Rotor Refinishing

The rear disc brake rotor (2C026) is a top-hat section-type rotor of cast iron. A new simplified method of measuring maximum allowable stock removal using a standard hand micrometer eliminates the need for special tools as on previous rear disc brake rotors . However, a Rotunda mounting adapter will be required for use on the brake lathe for refinishing.

All rotor refinishing must adhere to the rule that equal amounts of rotor stock are removed from each braking surface each time a rear disc brake rotor is refinished.

The minimum allowable overall rotor thickness continues to be stamped on the rear disc brake rotor and must not be exceeded.

NOTE: Using a micrometer to measure rotor thickness simplifies previous rotor measurement procedure, but it is mandatory that an equal amount of material be removed from each side of the rear disc brake rotor each time the rear disc brake rotor is turned.

1. With a suitable micrometer, measure the overall thickness of the rotor braking surface at four equally spaced points around the rear disc brake rotor .

2. Using the lowest reading from Step 1, subtract the minimum allowable thickness stamped into the rotor. The difference, if any, represents the total amount of material available for machining. A thickness reading less than the minimum rotor thickness requires rear disc brake rotor replacement.

3. After measuring the rear disc brake rotor , the rear disc brake rotor should be installed in the lathe arbor using the special adapter that is required for proper rotor alignment. Never use a lathe that cuts only one face of the rear disc brake rotor at a time. It must be a simultaneous straddle cut. Install a dial indicator to read rotor lateral runout near the center of the rear disc brake rotor braking face. If runout is 0.050mm (0.002 inch) or below, proceed to machine rear disc brake rotor . If runout is over 0.050mm (0.002 inch), loosen rear disc brake rotor on the arbor, and rotate the rear disc brake rotor 90 degrees. Reread the runout, and if it is below 0.050mm (0.002 inch), proceed to machine the rear disc brake rotor . If runout is still over 0.050mm (0.002 inch), again loosen the rear disc brake rotor , and rotate it an additional 90 degrees. Recheck the runout. If runout is 0.050mm (0.002 inch) or less, proceed to machine the rear disc brake rotor . If the runout still exceeds 0.050mm (0.002 inch), return the rear disc brake rotor to the best runout position obtained. If the rear disc brake rotor runout can be brought below 0.05mm (0.002 inch), proceed to machine the rear disc brake rotor . If the rear disc brake rotor cannot be brought below 0.05mm (0.002 inch) runout, it must be replaced.

4. Set the cutting tool to just contact the high spots on the rear disc brake rotor , then adjust the cutting tool to the minimum depth required to clean up the rotor face. Equal material must be removed from each side. Do not exceed the allowable stock removal. Clean all cuttings and chips from the rear disc brake rotor before installing it to the axle.