Stance coilovers at full pre-load

[freakyjason]

When you increase the pre-load on the spring, essentially what you're doing is compressing the spring and increasing the spring rate (correct?). So, at full pre-load on a set of stance coilovers with the 8kg 6 kg setup, what would the front spring rate be? Would it increase it a lot? Thanks!

[Gabes13]

A: 8k front 6k back

Only progressive springs increase in rate during load.Stance coilovers consist of linear springs, so the rate shouldn't change.

[freakyjason]

I just did a very quick calculation as a proof of concept: the stock front spring height is 175mm with a spring rate of 8kg/mm. When fully compressed, the height of the spring is about 139mm. When you use the force on a spring equation (simply Fs = k * x where k is the spring rate, x is the displacement of the spring and Fs will be a constant based on the initial conditions of the stock spring at zero pre-load). Solving for k when x is 139mm gives you a spring rate of a little over 10kg/mm. Could this be so? Seems like a crazy increase in spring rate for such a small displacement. Let me know if I'm making sense to anyone here.

[freakyjason]

Only progressive springs increase in rate during load.Stance coilovers consist of linear springs, so the rate shouldn't change.

Yeah, after doing a bit more research, that seems to be the case. Makes perfect sense. Thanks!

[the converted]

not quite right. srping rate is 8k/mm open length is 175 compressed length is 139. So if you were to calculate the force on the spring at that length you would have 8k/mm*(175mm-139mm)=288kg before the spring will deflect at all. I'm not sure if that is coil bind or not, but regardless it would be 288kg to get it to move at all, and then 8kg for each additional mm after that.

As for what it would do for your ride, you would essentially have your tires being the springs and your car would bounce everywhere.

[freakyjason]

Okay, that's exactly what I needed to know! I'm new to coilovers and I've been spending the past couple of days experimenting with all sorts of different set-ups. Thanks for the info! However, i don't believe this would have the tires of your car being the springs. Each of the front corners of the car weighs about 288 kg so just by taking the car off the jack you are overcoming that initial 288 kg load required to deflect the spring. And, like you said, the spring rate does not change so it is obviously still 8kg/mm for every mm deflected after that. I think that maybe on the lower dampening settings it might be bouncy. I'm going to try it out though and I'll let you know.