Spring Length Question
 

Hypothetical question.
What's the difference between fitting a 5 inch spring and a 6 inch spring of the same rate with the spring perch 1 inch lower?
Assumes that the spring perch has adequate adjustment and the spring is fully seated at maximum droop.
Ta.

1 inch.
DougW

1 inch less bump travel?

The longer spring will provide more travel before coil bind. May or may not be an issue depending on the setup. Also the 6" spring will be marginally heavier, if that makes a difference to you.

This! I doubt that coil bind is going to be an issue with either free length on these cars though, unless you're running really low spring rates.

5 inches is a pretty short spring though...I wouldn't run them on a KW for example.

- Andy

Yeah, 5" is kind of short. Maybe if you had a damper with crap travel and ran super low it would work.

I was wondering this - what do you guys assume for bump stop compression? I'm assuming "fully compressed" is about 0.5" of the free length, but I'm thinking it might be longer than that.

Depends on the bumpstop of course and sometimes that data is available.

For the purposes of avoiding coilbind we typically assume a much larger % of the bumpstop can be compressed.

- Andy

This thread is boring without the expert opinions of Ubersuber....:D

Because of their spring rates, or because of their shock design?

I would think it depends more on how much the spring is compressed between free length and static ride height than anything else, which is mostly going to be driven by spring rate.

KWs have a lot of available stroke. Yes if they're slammed it's not a lot of bump travel. But at a realistic ride height you have a good amount of bump travel...probably more than the a 5 inch spring has before it binds (which is a problem).

- Andy

Ah, gotcha. My thought was that with stiffer springs you're running less pre-load and will run out of damper stroke before running into coil bind. Guess it really depends on how much stroke you have and spring rate.

Yep, the kw have about 5.6" of total damper stroke in the front. With my ride height 1" lower than stock, using a 7"/7k spring, I actually only have 0.12" of margin before coil bind (spring travel left when the damper is fully bottomed), assuming 50% bump stop compression. I was surprised to see it was that close.

If I dropped to 1.5" lowered I'd have 0.5" before coil bind.

I should probably lower the car a bit.