Ground-Control coilvers on my 318iS

[royalflush313]

Well after much debate (with myself), I have decided to buy the ground-control coilovers.

I will be using my Bilstein Sports shocks, and see how it goes. I'm not going to be slamming the car to the ground, so I should be okay.

I just got off the phone with GC, and for spring rate, they suggested around 350 front, 450 rear.

Now, I know that many of you are tired of helping me because of my indecisiveness but well.. uum yah.

So, help me pick a setup (spring rate and height), keep in consideration that I have a 318iS, Bilstein shocks, daily driver, and would like to lower approx. 1.4" in the rear and a tad bit more in the front.

Thanks.

- Hiro

[Mystikal]

You're going to want around 5.5" front length and 6" rear.

Those springs rates are good for a daily driver.

[BimmerToad]

I'm currently using 475R for my daily driven 318iS with revalved bilstein sports. The ride seems pretty good, kinda stiff, but definately streetable. I have 350s for the front, but I am still waiting on parts for the front, so I'm running blown stock struts and springs in the front currently.

If you're going to run a GC setup with bilsteins, I'd recommend you get them revalved, and at least cut the front bump stops an inch to gain some suspension travel, especially if you run stock strut mounts.

[royalflush313]

I'm currently using 475R for my daily driven 318iS with revalved bilstein sports. The ride seems pretty good, kinda stiff, but definately streetable. I have 350s for the front, but I am still waiting on parts for the front, so I'm running blown stock struts and springs in the front currently.

If you're going to run a GC setup with bilsteins, I'd recommend you get them revalved, and at least cut the front bump stops an inch to gain some suspension travel, especially if you run stock strut mounts.

where can I get them re-valved, and to what specs? Idea on how much that might cost?

[BimmerToad]

Revalving IIRC is $60 a shock (basically a rebuild of the shock to your specs). I called the guys at Bilstein and told them I was going to run roughly a 2x stiffer rear spring, and they suggested an increase of 30% rebound to the rears. It feels pretty good, but I don't really have any room for comparison.

As for the fronts, I need to drive with them in first to feel if the valving is decent.

[M42Technik]

I just got 6" front and rear springs with 325/450 rates. Should be fine.

Also, get the Camber plates from GC. The suspension travel you gain is worth the money.

[e30excel]

what would people recommend for a 318 that sees track use

spring rate wise??? for GC's

[royalflush313]

I just got 6" front and rear springs with 325/450 rates. Should be fine.

Also, get the Camber plates from GC. The suspension travel you gain is worth the money.

how does camber plates increase the suspension travel ? :?

Are you using Konis or Bils? And did you "at least cut the front bump stops an inch to gain some suspension travel, especially if you run stock strut mounts"?

[M42Technik]

how does camber plates increase the suspension travel ? :?

Are you using Konis or Bils?

Koni's.

http://e30m3performance.com/installs/GC_susp/GC_susp3.htm

[royalflush313]

^ Thanks for that link.

Should I be okay with just the camber plates, or do I still have to cut the front bump stops? :?

[M-technik-3]

where can I get them re-valved, and to what specs? Idea on how much that might cost?

Truchoice Motorsports.

[Jared K]

If you're going to run a GC setup with bilsteins, I'd recommend you get them revalved, and at least cut the front bump stops an inch to gain some suspension travel, especially if you run stock strut mounts.

It depends on your ride height. I had some Apex springs on my car and my ride height was too low. The front fender was only 23 1/4" from the ground & the front tires were tucked under the fender. At this point, I couldn't even compress the suspension if I pushed down on the fender, so the Bilstein's must have been constantly bottomed out. The ride, suprisingly, was not as bad as I thought it would be. Now, I installed a set of H&R Race springs. The fender is 24" above the ground and the top of the tire is basically even with the fender. There is some movement when I push down on the fender, so I assume that I have 3/4" of travel left.

I compressed my Bilstein sport struts by hand and there was only about 1/2"-3/4" of the shock shaft sticking out when I could really feel the bump stop. Wouldn't cutting the bump stop by 1" mean the shaft could compress right into the shock body? I'd cut the bumpstops, but I don't want to damage the shock seal. Below are some pictures I took. In my opinion, you wouldn't want that slight ridge near the end of the shock body at 5 3/8" to go past the seal.

[BimmerToad]

When you say 1/2 - 3/4" of shock shaft, do you mean the huge shaft which is exposed on the insert, or the actual shock piston? The bigger shaft is actually the shock body and the seal it moves up and down in is only a dust shield.

If you were to have 1/2 - 3/4" left on the shock body height before the top of the body hits the dust shield, then by looking at the bottom pic, it's safe to say that you're already compressed the stock length bump stops by 2 inches. If you were to cut that bump stop an inch, then (fender allowing) you'll have 1 inch more of predictable spring rate before you hit the bump stops. Once you hit the shortened bump stops, the bump stop will be a higher spring rate than the stock length stop, since bump stop spring rate increases, because there is less material to give to elastically deform under compression.