KIT-CAMSHAFT 20R4960 - Caterpillar

Lapping The Plate
If over 0.03 mm (.001") of material must be removed, use a lapping plate with 20 micron silicone carbide lapping compound and oil to work the plate. During the procedure, check the plate several times to make sure the complete surface has been lapped.
After the complete surface has been lapped with the 20 micron compound, use the "touch lapping" procedure to finish lap the plate. Also, use this procedure if less than 0.03 mm (.001") of material must be removed from the plate. The "touch lapping" procedure is shown in "Guideline For Reusable Parts, Piston Pumps and Motors," Form No. SEBF8032. If possible, check the surface finish. It must be approximately 0.2 micrometer (8 microinches).
If a port plate appears to be flat use the touch lapping procedure to make sure.