Clanking/Knocking Driveshaft?

[SDE30]

i have a stock 1987 325i 5speed. i hear a loud knocking/grinding noise from the center of my car right behind the front seats. it only makes the sound when im driving and pressing in the clutch to change gears. maybe the center shaft mount? it doesn't make the sound at idle or while driving. only when it's spinning freely with no load.

[wasabinuki]

My guess is the center support bearing, but you might also want to have a look at the Driveshaft / U-joints, and the "guibo". My suggestion is to replace them all at once when you are in there.

[jlevie]

My guess would be a bad guibo or bad center support bearing (CSB). If the rubber mount of the CSB has failed, in almost all cases the cause will be binding u-joints in the drive shaft. If the CSB and drive shaft aren't both replaced, a replacement CSB will have a very short life. If only the guibo is bad, it can be replaced independently of the drive shaft.

[ngcreese]

my guess would be a bad guibo or bad center support bearing (csb). If the rubber mount of the csb has failed, in almost all cases the cause will be binding u-joints in the drive shaft. If the csb and drive shaft aren't both replaced, a replacement csb will have a very short life. If only the guibo is bad, it can be replaced independently of the drive shaft.

+1