Chesnut new C5 Cobra pics

[john chesnut]

Suspensions have come along way from the 60's. The older suspensions and mustang based suspensions have relatively short control arms. The lower control arms are mounted high and the spindles are relatively short. The old cars used 15 inch wheels with a deep off set to get big tires to fit. The short control arms result in fast camber changes as the wheel moves through it's travel. This causes unpredictable handling and less grip. The high lower control arm mount results in a high roll center which causes the car to want to skate across the road surface rather than bite into it. The off set wheels and the position of the upper and lower ball joints meant that earlier cars had a large scrub radius. This results in hard steering, increased bump steer, and a lot of kick back felt through the steering wheel.
The Vette has 3 and 7/8 inches of travel at the shock. The Vette lower control arms are long and mounted to the chassis very low. The spindles are tall. And the ball joints are placed in the center of the wheel. The Vette control arms are attached to the chassis at precise angles. Except for the rear upper control arms none of them are mounted parallel to the ground. In the front the lower control arms are mounted angled down in the front. The top are mounted angled up in the front. They are mounted in this manner to keep the car from nosing down under braking and to keep the camber constant.
The Vette has a very low roll center and with 58mm offset wheels a zero scrub radius. If you draw a line through the upper and lower ball joint it should intersect the ground in the center of the tire contact patch. This is Zero scrub. If it doesn't then there will be a lever effect which you feel through the steering. It makes the steering hard. If you have driven a car in which every time you hit a bump the steering wheel shook and the car felt darty, it's probably because of a bad scrub radius.

In my opinion the Vette rear suspension is the best production one available. It is a true double aframe design. This means that the axle is splined and changes length as it goes through it's travel. Jags and old vettes used the axle as a control member. The wheel travels in an arc as the suspension moves. This causes decreased tire contact and less grip. Further as the ujoints wear the rear end will feel loose and less positive.
The old independent rears also could transfer to the power as good as a live axle. If you watch one under power you will see the rear of the car squat. As it does the tires move up in an arc. As they go to negative camber, tire patch is lost and you get less traction. Another problem with these rear ends, especially the old vette is that the roll center is high. This causes a snap oversteer condition.
The new Vette independent rear solved all of these problems. It has 50% anti squat desined into it. This effectively allows for up to 1/2 of the vechiles weight to be transfered to the rear tires under acceleration. The double aframes allow for pretty constant camber through out the range of travel and the wheel base stays constant. The older rear ends that use control arms to locate the rear hub to the frame feel twitchy because the wheel base actuall changes as the wheel moves up and down.
I am able to use the vette sway bars in the car as well. I use the stock vette rear bar and use a rear , heavier Z06 bar in the front.
The handling on the car is impeccable. It can be adjusted from slight understeer to slight oversteer. It corners flat. You can feel the rear end working and can power slide it if you want.
Wheels can be a limitation with my car. With out flaring the body you need to use a 58 mm offset. Up to 10 inch in the front and 12 inch in the rear can be used. Vintage Wheel makes a 18inch wheel with the older wheel look with the correct offset. Otherwise there is a good selection of Vette wheels.
I am running the stock Vette brakes. They are more than enough for this car unless it is going to be heavily raced.
The C6 vette has the same suspension geometry as the C5. As far as mounting to the chassis the only difference is the upper rear control arm mounts. This can be accomodated for when the frame is built. By using the Vette parts I knew that I would have a good supply of these great parts for years to come.