I'm trying to fine-tune the suspension on my M coupe and find myself in need of the smallest swaybar I can locate that will fit.

I suspect an E30 3-series or the 318ti will be good sources. Does anyone know if the bar for any of these models is roughly the right geometry and in the 14mm - 15mm range?

Thanks in advance,

Mike

what leads you to think that a small bar is called for?
just curious

have you tried totally disconnecting the rear bar?

what leads you to think that a small bar is called for?
just curious

have you tried totally disconnecting the rear bar?

Without spending too much time and bandwidth on a response: the rear swaybar on my coupe is "deleted" and despite the fact that I've dialed in the suspension to the point that the car is very effective in most turns, I'm still lifting the front inside wheel.

My choices are extensive effort to retain either 700 lb/in or 800 lb/in springs in the back or experiment with a very small swaybar. The swaybar will be *far* easier to test.

Mike
SCCA Solo2 ASP M coupe

I don't know the acutal size of the ti bar, but I can tell you it's TINY. I mean it looks like it's <10mm.

Without spending too much time and bandwidth on a response: the rear swaybar on my coupe is "deleted" and despite the fact that I've dialed in the suspension to the point that the car is very effective in most turns, I'm still lifting the front inside wheel.

Why would a rear ARB solve said problem?

The lift is more a result of too low of a roll center (is your car dropped more than 1" from stock ride height?), shortened suspension travel, heavy rebound settings, and stiff front ARB's.

AFAIK, nothing fits an M coupe besides the stock rear bar because of clearance for the diff cover. I believe that all years use the same size.
Sometimes you can really soften up a bar by using soggy bushings.

What about milling a stock bar down some? Might be hard to control how much softer you make it, but it's a thought.

Chris

I've done that before, I forgot. Its real easy. I've used a disc sander to avoid stress risers.

I'm trying to fine-tune the suspension on my M coupe and find myself in need of the smallest swaybar I can locate that will fit.

I suspect an E30 3-series or the 318ti will be good sources. Does anyone know if the bar for any of these models is roughly the right geometry and in the 14mm - 15mm range?

If an E30 rear swaybar will indeed fit the M Coupe, the 87-91 325i/is came with a 12mm rear bar, and the E30 M3 came with a 14.5mm rear bar.

As for not fitting with an M Coupe diff cover, many E30 cars are sporting this rear cover with aftermarket swaybars and it doesn't come in contact with it. Dunno how the bar is routed on an M Coupe though but i presume it's roughly the same as on an E30 since the M Coupe's rear suspension system is E30-based. But if the M Coupe rear bar is shaped differently then it might be a problem......

Pic of M Coupe cover on E30 M3 with larger aftermarket swaybar:
http://www.e30m3performance.com/installs/Diff_cover/MDiffcover_bg.jpg

Why would a rear ARB solve said problem?

The lift is more a result of too low of a roll center (is your car dropped more than 1" from stock ride height?), shortened suspension travel, heavy rebound settings, and stiff front ARB's.

Hey Racer,

what do you mean by "too low of a roll center"? Are you saying that lowering more than 1" is beneficial or harmful?

Beneficial in that it lowers your COG, harmful in that as your lower your ride height, the roll center drops exponentially. Most of the "race" setups people run on the front of BMW's results in a roll center below the ground that also moves horizontally quite a lot under roll conditions.

The guys at RRT have done a lot of modeling of the front (and are working on the rear) suspension of the E36 and E46. I've seen the computer programs and models they have come up with, as Barry is helping us come up with some better geometry for the front of our race car. I believe most of your questions about roll center are answered in this thread by James of RRT (JamesM3M5):

http://forums.bimmerforums.com/forum/showthread.php?t=176543&highlight=roll+center+rrt