Corolla Sport Coupe L4-1587cc 1.6L DOHC (4A-F) (1988)
Brake Rotor/Disc: Technical Service Bulletins
Brakes - Correcting Vibration Concerns
REFERENCE BRAKES
NUMBER 008
DATE 09-21-90
MODEL
AE92-
TITLE COROLLA BRAKE VIBRATION
One of the major causes of brake vibration is rotor thickness variation. The term "Thickness Variation" is not to be confused with rotor runout.
Thickness variation is the difference in rotor thickness as seen in figure "A". Rotor runout is the deflection of the rotor as it is spinning; as seen in figure
"B".
Driving several thousand miles in a vehicle with excessive rotor runout could cause an uneven wear on the rotors resulting in thickness variation. This is
caused by the pads constantly making slight contact with the rotor; even if the brakes aren't frequently applied. Also, rust, high humidity, road salt, and
sea breeze accelerates rotor wear resulting in increased thickness variation.
When correcting brake vibration, follow the procedures outlined following page.
(FIG. 1)
REPAIR (INSTALLATION) PROCEDURE:
1.
After removing the rotors, clean the contact surface between the axle hub and the rotor with a wire brush to remove any rust that may have
built up.
2.
Temporarily install the new rotor onto the axle hub and tighten all four lug nuts evenly to (76 ft.lb. or 103 N-m) with a torque wrench .
3.
Mount a magnetic base dail gauge as shown in FIG. 1, and measure the runout at a point of 10 mm (0.39 in.) from the outer edge of the rotor.
(FIG. 2)
4.
If the rotor runout exceeds 0.0020 in. or 0.05 mm, reposition the rotor clockwise to the next hub bolt for phase matching. Retorque the lug nuts
and recheck the runout again.