metal prop mounting question

[Bevan]

I was getting ready to mount the hartzell prop today. My hangar neighbor came by and mentioned his prop had a thin like paper sheet of something between the prop and the flywheel (he didn't put it there). Is there supposed to be somthing between the two metal surfaces and if so, what for?

Bevan

[Walt]

It's used as a shim to correct tracking errors, a good prop with a good crank flange should not require any.