I have a shuddering cluthch on my '89.  It started right after a major soaking of the engine compartment with cooling fluid when a cooling line broke.

The shuttering has lasted about two months, is gradually subsiding,  but not completely gone.  I think the coolant got onto the clutch plate and is causing "grabing" either from some gunk build-up or some change to the plate material.  Well at least that's what I'm hoping.

Ed
Syracuse, NY
'84 Westy
'89 Wolfsy