Just to add my 0.02$ Dick Guldstrand said that the composite rear spring tens to bend on hard cornering andhe would preffer using steel leafs at the back. I'm using composite on both ends and the weight savings are huge!
Back to the first question, the rate is 35lbs.

groovyjay said: Just to add my 0.02$ Dick Guldstrand said that the composite rear spring tens to bend on hard cornering andhe would preffer using steel leafs at the back.

Only he would push a Corvette that hard anyway. For autocross I have not heard of any problems with the composites.
They used them front and rear for every C4 and I never heard of them breaking either.

Just to throw in another 0.02$ I've seen brand spanking new composite spring snap in two piece when the car hit a speed bump. I have also read horror stories about how the composite spring start saggin after some time.
However, like I said I have them both front and rear, I'm very pleased about the quality. I've build my car to be driven hard, even Guldstrand hard and it should be able to corner well in 120mph+ too.
Why didn't I find this site beofre, this is great place!