E70 3.0si Occasional Steering Wobble on Braking

[Cactus_BMW]

Hi All,
Looking for some guidance on a weird braking issue I'm experiencing. This is on my '08 X5 3.0si, 67K miles, which I purchased about 6 months ago. Within a couple weeks of buying it, I had the truck in to a BMW dealer for a couple of recalls, and they gave it a full inspection. Nothing significant noted, other than rear brakes were due for replacement, which I had them do at that time. In the iDrive info center, it does now indicate I have about 3,000 miles left on the front brakes.

What I'm occasionally experiencing is a wobble in the steering with moderate braking. When this is occurring, I also feel a minor pulsing in the brake peddle, that matches timing and intensity of the steering wheel wobble.

The issue that confuses me is, this is not happening consistently. I might go a week or two, with typical driving, and not feel any wobble or pulsing at all. Then it'll come back, from the same driving conditions, and last a day or two before fading away again. So its only about 1/4 to 1/3 of the time that I'm feeling the pulsing.

If this were warped rotors, the wobble should be felt constantly, right? Other possible relevant items: this X5 has the bigger BMW 214 wheels [Front: 20" X 10" Back: 20" X 11"], tire tread wear all looks even; and I frequently check pressures - keeping them properly inflated. Also, I'm in Phoenix AZ, its still summer here, with the high ambient air temps still hitting 105 - 115. But, its a dry heat.

Thanks for any thoughts, ideas, notes about similar experiences.


- Cactus_BMW

[ryansbmw]

Sticking caliper maybe?

[heatmizr]

Basics -
have you taken off the wheels and had them checked for straightness?
While they are off have you checked the condition of all Pads and rotors?
And all caliper mounting bolts for tightness? Use a wrench, might not detect by hand.

[ryansbmw]

Check out the thrust arms as well. When the bushing goes, shaking while braking a pretty common sign.