View Full Version : Eibach Vs Racing Dynamics

02-02-2002, 04:38 AM
e30 fans what do you guys think?

RD sways & strut bars?

or Eibach?

eibach only makes a front strut for e30's
so for sure that will be RD...
but what about sways? who do you guys trust more? who makes a better product? RD is about 50 bucks cheaper than the Eibachs

and for suspension..

Ground Control coilovers w/ eibach springs VS. Spax coil-overs w/ spax springs?

02-02-2002, 01:47 PM
I heard RD's are better cuz they're adjustable and the eibach's arent.

GR8 Ride
02-02-2002, 02:43 PM
Both the Eibach and the RD sway bars are adjustable.

There is one primary difference between the Eibachs and the RD (actually, most other sway bar brands). Eibach builds two kits, one for the E36 non-M3, and one specifically for the E36 M3.

The E36 Non-M3 Eibach sway bars size up at 28mm front / 21 mm rear. The M3 specific Eibach sway bars are 26 mm front and 24 mm rear.

There are a couple of reasons for this. On the stock E36 cars, tire and wheel sizing is identical front and rear, while the M3 had 225/45/17 on 17x7.5 inch wheels up front, and 245/45/17 on 17x8.5 wheels rear. This staggered setup promotes understeer (suspension design by lawyers...), so the sway bar setup is designed to counteract the built in understeer.

As well, the M3 setup bolts to the strut, and not to the lower control arm as in the rest of the E36 lineup. Because of the mechanical advantage gained in bolting to the strut, a smaller diameter bar can be used to gain the same weight transfering abilities.

RD sway bar kits is 27 mm front / 22 mm rear, and is identical for both M3 and non-M3 applications.

If you're running identical wheel / tire sizes all around, this may change your choice of sway bar setups.

I just changed my sway bars from the Eibach non-M3 kit to the RD setup, primarily because it's part of the complete Gruppe N suspension package. I'm also running identical wheel / tires sizes all around, so I don't need as stiff / large / heavy a bar in the rear to counteract understeer.

One thing to consider with sway bars; their primary function is NOT to reduce body roll, in spite of what people may claim. A sway bar's true purpose is to manage weight transfer from side to side, and to maintain maximum contact patch on the road.

Body roll itself should be controlled by springs / shocks. Most Club racers, once they get above the 700 lb-in spring rates, actually begin to reduce (or even eliminate) the size of their sway bars.