Brake Rotor/Disc: Testing and Inspection

FRONT BRAKE DISC THICKNESS CHECK





1. Using a micrometer, measure disc thickness at eight positions, approximately 45° apart and 10 mm (0.39 inch) from the outer edge of the disc.
Brake disc thickness
Standard value: 26 mm (1.02 inch)
Limit: 24.4 mm (0.96 inch)
Thickness variation (at least 8 positions)
The difference between any thickness measurements should not be more than 0.005 mm (0.0002 inch).
2. If the disc is beyond the limits for thickness, remove it and install a new one.


FRONT BRAKE DISC RUNOUT CHECK





1. Remove the caliper support bolts, then raise the caliper assembly upward and secure by using wire.
2. Inspect the disc surface for groove, cracks, and rust. Clean the disc thoroughly and remove all rust.





3. Place a dial gauge approximately 5 mm (0.2 inch) from the outer circumference of the brake disc, and measure the runout of the disc.
Limit: 0.05 mm (0.0020 inch)

NOTE: Tighten the nuts in order to secure the disc to the hub.

FRONT BRAKE DISC RUNOUT CORRECTION
1. If the runout of the brake disc is equivalent to or exceeds the limit specification, replace the disc and hub, and then measure the runout again.





1) Before removing the brake disc, chalk both sides of the wheel stud on the side at which the runout is greatest.





2) Remove the brake disc, and then place a dial gauge as shown in the illustration; then move the hub in the axial direction and measure the runout.
Limit: 0.05 mm (0.0020 inch)
If the play is equivalent to or exceeds the limit, disassemble the hub knuckle and check each part.





3) If the play does not exceed the limit specification, install the brake disc at a position 180° from the chalk mark, and then check the runout of the brake disc again.
2. If the out cannot be corrected by changing the position of the brake disc, replace the brake disc.