Front

Measure the thickness of the disc brake rotor to determine if it is within the specification. Refer to Specifications. Disc brake rotor minimum (discard) thickness is also cast in the disc brake rotor. Disc brake rotors have a minimum thickness dimension (minimum wear thickness or discard thickness). This is not the refinishing dimension.

CAUTION: Never refinish a disc brake rotor to the minimum wear or discard thickness.

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

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

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

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

3. After measuring the disc brake rotor, the disc brake rotor should be installed in the lathe arbor using the special adapter that is required for proper disc brake rotor alignment. Never use a lathe that cuts only one face of the 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 disc brake rotor face. If runout is 0.05 mm (0.002 inch) or below proceed to machine disc brake rotor. If runout is over 0.05 mm (0.002 inch), loosen disc brake rotor on the arbor and rotate the disc brake rotor 90 degrees. Read the runout, and if it is below 0.05 mm (0.002 inch), proceed to machine the disc brake rotor. If runout is still over 0.05 mm (0.002 inch), again loosen the disc brake rotor, and rotate it an additional 90 degrees. Check the runout. If runout is 0.05 mm (0.002 inch) or less, proceed to machine the disc brake rotor. If the runout still exceeds 0.05 mm (0.002 inch), return the disc brake rotor to the best runout position obtained. If the disc brake rotor runout can be brought below 0.05 mm (0.002 inch), proceed to machine the disc brake rotor. If the disc brake rotor cannot be brought below 0.05 mm (0.002 inch) runout, it must be replaced.

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

4. A bench-mounted disc brake lathe machines the front disc brake rotor or rear disc brake rotor to the axis of the lathe arbor and will not reduce total lateral runout associated with stacked tolerance of the front disc brake rotor or rear disc brake rotor and wheel hub. Follow manufacturer's instructions on machining procedures.

With both types of brake lathes, set cutting tool to just contact the high spots on the front disc brake rotor or rear disc brake rotor, then adjust cutting tool to the minimum depth required to clean up front disc brake rotor face. Best results are obtained with a first cut that totally removes the old front disc brake rotor surfaces followed by a second light finish cut. The total material removed (combination of both sides) must not exceed the minimum lathe thickness that is marked on the inside of the front disc brake rotor and rear disc brake rotor.

To improve initial brake pedal feel and surface finish on a machined front disc brake rotor or rear disc brake rotor, lightly sand braking surface with 120 grit paper prior to road testing.

NOTE: On vehicle brake lathes machine the front disc brake rotor while it is on the wheel hub and is turning on the same axis as the wheel hub. This procedure reduces front disc brake rotor lateral runout to near zero by cutting the front disc brake rotor and rear disc brake rotor perpendicular to the axis of the wheel hub, thereby canceling the effect of stacked tolerance of the wheel hub front disc brake rotor or rear disc brake rotor. Follow the on-vehicle brake lathe manufacturer's instructions on machining procedures.