Hey guys I'm re-vamping the rear suspension in my '89 M3. Here is a list of parts I'm thinking about getting with some questions along the way.

1. IE trailing arm bushings
2. IE Subframe bushings (street)
3. IE Beefy Shock mounts
4. IE Rear Sway bar (19mm or 22mm) dont know which to get here. Is there a downside of going with the 22mm?

5. springs: can't decide here either. I don't know how much to lower. I don't want my rear tire to be under the fender lip much at all if any. I'm considering IE stage 3 race springs, H&R sport or race.

I realize with a stiffer spring that the sway bar does not need to be as stiff but still don't know what to get.

Suggestions / help would be appreciated.

Thanks,

Hugh

What about say a less stiff spring like a h&r sport with the thicker sway bar?

Would that be comparable to a stiffer spring with a thinner sway bar?

essentially, it is how you want to tune your car. some people tune with springs, and some people use anti-roll bars. Either use stiffer springs or a stiffer anti-roll bar to limit the body roll. Decide on your spring based on what the car is used for (ie- don't put race springs on a daily driver unless you like a rough ride) If you want a smooth ride- go with the larger sways

I'm in CA and I have Eibach Pro springs I pulled out of my M3 right after I bought the car (I installed a full GC coilover kit).

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Hey, thanks guys.

Do you think I would have any problem with too much oversteer if I have the thick bar on the back (22mm) but leave the stock one on the front (21mm)?

If this is a problem would I have the same problem with stiffer springs and thinner sway bar?

I need this car to drive to work (short) and to be able to handle aggressive mountain driving on the weekends. I also plan on going to some driving schools or trying out some track events but am not there yet.
Based on these needs do you think a sport spring would be aggressive enough or am I nearing race spring needs?

Thanks again,

Hugh

I am running HR Race Springs with the 19mm Sway bar. If you run the 22mm Sway bar you need to weld the reinforcments in so that you dont tear the mounts. I have the Racing Dynamics Sways - its a track car. Soon I will be going to GC Coilovers. The shocks I am running are Bilstein Sports. Its a tight set up. This winter I plan on doing the Subframe Bushes; Trailing arm bushes; and adding the ButtStrut. In addition to that I am also running the Sparco Strut brace on the Front and the Racing Dynamics Rear Strut brace. Like I said - Pretty tight. I was running pretty well at VIR last week in my HPDE Event - if I had more engine I would be able to keep up with the Z06 in the straights..... :) - I out run them in the twisties! - JT

Id say go with the stiffer springs. Less sway bar. I had oem M3 springs in my 325 and went to H$R Race springs and i like the ride so much more. Its honestly nicer over the small stuff.

If your thinking about going for H&R race springs or IE 3's you should look into IE's weld in adjustable camber caster things for the rear end. Possibly the KMAC eccentric trailing arm bushings.

If you dont want the tires in the fenders go for H&R race springs over the IE's cause the IE's sag in the rear more.

Best of luck and im sure youll love the race springs.