Chassis Set - Up

[GTMKris]

My car will be out of the paint booth in a week or so. Not long after that I plan on taking it to the alignment shop. In trying to find out what I should tell the guy running the machine I have read so much conflicting info that I don't really no what I should say. I found this in the other forum, is this still close to what you would shoot for in castor and camber adjustments?

That said, I think I would start at these static #s

Front toe 1/8 toe in. No more though.
Front camber -.5 to -.9 degrees. If you put in too much you will get bad tire wear depending upon driving conditions.
Front caster AS MUCH AS YOU CAN GET! Normal car would be 3-5 degrees, but the Vette goes extreme at 10 degrees!! No way you can, or should, get that on a GTM.

Rear toe 1/16 to 1/8 toe in. 1/8 in the rear is alot and if you go too far with toe in or have ANY toe out in the rear the car will want to rear steer all over the place.
Rear camber -.5 to -.9 degrees again depending on tire wear from given driving conditions.
Rear caster is really not an issue because the rear upright should not be going through the travel that caster effects much if at all, so as long as both sides are straight up to a little positive caster, that should be fine, and both sides should match.

Take this into the alignment shop for referrence. If you are having issues with bump steer changes, I believe that FFR sells rack lengthing kits to help with this.

On reading this thread from front to back Ls man says 1/16 front toe out and 1/8-3/32 toe in rear.

While Spytech had his best luck at 3/16 front toe in and 1/16 rear toe in.

Just looking for something that I can print off and hand to the guy and say here.....get it as close to this as possialbe. I don't mind doing the leg work but when info starts to conflit I figured that I should ask instead of guess.

[Roger Reid]

...That said, I think I would start at these static #s

Front toe 1/8 toe in. No more though.
Front camber -.5 to -.9 degrees. If you put in too much you will get bad tire wear depending upon driving conditions.
Front caster AS MUCH AS YOU CAN GET! Normal car would be 3-5 degrees, but the Vette goes extreme at 10 degrees!! No way you can, or should, get that on a GTM.

Rear toe 1/16 to 1/8 toe in. 1/8 in the rear is alot and if you go too far with toe in or have ANY toe out in the rear the car will want to rear steer all over the place.
Rear camber -.5 to -.9 degrees again depending on tire wear from given driving conditions.
Rear caster is really not an issue because the rear upright should not be going through the travel that caster effects much if at all, so as long as both sides are straight up to a little positive caster, that should be fine, and both sides should match....

That sounds like a good plan Kris.

[crash]

I believe I am the one that wrote that quote in the other forum.

Let me explain what front toe does from my experiences.

If you have a slight bit of toe in you will have a car that tracks straight, but doesn't want to "dive" into the corners. If you put a bit of toe out into the car, which is actually what we do on the race cars, then the turn in to corners is improved. It doesn't make it terribly unstable on the straights, but at the same time, it's no Sunday cruiser either. In other words, both setups are correct depending upon what you are trying to achieve.

Personally, I wouldn't have toe out in my daily driver, hence my recommendations for initial settings, but a slight bit won't "kill you" either. As I have said before, don't be afraid to just try this stuff out. Just be aware that what seems like small changes can have big effects upon how the car handles. Toe can be done by ANY GTM builder with just a couple strings and 4 jack stands, or a simple toe bar that is used for measuring toe in about 60 seconds. This "toe bar" can be made for ZERO $$ from scrap pieces of metal from around the shop. Toe plates, such as you see in Ted's video can also be used, and again are pretty cheap to make.

Now, again, as I have said previously, messing with static numbers is fine, but the proof is in the pudding, and since our suspensions are not a static system, it is also important to consider what the wheels are doing throughout their length of suspension travel.

The two ways to do this are computer modeling or actually measuring at different points in the suspensions travel. At this point, I don't think either has been done with the GTM setup. Joel, aka JCHracer may have though, or possibly David Borden?

[GTMKris]

Thank you Crash for taking the time for a well thought out answer. As you mentioned I will more then likely have to make make minor changes to get the car to handle just like I like it. That I don't mind trying as long as I can get it close from the alignment shop. I have found a guy that I hope will let me put my car on his scales so that I can do the hole weight bias thing like they have done in this wonderful thread. Also I have the bump steer kit installed.

This car will never see the track.

Thanks again and I will post my updates with how these settings work for me. Kris

[JCHRacer]

I believe I am the one that wrote that quote in the other forum.

Let me explain what front toe does from my experiences.

