draw the tab on a piece of paper. Make a copy of the drawing. Cut out the tab from the copy and tape it to the first page recopy and you can multiply your tabs pretty quickly.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/09E6EBCE-B35C-4B78-9655-0987CD6C1541-4314-000006A027032266.jpg

I can use autocad, but some times this method is just quicker and easier for simple shapes. I also don't need to leave the garage.

Next a little spray adhesive on your paper pattern and glue it to the metal sheet stock.

Next drill then cut out the shapes on the band saw being very careful not to touch the lines of the pattern.

Finally using a stationary sanding wheel or what ever you have handy creep up on the lines. If you are making many of the same tab, I bolt them together and sand them all at once.

Sure its lots of work to make tabs this way, however I like the fact that I have complete freedom with the shapes and I can make the same shapes out of aluminum and steel.

With a few tabs complete, I welded them on and started to measure for the struts.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/0E1CA007-6713-4DA4-BD8A-918112E224B5-4314-000006A019421A3D.jpg

Im sure there are better ways to make tabs, but this is one easy method i enjoy.

John

[kabacj]

Next step on the wing support was mounting the tabs and making the struts. I also added some cross bracing to the frame.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/099C6E3C-EE25-419C-98FC-6A3E538E0F57-2661-000006F44AC540B4.jpg

I made the two front struts out of some tubing with machined ends. The rod ends are left and right hand threaded so I can spin the tube and lengthen or shorten the strut. I turned off the welds because I thought it looked nicer. The ends are a press fit into the tube and I made sure to get good penetration so the joint would remain strong.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/06507BBF-E1EA-406A-92BF-54D358C08D91-2661-000006CC71B215D1.jpg

I have started a theme with the strut design. I'll make all the struts for the car using this design.

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

Merry Christmas guys

John

[frank23]

Normally X-design are stronger for cage purpose. If you don't have that extra room that the gutted doors would provide, than X-design provide similar protection without being as intrusive. As well as X door are cheaper than others.

[kabacj]

Normally X-design are stronger for cage purpose. If you don't have that extra room that the gutted doors would provide, than X-design provide similar protection without being as intrusive. As well as X door are cheaper than others.

Hi Frank. I agree an x in the door opening would be stronger. That was my origional idea. However I could not make it work without making entry and exit very dificult. Since the GTM is quite low and your knees are almost at the leading edge of the door entry and exit are already tight. I wanted to maintain ease of entry and exit so I went with NASCAR style. Since the frame structure is inboard of the fiberglass shell
gutting the doors does not buy you room like it does in a production car. Thanks for the input. If someone can make the x style work in a GTM I agree it would be better.

John

[crash]

If you go to half doors and put a shelf in, then not only can you beef up the side protection, but you now are sitting on a shelf when you get out and you aren't looking so silly crawling out of the car.

14159

[kabacj]

If you go to half doors and put a shelf in, then not only can you beef up the side protection, but you now are sitting on a shelf when you get out and you aren't looking so silly crawling out of the car.



Ha! No doubt Crash. That is a very cool setup.

John

[kabacj]

Although lots of people get the factory five setup with the overflow tank in the front of the car to work without issue, I chose to go with the tank mounted higher than the engine. I think its easier to bleed out the air from the system with this setup.

The mods I did to the cage in order to hopefully qualify it for SCCA and NASA created a nice little nook that I wanted to install the coolant overflow tank into. The corvette overflow is 2qts to full cold and has a total of 4.5 qts full to the rim. I wanted to have at least this much volume in my overflow tank. This tank is 5 qts.

I mocked it up in Google Sketchup to get the right volume then cardboard to check the fit. Then aluminum.

I copied the design of the input tubes from the corvette tank with a larger diameter hose going into a smaller diameter. I figure this design slows down the fluid flow and I am guessing that it allows air to come out of the system. What ever the reason some engineer figured it was a good idea so I kept it.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/C64CF794-F938-4232-ACAF-1196151D3778-5484-00000FDFAD5E4FF1.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/EABA8AAE-738D-4137-8ED3-964C78D8BFDA-5484-00000FDFB0363ECD.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/3B63CF29-182B-476F-8169-CD7E8EC5A59A-5484-00000FDFB2F592A3.jpg

There is this little hole in the rear hatch hinge support. so I turned a bit that fits into the hole then drilled and tapped it to accept a bolt.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/3933ED3D-EDE6-4059-BDB9-FEC6164FA0EB-5484-00000FDFB6312B97.jpg

Its a crazy tight fit, but it fits....just barely.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/CE0DFDC4-DB8A-4D6C-BA62-F09C3AC19E6F-5484-00000FDFBBD5A180.jpg

I added a second mounting bolt on the back to lock the tank into position.

This project took a while, but i think it was worth it.

John

[kabacj]

Mast Motorsports suggested that I run a vacuum reservoir with the individual throttle bodies. Of course one throttle body is only generating vacuum at any point in time. To provide a constant vacuum each is plumbed into a manifold.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/D4B57B98-DD8A-4D9F-BEF5-E2A9CC414F3C-6415-00000CE6031EE6EF.jpg

I researched all types of tanks. Production car vacuum tanks were expensive and not what I wanted. I was browsing through the Jegs catalog and I found this tank. It seemed like it could work. It was only 14 bucks so I figured i would take a chance. Worst case I would make a tank from aluminum.

The vacuum manifold has a -6 AN fitting. I purchased fittings and hose and got to plumbing the setup.

Of course the Jegs canister did not have the size fittings I needed. No problem. Lathe to the rescue.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/0AADF59B-D256-4909-AE98-9094E22DC34A-6415-00000CE8A4836847.jpg

the bottle had two fittings top and bottom like the one on the lower left. I needed a fitting for the top that would connect to the push lock hose. So I copied the Black fitting on one side and the lower left fitting on the other. That gave me the aluminum fitting on the top right.

The bottom fitting needed to connect to a very small vacuum accessory line for my heater bypass valve. I figured that small a barb would be weaker if I made it from aluminum so I opted for stainless steel. That also made it easy to just chop off the barb on the jegs fitting and weld on the new barb. See bottom right in the pic above.

Here is the new setup

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/0E336F32-4ED2-410F-938F-CA4AFB04E3D7-5237-00000B6F7D71531B.jpg

And the picture installed.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/3F0052EC-160A-4E40-9CA9-564CB0B557C3-6415-00000CE60070CABA.jpg

Neat and tidy install for 14 bucks. I was happy with that.

John

[Kempo]

John,
I've said it before and I'll say it again. You really are one hell of a craftsman. If it ain't available you just fabricate it. I'm definitely becoming a big fan of your work. Keep the updates coming buddy.

[GTM RACER]

you might want to make the cross member over the gearbox removable. It makes taking the gearbox and engine a lot easier to remove and replace. If you are really going to put some power to the ground with that, might I suggest checking the vertical loads of the rear toe links for twisting and compression.

[kabacj]

you might want to make the cross member over the gearbox removable. It makes taking the gearbox and engine a lot easier to remove and replace. If you are really going to put some power to the ground with that, might I suggest checking the vertical loads of the rear toe links for twisting and compression.

Hi GTM Racer.

Regarding the cross brace above the transaxle. With the current setup its necessary to remove the transaxle, clutch, and flywheel before the motor comes out easily. I might be able to squeeze it out with the clutch and flywheel still attached, but that’s more of a two man job. I have more in the way of the front accessories with the roll cage additions.

The motor has been in and out 5 times or more and I can do it with help from my 8 year old son who guides and watches the front accessories while I work the lift and twist the motor. The transaxle drops out the rear pretty easily I can do that myself with a cradle I made for my floor jack.

It would be nice to just lift the motor and transaxle out in one piece. I am not at the point where I bring a spare motor and transaxle to the track where a quick motor swap and transaxle swap is a premium. All that said I agree a removable cross brace would be very nice. Its on the list.

Regarding stiffening the toe links. The stock corvette pieces are good, but could be better. I replaced with aluminum links and rod ends.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/8FB4896E-E095-4C70-9EA3-D60BD1D4064F-10047-000014F912D3D436.jpg
These are both stiffer and the rod ends will take more of a beating and remain tight. Of course that moves the next weakest link to the frame brackets.

Boxing in the suspension mounting points is a project for another time as well. I am interested to see how the stock frame reacts. I am attempting to limit the scope of changes I make these days so I can be sure I am ready to start sorting out the car come March 30th.


John,
I've said it before and I'll say it again. You really are one hell of a craftsman. If it ain't available you just fabricate it. I'm definitely becoming a big fan of your work. Keep the updates coming buddy. You are too kind Hugo. I'm just having fun over here.

John

[GTM RACER]

I hope you are not going to use those shock mounts that are in the photo! They will not hold up in a high performance or track environment for very long.

[GTM RACER]

I hope you are not going to use those shock mounts that are in the photo! They will not hold up in a high performance or track environment for very long. About the cross bar: I presume you haven't tried taking any of these components out with the body permanently mounted.

[kabacj]

I hope you are not going to use those shock mounts that are in the photo! They will not hold up in a high performance or track environment for very long. About the cross bar: I presume you haven't tried taking any of these components out with the body permanently mounted.

Hi GTM Racer,

I do plan to use the re designed factory five shock mounts. The first design was a bit weak and Factory Five sent out a replacements to all owners free of charge. The new design might not be up to the task for a 25 hour, but i think they will be fine for a while. Ill keep an eye on them. I appreciate the concern. I have not heard of any failures of the new design, have you?

The motor comes out with the body on as well. Even without a cross brace removed, its necessary to move the motor back to get the water pump and accessories out from under the rear hoop. That is not possible with the trans axle attached and the rear transaxle mount still on the car. With the hatch off the engine bay is the same size with the body on or off.

If I was going with the quick change drive line I would do what Richard and team have done making the rear clip on the body removable. Then it might be possible to get the whole drive line out in one piece.

I would love to see any pictures you have of a working quick change drive line setup.

Thanks for the comments.

John

[GTM RACER]

Just reading post 114. NASA and SCCA doesn't allow cross bracing in the doors anymore. They spec out two door bars but not in a cross unless you add a bar or box plate at the intersection to eliminate the impact-knee action or hinging as if it is still one bar. It is the same configuration that the world challenge Ferraris use and is quite clean. I went back and looked at the door bars in my car and they are even with the factory cage, however, I have gutted doors and it looks like you would gain almost three inches from frame to outside the bar. With a removable steering wheel, it looks like you would have some pretty good ingress and egress. Adding the door bars to meet any sanctioned body is a challenge with the GTM. I don't see it any different than any other small import road racer.

John,
It is undeniable that your work and craftsmanship is second to none on this forum. It is a pleasure to see your hard work come together!

[scottvette1989]

John,
It is undeniable that your work and craftsmanship is second to none on this forum. It is a pleasure to see your hard work come together!

I have to second this statement. I read most of the posts in this GTM world but I look forward to updates to this thread above all others.
Scott

[mendo]

Hi GTM Racer,

The new design might not be up to the task for a 25 hour, but i think they will be fine for a while. Ill keep an eye on them. I appreciate the concern. I have not heard of any failures of the new design, have you?

John

Richard and his boys broke the new repaired design. I heard a rumor that there may be some of his race proven mounts that can be had.

[GTM RACER]

They broke a prototype design before the fix was sent to the public by FF. the "fix" was direct to them at the race and made on the spot. (the result of that is shown in the infamous picture of the sparks flying out the rear of the car) That is the fix failing.(prototype one, not the one sent). I believe ther is not anyone actually tracking the "fix" on a regular basis, but I do know those that do track regularly use the shock mount provided by Ted.

