GTM roll cage modifications and race car build log

[kabacj]

John, That is an awesome picture. I love the ITB intakes. (Hillborn?) I know that you've set this up for race only, but could something like that work well for street? I know that it isn't necessary for street applications, but it just completely "makes" the look of the car from the rear.

Great job with the body. The whole car looks great. Congrats!

Mike

Hi Mike.

Thanks for the kind words. Yes folks do use the ITBs on the street but they are very tricky to make smooth. They have so much torque on throttle tip in that the ride can be a bit jerky.

If you de tune them they are smoother.

So it depends what you want. I personally love them and would not use anything else.

[kabacj]

I cant believe the transporter and probably the 818c was 2 minutes away. I wish I had known! but I'm guessing you had to keep it under wraps.

Congrats on a beautiful job well done. I imagine few would suspect that that was a driveway paint job!

Yeah it was a big hit. Thanks for the compliments. After I cut and buff it and take the dust out it will be too nice to wreck on the track.

Oh well it will be nice for a few months.

[mlkwd1]

Yeah it was a big hit. Thanks for the compliments. After I cut and buff it and take the dust out it will be too nice to wreck on the track.

Oh well it will be nice for a few months.

John, Just got back from SEMA this morning. Your car looks fantastic with the body mods and the new paint. It was great talking to you and thank you for the swaybar and coilover photos as well as the technical help. Looking forward to seeing you at NJMP in the Spring.

[kabacj]

I cant believe the transporter and probably the 818c was 2 minutes away. I wish I had known! but I'm guessing you had to keep it under wraps.

Congrats on a beautiful job well done. I imagine few would suspect that that was a driveway paint job!

Thanks man. Yes the 818c was in our neighborhood. It was also a big hit at the show. Sort of a mini GTM at a far more affordable price point.

Insane conversion from the last time I checked in! The paint theme looks great!

Thanks very much.

John, Just got back from SEMA this morning. Your car looks fantastic with the body mods and the new paint. It was great talking to you and thank you for the swaybar and coilover photos as well as the technical help. Looking forward to seeing you at NJMP in the Spring.

It was great meeting you as well. It is going to be great running with another GTM at the track in the spring. We have a quite a few cars at the NASA races these days. It will be great to have another GTM in the factory five Pit.

[mlkwd1]

I stopped down to NJMP yesterday. It was very cold but there were plenty of cars running. I was on the waiting list but did not make the cut so I just stopped by with the GTM and my son for a couple hours to watch. At least 5 different people showed interest in the car and I spent most of the time showing them the car vs watching what was on the track.

[Brett33]

let me know when you guys are heading to NJMP, i live about 20 minutes away. I would like to see you guys run.

[kabacj]

I stopped down to NJMP yesterday. It was very cold but there were plenty of cars running. At least 5 different people showed interest in the car and I spent most of the time showing them the car vs watching what was on the track.

Ha ha yep that's the drill. People love the GTM.

let me know when you guys are heading to NJMP, i live about 20 minutes away. I would like to see you guys run.

It's probably not going to be until next year as everything shuts down come dec1

Speaking of people loving the GTM. Courtney Hanson is a big GTM fan. She asked me if she could drive it. I told her sure why not! I wonder if she will take me up on that.

[Presto51]

Speaking of people loving the GTM. Courtney Hanson is a big GTM fan. She asked me if she could drive it. I told her sure why not! I wonder if she will take me up on that.

Watch out John, if Courtney brings her father, you might not get your GTM back

Ron

[fastthings]

So cool, good show man.
Your mods are so cool. I like following what your doing.

[Aceflo]

John,

Have you had a chance to drive it yet, since you did the last roof mod?

-Rick

[kabacj]

John,

Have you had a chance to drive it yet, since you did the last roof mod?

-Rick

Hey Rick,
My GTM is down in Florida with the Factory Five team. It will head back up north early next week. Ill be sure to let you know how it works with the NACA duct and the glass installed. I have been researching smoke generators. I was thinking about filling the engine compartment with smoke so I can see how the air flows through it. I would like to do experiments with the cooling up front as well. Could be a little dangerous so i ill probably do the testing off public roads, but I am sure it will be interesting.

The next phase of the build is going to be all about aerodynamics and tuning the car for minimum drag and maximum down force. Ideally I will have a low drag configuration and a max down force configuration. This amount of tuning is far from necessary for racing at my level, but it sure will be fun to experiment.