If you have a slight bit of toe in you will have a car that tracks straight, but doesn't want to "dive" into the corners. If you put a bit of toe out into the car, which is actually what we do on the race cars, then the turn in to corners is improved. It doesn't make it terribly unstable on the straights, but at the same time, it's no Sunday cruiser either. In other words, both setups are correct depending upon what you are trying to achieve.

Personally, I wouldn't have toe out in my daily driver, hence my recommendations for initial settings, but a slight bit won't "kill you" either. As I have said before, don't be afraid to just try this stuff out. Just be aware that what seems like small changes can have big effects upon how the car handles. Toe can be done by ANY GTM builder with just a couple strings and 4 jack stands, or a simple toe bar that is used for measuring toe in about 60 seconds. This "toe bar" can be made for ZERO $$ from scrap pieces of metal from around the shop. Toe plates, such as you see in Ted's video can also be used, and again are pretty cheap to make.

Now, again, as I have said previously, messing with static numbers is fine, but the proof is in the pudding, and since our suspensions are not a static system, it is also important to consider what the wheels are doing throughout their length of suspension travel.

The two ways to do this are computer modeling or actually measuring at different points in the suspensions travel. At this point, I don't think either has been done with the GTM setup. Joel, aka JCHracer may have though, or possibly David Borden?

I have computer modeled the GTM/Vette suspension geometry but only as a baseline for the race suspension I am designing. With the stock Vette bushings, the computer model is of very little use....when the tires are loaded up under cornering, braking and acceleration, the tires are not going to point in the same direction as on the alignment rack.

I'm with Crash on this one. For a "well behaved" and stable street car, start with the recommendations of this thread and then experiment until you get the feel you are looking for.

[The Stig]

I have computer modeled the GTM/Vette suspension geometry but only as a baseline for the race suspension I am designing. With the stock Vette bushings, the computer model is of very little use....when the tires are loaded up under cornering, braking and acceleration, the tires are not going to point in the same direction as on the alignment rack.

I'm with Crash on this one. For a "well behaved" and stable street car, start with the recommendations of this thread and then experiment until you get the feel you are looking for.

Joel,

What type of bushings are you and Crash thinking of the keeps the tires/wheels pointed where they should be?

Since the Control arm assemblies are the only Donor parts left on my car, (and the steering column), I may as well consider "re-building" them as well at some point...

BUT... I don't want it to ride like a tank!!!

[Roger Reid]

...Since the Control arm assemblies are the only Donor parts left on my car, (and the steering column), I may as well consider "re-building" them as well at some point...

BUT... I don't want it to ride like a tank!!!

I know this is not a donor thread but if you are only using the suspension components and the steering column, would you change your mind about going the donor route?

[The Stig]

I know this is not a donor thread but if you are only using the suspension components and the steering column, would you change your mind about going the donor route?

No. I think that the donor route is still very valid. Especially where budget & keeping costs down are concerned. In my build, I just found myself making decisions to change one thing and then another, until I got to the point that there wasn't really much left to change.

I absolutely think that it makes sense to use donor cars with these builds though.

[JCHRacer]

Joel,

What type of bushings are you and Crash thinking of the keeps the tires/wheels pointed where they should be?

Since the Control arm assemblies are the only Donor parts left on my car, (and the steering column), I may as well consider "re-building" them as well at some point...

BUT... I don't want it to ride like a tank!!!

I don't think you can describe it as "should be", just a compromise. I am going with solid, teflon lined, spherical rod ends or needle/roller bearings at all inboard suspension pick-up points.....I am making all my control arms from scratch. Very little deflection under load but the "ride quality" suffers. Not something I would suggest for a daily driver. My car is intended for track days with occational street use so I can live with the harshness. As a compromise some people replace the soft rubber bushings with a harder plastic (usually urathane) but I dont like that option because they tent to stick if you dont grease them often. Pfadt (sp?), the Corvette racing guy has a spherical replacement kit I believe for the stock Corvette control arms. For a daily driver, I would stay with the Stock Corvette bushings and play with the alignment untill I got something comfortable.

[The Stig]

I don't think you can describe it as "should be", just a compromise. I am going with solid, teflon lined, spherical rod ends or needle/roller bearings at all inboard suspension pick-up points.....I am making all my control arms from scratch. Very little deflection under load but the "ride quality" suffers. Not something I would suggest for a daily driver. My car is intended for track days with occational street use so I can live with the harshness. As a compromise some people replace the soft rubber bushings with a harder plastic (usually urathane) but I dont like that option because they tent to stick if you dont grease them often. Pfadt (sp?), the Corvette racing guy has a spherical replacement kit I believe for the stock Corvette control arms. For a daily driver, I would stay with the Stock Corvette bushings and play with the alignment untill I got something comfortable.

