Pro Shock Spring Rates

[Naumoff]

Does anyone know what the front and rear spring rates are on the 427 models with a FE engine.

I found a formula to due this and came up with 350#/ per inch for the front spring.
Spring rate = GD to the fourth power/ 8ND to the third power

G =Torsional Modulus for steel = 11.25 x 10 to the sixth power
D = wire diameter in inches
N = Number of active coils
D = mean coil diameter in inches. mean diameter is:
I.D. = 1 wire plus inside diameter
O.D.= 1 wire minus outside diameter
8 = a constant for all coil springs

I would also like to know if I can get a shorter spring for the front as it is adjusted all the way out and I still have to much of a gap between the tire and the fender.
Rear adjustment is fine.

Thanks,
Tony

[eliminator]

Probably from 300# to 325#, majority.

I had 325# put on mine and didn't like them, went to a Hypercoil 10" 350# on the front when I changed over to Bilstein Shocks.
Yes, you can get a shorter spring, it would have to be a 8", your right the 10" are too long. The ideal length for a Unique 427 S/C with a FE big block is 9" and nobody makes them.
I have tried the 8" springs, I am currently running 8" 375# on the front, still need to do a little work there. The current shock is a little too long so you have to get the car up pretty high to have the right rebound and compression.
You need a minimun of 4 inches of travel at your correct ride height, 2" - 2 1/2" compression , then 1 1/2" - 2" of rebound. Thats really the best you can do at the ride height everyone wants, low. To get 5 inches total you have to get the car up there, (eye to eye distance on the shock, top mount bolt to bottom mount bolt). If you look at the old pictures of the race cars they were up there, 3-4 " of body above the tires, they had to be to get the 5-6" of shock travel you need for racing.
So, I wish I had a set of 9" springs that were 350-375# for the front.
8" springs are used in the rear, I like the 325# rate for them.

[Naumoff]

Thanks for the info Rick,

Rear end is adjusted up as high as it can go without going into positive camber.

Alan has shorter spring available.

Did you go to a spring shop and ask about collapsing one or two coils and retempering the spring?

The only problem with that, by the formula, is your spring rate goes up.
A shorter spring with the same spring rate must have a smaller wire.

[spd4me]

Tony
I just contacted the tech people at QA1 concerning adjustable shocks for my FIA. My ride height of shock (center of eyelet at top to center of eyelet at bottom when in nomal riding position) is 12" and front half weight of car approx. 1340 lbs, they recommended an "Ultra-Ride" UR 4855B with a 10-300 (10" 300 lbs) spring. The shock has a preset compression and 12 rebound adjustments. I'll put on next week and see how they do.Purchased from Naake Suspension Specialists in CA www.naake.com Springs compress to 10" and 14" extended.
Bob

[Naumoff]

Bob,
Let us know how they work and post some pics.:shift: