I have just started getting this noise in my 2003 R50. It only happens when decelerating and its frequency changes with speed. I replaced the discs last weekend and that was my first thought but they seem OK still. Also braking while its happening does not change the noise.
It's not a knock/thump like from a mount, its speed variable continuous

Put it up on blocks, the wheels move freely, manually moving the wheels they feel smooth.
Ran it while I was on blocks (had to disable DSC) and it did not (seem) to do it
Braking does not change the noise
Engine on/off - no change
Clutch in/out - no change
Can't isolate which side because I can't duplicate when its on blocks but when I drove past a helper he "thought" it sounded louder on the left which matches what I think...

An ideas are appreciated. :puzzled:

Mike

Could be your wheel bearings. Speed related sound, motor or no motor, tranny engaged and disengaged. This basically eliminates the drive train except for the CV joints.

anyway of testing for that outside of a replacement?

If the wheels bearings are worn they normally feel rough when you turn the wheel by hand, or if you hold the top and bottom of the wheel and try to rock it any play in the bearings is noticeable.
Driveshaft CV joints normally click or knock when steering on full lock going slowly if they are on the way out?

I spent most of my youth either driving or fixing a 1960 Mini and I am sure it's not the CV's. Checked and does not feel like a wheel bearing.
In reality the front axles are still connected to the diff even when everything is disengaged, does this sound like it could be a buggered diff?
My next step is to take it to a dealer I just don't want to pay them the big bucks for a stupid issue.

Mike

When you are decelerating the front suspension is a bit lower, could it be something catching when this happens? Just an idea.