JPSC Forum

what spring rates are people running . Ive currently got ( according to the build manual ) 100lb 9" long. These are to be changed for 8" long as I need to lower the rear.
The IRS is the early single wishbone and strut type. The new spyder tub gives too much wheel to arch clearance so the need to change to shorter springs.
If they are 100lb springs that are on there ( no markings) they do seem alright although 100lb does seems a little soft?

Depends what engine you are running (weight wise) and what you are doing with the car. I was under the impression stock Fury springs where 180 front 120 rear. My Phoenix has 225 front and 180 rear.

Thanks For reply Jef.
Its got a 2.0 Silvertop in it and will have mixed use. Driving between Coventry and trackdays at brands and othe midland locations.
Hopefully I'll be getting the car back this week so will have a measure of the I.d's.

I wouldn't run any less than 225 front 180 rear even in BEC 's and that also depends on how much piston travel is available once you are in the car . There's no ''one size fits all'' regarding spring rates and lengths. A guy weighing 16 st on 180 rears is going to bend the link arms but if you're 10 to 12 st the piston will still have travel if adjusted . The original 130 rears on nearly all Sylva kits was totally useless .

100lb sounds like a live axle rate not an IRS rate.

Do you need a shorter spring to reduce the preload as you have insufficient adjustement on the coil over?

Andrew

this was the reply i had from pro tech shocks for my IRS fury

"The last customer we done some for were 12 1/2” fully extended eye to eye centres with bonded bushes 1/2” x 1 1/4” If these length are no good and they are not damaged we would take them back and make them to what ever alterations you may ask for."

i ended up with 180lb fronts and 150lb rears. although it hasn't turned a wheel yet, so i cant say whether its right or not!