In Reply to: Is my throwout bearing gone? posted by Tim Collins on January 26, 2000 at 20:03:20:
If the clattering stops when the clutch is pedal is down, this sounds like your mainshaft bearing has gone out or something in the transmission. Throwout bearing will make noise when the pedal is pushed down because it is loaded up with pressure from pushing pressure plate. Transmission is now disengaged and not spinning so it doesn't make noise.
If you let the pedal up in neutral clutch is now engaged spinning mainshaft causing your noise. Forward gears are not engaged and not spinning so its probably not layshaft or output shaft.
Good luck to you,