Its a long winter and the car is sort of done. So I need to fix that.

So cool, good show man.
Your mods are so cool. I like following what your doing.

Thanks Gene. You will be happy to know that lots of the GTM customers I spoke to at SEMA have watched all of your videos. We like to follow what you did as well!

Watch out John, if Courtney brings her father, you might not get your GTM back

Ron

HA thats true Ron. Courtney is really a cool person. You can tell she really loves cars. She grew up on the race track so she has the race car bug. Once you get bitten there is no cure.

[kabacj]

The record warm temps were a great reason to get out and take a spin in the GTM.

It's time to start constructing a new splitter.
As you can see the old splitter is a bit under sized now that I have widened the front of the nose to cover the 295 tires. The splitter is just held in place with clamps.

It's too bad because the current splitter is a nice high quality light weight part.



We were talking about the little winglets I added to the front lower edge of the wheel arch and the possibility of them interfering with tire removal.

Turns out the tires clear with the hood up or down.

[Roger Reid]

Nice fender work. You might consider an aluminum splitter. Shane widened the front of my car for 315's then made a wider splitter and wrapped it in carbon fiber print vynl material. Looks great. Your wheels look great. Are you worried about the wide front tires not getting enough heat for track days?

[kabacj]

Nice fender work. You might consider an aluminum splitter. Shane widened the front of my car for 315's then made a wider splitter and wrapped it in carbon fiber print vynl material. Looks great. Your wheels look great. Are you worried about the wide front tires not getting enough heat for track days?

Hi Roger.

Yeah actually aluminum would be the easiest way to solve for the splitter if I was only driving on the street or occasional track days., but since I have ripped off and destroyed 2 splitters so far, I need to make the splitter that is both strong and a sacrificial part.

I reused the composite splitters until I either lost or ground off big enough chunks to make repair and reuse too difficult.

I was thinking using a combination of balsa and carbon fiber if I go with a moldless solution or maybe carbon fiber and foam if I make a mold. Then an aluminum sheet under tray as that part hopefully will not take as much abuse.

I really like the idea of aluminum , but a composite part that harmlessly rips off and lets me keep going is better than something that will bend and stay attached I think.

Regarding the wider front tires.

I found that I needed to adjust my driving style trail brake later and carry more speed into the mid corner section of the turn and scrub speed with the tires as the tire size got bigger in order to get heat into them.

That’s exactly what you were not doing with the 245s or smaller width tires. Like all production cars the GTM was setup to drive safely on the street as the front will push before the rear lets go. Its much easier to control a car that’s pushing understeer then a car that suddenly breaks rear traction.

To make the bigger front tires work I needed to add front spring to support the added loads and tune the roll bars so the car was neutral mid corner. The next goal is adding more aero grip up front this way I can tune the car for the fast sweepers where I can pickup time and just deal with a little more push in the slower corners.

Tire choice also determines how big you can go up front and still get heat into them.
Hoosier A7s heat up in 1 lap. If I did not flat spot one tire a weekend they would be my go to front tire. Even the hoosier S80s heat up pretty quickly and are much more durable. I like to use them with the s100s or the R7 rears.

I guess I could get a $10,000 dollar racing ABS setup, but eh I think ill just burn up tires for now.

[mlkwd1]

John, the warm weather has been great. Too bad Millville did not have any late dates because it was colder in Vegas at SEMA. I used the splitter Shane sells and asked him to make it from 1/8 vs 1/16. It is pretty robust. Had it powder coated charcoal black. I did not use CF for the same reason of destroying them. I actually hit my CF side rocker on a speed bump this weekend and dinged it up a little despite the HDPE strips under the car that I thought would provide clearance. I was concerned about the aluminum splitter dragging over the rumble strips or the driveway entrance so I put thin HDPE strips under and they are loosely riveted on. They will sheer off if they are hit hard. I may have a copy of the splitter curvature if you want a starting point to get the front arc right and then blend in the sides. Let me know if you want a copy, I try to find it and drop it in the mail to you.
Michael

[kabacj]

John, the warm weather has been great. Too bad Millville did not have any late dates because it was colder in Vegas at SEMA.

Hi Michael

Yep I also was looking to get out on the track, but it seems that everyone has shut down for the holidays.

Your setup looks great. The rub strips will help you out on the few spots on the track where it's possible to make the splitter touch.

