Help: Humming Noise From The Rear ???

[oe_tuning]

hey guys & gals...

I have an e36 and i got this humming noise from the rear.
It only happens around 50 and 110 km/h speed (the noise is gone below and above those speed) + it only happens when i step on the accel pedal.
The sound instantly gone when i release the accel pedal.

Any idea what could be the problem?

I've done alignment and balancing for all wheel, and the tyre threads are 85% good.

Thx for all your ideas !

[e36surge]

Check rear driveshaft, oil level in rear differential and check for rear wheel bearings... they hum when they start going... and check in that order to narrow things down.

[93 325i]

^^ precisely.