Awful noise from underneath car

[chesticals]

Hey guys

Ive been having this issue for a while, and its starting to bug me. Basically it seems like it only comes into play after ive been beating on the car a bit. A bunch of hard launches or after i go over 230kmhr is when it seems to take effect. For about 45 mins of driving after it makes this awful noise coming from somewhere underneath the car, its quite hard to pinpoint, as noise bounces all over the cabin. It sounds almost like a brake caliper rubbing on rotor, sort of a constant shhhhhhh sound, and it continually gets quieter until i can barely hear it again. Which makes it very difficult to diagnose, as its hard to take it to someone and show them.

It happens anytime the car is in motion, any gear, neautral or clutch in as well. No difference when applying brakes. Over 40kmhr it dissolves away with the added road noise.

Any ideas? Wheel bearing? Bmw said maybe its the diff? I had the diff fluid checked, it was at the proper level and didnt look bad.

Any imput is appreciated, thanks

[1and1]

Any change to the symptom reflective of vehicle speed or engine RPM?

For particularly hard to pinpoint sounds I suggest heading for a covered parking garage or other area where you have lots of surface area that can reflect the sound back to you to help pinpoint the originating area & help you hear the sound more clearly. Also helps if you can bring a second person to help listen or even be outside the car to listen.

[chesticals]

No change relative to RPM, only vehicle speed. No real change in pitch, but it doesnt happen when im stopped, it starts at 1kmhr and sounds the same until about 20-30kmhr before it begins to fade into the road noise.

And thank you for the tips, ill have to give that a shot!

[Ric in RVA]

I would put money on a front wheel bearing.

[chesticals]

Ok cool, any test i can do to see if its the wheel bearing?

[MightyMouseTech]

Edit: just noticed you said it only happens when moving...

[1and1]

Wheel bearing sounds will, typically, change pitch when turning as the load increases on the outside corner. So, for example, more noise during hard left turn then the front right bearing is failing since the FR corner is seeing increased load.

[Ric in RVA]

jack it up and pull hard top and bottom and side to side.

Feel for a faint clunk.

Then spin it and see what it sounds like...you might pull the caliper to let it spin easier. If it rumbles replace it!!


Check your guibo and center support bearing too?

[miro2296]

Any changes made to the car recently?