Like you i was concerned about curbs and rumble strips but to date I have never hit them when I was on the right line. If you drop a wheel off the track. That's where the problems start. Many times the rut on the outside of the track is deep enough to lower the splitter or side skirts on to the pavement. Most of my damage has happened this way.

If you go up to limerock park in CT it's possible to grind the outside corner of the splitter on the ground in the last turn called the downhill. The turn loads up the front suspension far more than a flat turn. It's a fun turn, however the first time the splitter hit and made a loud scraping noise it sure got my attention!

This is the best picture I could find. I guess there are few pictures of this spot from this angle because the camera person is sitting directly where cars hit the wall.

[mlkwd1]

Thanks for the compliment. I intended not to use the rumble strips on Thunderbolt. My driving skills proved that not practical and by the second lap I ended up on the top in turn 6 or 7 by accident. When it did not hit the splitter and I used them to straighten out the turns leading into the straightaway with no issues. Looking at the turn above, I will definitely have a front tire rub with the 275s. The Toyos stick out a little past the when and there is no clearance. I plan to tuck the wheel in a little but it is down the list a ways.

If you need any HDPE, I have a local industrial supplier that had a huge selection of scrap pieces for a very reasonable price. I am there frequently and would be happy to ship it to you.

[kabacj]

With all of the mild weather in December and early January I have been driving the GTM instead of working on it.

I took it to the my sons Cub Scout pack night where they had a car show as a lead up to the Pinewood derby. I let all of the kids sit in the GTM. That was a big hit. The looks on their faces sitting in the car were priceless.

In between driving. I did make one change to the windshield wiper setup that I think others could benefit from.

When i fit the hood I moved the back edge of the hood right up to the windshield glass.
I figure this is a bit better for aero and I also like the way it looks.

I knew this would make the windshield wiper and arm a tight fit, but I came up with a solution.

First upgrade the wiper to a nice low profile Bosch design.



Here is the wiper model in case you want to use it.



After a little bending of the wiper arm I was able to get a very nice fit.

[Aceflo]

John ...you rock.

Thanks for all the tips you provide.

Rick

[mlkwd1]

John, good idea for the Pinewood Derby, I am sure the kids went crazy. It is great to be the dad with the coolest car. I am the cub scout pack leader for my son and he constantly asks to take the GTM to our meetings. He asked to pain it using the orange like my GTM. He loves when I pick him up from after school activities and all the kids (and dads) crowd around the car. We were going to have the PWD on Sunday but the coming snow forced us to postpone the date. I actually flew home from working in Tampa this morning to be here for the PWD otherwise there was no good reason to leave 75 degree weather.

Millville just posted their schedule for 2016. Got to get my dates picked in the next couple of weeks. Also want to try Lime Rock and Watkins Glenn this summer.

Wiper fits nice. After seeing the hood setback while at SEMA, I was not sure you would have the clearance.

[kabacj]

Thanks for all the tips you provide.

Rick

My pleasure Rick. The fun part of this build is all the little custom bits that you can add to make the car yours. I was lucky enough to have these wipers on my truck so I just swapped one in. It fit. A quick amazon prime order and I had one for my GTM.

John, good idea for the Pinewood Derby, I am sure the kids went crazy.

Hey Michael! Yeah both the kids and parents were excited. Lots of parents got pictures of their kids in the car. Another dad has an euduro car and a 68 firebird that he owned since high school. We both spent time indoctrinating the kids in the car hobby. Besides Scouts building good citizens, I want to make sure we turn out as many gear heads as we can!!!

Millville just posted their schedule for 2016. Got to get my dates picked in the next couple of weeks. Also want to try Lime Rock and Watkins Glenn this summer.

Yes I plan to visit NJMP in March and April and July . We will see when lime rock have un muffled days as its difficult when you cant race on Sunday. Watkins Glenn will be great this year with the fresh pavement. I also plan to be there at least 6 days.

I am looking forward to chipping up my fresh paint and making a mess of the white car. I am sure we will meet up at the track.


John

[The Stig]

These are some serious brake calipers and rotors that you've got there!

Love the HRE wheels also!

Mike

[Kempo]

He John!!!!!! haven't posted in some time but have been following a few threads. As you may know this is one of the. The work you have don in this car is just INSANE!!!!! The amount of attention to detail is amazing. You have built a top notch race car. Love the body mods, choice of colors and those wheels are AWESOME!!!!!! Keep up the good work!!!

[kabacj]

These are some serious brake calipers and rotors that you've got there!

Love the HRE wheels also!