[mendo]

They broke a prototype design before the fix was sent to the public by FF. the "fix" was direct to them at the race and made on the spot. (the result of that is shown in the infamous picture of the sparks flying out the rear of the car) That is the fix failing.(prototype one, not the one sent). I believe ther is not anyone actually tracking the "fix" on a regular basis, but I do know those that do track regularly use the shock mount provided by Ted.

makes sense! Ted's piece is nice. I will be running the fix on my street only car until I get extra money to upgrade.

[kabacj]

They broke a prototype design before the fix was sent to the public by FF. the "fix" was direct to them at the race and made on the spot. (the result of that is shown in the infamous picture of the sparks flying out the rear of the car) That is the fix failing.(prototype one, not the one sent). I believe ther is not anyone actually tracking the "fix" on a regular basis, but I do know those that do track regularly use the shock mount provided by Ted.

Good information GTM racer. Do you know if the prototype part and new production part were the same? Any pictures of the failed part? Does the PDG GTM run the same part Ted sells? No doubt Ted has a wealth of first hand racing experience. Ted also makes some very high quality parts for sale. Ted has helped me with a few aspects of my car and I value his opinion. I would just like to hear more first hand account regarding what failed during the 25 and why.

The 25 hour finds the weak link in every system. Things that never fail under normal racing use fail under the stress of the 25 hour. That's what makes it such a cool event.

When I am ready to address the lower shock mount I think I am going to machine and weld something up. Both Ted and factory five need to make parts that work, are cost effective, and easy to install.

I only need to make parts that work. The time and effort required to make and install the part are a bonus.

Good discussion. Thanks for the input.

John

[LS MAN]

Hey Guys, the PDG GTM has been using our rear mounts for 4 or 5 years, with no problems so far.
http://quickracingproducts.com/html/chassis.html

Thanks,

[kabacj]

Hey Guys, the PDG GTM has been using our rear mounts for 4 or 5 years, with no problems so far.
http://quickracingproducts.com/html/chassis.html

Thanks,

Well Ted that is a record to be proud of. Nice job on the design.

John

[kabacj]

Yesterday was snow blowing and shoveling all day long to remove the 20 inches of snow. Even my truck without a plow got into the act.
http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/ECC2E3F4-B638-432D-9AF7-593B8885CB2C-17461-0000242509CC274E_zpsc402300d.jpg

Today it was time to get some work done on the GTM. A few months ago I had installed a piece of lexan just to close up the window. But the fact that the window opening was not perfectly oval bothered me.

So out came the bulkhead. I pulled out the lexan and started reshaping the opening. A while back, I had attached a strip of aluminum to the stock opening in order to fit the roof bars.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/rearwindow_zps22331ecf.jpeg

So I needed to weld up a patch in each corner before I moved the semi circle that makes each end of the window about a half inch downward.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/F54CB6AB-EBBB-4AE8-8517-28D00E3F21AC-17461-00002424BD645635_zps69e697cb.jpg

Next was trim a half inch off the bottom half of the window. I welded up all of the holes I will not use and installed the window.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/60283B20-A454-4B45-8246-2609639604D6-17461-0000242491C1B624_zps6cf968e4.jpg

So with that sorted I decided I needed a activated carbon canister to prevent the vent on the gas tank from releasing fumes.

I machined up some parts and used a length of tubing I had left over from making my cooling system pipes. A little welding and i had this. I glued some open cell foam to the bottom of the canister to prevent any of the carbon bits from falling into the tank.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/1ACF50E1-8CD3-415E-A112-7D2312941064-17461-00002423FABB9B84_zpse5a0b64b.jpg

I was able to use the hole in the rear hatch mount to attach the canister. A small length of Tygon fuel resistant tubing forms a flexible joint between the canister and the tank.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/AD1D848A-43E4-42B1-BBF4-C8A52B080512-17461-000024226B1BC4FD_zps377d29ba.jpg

I purchased some crankcase vent filters and one to the hole in the top of the canister and here it is.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/64F27844-BA4E-4446-99A2-F0900CAC394B-17461-000024226721E9F3_zps6da7899d.jpg

John

[RumRunner]

John,

What you accomplish in a few hours would take me days. Hats off to you, sir! And it looks really good.

-Michael

[kabacj]

Thanks Michael. Don't let the magic of the Internet fool you. This took around 8 hours. I have a system to keep the family happy. 3 hours from 6am till 9. Then five hours between 9 and 6.

It also helps when I keep redoing the same thing. The second and third time are much faster.

John

[JCHRacer]

Hey John,

How is your progress getting sanctioning approval for the cage? Any updates?

[kabacj]

Hey John,

How is your progress getting sanctioning approval for the cage? Any updates?

Hi Joel,

The local scrutineers have signed off that the cage "looks good to them". They actually said its over kill. I was happy to hear that. Sadly these guys don't have the authority to approve a non standard cage. Their job is to enforce the rule book. The next step is to lobby the NASA national Safety board regarding the structure. Of course they want an engineering opinion on the strength of the GTM setup compared to the standard setup they show in their rule book. I am not an engineer. In the end I need to show them some proof that this cage design is at least as strong as their approved design which allows them to continue to have insurance. It always boils down to that these days.... oh well.

The current NASA rules have exceptions for other rear engine production cars, however none allow the setup we have in the GTM.

Regarding SCCA they have a spring tech event locally here ill bring GTM and see what feedback I get. SCCA also have a auto cross event April 7th. I will bring the GTM to the autocross so I can get some slow speed setup info.

Since I need to sort out the car for at least a few weekends I hope to try to lobby folks/ make connections at those events and go from there.

Unfortunately the first NASA event, March 30t at Lime Rock Park in CT, has a noise restriction of 88db. Clearly none of our cars are that quiet. I still have plenty of loose ends to tie up before then so building an 88db exhaust and re tuning the motor are out of scope. The next event is April 19th. I will attend that one and sort out the car and see how close I am to race ready condition.

BTW love your car. It sounds awesome! The finish is in sight!

John

[GTM RACER]

John,
Mike has a muffler set up that is quiet enough for Lime Rock. Get a hold of him. I went through an unorthodoxies cage design that would withstand 150 mph = rollovers and NASA wanted numbers. I provided numbers from a structural program and still. because it did not look similar to the three designs, they declined the effort. You are right it is all about insurance and who would pay out in a court case. I was told that the wagon wheel approach has a very good chance of approval on its own merit! Sometimes too many bars are not a good thing. A race friend of mine had a Toyota that had a very strong cage...hit the wall and the impact went right to the seat and broke his back. The car was too rigid. Great work, by the way!

[kabacj]

This weekend I finally had some reasonably nice weather, and no little projects getting in the way of a drive, so I decided it was time to take the car for its first drive around the block.


http://youtu.be/BeGcvtuaS6E


I was just taking it easy and figured I would just get on it a little to see how it accelerated. Holy cow!! Barely any throttle and I broke the rear tires loose. It did not do anything evil. Just stepped out a little. HA that was fun! I know they are stone cold, but still. Sheesh what was I thinking to get a 630 hp motor. Oh well with warmer weather and a bit of setup I'm sure it will be just fine. Man this is going to be fun to drive on the track. :cool:




John,
Mike has a muffler set up that is quiet enough for Lime Rock.

Thanks GTM Racer.

[RumRunner]

John,

Looks good, sounds great. The first drive around the neighborhood is a big milestone - for you and your neighbors - Congrats!

-Michael


GTM # 327: In prime, wet-sanding time.

[Kalstar]

This weekend I finally had some reasonably nice weather, and no little projects getting in the way of a drive, so I decided it was time to take the car for its first drive around the block.


http://youtu.be/BeGcvtuaS6E


I was just taking it easy and figured I would just get on it a little to see how it accelerated. Holy cow!! Barely any throttle and I broke the rear tires loose. It did not do anything evil. Just stepped out a little. HA that was fun! I know they are stone cold, but still. Sheesh what was I thinking to get a 630 hp motor. Oh well with warmer weather and a bit of setup I'm sure it will be just fine. Man this is going to be fun to drive on the track. :cool:





Thanks GTM Racer.

Go Daddy, go Daddy, go Daddy. Very cool, congrats on a couple of fronts.

[carbon fiber]

looks good man! i'm digging the details of your build. good to see you're at the go-kart stage. keep it up!

[Presto51]

Very Nice John, very nice

Thanks for sharing

Ron

[JCHRacer]

Hi Joel,

The local scrutineers have signed off that the cage "looks good to them". They actually said its over kill. I was happy to hear that. Sadly these guys don't have the authority to approve a non standard cage. Their job is to enforce the rule book. The next step is to lobby the NASA national Safety board regarding the structure. Of course they want an engineering opinion on the strength of the GTM setup compared to the standard setup they show in their rule book. I am not an engineer. In the end I need to show them some proof that this cage design is at least as strong as their approved design which allows them to continue to have insurance. It always boils down to that these days.... oh well.

The current NASA rules have exceptions for other rear engine production cars, however none allow the setup we have in the GTM.

Regarding SCCA they have a spring tech event locally here ill bring GTM and see what feedback I get. SCCA also have a auto cross event April 7th. I will bring the GTM to the autocross so I can get some slow speed setup info.

Since I need to sort out the car for at least a few weekends I hope to try to lobby folks/ make connections at those events and go from there.

Unfortunately the first NASA event, March 30t at Lime Rock Park in CT, has a noise restriction of 88db. Clearly none of our cars are that quiet. I still have plenty of loose ends to tie up before then so building an 88db exhaust and re tuning the motor are out of scope. The next event is April 19th. I will attend that one and sort out the car and see how close I am to race ready condition.

BTW love your car. It sounds awesome! The finish is in sight!

John

Congrats on getting it running John. Looks Awesome.

As far as the sanctioning bodies go, you have had the same experience that many people have had when you just can't make it the rule book. While I have performed a structural analysis and determined that my cage (and yours) is as good or better than a cage built to the rule book under most loading conditions, I can’t guarantee that it is superior under every possible circumstance. Plus you have the liability thing....I feel safe in the cage I built but I'm not going to take the responsibility and the liability of certifying the design for someone else's use. Blame the lawyers and insurance companies.

Let us know if you make any progress with the scrutineers.

[kabacj]

While I have performed a structural analysis and determined that my cage (and yours) is as good or better than a cage built to the rule book under most loading conditions

Joel your cage design is awesome. I think it both looks nice and of course unlike me you can actually test what design is best. Thanks so much for sharing the design. I will get the cage approved. I totally understand the lawyer / insurance thing. Its a sad state that we all must fear for our lively hoods at the hands of ... well don't get me started. Ill find a way to get it approved and hopefully give back a little.


Very Nice John, very nice Ron

Hey Ron Thanks!


looks good man! i'm digging the details of your build. good to see you're at the go-kart stage. keep it up!

Thanks CF! Hopefully ill have some cool CF details to add to my car pretty soon...


Go Daddy, go Daddy, go Daddy. Very cool, congrats on a couple of fronts.

HA, HA. Thanks Jim. I owe the ITB idea to you. Yeah I am a pretty lucky guy that the family are always cheering me on.


John,

Looks good, sounds great. The first drive around the neighborhood is a big milestone - for you and your neighbors - Congrats!

.

Thanks Michael

The video does not do the sound justice. I am really pleased with the package. It definitely is more work to package the ITB setup, however it just sounds special. And nobody called the cops! That was nice.


