BimmerFest BMW Forum banner
1 - 4 of 4 Posts

·
Registered
Joined
·
130 Posts
Discussion Starter · #1 ·
I bought a 2007 CPO X3 with 36K miles last fall. After 3K miles we developed a shimy under braking at highway speeds. BMW put new front rotors and pads in under warrantee. Now, 3K miles later same problem developing although not as pronounced. BMW threw another set of front rotors and pads in under warrantee.

In the 5 different BMWs that we've owned I never warped a rotor so its not likely to be my driving style. However, the rear rotors have no where near the shine as the fronts suggesting that they are not getting the same work out. BMW siad they never see issues related to brake biasing.

Anyone else consuming rotors at an alarming rate? If so, what was the cause?
 

·
Registered
Joined
·
3,892 Posts
Your dealer appears to be throwing money at the problem without diagnosing it properly.

Could be something other than the rotors even though you think it is now not so pronounced.

I'm surprised they didn't suggest it's your fault! - such as for not bedding-in the brakes properly.

Or for washing the wheels right after doing some high speed stops.

But maybe they are one of the better dealerships - at least they are cooperative.

The fronts are designed to do more work than the rears, because the rear rotors are thinner and the pads a bit smaller.
But most owners find that renewal times more or less coincide give or take a few thousand miles, with the fronts usually outlasting the rears.

The rear rotors could look less shiny becuase they have to deal with more road debris back there, so may pick up score marks more than the fronts.

So your dealer could be right in that there is not a biasing issue.

But unless they definitely checked the old rotors for runout, or examined them for uneven friction material deposits, I doubt that warping is the problem.

And they would surely have checked for one or both front calipers sticking.

I'd lean more toward something like a tire defect, or worn steering or suspension component.

Might be worth checking your P/S fluid level, particularly if you feel the vibration through the steering wheel as opposed to jus the brake pedal?
 

·
Registered
Joined
·
133 Posts
Have your shop check your thrust arm bushings and lower control arms, both of which are often the cause of shimmy under braking in many models of BMW. And there are alternatives to OEM.

Ub
00 M5, 05 X3, 08 X3
 

·
Registered
Joined
·
130 Posts
Discussion Starter · #4 ·
The shop actually checks run out before they do anything. In both cases run out was more than spec. The problem also goes away as soon as they put on new rotors. So it really does seem like the rotors. Here were my suggestions - although BMW discounted all but the last.

Bias is too much toward the front.
If there is a "auto dry" feature (not sure there is), is it dragging the fronts too often.
Front calipers bad.
Sometimes new rotors just go bad.

BMW did say that if it happened again they would really start ripping things apart.
 
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top