Mike

Thanks Mike. The 14 inch stop tech rotors are great for track work. As a bonus they look serious too . Yeah the HREs were made to their race spec with knurled beads to keep the tire from slipping on the rim. Since they are milled from billet they are super strong but also very lightweight.

Oh and btw all the work you have done on your car will be worth it as soon as you take it for that first drive.

He John!!!!!! haven't posted in some time but have been following a few threads. As you may know this is one of the. The work you have don in this car is just INSANE!!!!! The amount of attention to detail is amazing. You have built a top notch race car. Love the body mods, choice of colors and those wheels are AWESOME!!!!!! Keep up the good work!!!

Thanks Hugo. I'm far from done , but at least I'm at a point that I could claim I'm done.

Your car was my inspiration to go with white.

Now that we have 24 inches of snow on the ground I think it's safe to say I can get back to work on the GTM as I will not be driving it any time soon.

[kabacj]

Finally a warm day when I had time to sort out a new front splitter for the GTM

After widening the front fenders to cover my race tires and pulling the hood back toward the windshield the beautiful factory five carbon splitter no longer fit.







Time to make a new one. The goal is to maintain the tilt hood but also close out and much of the under tray as possible.

Ideally create a Venturi under the front axle line to increase front down force.


Step one was to cut out a template from plywood



Next I cut the shape and trimmed so I could maintain the hood tilt




Finally I formed the center section.



At this point I started to run out of daylight.
I'm not sure if I will go with the ply core laminated carbon fiber or make a female mold off of this part when it's done.

At least I'll be able to test airflow over this part before I commit to a mold.

John

[carbon fiber]

Go ahead and make a mold. You'll be glad you did.

[Fraser D]

Go ahead and make a mold. You'll be glad you did.

Yes I agree. That way you can just go ahead and knock a couple out whenever you need them.
If you make a mold it will be easier to get a little creative as well. e.g vertical planes on the outer edges of the splitter

[kabacj]

Go ahead and make a mold. You'll be glad you did.

Yes I think this is the way to go. I don't have any experience creating a mold where I laminate a foam or wood core, but I'm sure there is some information available.

Yes I agree. That way you can just go ahead and knock a couple out whenever you need them.
If you make a mold it will be easier to get a little creative as well. e.g vertical planes on the outer edges of the splitter

Agree I'm looking to try these two types of ends on the splitter. These two splitters also demonstrate the two types of construction. One is a plank and the other looks to me like a core material covered by laminate. I like the core laminate solution. I just need to figure out how to do it.





These cars also show two types of dive planes I want to try. Note that I don't think the rules for the weather tech series allow the prototype class to extend aero elements past the plane of the wheels. It's clearly better to have the dive planes and vortex generators hanging out in the air next to the car. Super unlimited does not have any such rule so mine will be in the airflow next to the car.

[mlkwd1]

John, Splitter pattern looks great.

We had plenty of good weather this winter. I found myself using the car instead of working on it as well. Put some effort into it this past week and got the longer wheel studs installed and installed the 14 inch front brakes. Back brake kit comes in tomorrow. The only ting I am still missing is the shocks and sway bar which have been ordered since December. You going to NJMP mid-April? I am planning to sign up this weekend for Saturday and Sunday. Hope to see you there. Michael

[The Stig]

Hi John, I have a question that I'm curious about.

Are you using stock wheel hub/bearing assemblies, and if so how do they seem to be holding up? I would imagine that Mike (Crash) Holland could add to this as well. If you upgraded, to a more stout hub for track use, would you mind sharing what you went with?

The reason I ask, is that my hubs are from a donor which had 99k+ miles on it. It's bothered me for a while, to the point that I've wanted to overhaul the entire suspension. (Arms, Spindles, ball joints, hubs, etc.) I have the new arms, and I'm trying to decide whether to go with stock hubs and ball joints or upgrade to Pfadt Engineering hubs. I have their poly bushings that I plan to use as well. I have an adjustable upper control arm set up for the front, which should help me dial in the alignment much tighter. So I think I'll be able to feel good about the safety aspect, when I take my wife for a ride. (And yes, I'm pretty sure that will happen...)

I don't mean to hijack your thread, but you are doing a lot of real world testing on the track; most of which directly applies to what the rest of us should be watching out for.

Thanks,

Mike

[kabacj]

John, Splitter pattern looks great.

