GC coilover rates

[robgoesvroom]

Hello everyone,

I'm going to be purchasing the ground control coilover conversion kit and wanted to get 2nd opinions on spring rates.

I spoke to Jay at ground control and he suggested 440f / 625r. I feel that this might be too harsh for my use. Any suggestions for spring rates?

I don't plan on shortening the strut housings, I have bilstein dampers that are fairly new. The car is a daily driver, and sees autox 3-4 times a year and perhaps more in the coming years. The car does see occasional mountain drives, mainly Mullholland dr, Malibu canyon, glendora mtn. It is also my daily driver.

I also fully load things in the car as I live in socal and go to college up north. Also, I'm really not looking to "tuck" my rear wheels in.

Current specs:
1990 325is
H&R Sport Springs (1.5" drop rear, 1.25" drop front)
Bilstein sports
15x8
225/50/15
all 4 rolled, however, right rear rubs on dips


I am basically looking for springs rates that are in between the H&R sport and race as the springs are too soft for me. I did look at the spring rate master list but am unable to tell which rates apply to my use

Thanks in advance.

Here is a photo of the current stance of my car,

[sharky]

The rates Jay suggested are perfect for you IMO, I run a slightly stiffer rate and it is still very tolerable, plus I am old and ornery so I dont like too stiff.

[Mike The Bavarian]

those seem high right now, but they're really not bad.

[Eastbaybimmer]

What wheels are you on? Those look great. Im installing my GC coils right now, 375/475 I think.. I have an m42 so my car is a bit lighter..

[robgoesvroom]

eastbaybimmer - they are the TRM C1 from tirerack. Please do let me know how those 375/475 rates work out for you. I really don't want to be bouncing on the freeways with 440/625. 375/475 seems more reasonable

[Eastbaybimmer]

Remember, the 318is is about 200 lbs lighter, but I understand your concern. I'll let you know how it goes.

[z31maniac]

I drove around on 550/750 on 17s with 40series. Granted that was on the custom valved Konis, but the proper damper can still make higher rates streetable.

Personally, I'd go with Jay's suggestion. He spec'd out my rates on my swap car and has helped many others as well.

[efeldman]

im about to install mine as well. Jay recommended something similar for me too, and i live in a city so i wouldnt worry about that at all. does anyone have any advice for installing these bad larrys? my koni yellows are here and everything is ready to go. any major bumps to look out for?

[liquidgroove]

I had F: 375/R: 475 and found rear to be too soft.

I later changed the rear to 6" 525lbs and I was more happy with it on the street and track.

Now I start doing more track and found both front and rear to be too soft.crazy:
If I have to choose again, 425/625 sounds pretty good to me.

[sarcasmkillsme]

Just listen to Jay, he knows what he's talking about. You will be disappointed if you go any softer.

[psyber_0ptix]

i'm running 450/650

[619E30]

I'm running 600f/700r

[Van Westervelt]

This is a very common misconception people have. The rates have to do with the stiffness of the spring, not the harshness. Your car will actually feel more harsh with a progressive spring like the H&R Sport or Race, than it will with a linear spring like the ones from GC. The ones he recommended will be stiffer, but it will actually feel smoother if all is matched up well.

[psyber_0ptix]

and don't neglect dampers. a super stiff spring that is under-damped won't feel too nice either.

anyone know what the OTS Bilstein Sports are valved up to?

[drumad]

arent those rates too high for billy sports?