John

[kabacj]

I'm back in thrash mode again. I am pushing to get the car into an auto cross the weekend of April 6th. Then out for the NASA weekend at NJ Motorsports Park on April 20. I figure autocross will be a good slow speed shakedown prior to going out on the track.

This weekend I wrapped mounting the ISIS cells. I have three modules mounted up front.

The master cell, one power cell, and an in motion motor controller.

I like the Isis because its easy to troubleshoot . It's light weight compared to the painless setup and I can add all of the little details and features of a new car into my GTM. Lots of gizmo factor with this setup.

I hate looking at wires so I wanted to hide as much of the Isis setup as possible while still keeping it accessible for easy maintenance and keeping the wire lengths as short as possible.

Not too many choices regarding where to install it.

I installed the power cell and the in motion motor controller on the passenger side. Also installed here are the high amp fuse block for power distribution and low voltage Isis power shutdown solenoid.

the view from the top

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/18F79E86-4C7C-41EA-9B88-A90B6A938931-6917-00000DDD8A32E6D3_zps721061e0.jpg

the view from the passenger foot well

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/F35DE4EA-6217-41F6-AC1E-B5072C6910F9-6917-00000DDD8E8F5F16_zpsf080d8ea.jpg



On the driver side I installed the master cell. I tipped it so its easier to see when sticking my head under the dash for programming and diagnostics.

the view from over head

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/AD22DAEE-9BF4-43C3-8CE3-28BAFAC92F21-6917-00000DDD9274FFC9_zps10a2ab84.jpg

the view from the foot well.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E710591B-D2EC-45BB-BFDB-ED7622E56A4A-6917-00000DDD951637A3_zps0421508d.jpg


I end up with two stand alone computers.

The Engine Control unit which powers/ controls fans, fuel pump, gauges, AC clutch. The Isis controls everything else with power. The only think I lack with the ecu for track duty is brake lights.

I did not expect the ECU to control so much but Mast Motorsports design the system to drop into anything from a muscle car to a race car. The ecu will also control turbos, NOS, Methanol injection it even will adjust/ calibrate the speedhut gauges. For now ill get the headlights and brake lights working using the ISIS...

John

[kabacj]

This weekends focus was the seat and harness setup for the passenger and driver. First thing was strengthening the passenger floor so I could bolt the seat to the pan without the bolts pulling through.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/29D29A71-7AC1-4668-B2A8-068F17C4E9EE-1988-000004D38C74FDFF_zps977f46ae.jpg

While I was at it I removed the lower right belt mounting plate to relocate the belt attachment point lower to the floor. The anti sub straps were rubbing against the seat bottom and it was hard to pull them tight.


http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/4658598E-EBD8-4D75-8995-9FD6AA259B8E-2107-000005AB5F06A356.jpg

I hate cutting things back out. This little guy was welded in there good.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/CD504DA0-F8CD-4F78-B67B-9576BD8B5513-1988-000004D38FBD96C4_zps1412465f.jpg

I made a few rings to use instead of the eye hook that came with the belts.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/C6CC1276-1459-4E85-AE10-32F1B450C070-1988-000004D4038CB87C_zps83f7c55b.jpg

A little cutting and I had a low profile belt mounting point.


http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/14f45292-e8aa-44e5-a979-c8e5c705d8bb_zps7b194467.jpg

[kabacj]

Next was the fun and time consuming part. I needed harness bars to attach the belts to the mounting points I welded to the cage.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/9CD804C5-F459-48A9-BAF7-4C2D2292FADE-12937-00002A3482A0D2C6.jpg

I got some hex bar stock and bored out a hole. I cut it in half.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/24A4108D-12E8-4AFB-9CFA-25DA77F00A84-1988-000004D376D16F05_zps6fd28692.jpg

Then I hollowed it out.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/4C3172D8-6AF9-46B5-842B-C2E5236039A3-1988-000004D3797FB2BA_zps365345d2.jpg

Then I welded them up. The lower bar Fits the stock seats on both sides. I moved the kirkey road race seat two inches inboard so I also needed to move the belt locating rings inboard in order to keep the belts centered relative to the holes in the seat.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/AB00637C-B61B-401D-A2BF-702939AFD39F-1988-000004D380176C6C_zpsd019c924.jpg

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/7570761F-BF99-4491-908F-78D136BAB3E8-1988-000004D38290F866_zpsc2fabae1.jpg

When I have more time i will make a third bar that matches the bottom one. This way I will have a matching setup for the street and the harness bar setup for the road race seat.

It took me a whole day to make the first bar. The second only took a few hours. I ran out of time before I could mount everything and take a few pictures.

The only thing I need to work out is how to brace the back of the seat against the firewall. Its a well made seat, but mounting the back to the firewall will stiffen it up. Anybody have ideas on an approved method of bracing?

Thanks
John

[mendo]

How about attaching it to the Harness Bar? seems logical to me!

[fastthings]

Good show man, looks good.

[LCD Gauges]

Damn, look at that roll cage addition, and the link bars! If there's a top five GTM builder's list, you are definitely on it. I need to keep an eye on this thread for floor re-inforcement ideas. My plan is to weld a plate to the underside of the floor pan to keep the seat clearance higher, but that might be difficult for welding a decent bead. I'm also ready for the seat belt install, and I see that you've modified the anchor points. Are you using theC5 belts, or something else?

[kabacj]

My plan is to weld a plate to the underside of the floor pan to keep the seat clearance higher, but that might be difficult for welding a decent bead. I'm also ready for the seat belt install, and I see that you've modified the anchor points. Are you using theC5 belts, or something else?

Hi Tino. You could definitely weld a plate under the floor pan, but its much harder to weld over your head, and you only lose an 1/8 of an inch with the plate on the inside. I am using a six point system from Schroth Racing.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/Untitled_zps3d6b6939.jpg

Yes I did need to add mounting points for the harness. It took a little trial and error to get all the mounting points in good locations where all the adjustments worked as designed. With the seat only a half inch off the floor pan the anti submarine belts were more difficult to install. Normal cars have he seat at least a few inches higher off the pan and as a result have easier belt routing options. Also note that the top mounts on my setup wrap around the harness bar I made. I did not use clips on the top, but I could have. I thought the bars looked nicer.



Good show man, looks good.

Thanks Gene. BTW no doubt the individual carbs on your sons car are more work, but you don't see them every day. I personally like that. And they look and sound so cool.


How about attaching it to the Harness Bar? seems logical to me!

Hey Mendo, some racing organizations require additional bracing to mount the upper part of the seat to the cage. or body structure of the car.

Something like this.

http://i1073.photobucket.com/albums/w389/kabacj/brace_zpsf433b43a.jpg

I don't like the idea of a pole pointed at my spine, and every forum has some horror story of a guy who was injured because his seat failed for some reason. I figure there might be a solution out there that we could borrow or modify to fit the GTM.

Maybe I will just brace the seat along the lines of many of the full containment seats out there and not add any additional mount. It does need something. I'm unsure what the right thing to do is so was looking to see if anybody has seen or experienced a solution that works.


John

[vnmsss]

Wow, John! You've been a busy, busy man! Thanks for posting all the pics...I truly appreciate how much work (design/engineering/fabrication/installation) you've devoted to making your GTM an amazing race machine! Big kudos, my friend....Very nice work!

Karen

[JCHRacer]

Hey Mendo, some racing organizations require additional bracing to mount the upper part of the seat to the cage. or body structure of the car.

Something like this.

http://i1073.photobucket.com/albums/w389/kabacj/brace_zpsf433b43a.jpg

I don't like the idea of a pole pointed at my spine, and every forum has some horror story of a guy who was injured because his seat failed for some reason. I figure there might be a solution out there that we could borrow or modify to fit the GTM.

Maybe I will just brace the seat along the lines of many of the full containment seats out there and not add any additional mount. It does need something. I'm unsure what the right thing to do is so was looking to see if anybody has seen or experienced a solution that works.


John

I was planning on filling the space between the back of the seat and the firewall with expanding foam like this stuff:

https://www.pegasusautoracing.com/productdetails.asp?RecID=1038

Should spread the load, it's light weight and will be WAY safer than the spine pole.

[Fraser D]

You could use something like this?
Not sure if it abides by the rule book.

http://www.jegs.com/i/JEGS+Performance+Products/555/70291/10002/-1

[kabacj]

Wow, John! You've been a busy, busy man! Thanks for posting all the pics...I truly appreciate how much work (design/engineering/fabrication/installation) you've devoted to making your GTM an amazing race machine! Big kudos, my friend....Very nice work!

Karen

Thanks so much Karen. After 2 years I am really excited to get the GTM out on the track. Hopefully I'll be half as successful as you were with your coupe.




I was planning on filling the space between the back of the seat and the firewall with expanding foam like this stuff:

https://www.pegasusautoracing.com/productdetails.asp?RecID=1038

Should spread the load, it's light weight and will be WAY safer than the spine pole.

Great idea Joel. I like the fact that it spreads the load and is a great way to absorb energy in the event of an impact.


You could use something like this?
Not sure if it abides by the rule book.

http://www.jegs.com/i/JEGS+Performance+Products/555/70291/10002/-1

Thanks Dave.

I had not seen this mount. Of course I could never buy something I can make. :). This is a great design to copy elements from. Thanks for posting.

I was also thinking of welding some C channel to my seat like they did on this seat.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/C7D0E1C5-0B85-466D-BC80-5FF7761EE49B-1063-000001474302CFFC_zps5b6959ad.jpg

I figure I can mount a bracket like the one Dave posted but only need to worry about stabilizing the seat laterally. Preventing the top of the seat from twisting sideways in a side impact. Then using Joel's idea I can prevent the seat from folding in a rear impact. Then with some C channel I can stiffen up the shoulder and hip bolsters to prevent them from flexing and folding with a side impact.

Before I started all this I researched the companies that make custom full containment seats. They are both expensive and difficult to get fitted without bringing the whole car to their shop.

As we have discussed there is little room to fit a guy taller then me two inches under the stock cage height with a helmet on.

My ability to mount and tilt the seat at the ideal position was key.

Thanks for the suggestions guys.

Ill post what I come up with.

John.

[crash]

FYI on the foams. I have looked at many of those and they usually have a pretty low temperature threshold and will burn easily. I believe one of the foams I was looking at that had OK properties was "tiger foam" but it was awhile ago. As I say, just an FYI to make sure you aren't putting something flammable right next to the driver. :)

[kabacj]

This weekend while I was standing staring at the car a design idea came to me. I knew how I would mount the rear wing. I wanted it to be adjustable and I was going to do that using links and rod ends, but I could see that I would need to make seven or eight links to keep everything locked in place. I did not like that idea.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/FF50C65D-C93B-4565-AB28-987B98206307-3799-000009DF7F7B712B.jpg

When something is right I look at it and say that obviously the way you solve that problem. (course it was not obvious to me at the start of the project)

I wanted the solution to be light and adjustable.

This is what I came up with.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/E548D06E-A43C-4111-A48A-2E7EF3460560-2718-000004F42A9B7AE3_zps2f67aeeb.jpg

The wing support transfers the down force into extensions I added to the rear frame.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/CA2E5799-29DA-4677-9747-DB548DDD9601-2718-000004F439374D6E_zpsfe9c6dfd.jpg

The load is also transferred to the lower mounting points with some half inch square tube.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/EE2CE5D5-D184-4271-AF32-0B8B36698A90-2718-000004F43F8F1586_zps34ddf4f6.jpg

a top view

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/EE820428-DDC5-4C28-A9EA-3317C52D8F8E-2718-000004F4311C4C76_zps5ae7a5f1.jpg

I am really happy with how strong this setup is. It does not flex at all even when I throw my weight on it and yank.

