Z3 Rear Sway Bar Fit?

[bullmand]

I'm going to drop this post from the old Yahoo group here for future reference. Credit goes to Brian Brown.

I've used the M Coupe 19mm rear sway bar with an otherwise stock 318ti sport suspension. It works very well at reducing the tendency to understeer, but without making the car tail-happy.

Here's the part numbers for stuff that's different:
(1) 33 55 2 693 754 19mm rear stabilizer bar
(2) 33 55 1 094 551 19mm mounting bushings
(2) 31 35 1 124 995 Support straps for above bushings

Part numbers for the rest of the linkage hardware (same as original, but not a bad idea to replace):
(4) 31 33 1 092 887 Self-locking M8 collar nuts
(2) 33 55 1 135 307 Stabilizer end links <<<good idea to get new
(2) 33 32 1 127 717 End link brackets *
(2) 07 11 9 912 501 M8x43 hex bolts
(2) 07 12 9 964 655 Self-locking M8 nuts *

* I haven't tried this, but some people have reported using the stronger end link bracket from the front stabilizer in place of the original brackets listed above:
(2) 31 35 1 127 263 End link brackets
(2) 31 11 1 114 348 A10, 5x22 Flat washer
(2) 07 12 9 964 672 Self-locking M10 nuts

People with stock M-Coupes have been breaking the attachment tabs on the trailing arms (just like the E30's with aftermarket bars), so I would highly recommend welding in reinforcements when using this bar. Dinan sells prefabricated pieces of sheet metal to do this, but anybody that can weld could probably come up with some suitable pieces on their own.

[BimmerBum]

Until you have enough rear spring rate a larger rear bar is helpful. I have a 22mm rear bar on my Z3 coupe with otherwise stock suspension and I really like it. Virtually all of the understeer is gone replaced with a easily modulated throttle oversteer. If I ever go to coil overs with 500+ rear spring rates I would probably go back to a stock bar or even a stock non-sport ti bar.

I (BimmerBum) sponsor a Z3 Coupe running autocross in C Stock. When he asked whether he should run a larger front or rear bar (he had to choose) most of the Z3 community told him to run a big front bar. I was able to talk him into a larger rear bar and he could not be happier. The car is on stock springs with Koni's and an H&R 19mm rear bar.

[zoner]

Wondering if the H&R 19mm rear bar is worth the extra $50 over the OEM rear 19mm bar...?

[BimmerBum]

Originally Posted by zoner

Wondering if the H&R 19mm rear bar is worth the extra $50 over the OEM rear 19mm bar...?

Yes. The H&R bar has urethane bushings (in effect making a stiffer bar) and it is adjustable allowing for a little fine tuning.

[jca]

Sport models have thicker sway bars than base models. Can anyone describe the difference in handling between the two models, from experience? Thanks if you can.

[BimmerBum]

Sport models have thicker front and rear sway bars along with shorter and stiffer springs and stiffer shocks and struts. Both sport and non-sport models tend to understeer at the limit but I would say the limit is slightly higher for the sport models. To dial out the understeer you need to venture out into the aftermarket or get creative with OE parts.