Brake Rotor/Disc: Testing and Inspection

DIAGNOSIS AND TESTING - DISC BRAKE ROTORS

FRONT ROTOR MINIMUM THICKNESS

Rotor minimum thickness is 0.889 in. (22.6 mm). Do not resurface a rotor if at minimum thickness. Machining would cause thickness to fall below this limit.

Measure rotor thickness at the center of the brake pad contact surface. Replace the rotor if worn below the minimum thickness, or if refinishing would reduce thickness below the allowable limit.

FRONT ROTOR THICKNESS VARIATION





Variations in rotor thickness will cause pedal pulsation, noise and shudder.

Measure rotor (2) thickness a minimum of six points around the rotor face with a micrometer (1). Position the micrometer approximately 3/4 in. (19 mm) from the rotor outer circumference for each measurement.

Thickness should not vary by more than 0.0005 in. (0.0127 mm) from point to point on the rotor. Refinish or replace the rotor if necessary.

NOTE: A hub mounted on-vehicle lathe is recommended. This type of lathe trues the rotor to the vehicles hub/bearing.

Front rotors and hub/bearings are matched mounted for minimum lateral runout. Before removing the rotor, mark the rotor and hub/bearing to maintain original orientation.

FRONT ROTOR LATERAL RUNOUT





Check rotor lateral runout whenever pedal pulsation, or rapid, uneven brake lining wear has occurred.

The rotor must be securely clamped to the hub to ensure an accurate runout measurement. Secure the rotor with a minimum of 3 lug nuts and large diameter flat washers on each stud.

Use a dial indicator (1) to check lateral runout.

Maximum allowable rotor lateral runout is 0.002 in. (0.05 mm).

REAR ROTOR MINIMUM THICKNESS





Minimum usable thickness of the rear disc brake rotor is 0.299 in. (7.6 mm). The thickness specification is located on the center section of the rotor.

Never resurface a rotor if at minimum thickness. Machining the rotor would cause the thickness to fall below the limit.

Measure rotor (2) thickness at the center of the brake pad contact surface using a micrometer (1). Replace the rotor if worn below minimum thickness, or if refinishing would reduce thickness below the allowable minimum.

REAR ROTOR THICKNESS VARIATION

Variations in rotor thickness will cause pedal pulsation, noise and shudder.

Measure rotor thickness at a minimum of six points around the rotor face. Position the micrometer approximately 3/4 in. (19 mm) from the rotor outer circumference for each measurement.

Thickness should not vary by more than 0.0005 in. (0.0127 mm.) from point to point on the rotor. Refinish or replace the rotor if necessary.

REAR ROTOR LATERAL RUNOUT





Check rotor lateral runout whenever diagnosis indicates pedal pulsation and rapid, uneven brake lining wear.

The rotor must be securely clamped to the hub to ensure an accurate runout measurement. Secure the rotor with the wheel nuts and 4 or 5 large diameter flat washers on each stud.

Use a dial indicator (1) to check rotor lateral runout. Maximum allowable lateral runout is 0.003 in. (0.76 mm).