We had plenty of good weather this winter. I found myself using the car instead of working on it as well. Put some effort into it this past week and got the longer wheel studs installed and installed the 14 inch front brakes. Back brake kit comes in tomorrow. The only ting I am still missing is the shocks and sway bar which have been ordered since December. You going to NJMP mid-April? I am planning to sign up this weekend for Saturday and Sunday. Hope to see you there. Michael

Hi Michael

I'm not sure how my April track events are going to sort out. Ideally I'm going to make the NASA race April 15,16,17. Just depends on some other commitments I have.

You will be happy with the upgrades you have there. I'm looking forward to getting out there with you. Not too may on track photos with two GTMs. I can't wait. I'll let you know

[kabacj]

Hi John, I have a question that I'm curious about.

Are you using stock wheel hub/bearing assemblies, and if so how do they seem to be holding up? I would imagine that Mike (Crash) Holland could add to this as well. If you upgraded, to a more stout hub for track use, would you mind sharing what you went with?

Hi Mike I'm glad to share. I upgraded to SKF hubs, poly bushings and upgraded ball joints as well as toe links and a bump steer kit front and rear. SKF hubs are standard on the C5 zo6 and are commonly used by anyone tracking their c5 or c6 corvette or GTM on the track frequently. They are known to stand up to a whole season of racing.

The reason I ask, is that my hubs are from a donor which had 99k+ miles on it. It's bothered me for a while, to the point that I've wanted to overhaul the entire suspension. (Arms, Spindles, ball joints, hubs, etc.) I have the new arms, and I'm trying to decide whether to go with stock hubs and ball joints or upgrade to Pfadt Engineering hubs. I have their poly bushings that I plan to use as well. I have an adjustable upper control arm set up for the front, which should help me dial in the alignment much tighter. So I think I'll be able to feel good about the safety aspect, when I take my wife for a ride. (And yes, I'm pretty sure that will happen...)

I don't mean to hijack your thread, but you are doing a lot of real world testing on the track; most of which directly applies to what the rest of us should be watching out for.

Thanks,

Mike

No hijack Mike. The point of the thread is not for track only or racing only. The goal is to tell everyone how I got the most from my GTM. Regarding your 99k mile suspension. Yes I agree a refresh is a good idea. The bushings are old and worn I'm sure. I don't think it's a safety issue, but the extreme capability of the GTM will highlight any worn parts. After all the work you have in your car the work you have done to upgrade your suspension is worth it. We all want the GTM to drive as well as it looks. A fresh suspension and a good alignment are key to that goal. In my opinion anyone who reports handling issues at triple digit speeds needs to focus on the old corvette parts they put in their pride and joy and the alignment they gave the car.

I don't mean to sound harsh, I just wish suspensions would get a little more love. They are not as cool as nice paint or 1,000 hp but they are a key part of any super car. You are doing the right thing.

BTW. My wife will not ride in the GTM. She says it's pretty but too scary. This is from someone who has only driven fast manual sports cars her whole life HA! My kids on the other hand LOVE it !

Hopefully that's helpful. Thanks for asking. It's a very important question.

John

[The Stig]

Thanks John.

The Pfadt hubs that I mentioned are the SKF hubs for 97-08 Vettes. I don't really intend to track my car, but I figured if they could handle a year of track abuse, they can certainly handle anything that I would put them through, and still hold up.

I am also doing the upper and lower joints, but I haven't decided which one's I'll use. I think the solid joints from Pfadt may be overkill for my purposes. I would image that they transfer a lot of road noise as well. What are your thoughts on that?

The toe links are on my list as well. Again, not sure if I should replace with the GM part or look for something a little more robust.

I agree with your view of the importance of the suspension. It doesn't make sense to build a fast quick car that doesn't handle or stop as well as it goes...

It also makes little sense to spend a large amount to get the suspension dialed in if it's going to move on you in a turn or during acceleration and braking.

Thanks for the info.

Mike

[mlkwd1]

BTW. My wife will not ride in the GTM. She says it's pretty but too scary. This is from someone who has only driven fast manual sports cars her whole life HA! My kids on the other hand LOVE it !

Hopefully that's helpful. Thanks for asking. It's a very important question.

John[/QUOTE]

John, too funny, my wife got only one ride and has not asked again. The kids on the other hand always ask what car I am picking them up in. I drop my youngest off at a boy scout dinner on Saturday and he was immediately surrounded by Older scouts asking if he was rich and telling him he had the coolest car. When it came time to pick him up and I showed up in my truck it was a huge disappointment while all the kids waited to see the car again.

