I have an 05 545 with 63k and just replaced the front pads and rotors. Shortly after the install I started experiencing steering wheel shimmy while braking. I observed uneven wear on the rotors as if the pads were only contacting the bottom two thirds of the rotor surface. So I took the rotors to have them turned and went through the bedding in process again. At first everything seemed fine. Then I started noticing the simmy again when I would brake at higher speeds (above 55 mph). It does great below that!

It's just after Christmas so I don't want to spend more money than I need to, but will do what's right for the brakes. I'm thinking I got a pair of bad rotors and I'm not thrilled thinking about turning new rotors a second time. Do you agree with this and are there other things I should consider? Any help would be greatly appreciated!

 

I wouldn't turn them again. Did you buy the rotors from a dealer?, or at the least from an OEM or better source? When they turned them the first time, did the shop mention that they had to take a lot of material off? Maybe someone around here has a good way of confirming whether a set of rotors is bad.

Given the timeline it obviously seems like it's the brakes causing the shimmy, but don't necessarily rule out wheel balance OR even upper control arm or other suspension bushing failure/wear, which I've found to exacerbate just about any slight vibration issue. The typical diagnosis of upper control arm bushing failure is a shimmy under light/medium pressure braking.

 

Make sure your brake caliper slides smoothly, as a non sliding caliper will hang up and overheat a rotor.

 

If everything was torqued-down properly during the replacement, it could be that you have a warped rotor. If you bought the OEM BMW (Zimmerman brand) rotors, I don't you are supposed to resurface them in any way. I was told that they were made of softer materials than aftermarket ones to enhance stopping power. If you replaced them with aftermarket stuff, I'd get them to replace the bad ones that you ended up resurfacing.

 

I hate to admit it, but I didn't purchase OEM rotors. I bought Centric rotors from Tire Rack hoping they would be fine. The pads are Padgit Red from Bav Auto. When the rotors were resurfaced they told me they had to take alot off and it had alot of wobble and had to be turned at a slower RPM. I had NO symptoms before replacing the brakes so I'm not sure about the suspension. Of course it is a 5 yr old car with 63k on it. BTW, the tires are old and will be replaced in January. They do have some vibration at speed. Thoughts?

 

did you clean the hub face with a wire brush before mounting the new rotors?

 

I cleaned the hub very well - twice! Took everything apart between original install and turning the rotor to be sure everything was done right.

 

Easiest thing to do is check for run out. Well that is if you have a dial indicator.

 

Concur. That is the best way to check the rotors and dial indicators are cheap enough.

http://www.harborfreight.com/catalog...ial+indicators

 

And yes you will get pulsations on some cars if you over torque the wheels or turque them unevenly. Funny the things you take for granted when you do things a certain way all the time.