I would like to get some opinions on spring rates for road racing. I've got the large bar's 36-25, C-5 Vette wheels, 245-35-17 front & 275-35-18 rears, 350 with a M-21 trans.I haven't weighed the car (not all together yet) but we have a fairly heavy 10 point cage, 4 door bars on each side so 3300 lbs. wouldn't surprise me, I'm the heaviest driver at about 260 lbs. Thinking about 750-800 in front, 175-200 rear. I've heard of some people running 1200 front & 400 rear which seems way over sprung to me especially on rougher tracks but thats why I'm asking. So if you have any racing background any info will be greatly appreciated. Thanks.

 

I would suggest heading over to frrax.com. You have to register and be accepted before you can view the forums but it's the best knowledge base for tracking these cars to be found. It's pretty common to run heavy springs in the front to counter the rear going light under braking.

 

Hey lemons. Do you know which brand of springs you're going to run? And shocks?

I don't think you're so far off with 750/175 as long as you have the damper to control them.

1200/400 is pretty stiff but some racers have success limiting suspension travel on smooth tracks. The 3rd gen strut configuration doesn't favor a ton of travel.

The fun part about racing is trying (i.e. on track testing) then making the necessary improvements. We can usually hit springs in one or two tries...

ramey

 

the fact is that most people would be happy with a fairly large range of spring rates in their cars, as long as they are close to reasonably balanced front and back, and then you can fine tune with things like strut settings (with Konis or tokicos) and sway bars, and even sway bar bushings.

You'd be fine with something in the range that you listed, but I know I'd be tempted to go with something a little stiffer for track use. I personally like something around 900# front and 225 rear, and if needed softer sway bars. I'd rather have stiffer, specific rate springs controlling transient response (preventing diving durring braking, better controling the rear suspension when going from neutral to acceleration...). Of course, the rougher the surface that you're running on the less spring you want and the more you want stiffer sway bars...

1200/400 seems way too stiff for anything but something glass smooth, and 400 is probably too stiff for 1200 fronts, unless you've relocated the panhard bar mounts downward or much larger rear tires. Something in the 300# range is probably more appropriate.

FWIW, my favorite setup had 890# front and 225# rear, with 32mm solid and 24mm rear bars (rubber bushings on the back bar, poly on the front), and that car saw a lot of street time...

 

Nice one 83 crossfire. Very helpful info!

Merry Christmas

ramey

 

Thanks for all the info, I haven't checked the sites suggested yet but will in the next few days. We have Konis all around, there pretty old but very low miles. They were installed on a IROC & wrecked shortly after, a friend of mine bought both the IROC & the 86 Berlinetta, swapped all the suspension then let it sit, I traded a little labor for the 86 installed my engine-trans and went racing. Now I have a partner with the car who has helped with some of the upgrades, M-21, 98 rear & 3 sets of C-5 vette wheels, my only stumbling block (besides money) is talking my partner into stiffer springs, he thinks that the 550-155 combo works perfect, now with all this info I should be able change his mind. This is a 24Hrs. of Lemons car so even when we put on nice parts were getting pretty good at making them look like old junk! Thanks.