Does the spring length or the GC mount position determine the amount of stroke lost in the shocks?

What are the recomended spring lengths and GC mount position to get a balance of lower ride height without losing too much suspension stroke? Useage is a street car with moderate auto-x/track time. Thanks!

 

In general, the stoke is determined strictly by the shock dimensions (which you cannot change), bump stop length, and the ride height. It doesn't matter how long the spring is, except in the extreme case that the travel is limited by the spring coil-binding. I had some 8" 250 lbs/in springs that did that, but most springs that people run won't coil-bind. The travel ends when the top of the shock hits the bump stop at the top of the coil-over assembly.

-Max

 

Thanks for the reply. A little confused, if ride height is one of the determining factors of stroke, is not ride height determined by spring length and the mount position of the GC kit?

 

Ride height is determined by the position of the collars in conjunction with whatever springs you are running. But the particular springs and collar position you choose to achieve a certain ride height doesn't determine the travel -- it is just the ride height that determines the travel. Travel is determined by ride height, no matter what springs and collar positions you use to achieve the desired ride height. For instance, if you chose a ride height of 25.5" from the ground to the top of wheel well arch (*), you will have the same travel no matter what springs and collar positions you use. Imagine the car with no springs at all that just levitated at your desired ride height -- the travel would be the same as it is with any spring/collar position combination because it ends when the top of the shock body hits the bump stop. For a given set of shocks and bump stops, ride height is *the* determining factor for stroke (nothing else matters). Does that make sense?

Other coil-overs have adjustments for both the position of the damper (effectively changing the length of the shock body) and for the spring collar and thus give some additional flexibility in setting the travel (and spring pre-load). With the GC kits, you can only move the spring collar, and thus travel is determined solely by ride height for a given set of shocks and bump stops.

You can change the travel with different bump stops, too. But I have assumed for purposes of this discussion that you have a single set of shocks and bump stops.

You can screw things up by running springs that coil-bind before the end of the travel (like the 8" 250 lbs/in ERS springs I tried once). But I will assume that any spring choices made will allow full travel (shock hits bump stop) before coil-binding. Coil bind is abrupt and not something you want.

(*) Note that this measure of ride height is also dependent on your overall tire diameters, but for purposes of this discussion, we can just assume one set of wheels and tires.

-Max