Runout Check

CAUTION: To maintain safe braking performance, the disc brake rotors must be kept within allowable service specifications.

Before re-finishing or re-processing the brake disc surface, the following conditions should be observed:
- Check for scratches, rust, saturated lining materials and wear. If the vehicle is not driven for a certain period, the sections of the discs that are not in contact with the lining will become rusty, causing noise and shuddering. If grooves resulting from from excessive disc wear and scratches are not removed prior to installing a new pad assembly, there will momentarily be inappropriate contact between the disc and the lining pad.
- Run-out or drift. Excessive run-out or drift of the discs will increase the pedal depression resistance due to piston knock back.

Remove Guide Pin:

1. Remove the caliper support bolts, then raise the caliper assembly upward and secure by using wire.
2. Inspect the disc surface for grooves, 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 is 0.08 mm (0.0031 inch)

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





4. If the run-out of the brake disc is equivalent to or exceeds the limit specification, change the phase of the disc and hub, and then measure the run-out again.
a. Before removing the brake disc, chalk both sides of the wheel stud on the side at which run-out is greatest.

Measure Play With Dial Gauge:

b. 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 play. The limit is 0.05 mm (0.0020 inch.)
c. If the play is equivalent to or exceeds the limit, disassemble the hub knuckle and check each part.
d. If the play does not exceed the limit specification, install the brake disc at a position 180° away from the chalk mark, and then check the run-out of the brake disc once again.
5. If the run-out cannot be corrected by changing the phase of the brake disc, replace the brake disc or turn rotor with an on the car type brake lathe (Accuturn-8750, or equivalent). Be sure to follow the exact brake lathe manufacturer instructions. Rotors turned on the vehicle will often have a lower run-nut than a new disc.