Thickness variation can be inspected 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 in from the edge of the rotor.
A rotor that varies by more than 0.03 mm (0.0012 in) can cause pedal pulsations and/or front end vibration during brake applications. A rotor that does not meet these specifications should be refinished to specifications or replaced.
During manufacturing, the brake rotor and the tolerances of the braking surface regarding flatness, thickness variation, and lateral runout are held very close. The maintenance of close tolerances on the shape of the braking surfaces is necessary to prevent brake roughness.
In addition to these tolerances, the surface finish must be held to a specified range. The control of the braking surface finish is necessary to avoid pulls and erratic performance and to extend lining life.
Important: Permissible lateral runout is a maximum 0.03 mm (0.0012 in). If lateral runout exceeds the specification, ensure that there is no dirt between the rotor and the hub and that contact surfaces are smooth and free from burrs.
Using a commercially available dial indicator, check lateral runout as follows:
- Position the transaxle in NEUTRAL.
- Remove the front wheel. Refer to Tire and Wheel Removal and Installation .
- Fasten the brake rotor to the wheel hub with 2 wheels nuts.
- Fasten a dial indicator to the brake caliper.
- Set the gage probe tip to approximately 10 mm (0.39 in) from the outer edge of the brake rotor, perpendicular to the disc and under slight preload.
- Remove the dial indicator and the wheel nuts that connect the rotor to the hub.
- Refinish the rotor, if required, with precision equipment. Discard the rotor if it fails to meet the above specifications after refinishing.
- Install the front wheel. Refer to Tire and Wheel Removal and Installation .
Important: Since accurate control of the rotor tolerances is necessary for proper performance of the disc brakes, refinishing of the rotor should be done only with precision equipment.
