Rear Brakes

Rotor Inspection
Brake rotors are manufactured with close tolerances for thickness variation, flatness, and lateral runout, but pits and grooves are created in rotors during usage. Lack of uniformity of the braking surfaces of the rotor can cause inadequate braking and a pulsating pedal during braking. The surface finish of the rotor is also important because an unsuitable surface finish can cause pulling and rapid wear of the brake shoe lining. If a rotor does not meet the specification, it should be refinished to specification or replaced. Refinishing of the rotor should only be done with precision equipment.





Thickness variation can be checked by measuring the thickness of the rotor at four or more points around the circumference of the rotor. All measurements must be made at the same distance from the edge of the rotor. A rotor that varies by more than 1.0 mm (0.04 inch) can cause pedal pulsation and/or front end vibration during braking. Thickness can be measured with a commercially available micrometer and should be 10 mm (0.39 inch) or over.
Light scoring of the rotor surfaces is acceptable if it does not exceed 0.40 mm (0.016 inch) in depth. Scoring measurements can be made with a commercially available brake micrometer. Lateral runout cannot exceed 0.8 mm (0.03 inch). If lateral runout exceeds the specification, make sure that there is no dirt between the rotor and the hub and that hub-to-rotor contact surfaces are smooth and free from burrs. Use a commercially available dial indicator to check the lateral runout according to the following procedure.

1. Position the transaxle in NEUTRAL and raise the vehicle.
2. To preserve wheel balance, mark the relative positions of the wheel and hub, and remove the rear wheel.
3. Fasten the brake rotor to the wheel hub.
4. Mount a dial indicator on the brake caliper.
5. Place the indicator tip approximately 10 mm (0.39 inch) from the outer edge of the brake rotor, perpendicular to the disc and under slight preload. Observe the indicator gauge while rotating the rotor.
6. After measuring is completed, remove the dial indicator and the wheel nuts.
7. If necessary, refinish the rotor with precision equipment. Measure the runout again after refinishing. If the runout exceeds 0.8 mm (0.03 inch) after refinishing, the rotor should be replaced.
8. Align the marks that were made before wheel removal, and install the rear wheel.





9. Lower the vehicle.