[bigfy39]

Hey Guys,

I am hoping you can help me diagnose a noise/vibration that I am experiencing.

My car has just over 100k miles on it and is an 06 e90 330XI 6MT. I am noticing a knocking noise from my front driver's side axle, it becomes more or less frequent based on the rotation speed of the wheel; when going highway speeds I can feel a slight vibration in the steering wheel.

My mechanic recently changed my front axles due to worn CV boots, did a 4 wheel alignment and balanced the tires so my initial thoughts are that these items are not causing the issue.

I know that the car needs the transmission mounts and/or engine mounts to be replaced because I am getting a strong amount of backlash/drivetrain whip on abrupt throttle movements. Could these be the culprits?

One thing I noticed is that if I cruise at highway speeds and put the car in neutral, I can still hear the knocking sound and I still get the vibration.

Any of your thoughts are greatly appreciated!

[scotty_miller]

I'd probably check for a shot wheel bearing although you definitely would hear that, warped rotor or loose caliper and make sure your wheel is seated properly on the hub. But I'd definitely change your motor and transmission mounts.

[Gon]

Have the shop you did the alignment at recheck it to make sure it's balance. If that doesn't work I would bring the the wheel mounted on the trouble axle to a tire shop to make sure it's balanced as well.

[bigfy39]

Hey guys,

Thanks for your input. The problem was an unbalanced wheel. I rotated the tires last night and the steering is smooth with no knocking sound.