[kabacj]

Thanks John.

The Pfadt hubs that I mentioned are the SKF hubs for 97-08 Vettes. I don't really intend to track my car, but I figured if they could handle a year of track abuse, they can certainly handle anything that I would put them through, and still hold up.

Yep I agree. You could go either way with the hubs. The SKF hubs that Pfadt sell would last longer under any conditions, but I dont think you would notice that they are "better" I look at this type of purchase this way. I never say oh I wish I got the cheaper ones this is too high quality for me. But that's me. You cant go wrong as long as you have new hubs.

I am also doing the upper and lower joints, but I haven't decided which one's I'll use. I think the solid joints from Pfadt may be overkill for my purposes. I would image that they transfer a lot of road noise as well. What are your thoughts on that?

I think you are talking about the Spherical bearings kits for the upper and lower control arms. I agree. Don't get those. They do transfer road noise and are harsh. They need periodic rebuild. The poly setup is fine even for racing. The poly setup is will last the life of the GTM. Its a good setup. I have considered the spherical setup for racing, but still have not pulled the trigger. That tells you something about how good the poly setup is.

The toe links are on my list as well. Again, not sure if I should replace with the GM part or look for something a little more robust.

For street driving with an occasional track day I think you are fine with the stock GM parts. You do need to make sure they are in good shape. If they don't look new I would change them out. They are not expensive. Slop in those joints is bad news. Unless you plan on spending lots of time over 120mph you will not need the bump steer kit for the rear alignment so new stock parts will work fine.

I agree with your view of the importance of the suspension. It doesn't make sense to build a fast quick car that doesn't handle or stop as well as it goes...

it it also make little sense to spend a large amount to get the suspension dialed in if it's going to move on you in a turn or during acceleration and braking.

Thanks for the info.

Mike

Yep exactly right. Even with street tires and everything stock (but in good condition) from the Corvette the GTM has insane capability. Restoring the C5 suspension components to as new condition, or upgrading where needed for your application, is always the right thing to do.

I'm looking forward to seeing your car in person. I'm sure its going to be stunning.

John

[kabacj]

John, too funny, my wife got only one ride and has not asked again. The kids on the other hand always ask what car I am picking them up in. I drop my youngest off at a boy scout dinner on Saturday and he was immediately surrounded by Older scouts asking if he was rich and telling him he had the coolest car. When it came time to pick him up and I showed up in my truck it was a huge disappointment while all the kids waited to see the car again.

HAHA yep. The GTM is really a special car. I always remind the kids that they could build a car like this too. Its never too early to start dreaming.

[crash]

Stig- The hubs you would want are SKF 5049's. There are other hubs that come on ZR1 Vettes, that according to SKF, are designed internally the same as the 5049, but they have a different number of drive splines and a different wheel speed sensor, so I would not recommend those.

That said, you really don't need to spend the $$ on the 5049s until there is an issue. There is no catastrophic failure, or anything like that if the regular hubs go bad. At least we have never seen that. For many years we would simply run the stock hubs until they started noticeably "howling" and then we would replace them. That was about 20 hours of serious racing. We never had one fail terminally, just start making a bunch of noise. It was loud enough that it was easily recognizable on video from inside the car.

On the flip side, since going to the 5049 hubs, we have never worn a set of those out. We started out rotating those out for the 25 hour race, but after extensive racing on those hubs, have found that the 5049 is darn near indestructable. The issue is with the cage material that holds the balls, which I am told is plastic in the regular hubs and metal in the 5049s.

We are now running the solid spherical bearings in the rear of the car and have had very good results. If you have read some of my other posts, we were having some tire wear problems and I changed a number of things in the rear of the car to address this, one of them being the poly bushings, and the wear issues have gone away. For our purposes the solid mounting just doesn't hurt, and the poly may have been an issue. Really no need to make this change on a street GTM.

BTW, here is a picture of the hubs I built for the 2015 25 hour race...IMG00843-20151119-1346.jpg

[longislandwrx]

did you finish the splitter?

[kabacj]

did you finish the splitter?

Hey man.

Sadly I did not. Family vacation and weekends away from the garage eliminated my GTM time.

The good news is this weekend promises great weather and I'll be home.

I plan to develop the shape as I go and the ability to take the GTM out for some "wind tunnel" testing is key to making progress.

I'll report back on how things go.

John

[longislandwrx]

let me know if you need a copilot for additional data analysis