jcmbird

I was trying to avoid a talent issue. I'm chasing a 430 ferrari challenge car, I like listening to it. I'm looking for technical help with springs. Ken thanks for the input, great video. Jay

gkmccready

C5Z: 526# / 714#
C5T1: 582# / 793#

You can't compare those to coilover spring rates directly, though. You need to calculate the wheel rates and compare those.

http://forums.corvetteforum.com/auto...al-thread.html

As an example:

C6T1 is 582# / 850# which work out to wheel rates of 176# / 130#. Coil overs that are 475# / 575# work out to wheel rates of around 210# / 215# ... so even though you see the lower pound/inch number for a coilover don't go thinking people are running less spring...

Also keep in mind that a common VBP leaf set up is 1100 # / 800# which is 302# / 128# when you work out wheel rates...

IMO, you can build a car either way, it's just a choice you make like which swaybars you want to run...

jcmbird

thank you very much. Would you say the 1100frt/800rear# vbp setup is balanced ? seems stiff in the front or soft in rear. So the front is stiffer than the t1 setup ? stiffer is ok, do you recommend these vbp springs?

gkmccready

I currently have 475# / 575# DRM coilovers. I drive the car on the street and the track. I love them. Some people would find them tough on the street, I guess.

LGM ships 750# / 650# but I think they're much more track focused. Two other well respected racers suggested 650# / 600# as a good starting point. And you've always got the HardbarUSA dual-rate option that offers a soft initial rate to soak up the bumps and rumble strips and then moves to a higher rate to offer the support required. The options are endless and each and every vendor has either themselves been successful, or has somebody else running successfully on their configuration -- so it's all about what works for you.

With the number of folks running those VBP springs they certainly work. But you will need shocks valved correctly to support them. I suggest you talk to RAFTRACER if you're considering VBP springs -- he can help you get shocks valved correctly for them.

I'm not exactly sure what changes with the leafs vs coils, but almost everybody that goes VBP ends up with 150+% more rate in the front. Whereas with coilovers most folks keep it in the -10% to 35% range. The Hyperco leafs stay in the 35-40% range.

A while back I said I wished all the vendors showed up with cars with their particular packages set up and I could drive them all and pick the one that felt best for me... otherwise you just take your chances and hope you make the right purchase up front, or you iterate through until you find what you like. What feels great to somebody else just may not be your cup of tea. The Vettes seem to be open to a lot of different combinations and they all can turn front running times.

Try to find local cars that people will give you a ride in, or let you drive...

DarkMastyr

gkmccready, one of these days I'd like to get a ride in your DRM equipped car. My Z51 feels just fine for now, especially for dual track/street duty, but I'm always tempted to go COs.

gkmccready

Let me know and we'll try to meet up. The car has some other toys (VBP swaybar bushings, Pfadt poly bushings, Wilwood front brakes, CCW wheels, etc) so it may not be entirely apples to apples but you'll definitely feel the difference between the stock shocks/springs and the DRMs. You'll be shocked how early you can get back on the throttle.

John Shiels

mine is 1200/900 VBP I need more because of the aero but I would go heavier on my car now and may do it. VBP can only get so much material in the mold for the leafs so 1300 is about tops for a front spring. DRM said the coil-overs are at different angles front and rear so the rates are different when you look at coils vs leafs front to rear.

The shocks I have are re-valved Bilstiens.

gkmccready

1200/900 leafs are somewhere around 825/450 coilovers. Wheel rates end up 363/151 for the leafs, and 344-364/143-168 for the coils... the coils change rate because the angle of the spring changes. The leafs also change rate because the pad slides a bit on the lower control arm, but I don't have a good idea of how far so I can't easily calculate how much it changes the rate through travel.

In theory, the leaf spring/lower control arm contact point moves further outboard as it goes through bump travel, giving the spring more leverage, so the rate of a leaf actually goes up as you move through the travel. On the other hand, with the coil the spring angle changes and you lose rate as you move through bump travel. This all assumes I can think of a leaf spring as having a 90deg angle to the control arm all the time.

There's a bunch of math in the thread I mentioned earlier...

jcmbird

thanks, Now would you say this is ok without a wing? why is stock and t1 a different frt/rear bias[stiffer rear]? and who could help with the right shocks? Jay

ScaryFast

I got a little indignant there, didn't I? Perhaps a bit misguided...still good advice, just not at all what you asked for

0Vector Vette

Really Jon! Did your opti-spark break again?
Robert

ScaryFast

Nope, got that fixed permanantly. And the ensuing oil leak caused by a defective oil pan gasket.

It's all done and ready to rock for the winter. Thinking seriously about ARRC, though. Me, Ken, and others.

Also, the upcoming C5 project should keep me out of optisparks forever!

John Shiels

Racerafter has good knowledge of leafs. Few others I know order springs near my rates or the same. You can buy Bilstiens and get them re-valved or buy some other type for more money like a Penske. Bilstein has the rates for my car and others. THere was a guy there Jack but he has passed away Guy Anerky may be able to help. Street or track only?