Sorry guys...GC Spring Rate for DD questions...I searched

[CubbyChowder]

Hey guys, I'm sorry if this is a subject that's been covered numerous times. I've been searching for hours and have found lots of good info, but it's hard to apply all this info to my exact configuration. So here goes...

I have a 1991 318is on stock suspension. It is strictly a daily driver, something fun to cruise around in.

I want to build coilovers for it, something that will get it low enough for my taste. Something that can slightly tuck my 205/45/16's front and back, but still provide a decent ride quality for a street car. I realize the car will be significantly stiffer than stock, I'm used to it. Not new to coilovers, just a bit confused on what setup to run for an e30. I'm leaning towards the GC kit.

I will be shortening the front strut housings 2"

I will run IX Bilstein HD's in the front and probably 82-02 Camaro KYB's in the rear.

As for spring rates, it's hard to decide what's best for me. Can you more experienced guys provide some advice or insight? Any help would be appreciated. Again, sorry if this frustrating for some of you, but I did search quite a bit.

[Vivek]

For an m42 I'd suggest you go about 425# up front. That's a 5" spring, so keep that in mind when you're sectioning your housings. If you'd like a 6" spring then you have more options when it comes to rates--people tend to like 440#. Depending on what you want, around 650 would be decent in the rear. The issue is that a 5" spring really limits how low you can drop the rear. Some people (not me) like the front rake, so you may be fine with that. I can post up a pic of my car on 5" 750# rear springs, it's not low at all. I do believe, however, that you can run the delrin centering rings on the top and bottom in the rear to go pretty low. That'll be tucking quite a bit of the tire size you specified.

Contact ground control directly if you have questions that we can't answer. They know much more about their spring rate options than I do.

[CubbyChowder]

For an m42 I'd suggest you go about 425# up front. That's a 5" spring, so keep that in mind when you're sectioning your housings. If you'd like a 6" spring then you have more options when it comes to rates--people tend to like 440#. Depending on what you want, around 650 would be decent in the rear. The issue is that a 5" spring really limits how low you can drop the rear. Some people (not me) like the front rake, so you may be fine with that. I can post up a pic of my car on 5" 750# rear springs, it's not low at all. I do believe, however, that you can run the delrin centering rings on the top and bottom in the rear to go pretty low. That'll be tucking quite a bit of the tire size you specified.

Contact ground control directly if you have questions that we can't answer. They know much more about their spring rate options than I do.

So if I were to get a 5" spring, would I section my housing only 1" instead of 2"?

What exactly is the advantage/difference of running a 5" spring instead of a 6" spring, both with different rates?

I actually called GC a few weeks ago to call about spring rates and the guy seemed really antsy and kept telling me to call back when I'm ready to order so they can help figure out my spring rates. I told him I was basically ready to order, just needed a recommendation on rates and he kept insisting that I call back when I am really ready, he didn't give me any info on spring rates whatsoever. I was honestly confused. I just felt like he didn't feel like dealing with another e30 guy.

I guess I'll give them a call again.

[DRTSRFR]

You didn't ask for Mark:D

Vivek and I spent 3 weeks talking before he made his decision.

[Vivek]

As stated, call Mark. FWIW I run 5" front and rear 425/750. That setup is meant to be balanced for an m42 vert that has more weight in the back than a coupe (balance is about 51/49 according to my local truck scale). Yours would be less weight in the back so you'd want slightly closer rates front and rear. I'm not quite sure of GC's rates between 650 and 750, but something around there should be good, i'd lean a bit closer to 650 with a 425 front. That'll be a comfy DD (relatively).

Figuring out how much to section off the front is pretty simple, but basically with a 5" spring I'd suggest sectioning 1-2" depending on how low you want and if you're running camber plates (remove nearly an inch of stack height depending on the plate). If you ran a 6" spring I'd definitely section 2". The front can go infinitely high or low depending on how you set it up, the back is all you need to worry about (and it's much simpler).

[CubbyChowder]

As stated, call Mark. FWIW I run 5" front and rear 425/750. That setup is meant to be balanced for an m42 vert that has more weight in the back than a coupe (balance is about 51/49 according to my local truck scale). Yours would be less weight in the back so you'd want slightly closer rates front and rear. I'm not quite sure of GC's rates between 650 and 750, but something around there should be good, i'd lean a bit closer to 650 with a 425 front. That'll be a comfy DD (relatively).

Figuring out how much to section off the front is pretty simple, but basically with a 5" spring I'd suggest sectioning 1-2" depending on how low you want and if you're running camber plates (remove nearly an inch of stack height depending on the plate). If you ran a 6" spring I'd definitely section 2". The front can go infinitely high or low depending on how you set it up, the back is all you need to worry about (and it's much simpler).

Thanks a lot for the detailed responses man, I really appreciate you taking the time. All these numbers get a bit confusing to me. I'll give Mark a call tomorrow and see what's up. Don't know if I'll be running camber plates yet.

[ChaosTheory]

You didn't ask for Mark:D

Vivek and I spent 3 weeks talking before he made his decision.

+1

Mark knows his stuff and he's a genuine guy. Helped me adjust my ride height on my e36 m3 today. I am very comfortable with the coilovers now and deff glad I contacted Mark, he saved the day!

[CubbyChowder]

Talked to Mark today, super cool and helpful guy. Ordered 440f/650r for my 318is, can't wait!

[DRTSRFR]

Thank you very Much!

I'm glad I got a chance to talk with both of you!

[drexcell]

I have a 1991 318is with a S50 swap. I am new to this stuff and it sounds like there are a lot of options. Mark, I will be reaching out to you sometime this coming week.

[DRTSRFR]

I'll be here when you're ready!

[Danny]

Mark is awesome. One of the best customer service people I've ever talked to in regards to BMW related activities.

[DRTSRFR]

**blush**

Thanks Danny !

[whodwho]

From now on you’re the only one that is allowed answer the phone!!

[DRTSRFR]

Haha!
You can always ask for me.
If I'm not available, leave a number. I wear many hats here, but I do my best to call everybody back.