Cork is a good material for clutch friction plates, as long as they aren't overheated by excessive slipping.
They are nice and "spongey" so help absorb transmission shocks, and have very good gripping ability.
The ones shown here were bought from:
Portugal Cork Co Pty Ltd, Sydney Australia
Ph: 02 9676 8400
Dimensions: small end 12mm diameter, large end 17mm diameter, length 25mm.
Note these are solid corks, not reconstituted type.
$21 for 100 in 2012
Boiling the corks first makes them more pliable, easier to fit in holes. 90 required for the 3 friction plates:
Set of plates with corks inserted, prior to machining.
After fitting I dried them out in the oven for 10 minutes:
Setup for grinding flat the faces of the cork plates. Angle grinder fitted to a lathe does the job. It's easy to make both sides parallel this way.
It's a dusty job, but a vacuum cleaner nozzle mounted close to the grinder collects most of it:
Finished plates, ground to maximum 1/4 inch thickness: