I am rebuilding this bike, and had the dreaded rumble...so I took it apart, the rivets on the shaft actually looked good (replaced with a K1100 shaft nonetheless).  I think it was the spring of the thin gears that was bad..whatever.  Took off the clutch and I think the clearance is 4.6mm (cut off is 4.5mm).  Was going to replace the friction plate alone, but noted a small amount of run out centripetally (i.e. going out to in on the.....

well, i had written a longer post, but lost it .  

ultimately, I was worried about replacing pressure plates because of the amount of drilling on the original plates from the factory...like for balancing.  i spoke with max bmw about how they balance the clutch after they work on it...they claimed they dont...they just replace the pressure plates and the friction disc as a whole and claim they haven't had problems


maybe the whole clutch balance argument is really another example of German over engineering (which is awesome by the way..the service manager at Max I spoke with said he has a K75 with 5000000 miles on it...fantastic).

I will try to have my presure plates resurfaced, and if I can't i will just replace the friction disk and go from there.

any comments from the more expert with the K bikes.