Quote:
Originally Posted by pungo
I have heard the rattling sound is the throw out bearing several times. I have trouble understanding how a throw out bearing would make noise when it's not even spinning out and not really doing anything when the clutch pedal is not pressed. What goes wrong with the bearing to cause the noise if it's not even spinning. I'm only familiar with bad bearings when they are spinning, not when they are stationary. What am I missing. 
My 07 Z4 coupe had a rattle at a few miles thousand miles. It was faint and could only be heard in a quiet environment. I never did anything about it. I though it maybe had something to do with the dual mass flywheel springs. |
As the TO bearing wears, the clearance between the balls and the races increases. When the load is off (clutch out) the bearing is just lightly in contact with the pressure plate so it's spinning a bit and rattling as much as the worn clearances allow. When you depress the clutch it forces the balls against the races so there's no clearance for the rattling to happen. You get this when the races and balls are still smooth but just worn. If you get some pitting in the races and/or the balls but there's not a lot of wear (yet), you get the opposite effect. Noise when you depress the clutch and it quiets when you remove the load. If you've got worn AND pitted balls/races you get rattle when the clutch is released (no load) and possibly whine and squeal under load.