ROTOR MINIMUM THICKNESS
Measure rotor thickness at the center of the brake shoe contact surface. Replace the rotor if below minimum thickness, or if machining would reduce thickness below the allowable minimum.
Rotor minimum thickness is usually specified on the rotor hub. The specification is either stamped or cast into the hub surface.
Scheme 100
| 1 - DIAL INDICATOR |
Check rotor lateral runout with Dial Indicator Set (special tool #C-3339A, Set, Dial Indicator) (1). Excessive lateral runout will cause brake pedal pulsation and rapid, uneven wear of the brake shoes. Position the dial indicator plunger approximately 25.4 mm (1 in.) inward from the rotor edge.
Note. Be sure wheel bearing has zero end play before checking rotor runout.
Maximum allowable rotor runout is 0.050 mm (0.002 in.).
Scheme 101
| 1 - MICROMETER |
|---|
| 2 - ROTOR |
Variations in rotor thickness will cause pedal pulsation, noise and shudder.
Measure rotor thickness at 6 to 12 points around the rotor face.
Position the micrometer (1) approximately 25.4 mm (1 in.) from the rotor (2) outer circumference for each measurement.
Thickness should not vary by more than 0.015 mm (0.0059 in.) from point-to-point on the rotor. Machine or replace the rotor if necessary.