Rear spring coil binding
 

I am currently running Koni yellow revalved shocks, spring rates, 450# 7" fronts and 350# 7" rears. I am coil binding the rears at Lime Rock, at the bottom of the downhill and on Boston roads. Do others have problems with this spring rate? do I need an 8" spring for more travel and or up the spring rate to 375? I did cut 20mm off on 55mm bump stop for more shock travel, should I run them full length? I was thinking about rerunning my old setup 550/450 however found this setup a little to jarring with the revalved Koni's. What if I sold the shocks went with stock Koni yellow's with the 550/450's??? would that be a better option??

I don't know the exact set-up that you have. But are you sure it's coil bind and not just hitting the bump stops? If its bump stops, sure, try shorter ones. Or raise the ride height a bit if you can. Measure the distance from the top of the shock body to the place it will hit and compare it to the total amount of space between all the coils. As for the last question, too many variables to tell whats best from here.

Thanks for the reply, I know it's coil binding due to the wear/rust marks between the coils. The fronts have no marks at all...

If you're coil binding you in fact need a shorter spring, not a longer one. Think about how long the spring is when fully compressed; a shorter spring will still be shorter even when coil bound. Cutting off 20mm (about 3/8") of the bump stop my be exacerbating the problem as well. It would be much better to hit the bump stop rather than coil bind the spring.

The other way around,

350# 7'' (4.24" to coilbind, requiring 1489 fc-lbs)
350# 8" (4.70" to coilbind, requiring 1645 fc-lbs)

also 20mm is about 3/4"

Sorry; you're right.


What brand spring? Makes sense that if the springs are rated the same and wound from the same diameter wire then the 8" will have fewer active coils per inch. I was hoping the shorter spring would be thinner wire.

If you're only coil binding in the worst of spots I would put the stock bump stops back on. Anything is better than coil binding. Longer than 8" available?

No big deal...the springs are Eibach, and yes regarding a longer spring that 8" the next length is 10" however, need to take some measurements to confirm fitment with GC coilover.