I just need to fabricate and add a receiver type setup so I can add a rear tow hook or a drag chute depending on the situation. the connector will be hidden with the license plate in place. After that a little paint and on to suspension setup.

John

[sk7500]

More chassis artwork! Love it!

[kabacj]

More chassis artwork! Love it!

Thanks Steve.

This weekend I built my receiver setup. With this setup I can attach a tow hook or a drag chute. I started with a very simple idea of using some of the spare 1.5 inch DOM tubing from the roll cage and turning down bar or tube to fit inside.

Well I did not have any 1.5 inch aluminum laying around but I did have some one inch.

Of course I needed to use what I had. That meant I needed to make some bushings to fit inside the 1.5 inch roll cage tubing.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/A00F6853-12A0-4E44-B43C-9246C6E49617-441-000000459AAC90FA_zps17c0cf76.jpg

I made the bushings out of 6061 aluminum. Each bushing is a press fit into the steel tubing. Then I spent too much time fitting the 1 inch tube inside the bushings. I got the fit so precise the when I took the aluminum tube off the lathe it was warm from the friction of polishing. It would not fit into the bushings. When the pipe cooled it would slide into the bushings perfectly.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/7F796096-52EB-41FD-8835-BB8CA0564F7A-441-000000459DEA70F5_zps934f8162.jpg

Of course this was totally impractical. I knew it, but I was having fun.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/A690B6A4-A1B9-4CDB-BAB0-E9BBDF095475-441-00000045A085A273_zps1fa3b21c.jpg

I used the aluminum tube as a jig to keep everything aligned as I welded. I welded the bushings on to the transmission carrier . In spite if my best efforts trying to balance the heat and warping as I welded. The weld cooling slightly warped the alignment and tightened everything up.

I pressed the bushings out opened them up two thousandths and they are good to go.

There are definitely easier ways to do this. The time invested will pay off when I can swap a tow hook for a drag parachute with one bolt.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/074A218C-4FD4-4CDF-B74C-C93C2F01FBFE-309-00000020C5F36971_zpsfb171d78.jpg

John

[sk7500]

To say you have a passion for cool chassis stuff would be the understatement of the year. You need to have a clear body made. I'm not sure but it might be a sin to cover up your work.
PM me your e mail address. I have something I want to send you.
Steve

[The Stig]

I have to agree with Steve.

It seems a shame to cover such nice work with the body! Even if it's a body that looks as nice as the GTM.

Congrats and great work!

Mike

[kabacj]

Thanks Mike and Steve. I am having lots of fun with the frame mods. I did consider for a second how I could drive the car without a body, but the rocks that rain down all the time as they are thrown off the tires take the fun out of the no body configuration.

I have lots of body mods planned and then interior mods. So I should be busy for a few more months.



John

[Fugly_Old_Cowboy]

Great jod on the mods!!!
When the mods to the frame/cage are finished, are you going to re-powder coat or paint???

For us guys that are NOT "vertically challenged" (6' or over) any ideas on fitting an "approved" cage without lifting the roof? I don't think laying the seat back is going to be an option for me (I have a 38"inseam & will probably be cramming the seat all the way back to begin with)...

[kabacj]

Hi Cowboy

I repainted the sections where I removed the powder coat with POR 15. It's almost as durable as powder coat. It looks the same and it's much easier.

If you want to use the approved design. You can install the cross braces and additional hoop behind the driver and just move the pedal box forward.

Moving the pedal box wil require reconfiguring the bracing to make room for your feet.

Prior to this project I didn't have any experience building/ modifying frames. I tried to limit the changes I needed to make.

In hind sight, anything is possible. It just depends how badly you want to do it. You will find that every change requires a cascade of other changes and lots of time.

Before you commit to any drastic changes. I would sit in the car, get yourself a Kirkey intermediate road race seat that you can modify. There is tons of room to be gained just by sitting on the floor pan and adjusting the seat angle.

Solving all the little problems you create is part of the fun. It also makes you appreciate how nice it is that factory five give you all the parts and step by step instructions.

John

[LCD Gauges]

I see that all the welding lessons I gave you, paid off. I'll be sure to send your certificate of achievement this week.

This is now the JohnTM, not GTM.

[kabacj]

I see that all the welding lessons I gave you, paid off. I'll be sure to send your certificate of achievement this week.

This is now the JohnTM, not GTM.

Ha! Your lessons and 10 bottles of argon worth of practice and here I am!



Working like a madman to get my car and trailer ready for this weekends track event.

I repainted the car satin hot rod black because the epoxy primer did not look nice at all and I had a little more body work to cover up.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/77F5C9B4-F6BF-4E1E-B60F-B2DF41762E3D-448-0000002A2647E198_zps7642a13c.jpg

The satin black is actually a pretty cool look. I'm a shiny car guy but it will be fun to play with this paint style while I finish the car.


As I modify the body ill just keep it looking reasonably good with a quick coat of satin black. Then i will strip it all off for final paint. I have only had black cars/trucks I can't break that streak now.

I was working on the alignment and I noticed something that might
Be useful for folks.

I lowered my car a little with my custom ohlins shock Setup. That requires adjusting the bump steer. I have the ffr bump steer kit as well as upgraded tie rods in the rear that also includes a bump steer kit.

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)

In order to eliminate any bump steer I used the shorter factory five stud and shims on the rear and the corvette lowering kit stud on the front. This way I got more adjustment in the front.

In order to eliminate bump steer I needed to drop the rear tie rods roughly half inch or 6 factory five shims and almost 3/4 inch in the front.

If you follow the directions on the car build for ride height i suspect you gain a little with front bump steer adjustment. Front and rear adjustments are required if you lower the car.

The car is not very street friendly this low but I don't mind. I might change my mind after I get some time on the road however.

Speed bumps are not my friend.

John

[kabacj]

There is this saying that work expands to fill the time allotted. For some reason in my case it seems like work expands to twice the time available.

Of course I do it to myself.

Friday night 6:00pm: I had planned on taking the day off Friday before the race weekend to pack and clean up loose ends. Well that did not happen. So I got home at 6.00 and I had I needed to hang the doors, mount the gauges, remount the seats and belts, figure out the air filters, mount the rear view camera screen install the passenger tunnel side panel, close out the panels in the front wheel wells so I don’t get blasted with rocks and sand, attach the hood and hinges, attach the rear hatch, pack my stuff, mount the fuel filler to the body, mount the wing, finish the alignment and transfer tools and parts into the trailer and load the truck then drive 3 hours to Millville NJ. I can say I was almost at the point of giving up.

Its not like I waited to the last min to get all this stuff done. I took off wed, painted the car, rebalanced the GTM tires, put new tires on the trailer, and lubed up the bearings and gave the trailer a once over. Unloaded all the stuff I store in the trailer including my next project. Double checked every nut and bolt on the car and remounted the rear cell of the isis kit and plugged everything back in. 4.5 hours of sleep on thurs night.

Back to Friday night.

I had hoped that the doors would just bolt up and fit because I had adjusted them so they were absolutely perfect closing and latching smoothly. I forgot I took the doors all apart after I assembled them in order to close up the area where the striker exits the fiberglass. That was a terrible idea.

Now my doors did not latch properly again. The guys who have fit the doors know how sensitive they are to adjustment. Make a very slight adjustment in the wrong direction and they don’t fit well anymore. I think part of the reason that the doors are difficult to fit is that the factory leave a lot of extra fiberglass on the edges of the door so you can fit the door to the opening Unless you are doing the body work at the same time as fitting the doors and internals a difficult job gets harder.

So just getting the doors to fit properly again took 2 hours. The hood went right on and fit pretty well. I had drilled 1/8th inch locating locating holes for all the parts. That was a good idea.

I put the rear hatch on bc I thought it looked nicer and just a little better aero. Finally mounted the rear wing. It was midnight and thunderstorms were heading in it was already starting to rain. I decided that pulling the fully loaded 25’ trailer in a downpour for 3.5 hours would not be the best approach. Even though it was late and raining, my wonderful wife helped me load up and my buddy and I agreed to head out at 3am. It was 1.30am. Time for bed.


3am. Still raining , working on an hour and a half of sleep. 645am we arrived. The Rain had stopped but the track was very wet . Little rivers running across sections of the track.

Since I still had the list above to fix I was clearly not ready for tech at 7am. So I started wrenching. Maybe I can get all this stuff done by the second session. Now this was the hard part. I cant tell you how many people came over to talk about the car. People just love this car. Old guys, young kids, racers ever body just loves it. The car is an absolute celebrity . So as the ambassador for our mark and our hobby, I did my best to keep working while talking with the all the folks that stopped by.

By 4:00 I was ready for tech.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/7B4D4173-2EB2-48C6-8C58-B0AF662B4446-5447-0000064A0C054EC1_zps5ce799f7.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/7B4D4173-2EB2-48C6-8C58-B0AF662B4446-5447-0000064A0C054EC1_zps5ce799f7.jpg.html)

I drive the car out and make my way to the tech station. You would think I was driving around with a naked Victoria secret model on the roof. Everybody stares. It helps that the car sounds unique as well, bc if people are not looking they do hear something that sounds interesting and check it out.

So I roll into tech (which they re opened for me as it was closed for the day) and the car draws a crowd.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/5AD6C0E7-B193-4390-87BC-22800E79B0BC-5447-0000068A3BBA4D81_zpsfa624a42.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/5AD6C0E7-B193-4390-87BC-22800E79B0BC-5447-0000068A3BBA4D81_zpsfa624a42.jpg.html)


Passed all the points of tech with only a slight suggestions on how I wrapped the shoulder belts around the harness bar… then the guy says can u just check the brake lights. Sure I say..nothing happens. What! No brake lights! CRAP. OK that’s seems impossible bc I did a really good job with the wiring. Everything soldered and shrink wrapped. Weather pack connectors in front of every load so I can just swap things out. Its actually setup so I can just take off the body by unplugging the power feed to the ISIS. The power cell is attached to the body. I tested it all out before I painted the car. I could even turn on the lights with my iphone. How is this not working!

Back to our trailer. I figured the sleep deprivation I did not plug something in properly. After going over the whole setup I could not find the problem. All the plugs are directional and fool proof! I could barely think clearly at this point and I was having a hard time troubleshooting the isis. I was having trouble just visualizing the circuit! I left all my paperwork at home. Time for extreme measures.

Lets go to autozone get some parts and just rig up a brake circuit. Of course I go to auto zone and they don’t have a universal plunger switch. I go to the counter guy. He is useless. Can you give me a make and model? Um… Now what….!!. My buddy says, Well my 1976 F100 had the perfect brake switch for you. See if they have that. Guy puts it in the system. 1 in stock!

Its designed for the GTM! I screwed out the corvette switch that I had reconfigured to be a closed when the plunger is out and the ford part just screwed in the other hole in the plastic mount from the corvette! This is impossible! I cant believe it fit! So I ran the wires, installed the switch, Stuffed the bare ends of the wire into the weather pack connectors on the brake lights taped them up and I had brake lights!

Im ready! I had missed the last session for the day, however I was not going to run anyway. Something about taking a car that I had a thousand hours in over 2 years that I had finished up 5 min ago out on a track where top speeds are 150 mph on 1.5 hours of sleep did not sound like a good idea.