Thanks Joel. That's what I've been thinking as well. I don't plan to have this car on the track very often at all. But I definitely want to do whatever I need to make sure that it is stable and handles well (and safely). There are lots of bumps in the roads around Charlotte, and I don't want to end up in someone's flower bed.

For my purposes, I agree that the softer (stock) bushings should be fine. If I find later that I need to, I'll look into replacing them.

[LS MAN]

Hey Vidal,
Ron is working on his new engine, should have it running soon.
We will get back to some engine & chassis tuning then.

Thanks,

[VD2021]

---

Ted and Ron,
I really eager to see some tuning. Any ideal when you Guys will be able to continue educating us? Thanks.

Hey Vidal,
Ron is working on his new engine, should have it running soon.
We will get back to some engine & chassis tuning then.

Thanks,

Ted,
Any chance you can do a MAF tune/calibration video? Preferably without a wide band and dyno. Thanks.

[spytech]

While Spytech had his best luck at 3/16 front toe in and 1/16 rear toe in.

Just wanted to clarify that I have 1/8 total rear toe-in. 1/8 seems to be the 'magic number' that many others have had success with.

Also remember that ride height itself is critical. My GTM drove like crap with 1/8 rear toe-in until I got the height set at over 4".

[Roger Reid]

...Also remember that ride height itself is critical. My GTM drove like crap with 1/8 rear toe-in until I got the height set at over 4".

I seem to remember quite a discussion on the other forum (back in 2009) about wheel diameters. That if they are too large, the a arm angles at normal ride heights become too extreme harming the handling.

[JCHRacer]

I seem to remember quite a discussion on the other forum (back in 2009) about wheel diameters. That if they are too large, the a arm angles at normal ride heights become too extreme harming the handling.

Just a guess here but changing the ride height, can affect the bump steer significantly. If you have a completed car and it does not feel "stable", I would check the bump steer (both front and rear) before going to any extreme static settings.

[Ron565]

Just a guess here but changing the ride height, can affect the bump steer significantly. If you have a completed car and it does not feel "stable", I would check the bump steer (both front and rear) before going to any extreme static settings.

Hey guy's, Just for reference My ride hight is 4.5 front and 5.0 in the back. I thought it is a good compromise regarding road conditions and speed bumps. I don't have any issues with bump steer.

Happy Building, Ron

[spytech]

Hey guy's, Just for reference My ride hight is 4.5 front and 5.0 in the back. I thought it is a good compromise regarding road conditions and speed bumps. I don't have any issues with bump steer.

Happy Building, Ron

Ron-

Random question - did you have to compress your springs or anything to get the ride height up to 5" in the rear? I'm at 4.25" right now and I could get maybe one more turn out of the collars on my koni coilovers on the driver's side, and I can't get any more turns on the pass side. If the sleeves didnt spin freely it probably wouldn't be an issue, but as a result I have to figure out a way to compress the springs a bit so I can get those remaining turns.

[mmaragos]

Ron-

Random question - did you have to compress your springs or anything to get the ride height up to 5" in the rear? I'm at 4.25" right now and I could get maybe one more turn out of the collars on my koni coilovers on the driver's side, and I can't get any more turns on the pass side. If the sleeves didnt spin freely it probably wouldn't be an issue, but as a result I have to figure out a way to compress the springs a bit so I can get those remaining turns.

I'm scratching my head on this one...are you adjusting the coilovers with the car on the ground (opposed to on a jack with the weight off the wheels)?

[LS MAN]

I am very impressed with these shocks.

The adjustable models feature an indicator to show the setting, no more "counting sweeps"
They have a unique spring hat, it installs at an angle, then locks onto the shaft.
The shock body & spring adjusters have a small groove, just slip in a small tie wrap to lock the adjuster, no set screws to damage the threads.

Genesiscompressionadj-1.jpgIMG_4955.jpgIMG_4958.jpg

[rev2xs]

Cool, what model of shock are you guys running? Is it the GB3?

I am very impressed with these shocks.

The adjustable models feature an indicator to show the setting, no more "counting sweeps"
They have a unique spring hat, it installs at an angle, then locks onto the shaft.
The shock body & spring adjusters have a small groove, just slip in a small tie wrap to lock the adjuster, no set screws to damage the threads.

Genesiscompressionadj-1.jpgIMG_4955.jpgIMG_4958.jpg

[Ron565]

Cool, what model of shock are you guys running? Is it the GB3?

Hi Revxs,

They are custom valved and so far I am very impressed. That's one of the things about Ted he gets it right the first time. Lots of homework and testing.

Ron