1. wheel bearing
2. brake dust shield (sometimes they get caught when removing the wheel)
a long time ago i had a strange sound kind of like that in my first b5....something has to be making contact with something else and it sounds like it's speed sensitive...check all spaces around the wheels to see what could be hitting.....i never did find out what my sound was...it went away after a couple of days...take some hard turns left and right and see if the sound changes
have you bottomed the car out. Or done any awd luanches?
it deff is metal on metal. can you get the car in the air(jacks and jack stands) to see if it goes away when the weight is unloaded?
most times to diagnose phantom grinding ill have a friend drive the car slowly in a parking lot. as i slide around and he drags me on a creeper. best way to find general spot of noise.
Catch me if you can
Supercharged Rwd b5--http://forums.vwvortex.com/showthrea...build-timeline