sperkins

What in the heck is going on here? Why such a huge difference in rates? I'm looking at swapping springs to use with my T1 bars, but this just confuses the heck out of me.

• C5 Z06: 526# Front, 714# Rear
• T1 (C5): 582# Front, 793# Rear
• VBP Sport 990# Front, 650# Rear
• VBP Extreme 1050# Front, 855# Rear

Zenak

tighter springs = more responsive ride and better tire grip. better handling in curves with all 4 wheels staying down on sharp curves.

DOWN SIDE is that riding in a EXTREME spring car on a bumpy open street road is jsut about as uncomfy as it gets.. and the wheel hop in the rear is horrendous in a pothole. SUPER tight springs, great for track.. bad for street legal driving.

I went with bilsteins/z06 springs at first as a cheap and easy mod over my z51 (especially if you can find em used).. but if $$ is no object coil overs & hige sways are so much better.

You are talking used set up vs. new coil over/sway set up is about 5x more $$$ is not more.

ps. I have a front/rear z06 spring barely used from gmparthouse.com and 4 barely used bilsteins, with barely used hotchkis bars and endlinks for sale if interested cheap. 3-4k street miles and only 1 road course, 1 auto cross on them :-)

Zenak

also if you are SCCA you got limits on what you CAN use by class. NASA is easier its just HP/wt pretty much so you can mod a lot more. Oh and i dont know how rain/wet track friendly they are either. Anyone have experience in their rain set up to share? Too stiff? personally I drop my pfadt coils about 4 clicks each in the wet to keep my traction better.

drivinhard

Scott, for a race car with no bent toward street, generally in my experience you are better off getting your roll stiffness from springs vs sway bars. It might be not quite as big of an issue since the leaf spring on the C5 ties both ends together naturally (which is what we are trying not to do), but in general, that's a good rule of thumb. That doesn't work on the street though because to get any roll stiffness from a spring you'd have to run high rates and the ride sucks. You want to keep the suspension ends un-coupled as much as possible, and obviously big bars don't lend themselves to that.

Since you are looking to bump a car up from one TT class to another (and you have the points ability) try maybe stiff springs and softer bars? it would be worth a try I think.

at min keep your FRC bars, you can try them, stock C5Z, and T1's. they are a pretty easy/quick change. Not so much for the leafs

just note (for your points sake) that the stiffer you go on spring, the more shock control you are going to need (if shocks were in your points plan). of course in your case, even 04Z shocks would be points so that may be a moot point...

trackboss

Don't let the huge numbers scare you. I have what would be considered race only front spring and I'd say it is completely drivable on the street. It's firm, but not harsh in any way. If ride is harsh look at the damping not the springs.

sperkins

Thanks guys. Street manners are not an issue. If I don't keep this car forever, it will be sold as a dedicated track car.

Just my luck, I sold the rear Z51 bar last week. I can't imagine it doing hardly any good since it's diameter was similar to a pencil.

I'll have to run what I have for the moment, but I'd like to swap springs in the future. What shock on the market would be good enough to control a 1,000 front spring?

John Shiels

revalved Bilstien Sports. Look for a used set to rebuild revalve. The second choice is spend more on adjustables. Mine are 1200/900 vbp T-1 anti-roll bars and it doesn't ride all that bad.

fatbillybob

I do not think those numbers for Z06 and T1 are published anywhere from GM. How did you get those numbers? Coilovers are an easy test with a spring tester. You need to fashion a rig to test a leaf spring and I have seen some pretty suspect ones.

gkmccready

Those look like numbers from a table I data mined off the internet. They look correct, and the C6 numbers were verified by VBP on their test rig. So it's apples-to-apples with the GM numbers versus the VBP numbers.

sperkins

You're right Glen. I copied it from an old thread:
http://forums.corvetteforum.com/auto...s-97-04-a.html

Coil overs would be nice, but I'm not going to be able to swing that for quite a while. I read a good bit last night about spring rates and suspension setup and it's all starting to make sense now. Thanks to all that gave input.