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DISC BRAKE ROTOR CHECK


caution Disc brakes must be kept within the allowable service values in order to maintain normal brake operation.
Before turning the brake disc, the following conditions should be checked.
Inspection item
 Remark
Scratches, rust, saturated lining materials and wear
  • If the vehicle is not driven for a long period of time, sections of the discs that are not in contact with the pads will become rusty, causing noise and shuddering.
  • If grooves and scratches resulting from excessive disc wear are not removed prior to installing a new pad assembly, there will be inadequate contact between the disc and the lining (pad) until the pads conform to the disc.
Run-out
 Excessive run-out of the discs will increase the pedal depression resistance due to piston kick-back.
Change in thickness (parallelism)
 If the thickness of the disc changes, this will cause pedal pulsation, shuddering and surging.
Inset or warping (flatness)
 Overheating and improper handling while servicing will cause warping or distortion.

BRAKE DISC THICKNESS CHECK

1.Using a micrometer, measure disc thickness at eight positions, approximately 45 degrees apart and 10 mm (0.4 inch) in from the outer edge of the disc.
Standard value:

    26.0 mm (1.02 inches) <Front (Except RALLIART)>
    24.0 mm (0.94 inch) <Front (RALLIART)>
    10.0 mm (0.39 inch) <Rear>
Limit:

    24.4 mm (0.96 inch) <Front (Except RALLIART)>
    22.4 mm (0.88 inch) <Front (RALLIART)>
    8.4 mm (0.33 inch) <Rear>
note Thickness variation (at least 8 positions) should not be more than 0.015 mm (0.0006 inch).

2.
caution
  • After a new brake disc is installed, always grind the brake disc with on-the-car type brake lathe.If this step is not carried out, the brake disc run-out exceeds the specified value, resulting in judder.
  • When the on-the-car type lathe is used, first install M12 flat washer on the stud bolt in the brake disc side according to the figure, and then install the adapter. If the adapter is installed with M12 flat washer not seated, the brake disc rotor may be deformed, resulting in inaccurate grinding.
  • Grind the brake disc with all wheel nuts diagonally and equally tightened to the specified torque 100 N·m (74 ft-lb). When all numbers of wheel nuts are not used, or the tightening torque is excessive or not equal, the brake disc rotor or drum may be deformed, resulting in judder.
If the disc thickness is less than the limits, replace it with a new one. If thickness variation exceeds the specification, turn rotor with an on-the-car type brake lathe ("MAD, DL-8700PF" or equivalent). If the calculated final thickness after turning the rotor is less than the standard value, replace the disc.

FRONT BRAKE DISC RUN-OUT CHECK AND CORRECTION
1.Remove the brake assembly, and then hold it with wire.
2.Temporarily install the disc with the hub nut.

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

    0.06 mm (0.0024 inch) <Front>
    0.08 mm (0.0032 inch) <Rear>

4.When the run-out exceeds the limit value, correct the brake disc run-out in the following procedure.
(1) Before removing the brake disc, mark the stud bolt on the side of greater run-out and its both sides with a chalk.
(2) Check for wheel bearing looseness in the axial direction (Refer to GROUP 26 - On-vehicle Service, Wheel bearing play check <Front>, GROUP 27A - On-vehicle Service, Wheel bearing end play check <Rear (FWD)> or GROUP 27B - On-vehicle Service, Wheel bearing end play check <Rear (AWD)>).
(3) When the looseness is within the limit value, install the brake disc after changing the phase between the hub and the brake disc, then check the run-out of the brake disc again.

5.
caution
  • After a new brake disc is installed, always grind the brake disc with on-the-car type brake lathe. If this step is not carried out, the brake disc run-out exceeds the specified value, resulting in judder.
  • When the on-the-car type lathe is used, first install M12 flat washer on the stud bolt in the brake disc side according to the figure, and then install the adapter. If the adapter is installed with M12 flat washer not seated, the brake disc rotor may be deformed, resulting in inaccurate grinding.
  • Grind the brake disc with all wheel nuts diagonally and equally tightened to the specified torque 100 N·m (74 ft-lb). When all numbers of wheel nuts are not used, or the tightening torque is excessive or not equal, the brake disc rotor or drum may be deformed, resulting in judder.
If the run-out cannot be corrected by changing the phase of the brake disc, replace the brake disc or grind it with the on-the-car type brake lathe ("MAD, DL-8700PF" or equivalent).