E30 Rear coilover setup

[Driftit 2078]

I am going to convert my suspention setup to 2.5' id springs. So that I am able to muck around with spring rates.

But I am just wondering if this is possible in the rear as I have not dealt with trailing arms before. Is it possible to have a coilover setup in the rear. i.e. Coil over shock. As I know this must offset all the weight on the arms to the very far edge rather than in the middle where the stock spring sits.

[CamB 48]

I am going to convert my suspention setup to 2.5' id springs. So that I am able to muck around with spring rates.

But I am just wondering if this is possible in the rear as I have not dealt with trailing arms before. Is it possible to have a coilover setup in the rear. i.e. Coil over shock. As I know this must offset all the weight on the arms to the very far edge rather than in the middle where the stock spring sits.

Some of the guys racing do it - they (substantially) reinforce the strut towers to take the weight, and usually convert them to take coilover shocks with a rod end. Reinforcement involves tying the strut towers together with a bar and triangulating to the floor, usually.

I've also seen reinforcement added to the shock mount on the trailing arm.

It's quite a lot of work! I wouldn't convert standard shocks.

Alternatively if you have a look at www.ground-control.com they have an adjustable perch arrangement which works in the standard spring position. TBH it's not a great system - I stuck it in JiB's car the other weekend and your ability to raise/lower the car within sensible height ranges, and keeping in line with certable rules, and sensible spring rates ... is a bit compromised. Having said that, it is pretty good with his spring choice (approx 600lb/in) and my choice of height (which isn't too low, so it isn't too badly cambered).

I believe it uses 60mm springs.

Edited October 23, 2008 by CamB

[JiB 0]

If you want to have a look at my car just give me a text. Won't really be free till after exams though.

Had it really low on 525lb front 650lb...very very much like a go kart.

Now has 475lb fronts and higher, not very go-kart like any more. I think because it's higher, less crazy toe on the rear, so the rear is heaps more stable.

[Driftit 2078]

Yeah I will have a look next time I see you Jonathan.

I think I will look into it more. I want to try and get my rear end much lower but with a good spring rate. The random brand springs I have now are just plain sh*t.

A mate of mine is one of the custom shock builders at Racelign. So changing them around is no problem.

Wish there was a cheap M3 setup sitting around.

[CamB 48]

Wish there was a cheap M3 setup sitting around.

That won't help your problem?

[Driftit 2078]

Yeah after reading around it seems like a real hassle. I might just look at the read height adjustible platforms from ground control.

[hybrid 1043]

Yeah after reading around it seems like a real hassle. I might just look at the read height adjustible platforms from ground control.

here is mine (shots of the rear are in there)

http://www.bimmersport.co.nz/forums/index....t=0#entry161415

[JiB 0]

Mine are pretty much identical to Hybrid's. But with a smaller straight race spring. If you want the rear lower, maybe go for some softer/longer springs so they'll be captive. Otherwise you'll have to look for keeper springs which are expensive in the not-so-common 57mm ID

[CamB 48]

It'd never work properly with keepers at the back I don't think, having mucked around with yours. When it was low, it was only 20mm off captive, so I'm not sure you could get keepers in there without lowering it even further (and it only had another 15mm or so it could wind down).

So it would have to be stupid low.

I think the only captive solution would be longer softer springs if you want to go lower.

I reckon a 2" spring would work fine.