After a good nights sleep and a final once over of the car in tech I got my stickers.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/F011EE80-8A99-4796-A021-FEB0DEE4118A-5447-0000068A38044DB8_zps2578fec3.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/F011EE80-8A99-4796-A021-FEB0DEE4118A-5447-0000068A38044DB8_zps2578fec3.jpg.html)

Some final tweaks to the alignment and I was out for my first laps.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/665EC2E0-48AA-4955-82D1-057F7E94B723-5447-0000068A354217A4_zps8c5ed038.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/665EC2E0-48AA-4955-82D1-057F7E94B723-5447-0000068A354217A4_zps8c5ed038.jpg.html)

WOW!!!! This car is awesome! Glued down in the corners. Stable under braking and accelerates like a bat out of hell. Like nothing I have ever driven. Much sharper then stock corvettes or 911s. The only comparison I know is the difference between a street bike and a GP race bike. The GP bike makes a modern sport bike feel like a dump truck. That’s how different this car is then a stock sports car.


http://youtu.be/TVTOsXfW9OI


Unfortunately I was having some difficulty shifting into 4th gear so I was limited to 127 mph. But it was rock solid stable at 127. I definitely need to adjust the shift cables. The other problem I was having is the clutch was slipping over 4500 rpm. As soon as the car got into the power the clutch would slip. That’s another thing I need to adjust . The ACT dual disk can hold 800 ft lbs so I am sure its up to the task. (hard to test going around the block however)

I could not put a string of corners together because as soon as things got going the clutch would slip.

Since nothing was fastened or sealed between the body and engine compartment I could smell the clutch. Not good. So I backed off and just ran around at half throttle. Ha! I was still pulling people in.

GREAT GREAT weekend. The car is so good out of the box ! Even with the teething issues I know when this thing is sorted its going to be a blast! I need to find some track time where I can just go in and out all day doing a few laps at a stint testing things out.

Getting the car street legal will help a little, while I can’t do the bonsai runs I can at least get things adjusted closer to what I need on the track.

After all that work I am so glad I built this car. Its was worth it.

John

[RumRunner]

John,

Simply Outstanding! Congratulations! I hope you realize that it wasn't just you waiting to get your car on the track - I'm certain there are plenty of others like me that have followed your build with amazement and anticipation for this very day. Reading your excellent post made me feel like all GTM builders out there had accomplished something through you. Can't wipe the stupid grin off my face!

And the satin black looks damn menacing!

Again, congrats.

-Michael

[sk7500]

Remember John,
Even the worst day at the track is better than the best day at work. I'll bet all your future track days will just keep getting better and better.

[Kempo]

Great write up John as I read it I could feel the sense of urgency to get things done to make the event. Thanks for sharing. The car looks mean in that hot rod black.

Check your clutch adjustment. Make sure you left the 1/8-1/4" gap between the pressure plate "fingers" and the trow out bearing. If you didn't you might be slightly depresing the pressure plate and making the clutch slip. I have the ACT twin disc as well and it handles my power level although, your engine it's a monster but it should be able to handle it. Check the adjustment. Congrats on that first track day on the GTM after all that hard work.

[Taz Rules]

Awesome work, John!

Especially considering the sleep deprivation, and stress from last minute rushing around...just getting the thing through tech was an accomplishment, and then doing over 120 mph on partial throttle and without a 4th or 5th gear...incredible!

Don't beat yourself up over the little things. They're teething issues, like you said. Right now, just sit back, grin your grin, and savour your accomplishment. You've earned the moment!

[VD2021]

John,

Congratulations! Simply Outstanding.

[JCHRacer]

Awesome John,

Congrats and thanks for the great writeup. I look forward to hearing more as you get things sorted out.

[mikespms]

Hi John,

It's great to see a plan come together, the car is looking good.Great pictures and video, what a marathon !
Bet you can wait to get it sorted out and do it again

Mike

[Roger Reid]

Nice write-up. All your hard work is paying off. Congrats.

[claybags]

John, simply OUTSTANDING!!!! Great write up also. Thanks.
Jeff

[Presto51]

How many times did you say?


http://www.youtube.com/watch?v=FPQlXNH36mI

[crash]

Yep, these cars are more fun than a red head and a jug of whiskey on a Friday night!

Glad you got some laps in. If the clutch is adjusted properly, this may be part of the break in process. All performance clutches I have run require a little bit of time where you have some slippage to transfer material from the disc to the pressure plate and flywheel surfaces. Are you, hopefully, using a sintered copper puck disc, or is it "organic"? The fact that you can smell the clutch leads me to think it is organic, and IMHO you should not be running that with that much HP/TQ. Either sintered copper or a carbon/carbon setup should be used.

[carbon fiber]

congrats! great story, and great comparison between street bike and gp bike too. out of all the stories i've heard, this one makes me want to finish the build the most!

[kabacj]

Guys thanks so much for the congratulations. It was definitely a marathon few days, but the pay off was great.

I think the problems I had with the clutch and shifting were due to a faulty Master Cylinder. At least that's the working theory. I was not getting enough throw from the master cylinder so I had to adjust it so I was not fully engaging the clutch when my foot was off the pedal and still not fully disengaging the clutch when I put pressure on it.

I compared notes with Hugo (kempo) who has the same transaxle, clutch and MC, and I seems pretty clear I have a problem with my MC.

I have the stock 3/4 bore so I will just swap that in and see if that solves the issues.

Crash, the ACT dual disk is an organic clutch but its designed for street / track. Its SFI rated With 800 foot lbs of holding power im sure its up to my 530 ft lbs of torque.

It slips very nicely without any vibration but its up to the abuse of the track according to the ACT marketing. I figure if I can make it work as both a street and track solution its a good choice. If I need to its easy to swap out the twin organic disks for sintered pucks. We will see if that's necessary.

If I can sort out all the little things I want to fix ill be back on the track in a few weeks. As soon as I unload the car and can take some more pictures ill post another update.

[Kempo]

I have that same ACT clutch kit with the organic discs. It holds the 485 ft/lbs that my engine puts out at the wheels. That is about 575 flywheel ft/lbs going with the average 15% drivetrain loss.

Are your 530 ft/lbs at the wheels or engine?

[kabacj]

I have that same ACT clutch kit with the organic discs. It holds the 485 ft/lbs that my engine puts out at the wheels. That is about 575 flywheel ft/lbs going with the average 15% drivetrain loss.

Are your 530 ft/lbs at the wheels or engine?

I am at 533 at the crank. I have not yet had a chance to put the car on the dyno for its final tune and to see what I actually get to the ground.

From your experience sounds like I should be OK.

John

[Presto51]

Yep, these cars are more fun than a red head and a jug of whiskey on a Friday night!

Man Crash did it again.

Manage to slip in a woman reference into a thread.

Have to admit, this boy does have a certain talent :rolleyes:

[kabacj]

Guys Crash does not over state how much fun this car is on the track. In order to get back out there asap I have a laundry list of things to fix.

Saturday AM I un loaded the trailer and took inventory of the issues I had with the GTM

First was the brake circuit.

The Isis indicated that I had a broken circuit. I knew the brake lights were ok from the light bulb to the weather pack connector since they worked fine when I ran power directly to them. I checked the fuse in the Isis. It was fine. Clearly there was a problem between the power cell and the connector in front of the light. Next I checked the continuity of ground wire in the wiring harness. No ground! I pulled the ground wire out of the harness. It was clipped!

I soldered the wire back together. Ahh all the lights work again. Well that took all of 5 min. Amazing how easy it is to troubleshoot problems on a full nights sleep. This was an impossible problem to fix on Saturday night with an hour and a half of sleep in the prior 24 hours.

The positive of this ordeal. I got this great switch to control the brake lights. I also learned to trust the Isis. When it says their is a circuit fault. There is a circuit fault.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpscd2b4d5f.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpscd2b4d5f.jpg.html)

Here is the part number for the brake light switch.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps6c9764d3.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps6c9764d3.jpg.html)

The shifting problem:

I compared notes with Kempo to confirm how the Mendiola setup should work. Hugo had a few suggestions regarding the possible issues. I dove into my problem.

I took out the master cylinder.

First problem. The push rod was bent. As I adjusted the pedals lower and lower the excess rod contacted the pedal arm. The rod was only one thread too long, however as the rod hit the pedal arm it jammed and slightly bent.

Next removed the circlip and opened the master cylinder. Immediately I knew I found my problem. One of the seals has a gouge in it.


http://i1073.photobucket.com/albums/w389/kabacj/null_zpsd6658556.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpsd6658556.jpg.html)

That was why I could not fully disengage the clutch and shift easily. Pressure was bleeding off. The bore of the master cylinder is smooth and undamaged. A 13/16 bore rebuild kit and I'm back in business. Just to be sure I swapped in a spare 3/4 inch bore master cylinder. Imagine that I can shift now! I ordered a 7/8 bore as I want a very short throw to go from the fully engaged position to the fully disengaged. Of course Kempo reminded me that I should be careful not to overdrive the clutch springs. I will start with a large air gap between the fork and throw out bearing and sneak up on the correct throw. I'll add a stop to limit throw if needed.

I did not notice the problem with the clutch testing at home. I had adjusted the clutch so the little pressure I could generate with the damaged MC would disengage the clutch. Unfortunately that meant the clutch would not fully engage. I could not even test half power driving in the neighborhood to get the clutch slipping.

I mentioned in my weekend recap that I went to the track with my gauges still in the original box taped to the dash. This setup got more then a few joking comments. In order to pass tech I needed something that looked a little stronger. I had sheets of aluminum to make a dash but that was going to take too long.

I had cardboard to make templates. Well the templates are going to be the final solution. I don't have time for anything else.

I did'nt need a speedo or gas gauge. So I mocked up a cluster with the tach, oil, and temp. Duct tape and cardboard actually make a pretty sturdy dash.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps3c3a9e48.jpg

http://i1073.photobucket.com/albums/w389/kabacj/null_zps33c1e110.jpg

I also added a screen with backup camera. I had this on full time as my rear view mirror. Also not mounted when I got to the track of course. I saw more people walking up to check out the motor while waiting to go out on the track then cars following me , but the camera is very useful.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpse7834877.jpg

Next track test session is may 18th. A few more things on my list to fix before I am ready for another test.

John

[crash]

Well, there are good things and bad things about having a race date deadline. It certainly gets things done, but sometimes not to the point that we might like. Now it's time to go back and redo/update things that need it. Sounds like this is what you are doing, and I am sure the next event you will have everything much better sorted and have a much better time. Not that it sounds like you had a bad time, but it is always more enjoyable when things are finished and the event goes smoothly. :)

[Stage7]

John. Great to read about your update. I left you a VM. I look forward to meeting you and seeing your build. Some buddies who also run LS engine ITB's are beginning to plan a get together this summer. It would be great to have you there.

[kabacj]

HI Stage!

Sorry I missed your VM. It was a bad connection so it cut in and out. I did not know it was you. I thought it was a wrong number. Yep it would be great to get together. I ll give you a call.


I will be at NJMP again the weekend of May 18th and 19th. NASA have a great event that you can do laps with your car for 50 bucks. Its called hyperdrive. See the NASANE.com website for details. It would be great to see a bunch of guys out on the track.

John

[GTM RACER]

congratulations on turning the corner! Although I have never driven the GTM at race speeds, I have seen and witnessed first hand of the smiles, sh*t eating grins, excitement,relief, and "I want to go again" expressions of what the GTM does! Great story! What you describe in your story is a prelude of entering the 25 hour race, where you finish the car just minutes before the race. The only difference is at the 25, you role the dice and go for it!

[kabacj]

I have seen and witnessed first hand of the smiles, sh*t eating grins, excitement,relief, and "I want to go again" expressions of what the GTM does!
HI GTM Racer,

Thanks so much. Yeah it was both a relief and super exciting to get the car out on the track. While it would have been nicer to be more ready, none of the things i finished on Saturday at the track had any issue. Surprisingly the biggest issue was a bad seal on my new master cylinder.

