There is nothing wrong with the stock FC3S side seals; the side seals see very little wear and stress when clearanced properly.  You can usually resuse your old side seals; make sure to inspect them for obvious signs of damage.  Try to keep the side seals in their original positions when you put them back during the rebuild.

Stock OEM side seals from Mazda are not cut down to the proper length, so most of you have to cut them yourself.  We like to clearance them on the tight side, 0.002" - 0.003" for street engines.  The best way we found to clearance side seals is it have a used, bad rotor as a jig.  Find the biggest grind stone (on a Dremel tool) that fits into the corner seal hole.  Lay the bad rotor on it's side, and slip the brand new side seal into a groove.  While keeping the grind stone turning in the corner seal hole, slowly slide the side seal into the rotating grind stone to shave the seal.  Be sure to do cutting in very small increments and check clearances periodically in your good rotor, preferaably in between the pair of installed corner seals in the proper groove - the side seal grooves do not have the same dimensions so you have to clearance every side seal one-by-one.  Make sure to "deburr" the cut end of the side seals, as to eliminate binding when inserting into the side seal grooves.

Questions?  Comments?  Send email to: