zigspeed10

These are available for other cars but not ours. Can someone explain why? Is there a technical reason or just simply no one has made them yet?

For a C5/C6 it looks like if we had upper and lower ball joints with an extended shank, that we could correct the roll center for lowered cars. I imagine if the pivoting ball remained in the same location but the shank was extended by 1 inch, it would have the same effect as drop spindles.

This is something I would like to learn more about, lets discuss.

froggy47

Solofast

Probably because they aren't needed.

If you lower the car about an inch it will be in the sweet spot for geometry anyway, so why bother...

Look up Dennis Grant's "Far North Racing" site.. On it somewhere he talks about how "somebody at GM knew exactly what they were doing with the C5, when you lower the car 1" the geometry is just about as good at it gets...

jtmck

While Dennis did say that....
The GM people built the C5 to run at the stock height.
Lowering the stock car takes away the handling.

To lower the C5 you need "roll center adjusters", which means, (change pick up points on the chassis)

My C5 sits 13" from the ground to the joint of rear fender and rocker panel in front of the rear tire and it handles pretty good

Jim M.

jtmck

I think you are refering to the circle track extended ball joints. If you could install the extended ball joints in the lower arm on a C5, you would lower the car, but there is not room in the wheel to do that.

The upper ball on the C5 is different than the circle track cars.
is in the spindle and an extended shank would not change the roll center like it does on their cars.

Jim M.

TalonDG

Necrothread - but I have your answer.

I did a measure and model on a C5 Z06, which generates all kinds of interesting data on the suspension geometry.

The Z06 has an inflection point on the camber curve that sits right at 1" below stock ride height. Lower the car 1", and you minimize the amount of variation in dynamic camber as the car rolls. You basically keep the tire in the same orientation relative to the ground no matter how the chassis moves in response to roll.

My memory is hazier here, but I also seem to remember that a 1" lowering kept the roll centre on one side of the ground plane... but I don't remember which side.

It was pretty clear from examining the suspension curves that all the happiness lined up at exactly 1" below stock ride height - and there was no way that it was just coincidence.

That makes sense from GM's POV too. Ship the cars with a little more ground clearance (most cars are not raced, so it's important that you not scrape and grind over every bump in the road) but optimize the suspension so that racers - who ARE going to lower the car, no matter what you tell them - maximize performance.

That C5 Z06 is VERY well designed. About the only way to make it better was replacing the rubber bushings with spherical bearings. Even converted to coilovers, we'd run about the same spring rate as OEM and the Penskes would be valved to match the OEM shocks.