I had adjusted my way around the problem at home and was unable to do any full throttle tests driving around the block. The only way to ID the problem was on the track. I tried a few times to adjust around the issue, not suspecting bad parts as everything was new. When I got home with the luxury of more time it was an easy thing to identify, test and fix. In the end I ended up with what I think will be a quicker shifting setup using a 7/8 MC.


I cant wait to get out there again next weekend.


John

[kabacj]

A few updates. I have the new 7/8 willwood master installed to operate the slave on the Mendiola master cylinder. It works very well with a shorter stroke but a heavier pedal of course. I was able to adjust the pedal height lower so that I did not need a limiter.

The extra bosses on the master cylinder bother me so I have taken them off. Since this is my fifth time I actually can cut/ file / bead blast and then polish up the willwood letters on the MC in a half hour.


http://i1073.photobucket.com/albums/w389/kabacj/null_zps1346a7f6.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps1346a7f6.jpg.html)

http://i1073.photobucket.com/albums/w389/kabacj/null_zps752b29db.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps752b29db.jpg.html)


This weekend I have some modifications for the crankcase pressure evacuation setup to capture the oil mist in the crankcase gasses as well as making a few catch cans.

Anyone familiar with STACK data loggers? Its an UK company who go way back in Formula 1 as they designed a stepper motor tac. The needle never bounces. The reason I was interested is Stack support the J1939 CAN protocol the MAST ECU uses and it looks like they have some slick software.

Just looking for some feedback.

Thanks
John

[crash]

Never used the Stack stuff. They always seemed to be a bit over priced for what you got.

[Hankl]

What I like to use.

http://i179.photobucket.com/albums/w284/hankl_album/Interior/DSCN0230.jpg


Hank :cool:

[kabacj]

Thanks Hank and Crash. Hank your endorsement means a lot. The thing I like about the Stack setup is the software. It seems open and configurable. I also like the video support. It's less focused on the hey check me out on the track and more focused on video as another data stream for analysis. It's very easy to compare two video laps with all the other captured data. Lots of reasearch still needed however.

Thanks
John

[kabacj]

Update

T-48 hours

I have addressed many of the little issues I discovered last visit to the track.

One thing that surprised me was the lower aluminum under the radiator. It bent somewhere between 100 and 130 mph.
http://i1073.photobucket.com/albums/w389/kabacj/null_zps8d01712a.jpg
Reinforcement of this piece was on my list, however I figured this piece was bending on the gen 1 GTMs because the air intake is so large. Turns out the gen2 also requires reinforcement if you plan on hitting the track or you live in Germany where you can exceed 75 mph on the road ;)

I used a piece of 3/4 square .063 aluminum. I plan on building something to fill the gap between the splitter and rad enclosure/ wheels. The square aluminum will act as a mount for this piece.
http://i1073.photobucket.com/albums/w389/kabacj/null_zpsca464a93.jpg

Second project was a vacuum canister to house my intake pressure sensor. With 8 throttle bodies I don't have a common plenum to measure intake pressure. I do have vacuum pickups at the base of each intake. These are combined and routed to this canister. With this setup I have a stable place to measure vacuum.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpscfb03db6.jpg

There was an open threaded hole in the top of the block so I built this canister to mount using that attachment.
http://i1073.photobucket.com/albums/w389/kabacj/null_zps79b8ad82.jpg


I think I am going to redo this canister after I make the intake and coil covers but this is good enough for now.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps457c4ce4.jpg

Only a few more things to finish before the next test.

John

[longislandwrx]

Great Job on everything. Car looks awesome. When's the next track day?

[kabacj]

Great Job on everything. Car looks awesome. When's the next track day?


Next track day is June 14 at Pocono Raceway. I hear the infield is repaved, and we get to use some of the high banks. Plenty of high speed running, which will be fun.

I am fltering through the hours of footage I have from this past weekend and I should have some fun clips to post in the next few days.

John

[JCHRacer]

Great work John....it's impressive to see someone get something done in a reasonable amount of time. I assume you are running with NASA. Are you running the HPDE or time trial groups? Did they approve the car for competition events?

Good luck and we all look forward to hearing (and seeing) more.

[kabacj]

I assume you are running with NASA. Are you running the HPDE or time trial groups? Did they approve the car for competition events?

Good luck and we all look forward to hearing (and seeing) more.

Hi Joel,

Yep I am running with NASA. I need to get a competition license and even time trials require a log book and a license from NASA. The only way to get those is to do HPDE and or the Comp school. Unfortunately I missed the comp school the first weekend of the year. As I get more comfortable with the car and work out the bugs in HPDE I will be ready to compete.

I hope to do time trials for the latter half of the season and start lobbying that the car can be accepted for racing by the end of the year. Part of winning the local guys over is showing up often. In the mean time I will keep working on the hundreds of little things that need completion.

Ill have a track day report out in the next few days. One thing I can say is the GTM is unbelievable in the rain. It would probably help if I had slightly waterproofed the car, but beyond that I was railing around corners faster then the 4wd cars.

more to come.

John

[LCD Gauges]

Nice John, you've been working hard I see! Love the engine details; that canister looks great too.

[kabacj]

Nice John, you've been working hard I see! Love the engine details; that canister looks great too.

Thanks Tino. Still lots to be done but itst progress.





Saturday started a beautiful sunny day. I breezed through tech and was out on the track by 10am. First laps were a test if I had fixed the clutch and master cylinder. All was well. I can put the power down. The car REALLY takes off now. The hardest thing is keeping the motor on full boil without upsetting the car. Smooth is the operative word here. I'm definitely not used to driving a car on the track let alone a car like the GTM. It's only my second time on the track in a car I own, however by the end of the weekend It was starting to feel more normal to have two extra wheels.

A few basic observations. I'm not going race pace yet but i am going much faster then you ever could on the street. The car is very neutral and forgiving. The front suspension anti roll bar and spring rate are a great starting point. The rear seems a bit soft. In a quick right left chicane. The front carves a turn without any push but the rear slides slightly then take a set and sticks. I ll try adding some preload in the rear and also make sure the cars alignment is correct.

So far I'm just out there lapping not changing anything. I keep going faster as I learn that the car is not going to put me into a spin without warning.

Saturday ended with a mad dash to fix my buddies rear brakes .


http://i1073.photobucket.com/albums/w389/kabacj/null_zpse3ae2a31.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpse3ae2a31.jpg.html)

it's pretty common for the corvette active handling to over use the rear brakes and build so much heat it melts the aluminum pistons in the calipers. That groove you see is actually the impression the back of the pad made in the piston! We could not find anyone with extra calipers at the track. All the salvage yards were closed. He went home for the weekend. See I knew I did not like those safety systems for a reason.

Saturday was looking to be a wash out. Steady rain and standing water for the first session. I'll pass. My car does not have the front splash guards installed yet. Just the trip to the gas pumps had water splashing in the leading edge of the doors.

By 11 am the rain was tapering off and the standing water was minimal. I had the inner conflict of do you really want to go off the track without anybody here to help? I don't have windshield wipers... I have little kids... Oh please John take your skirt off and get out there. So I did. It was wonderful! The rain was a perfect way to check the brake balance. The brakes that Stop Tech custom built are perfect. Tons of power. Easy to modulate and I never needed to touch the balance bar. Rain ex solved the wiper problem.

The wet laps were very productive. No unexpected spinning. i locked the brakes a few times and had quite a few white knuckle moments. But again great car. I could easily hook up exiting out of the corners. Once I got pointed WOT was no problem. I clearly have lots of setup to do yet, but for a car that has not been cross weighted or aligned very well I'm very happy.

With a car as radical as the GTM. Everyone wants to measure their car against yours. Even in the rain I had something for the WRX drivers and even the guy in the nissan GTR. Nobody could keep up once I was on pace even in the rain.

Lots of people went home due to the steady rain.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps387375e0.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps387375e0.jpg.html)


The after noon session had a dry line. Going much faster now that I have a better feel for what the car does at the limit. Rain is such a good way to learn the cars limits. You are going so much slower there is much more time to recover from a situation. Getting the car slowed down is a little scary however. It was just a matter of trusting that the car would actually slow from 130 in the wet. No technology to bail you out on this car. I love that.

The final session was fully dry and I was really cooking. I had dropped 7 seconds from my former fastest dry lap on this track in my friends c5. My top speed was 139 vs 121 in the c5. I have tons of time to gain with a clear lap , suspension setup as well as a proper alignment.

Here is a comparison of my c5 and GTM lap

Yellow is +1 G. Red is + 1.15G.


The c5 lap

http://i1073.photobucket.com/albums/w389/kabacj/null_zps8278edc6.png (http://s1073.photobucket.com/user/kabacj/media/null_zps8278edc6.png.html)


The GTM lap

http://i1073.photobucket.com/albums/w389/kabacj/null_zps3ff6914c.png (http://s1073.photobucket.com/user/kabacj/media/null_zps3ff6914c.png.html)


Things on the list to fix, improve, and finish

I need telemetry with CAN info from the ECU
Install the accusump since I am starting to pull more then 1G
Front splash guards
Transaxle cooler
Oil cooler
Install diffuser
Trim out the rear wing. (On full downforce currently)
Make a new front splitter and add canards

Still far from finished but having a GREAT time testing.

John

[carbon fiber]

awesome, but you need to add an in-car camera to that list!

[kabacj]

awesome, but you need to add an in-car camera to that list!

I have some onboard video. Just need to download and create a nice short clip. Should be done this week.

John

[crash]

Track reports are always great to read. Glad everything has come together for you. Looks like you are working up to the limits. Personally, I don't find the GTM, or any mid engine car, easy to catch once the limit has been passed with the rear grip. I have done it, but, for me, it is many times harder than a front engine car. One has to be VERY quick in response times. Hard to do that and also be smooth. Sounds like the wet track was a good experience. If there is not much to hit on a particular track, take advantage of as much rain time as you can get. As you said, things happen at slower speeds in the rain, and it is GREAT car control practice.

[kabacj]

Track reports are always great to read. Glad everything has come together for you. Looks like you are working up to the limits. Personally, I don't find the GTM, or any mid engine car, easy to catch once the limit has been passed with the rear grip. I have done it, but, for me, it is many times harder than a front engine car. One has to be VERY quick in response times. Hard to do that and also be smooth. Sounds like the wet track was a good experience. If there is not much to hit on a particular track, take advantage of as much rain time as you can get. As you said, things happen at slower speeds in the rain, and it is GREAT car control practice.

One of the reasons I chose NJMP to debut the car is there is nothing to hit (relatively). There are very few areas where you can get out of shape and hit somthing. During this weekend we had one guy roll his car.. that sucked, but he was fine. And 3 cars into tires after long trips across the grass. Sure wet grass seems like it speeds the car up, but for the most part this is a safe track for testing.

Regarding spin rate. Note that I have no basis for example regarding how hard it is to catch vs front engine cars. My only basis is motorcycles where in 11 years of racing I avoided crashing 2x in the rain by pushing myself up using my knee puck. (both times were just a reflex and I could not belive I was still on the bike) Every other time I was down before I realized I was crashing. So with that comparision I guess everything gives you plenty of time. I cant wait to go out in the wet again. I have lots to learn.

