I've already had the flywheel turned, the machinest said he took off 20 thousandths, and that I might need to put shims on it since it was for a hydraulic clutch. What are shims and do I need them?

 

I had my stock flywheel cut 15/1000 and used shims when I did my clutch. They make metal shims to go between the flywheel and crank, you would use a 20/1000 shim. Without them you can have problems with the clutch not disengaging all the way due to the change in distance from the flywheel to the hydraulic slave cylinder. Some people have had them cut and not used them and said they did not have a problem. I would use them if I had that much taken off.

 

Thanks for your help.
Where can I get them from?