GC rates/spring height for STOCK ride height (rallycross car)

[irish44j]

Toying with throwing on a GC coilover conversion setup for the rallycross car. I am going to use Bilstein HDs with uncut strut housings. The goal is to have the car sit at "about" stock ride height with the adjusters on the coilovers halfway (allowing me to go up or down a bit depending on the surface condition). I also want for the spring to have a bit of preload so it won't unseat at full droop (rallycross cars get full droop a lot, lol).

Keep in mind this is an M42 early 318 with no interior, so it's in the neighborhood of 2200lbs give or take.

My thought is to go with about a 250-300# rate up front and around 350-400# in the rear (giving it an effective wheel rate of 225-260 in the back considering the e30's motion ratio back there is about .65 or so). Remember, this is a rallycross car - so I want a bit stiffer than stock, but not a LOT stiffer.

To keep a preload I'm debating whether to go with 8" up front or 10". At full droop right now my front springs are a shade under 10" tall and seated, so leaning toward the 10s .

So, thoughts on any of that? If I use the stock spring seat in the front (trimmed) with the GC collar, what length do you think is best?

[Northern]

What springs are you running now? vert?

I feel like 300# will be ~2x what OEM are, and anything close to the OEM spring free length will sit a lot higher. Edit: I misread how you measured, but 10" sounds reasonable. The GE coils I'm running came with 6" fronts, and with the adjusters as low as they go, they barely tuck the front tires. I feel like 10" would be a good starting point, and you could take ~3" out of that via the adjuster.

[irish44j]

What springs are you running now? vert?

I feel like 300# will be ~2x what OEM are, and anything close to the OEM spring free length will sit a lot higher. Edit: I misread how you measured, but 10" sounds reasonable. The GE coils I'm running came with 6" fronts, and with the adjusters as low as they go, they barely tuck the front tires. I feel like 10" would be a good starting point, and you could take ~3" out of that via the adjuster.

Right now the car has H&R sports with a 1" spacer in the front. They are just too short and soft.

300# in the rear is about 50% more than stock, if that. 200# in the front is about 90% more than stock.

I'm leaning toward an 8" spring with a helper in case it comes loose at full droop (not sure if I'll need it or not). That should sit me at stock height with the adjusters at the top and leave me the ability to drop down 2" or so if I want to do a trackday or if we're running on smoother surfaces. I'm not sure if I can get 10" in there without binding under compression (which I don't really want).