And regarding the limits again I have learned the hard way how easy it is to cross the limit lose control and bin it. I did it all the time back in the day. In my invincable twenties a crash during practice would cost me a few dollars in fiberglass and paint and I was back out on the track the next weekend with a shiny new paint job. I truely belived that if you were not crashing you were going too slow. Course I would only go 10/10 in the race so I would be sure to finish..usually.

Now that im older and wiser. Creeping up on the limit is much cheaper and better in many ways.

Limerock has a skid pad that I can use when I visit later this year. I can try to spin the car there all I want :) Till then im not going to get it too out of shape as most people I speak with agree with you. After a certain point in a mid engine car spin, you are just along for the ride.

I would really like to get a good picture of the GTM crossed up with rear tires smoking front wheel on curb as I round a corner on the track for my new avitar.. but im still working up to that.


John

[Dave Smith]

I'm playing catch-up here John and I am simply SLACK-JAWED at what you've done!!!!! HOLY CRAP brother, that is AMAZING. You have built yourself a ticket into any FFR venue you choose (Im thinking SEMA will have a LONG line of companies wanting that car).

Huge congrats on some truly impressive work. I told my wleders about your kind comments as they take their responsibilities very seriously in welding, understanding that a soul travels within their steel tubes.

GREAT GREAT job!

Dave Smith

[fastthings]

I'm playing catch-up here John and I am simply SLACK-JAWED at what you've done!!!!! HOLY CRAP brother, that is AMAZING. You have built yourself a ticket into any FFR venue you choose (Im thinking SEMA will have a LONG line of companies wanting that car).

Huge congrats on some truly impressive work. I told my wleders about your kind comments as they take their responsibilities very seriously in welding, understanding that a soul travels within their steel tubes.

GREAT GREAT job!

Dave Smith

Holy crap, how nice.

[kabacj]

Huge congrats on some truly impressive work. I told my wleders about your kind comments as they take their responsibilities very seriously in welding, understanding that a soul travels within their steel tubes.

GREAT GREAT job!

Dave Smith

Thanks Dave. The journey has been aweome so far and I am just getting started! You,your team, and all the folks on the forum have helped me get here. As I have said before I stand on the shoulders of giants. It would be impossible to do alone.

I am far from done, but I will see you at the open house.

John

[sk7500]

DUDE!!!
You just received the most coveted compliment I have ever seen on this forum. A well deserved CONGRATULATIONS! 👍

Steve

[Kalstar]

There is nothing I can say that would even come close to acknowledging what you have created. It is almost a sin to put a body on that frame. Well done is a big under statement!

Like the old days on your bike, Does the GTM= fountain of youth?

[kabacj]

Thanks for the thumbs up Steve.


Like the old days on your bike, Does the GTM= fountain of youth?

What I can tell you is that turning a lap I am proud of is like no other feeling. It's Something I have not been able to do for many years. It brings me back to my younger days for sure.

As a gear head adrenaline junkie, it's a dream come true to complete fast laps in the GTM I built. I sure feel alive when I roll off the track.

If the fountain of youth introduces you to great people, teaches you new skills, and makes you feel more alive.. Then yes.

It's a fun car too. :)

John

[VD2021]

I am still amazed by what you have done and will continue to do. It is a work of art and I echo what J said.

I was thinking,..... I am even more impressed that you have chosen to share all of this with us. From the brainstorming, to the functional product, to the road testing of it all. At times, I feel as it I am in your garage or at the track.

Thanks and Job well done, John.

"GTM-R"?

[kabacj]

I am even more impressed that you have chosen to share all of this with us. From the brainstorming, to the functional product, to the road testing of it all. At times, I feel as it I am in your garage or at the track.




Hi Vidal,

I am sharing my experiences as others have shared theirs. I am glad you can ride along. I love riding along with everyone else and following progress. These builds are so much fun they must be shared.

I had promised a video of my last track visit.

Of course my budget iphone telemetry failed as it ran out of space on the phone on Sunday, however I go this clip from Saturday. Its not bad and gives you a flavor for the GTM on the track.


http://youtu.be/r7USCI7mXEI


Camera position was bad, it was raining a bit... but its still fun.

Next time ill have a better setup.

John

[sk7500]

That's an awesome track. Every track around where I live is in the middle of the desert. You drift a little wide you are cleaning for days. So grass and trees sure look inviting. Thanks for taking me for a ride in your car. :)

[fastthings]

Nice, I wanted to watch the mph go up more, the vid stopped before the end of the stretch.

[claybags]

Vid is superb!! Do you find yourself still leaning into the turns? LOL
Cheers, Jeff

[VD2021]

John,

More great stuff.

Where did you top before you had to slow again, there at the end of the video?

[fastthings]

Oh, I see now, that was the end of the straigt.

[carbon fiber]

nice vid, especially with the graphics in the lower left of the screen. the engine sounds great.

[kabacj]

Unfortunately for this lap I was not really driving in anger as it was starting to rain, and I had not had the pleasure of driving the GTM in the rain yet. On Sunday I learned how I could really get the car moving around without any major issues.


John,More great stuff.

Where did you top before you had to slow again, there at the end of the video?

HI Vidal,
There are a few drawbacks of this Iphone lap timer. The first is the GPS does not keep up with the car. You can hear the motor revving up but the MPH never indicates the true speed.

Right now the best way to tell how fast the car is going is using the rpm of the motor. To that end I am adding a video logger that has a CAN interface. This way both the video GPS, wheel speed, RPM and a bunch of other stuff are overlayed with the video data. Makes it a better datapoint.

For now however, since the GPS is equally inaccurate all the time I can tell when I go faster. The G sensor is actually quite good in the phone so that is also a good measure of faster laps as well.

What was my top speed? Prob between 140 and 145. Another thing about this phone lap timer is that it shuts down the top speed when I cross the finish line. A bit annoying...

On the other hand . I have a reasonable lap timer with video for 20 bucks in the app store. its going to cost me 100X that to get much better.

John

[crash]

140-145 is pretty darn fast on a closed course. We just recently did 145 at Thunderhill and that is considered really fast for a club raced car. If we break 150 we think they may want to add some restrictions to us as the speed differentials are pretty great between us and other cars.

[kabacj]

Vid is superb!! Do you find yourself still leaning into the turns? LOL
Cheers, Jeff

Its funny you mention that. I am far from comfortable driving a car as I am still learning. I get off the track and hop on the scooter and I said AHHH! This is what I should be riding. .. not the scooter of course, but everything is automatic for me on a motorcycle on the track. The track is so much smaller in a car. As the driver in a car you have so much less to do with which tire sliding as my weight is no longer a variable going around the corner. Having a ton of steel around me is kind of nice however.

John

[kabacj]

140-145 is pretty darn fast on a closed course. We just recently did 145 at Thunderhill and that is considered really fast for a club raced car. If we break 150 we think they may want to add some restrictions to us as the speed differentials are pretty great between us and other cars.

150 is pretty fast for sure. Im not sure how the sequential mendiola is geared, but I still am not getting a good run out of the corners. I am sure with the factory five mendiola setup there is more speed to be found. 4th gear is well placed to really put the power down. I can easily carry 10mph more onto the straightaway then start accelerating. With the stop tech brake setup slowing is no problem. It's funny people have said I want a six speed. I was one of those people that was worried 5 gears would not be enough. Besides highway cruising a four speed would be fine.


John

[crash]

I'm told Mendeola really is in development of a six speed and I was also told that we may be testing something for them soon. :)

That said, as you stated, I think the GTM could get away with a 3 speed if the engine is an LS3 or better. In other words over 420 FT/LBS of torque.

[kabacj]

Some how in my hurry to address all of the finishing touches needed on e GTM I neglected to verify the ride heights. The front looked high but I thought it was just because I spent 5 min installing the hood. In fact, my front ride height was way too high at 5.5 inches where the rear ride height is 4.5 inches which is ok.

With the stock springs I had expected more compression at static load in the front. Since i only got a half inch or so of spring compression my ride height was a bit too high. That left me operating in the upper half of the stock travel.

To fix this I swapped out the 8 inch stock spring for a 7 inch eibach at the same 450 lb rate.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps0abaaf3e.jpg

Now I have the required 4.5 inch ride height

The spring just rattles free with about 1/8 inch gap at full droop when the front is jacked up. I can either send the shocks back to install droop limiters, leave it as is, I can move the Lower shock mounting hole slightly so I can preload the spring and still get the proper ride height. I could also shorten the spring again and install tender springs that expand under no load conditions and compress flat under static load. I need to speak with the experts at performance shock to see what they recommend.

I don't think I need any stiffer springs in the front as the anti roll bar keeps the car very flat. The 450 lb springs support the car well under max braking . Maybe when I switch over to slicks ill need to stiffen things up but for now I'm happy with the stock rate.

John

[Roger Reid]

John
Try helper springs or also known as 0 rate springs. All they do is take up the slack so your spring doesn't rattle at full droop. I use these on my vette and work great. Pegasus has them.

https://www.pegasusautoracing.com/productselection.asp?Product=1876

They also have the spring deviders.

https://www.pegasusautoracing.com/productselection.asp?Product=1877

Roger

[kabacj]

John
Try helper springs or also known as 0 rate springs. All they do is take up the slack so your spring doesn't rattle at full droop. I use these on my vette and work great.

Roger

Thanks Roger.

Great idea.

I spoke with performance shock and we decided I would go with a 6 inch 450 lb rate springs with a 3 inch helper and coupler.

With this setup I get a 6.5 inch spring pack when you include the fully compressed helper spring the Torrington bearing and the coupler. Which will allow me to use the adjuster on the spring body to lower the car to 4 inches or what ever ends up working.

Ill have a setup that will not rattle free at full droop and the shock will be very close to centered in its travel.

Thanks for the great suggestion.

John

[kabacj]

The UPS man came yesterday with new suspension parts. Included in the packages were 6 inch 450lb springs, helper springs and couplers.

You can see the comparison of the stock setup vs the new setup.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsb3b4a722.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpsb3b4a722.jpg.html)

With this setup i can lower the car to the point that I cant get a low profile jack under it anymore with roughly 4 inches of clearance between the frame and the ground. That puts the radiator surround nearly 3 inches off the ground. I think I am going have issues hitting curbs on the track if I go much lower. Its not like these parts were engineered to skid along the ground, so I think i will just keep the car at 4.5 inches and see how it runs. Maybe drop it to 4 to see if there is any improvement. At 4 inches of ride height I would not be able to drive out of my driveway which has an almost flat apron forget about getting gas at a gas station or entering any parking lot.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps698408fd.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps698408fd.jpg.html)

here is the setup at ride height.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsb54b2f10.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpsb54b2f10.jpg.html)




I only have a few working days between now and my next track visit on the 23rd of June. As always lots to be done.

John

[kabacj]

Now that the ride height is setup, I can spend a little time on the alignment.

First step was to establish the baseline I used on my last track visit. I am new to alignment, so this weekend I spent just as much time understanding what I was setting, why I was setting it, and how it effects the car as actually making changes. As wood workers say measure twice cut once. I measured 10 times set and remeasured another 5 times.

In my opinion one of the reasons the GTM has a reputation for tricky handling is the fact that many shops don't set the car up properly and builders discount the importance of learning about and focusing on this step. I know I made some mistakes. Lucky for me my mistakes did not end badly.

Here are the settings I used on the last track visit.

Chassis setup for 5/19

Left Front Right front
castor 3.2' castor -3.0'
camber -2.8 camber -3.2
toe -5/32 in toe -5/32 in



Left Rear Right Rear
camber -1.7 camber -1.9
toe 7 /16 th toe 7 / 16ths

From my research and correct me if you disagree I was in the ball park on for my quick and dirty front end settings. I know some have used front tow out to gain on center stability. I think I have a little too much toe in. Camber and caster I think were ok.

