View Single Post
      11-28-2012, 05:53 PM   #17

Drives: 2007 M5
Join Date: Mar 2011
Location: Nashville, TN

iTrader: (0)

Wow, same issue here...2008 335xi. The pitch increases as the speed of the car increases, but has nothing to do with engine speed. I would think that this means it is something beyond the output shaft of the transmission, meaning transfer case, drive shafts, wheel bearings, axles, or tires. The sound is louder when the car is under load (accelerating or engine breaking) and when it is not under load, it gets quiet. I had new tires installed in August, and I was thinking that could be the cause. I will try rotating the tires around to see if the sound moves with them, but I really am leaning toward something with the transfer case.