Change the Whole shebang while your in there
Ie; pressure plate, clutch disc,and the ever important pilot bearing (an oft
over looked ,but nessasary part ) it's a real drag to do it twice !
If your clutch is chattering ,Are you sure the bolts holding the trans to
engine are tight? I had them come loose on an old datsun once and that was the
cause of my chatter

just a thought.

mike
85 westy 213k