The rear setup was not as good. I set the rear camber at what i guessed would be a good starting point. I set the rear toe at the track very quickly before my first run on my first day out.

Before setting the rear toe, driving around on the access roads around the track at 30-40 mph on my first track day I could feel that the rear end had something funny going on. Turns out the rear was way off.

I brought the car back to the pits. We put the toe plates on and sure enough 3/4 inch! of toe out the rear tires were not parallel to the front either. Oops. Clearly overlooked that setting. I am pretty good at eyeballing angles so I used the toe plates on the same side of the car to get the wheels close to parallel. No time to get the strings out to do this properly.

Then we set the rear toe with my buddy measuring while I adjusted the toe links under the car with the goal of 1/8 toe in. Whoops missed that setting too. I was still pretty far off the correct setting.

The thing I found interesting was that the car was not terrible to drive with the rear with almost a half inch of toe out. I'm not saying it was good. Left right transitions I could feel something was wrong. But it was still drivable.

Here are my current settings I am going to use for my next track day.


Left Front Right front
caster -3 castor -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

I started with all the wheels are parallel to the frame so I know this time I actually have the settings I think I have.


The tools I used.

Toe plates. I used longacre

Caster/camber gauge. Again a longacre part

Home made turn plates.
A few linoleum tiles with glass bead as the lubricant. I used a straight edge and a protractor to measure the turn angles. Worked well.

Strings to verify all the wheels were parallel to the frame. Then set toe with the strings and verified with the toe plates.



John

[crash]

Actually small amount of toe in helps tracking stability. Toe out helps the car during initial turn in, but can make the car "darty" down the straights. The 1/16 toe in looks about right. If you get too much toe in it will also become unstable, but what you have there looks good. Looks like you have quite a bit of camber, but if the tires are wearing and heating properly then that is what you need to go by.

[KeithBoden]

Kabacj: one Monday, after returning from NJMP, my friend started describing your car; he was surprised that I knew a little bit about it. I was hoping to see your GTM at the track sooner than later, but looks like I'll miss you at NJMP by a day this time! (My #388 won't be there Saturday, just my Camaro.)

On the topic of alignment, I noticed your camber numbers. I recently found, after adjusting lots of other things in search of the answer, that too much camber will also cause high speed stability issues, especially with any amount of braking (even without noticeable dive, and my Camaro has minimal bump steer.) I had overlooked it in my last read of Race-Car-Vehicle-Dynamics (1000 pages of awesomeness if anyone is looking for a good book) and backed the camber off from 2 degrees to 1. I believe the wider tires on the front of my Camaro (275's) accentuate the camber sensitivity, so 2 or more degrees might be fine for GTMs, or the tire you are running. However, if you find a stability issue that feels like the back end is swaying, or the front is darting, see what a degree less camber does for you. I'm excited to find out how much is different and how much I have to learn when I finish my GTM, but you never know, some things might be similar!

[kabacj]

Hi Crash and Keith

Thanks for the feedback.

Regarding the camber. According to Toyo, the RA1s like lots of camber. The fronts seem to be wearing evenly. The rears look to be wearing slightly more on the inside. Thats why i took some camber out. I really need to get temperatures across the tire to know for sure. That is on the list for this track visit. I don't have any stability issues going straight, but I did have some weirdness in quick right left transitions at around 70mph. I suspect that was due to the rear toe misalignment.

Keith the GTM is such an awesome track car. Although I will enjoy driving the GTM on the street it's impossible to even scratch the surface of its capability. You are going to absolutely love it.

One of the things that I found surprising was the information overload that I have been dealing with on my first few track events. Each time out I'm focusing on either teething issues with the car on the first weekend or the weather on the second weekend. Two tracks that I am still learning the fast line around. All that combined with learning how to drive a very high horsepower car with no real track experience.

I finally decided that a Stack DVL video and data logger would help me record more information for review later. Although I did have some issues capturing video and telemetry last weekend. When the system did work I got very useful data. What I thought was happening and what really happened we not always the same.

If all goes well ill have 3 cameras as well as a full log of the ECU, GPS coordinate data with inertial G meters.

I should be able to capture some good data.

John

[flotowngtm]

John,
What size tire are you running? The biggest RA1 tire I see on tire rack is a 275? I thought you were running the FFR wheels 12" wide?
(picutres dont show up on this network)

[kabacj]

John,
What size tire are you running? The biggest RA1 tire I see on tire rack is a 275? I thought you were running the FFR wheels 12" wide?
(picutres dont show up on this network)

245s in the front 335s in the rear. Yes I have the FFR wheel package. I got my tires soon after the earth quake in Japan. Almost immediately after the earthquake, there was a shortage of Toyo tires here in the US. I was lucky enough to find a supplier on EBAY who had plenty of 335 rears but the fronts were very hard to locate. I ended up calling 15 tire suppliers on Long Island until I found a place that had them in stock on the shelf. I don’t know what the availability is now, but I agree it does not look like many places have 335s in stock.

I chose the Toyo tires because unshaved they are an OK dry tire and a good rain tire. Since I only have one set of rims I wanted a set of tires that I will be able to pass DOT inspection for the street as well as drive in any track condition. I am sure there are other tires that meet this specification. Best of all I got both rears for 270 bucks! Both brand new. The inside of the tires had small indentations on them as if they were laying on a metal wire rack. That did not bother me at all. They work fine.

John

[kabacj]

On my first track day I built a temporary dash out of duct tape and cardboard.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps3c3a9e48.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps3c3a9e48.jpg.html)


It was very functional but not exactly pretty. It was time to make a more respectable temporary dash.

I cut and welded some aluminum into this frame. I then sprayed it with some wrinkle paint.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps4feed0ea.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps4feed0ea.jpg.html)

I added a bracket on the back so I could bolt the gauge cluster to the frame and steering column.

http://i1073.photobucket.com/albums/w389/kabacj/null_zps3cc4d85c.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zps3cc4d85c.jpg.html)

Next I drilled and tapped the frame and steering column to receive the same 1/4 20 stainless allen bolts as used on many of the interior parts.

I buried the wires in loom as best I could until I can make a shroud for the gauges

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsd193e8fa.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpsd193e8fa.jpg.html)

With this new setup I was able to move the gauges lower so I can see them all at once through the steering wheel even tho I am nearly sitting on the floor pan.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsc2b734aa.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpsc2b734aa.jpg.html)

The top position is open for the transaxle temp gauge. I left out the gas guage as thats unnecessary on the track.. Ha I say that after I ran out of gas the last track visit. I figured I had enough gas for one more 20 min run. Little did I know I did not. The car shut down 100 yrds from pit in. The good thing I learned is that my tow hook works. The pickup, flapper/ sump setup in my custom tank gets every last drop from the bottom of the tank. And the car does not sputter at all before it runs totally dry... I guess that,s good. :)

John

[kabacj]

Tons of fun. Monday and Tuesday at the track.

http://i1073.photobucket.com/albums/w389/kabacj/20130625_NJM_NO1_8877_zpsb9df52f7.jpg (http://s1073.photobucket.com/user/kabacj/media/20130625_NJM_NO1_8877_zpsb9df52f7.jpg.html)

It was exceptionally hot. With air temps in the mid 90s and very high humidity.

This was a great test for the cooling systems. I'm happy to report that everything worked perfectly. The motor hovered between 220 and 230 while the transaxle was between 180 and 190 degrees.

My iPhone on the other hand did not like the heat inside the car. The phone shutdown several times due to the heat. Hot rod black does not make for a cool car!

The alignment changes made a world of difference. The car is very neutral now. I was able to push the front and slide the rear without any uncontrollable results. I maxed out at 1.4 G verified using two telemetry setups. That's pretty good on unshaved toyo RA1s I think.

My buddy and I were having a blast chasing each other around.

To make the challenge between a 630hp GTM and a 350 hp c5 corvette fair I could only drive in 5th gear. He could use any gear. Fifth gear in the mendiola is super tall. This makes 5th a great cruising gear, but it kills acceleration out of the corners. My buddy was faster off most of the corners as well as having higher speed on the straight bits.

Running a tall gear around the whole track turns out to be very good practice. Since the track was open I could just concentrate on carrying corner speed. I have tons of experience carrying momentum in the corners from my 125 gp bike days. It's much more satisfying to go fast with less power as you need to work for it.

This week I learned how well the GTM carries speed. My best laps using only 5th gear was 2 seconds faster then my fastest lap last weekend at the track using all the gears!

Here is a map showing the difference in G loads comparing last weekend and this weekend.
The map below is a 5th gear run vs using all the gears.

Yellow is +1 G. Red is + 1.15G.

This is the lap before the alignment shifting as necessary

http://i1073.photobucket.com/albums/w389/kabacj/null_zps3ff6914c.png (http://s1073.photobucket.com/user/kabacj/media/null_zps3ff6914c.png.html)

here is one of the laps I did with the car in 5th gear only.

http://i1073.photobucket.com/albums/w389/kabacj/db2fe58045936c16780163faa3fe3840_zps3aa06d54.jpg (http://s1073.photobucket.com/user/kabacj/media/db2fe58045936c16780163faa3fe3840_zps3aa06d54.jpg.h tml)

I got some great video of the GTM on the track. I am working on editing that and will post it soon.

John

[rev2xs]

Very cool! I'm looking forward to your video ;)

So just to clarify, these are the alignment settings you had?


Left Front Right front
caster -3 castor -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

[kabacj]

Very cool! I'm looking forward to your video ;)

So just to clarify, these are the alignment settings you had?

Left Front Right front
caster -3 castor -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


Correct rev2xs. These are the settings I used at the track. Note that I have power steering. I have the electric MR2 pump on a manual switch. With the pump turned off, but using the power rack its driveable, but its tiring. I am not sure how this setup would feel using the manual rack that comes with the kit.



John

[kabacj]

I have lots of great footage from my last track day , but these were two particularly fun laps.

The rules of the game were. I could not shift the car and my buddy could use any gear he liked. We swapped lead follow all day long. Each of us had a our moments. It was great practice for me as the GTM has so much power I can just motor by whom ever I want. Without the benefit of a powerful motor the only way to go fast was to carry corner speed. My best laps in 5th gear only were 2 seconds faster then my fastest time last visit.

Worst I had was two wheels off. He had 4 that another awesome video. Always in good fun. No damage was done and everybody had a blast.



http://www.youtube.com/watch?v=ixZV9gcENQU

John

[RumRunner]

John,

Great video! I like the 5th gear only approach to driving on the track --- sure keeps it simple. Looks like you and your friend had a great time paying cat and mouse. Can't wait to see the videos when you get to use all the gears.

-Michael

[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.


http://www.youtube.com/watch?v=Qk38u3B9r2o

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.

http://i1073.photobucket.com/albums/w389/kabacj/Factory%20Five%20GTM%20roll%20cage%20modifications/engineblow_zpsa893baa2.jpg (http://s1073.photobucket.com/user/kabacj/media/Factory%20Five%20GTM%20roll%20cage%20modifications/engineblow_zpsa893baa2.jpg.html)

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.

http://i1073.photobucket.com/albums/w389/kabacj/null_zpsacb2c850.jpg (http://s1073.photobucket.com/user/kabacj/media/null_zpsacb2c850.jpg.html)

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.

http://i701.photobucket.com/albums/ww20/rev2xs/Photo0443_zpsd0528db8.jpg (http://s701.photobucket.com/user/rev2xs/media/Photo0443_zpsd0528db8.jpg.html)