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Brake Rotor Surface and Wear Inspection


Brake Rotor Surface and Wear Inspection

Caution: Refer to Brake Dust Caution in Cautions and Notices.

1. If the inboard friction surface of the brake rotor is not accessible, reposition and support the caliper with the brake pads. Refer to Brake Pads Replacement - Front (J55) or Brake Pads Replacement - Front (without J55) and/or Brake Pads Replacement - Rear (J55) or Brake Pads Replacement - Rear (without J55).
2. Clean the friction surfaces of the brake rotor with denatured alcohol, or an equivalent approved brake cleaner.
3. Inspect the friction surfaces of the brake rotor for the following Braking Surface Conditions:
^ Heavy rust and/or pitting
- Light surface rust can be removed with an abrasive disc.
- Heavy surface rust and/or pitting must be removed by refinishing the rotor.
^ Cracks and/or heat spots
^ Excessive blueing discoloration
4. If the friction surfaces of the brake rotor exhibit one or more of the Braking Surface Conditions, the rotor requires refinishing or replacement.
5. Using a micrometer calibrated in thousandths-of-a-millimeter, or ten-thousandths-of-an-inch, measure and record the scoring depth of any grooves present on the rotor friction surfaces.
6. Compare the groove scoring depth recorded to the following specification:
Specification
Brake rotor maximum allowable scoring: 1.50 mm (0.059 in)
7. If the brake rotor scoring depth exceeds the specification, or if an excessive amount of scoring is present, the rotor requires refinishing or replacement.





Brake Rotor Assembled Lateral Runout (LRO) Measurement

Tools Required
^ J 39544-KIT Torque-Limiting Socket Set, or equivalent
^ J41013 Rotor Resurfacing kit
^ J 42450-A Wheel Hub Resurfacing Kit
^ J45101 Hub and Wheel Runout Gage
^ J 45101-100 Conical Brake Rotor Washers

Caution: Refer to Brake Dust Caution in Cautions and Notices.


Important:
^ Brake rotor assembled lateral runout (LRO) exceeding the maximum allowable specification can cause thickness variation to develop in the brake rotor over time, usually between 4 800-11 300 km (3,000-7,000 mi).
^ Brake rotor thickness variation MUST be checked BEFORE checking for assembled lateral runout (LRO). Thickness variation exceeding the maximum acceptable level can cause brake pulsation. Refer to Brake Rotor Thickness Variation Measurement.

1. Matchmark the position of the brake rotor to the wheel studs if this has not been done already.

Important: Whenever the brake rotor has been separated from the hub/axle flange, any rust or contaminants should be cleaned from the hub/axle flange and the brake rotor mating surfaces. Failure to do this may result in excessive assembled lateral runout (LRO) of the brake rotor, which could lead to brake pulsation.

2. Inspect the mating surface of the hub/axle flange and the brake rotor to ensure than there are no foreign particles, corrosion, rust or debris remaining. If the wheel hub/axle flange and/or if the brake rotor mating surfaces exhibit these conditions, perform the following steps:
2.1. Remove the brake rotor from the vehicle. Refer to Brake Rotor Replacement - Front (J55) or Brake Rotor Replacement - Front (Without (J55)) and/or Brake Rotor Replacement - Rear (Without (J55)) or Brake Rotor Replacement - Rear (J55)
2.2. Using the J 42450-A, thoroughly clean any rust or corrosion from the mating surface of the hub/axle flange.
2.3. Using the J41013, thoroughly clean any rust or corrosion from the mating surface of the brake rotor.
2.4. Clean the friction surfaces of the brake rotor with denatured alcohol, or an equivalent approved brake cleaner.
3. Install the rotor to the hub/axle flange using the matchmark made prior to removal.
4. Hold the rotor firmly in place against the hub/axle flange and install one of the J45101-100 (1), and one lug nut (2) onto the upper-most wheel stud.
5. Continue to hold the rotor secure and tighten the lug nut firmly by hand.









6. Install the remaining J 45101-100 and lug nuts onto the wheel studs and tighten the nuts firmly by hand in a star-pattern.
7. Using the J 39544-KIT, or equivalent, tighten the lug nuts in a star-pattern to specification, in order to properly secure the rotor Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
8. If the brake rotor has been REFINISHED or REPLACED with a new rotor, proceed to step 4.
9. If the brake rotor meets; the following criteria, proceed to step 10.
^ The rotor is within specifications and is being REUSED
^ The rotor has NOT been refinished
^ The rotor does NOT exhibit thickness variation exceeding the maximum allowable level
10. Mount a dial indicator, J 45.101, or equivalent,. to the steering knuckle and position the indicator button so it contacts the brake rotor function surface at a 90 degree angle, approximately 13 mm (0.5 in) from the outer edge of the rotor.
11. Measure and record the assembled LRO of the brake rotor.
11.1. Rotate the rotor until the lowest reading is displayed on the indicator dial, then set the dial to zero.
11.2. Rotate the rotor until the highest reading is displayed on the dial.
11.3. Mark the location of the high spot relative to the nearest wheel stud, or studs.
11.4. Measure and record the amount of LRO.
12. Compare the brake rotor assembled LRO to the following specification:
Specification
^ Front brake rotor maximum allowable assembled lateral runout: 0.06 mm (0.002 in)
^ Front brake rotor (J55) maximum allowable assembled lateral runout: 0.127 mm (0.005 in)
^ Rear brake rot6r maximum allowable assembled lateral runout: 0.06 mm (0.002 in)
^ Rear brake rotor (J55) maximum allowable assembled lateral runout: 0.127 mm (0.005 in)
13. If the brake rotor assembled LRO is within specifications, proceed to step 1a.
If the brake rotor assembled LRO exceeds the specification, refinish the rotor to ensure true parallelism, refer to Brake Rotor Refinishing. After refinishing the rotor, proceed to step 14.






14. Mount a dial indicator, J45101, or equivalent, to the steering knuckle and position the indicator button so it contacts the brake rotor friction surface at a 90 degree angle, approximately 13 mm (0.5 in) from the outer edge of the rotor.
15. Measure and record the assembled LRO of the brake rotor.
15.1. Rotate the rotor until the lowest reading is displayed on the indicator dial, then set the dial to zero.
15.2. Rotate the rotor until the highest reading is displayed on the dial.
15.3. Mark the location of the high spot relative to the nearest wheel stud, or studs.
15.4. Measure and record the amount of LRO.
16. Compare the brake rotor assembled LRO to the following specification:
Specification
^ Front brake rotor maximum allowable assembled lateral runout: 0.06 mm (0.002 in)
^ Front brake rotor (J55) maximum allowable assembled lateral runout: 0.127 mm (0.005 in)
^ Rear brake rotor maximum allowable assembled lateral runout: 0.06 mm (0.002 in)
^ Rear brake rotor (J55) maximum allowable assembled lateral runout: 0.127 mm (0.005 in)
17. If the brake rotor assembled LRO measurement exceeds the specification, bring the LRO to within specifications. Refer to Brake Rotor Assembled Lateral Runout (LRO) Correction.
18. If the brake rotor assembled LRO measurement is within specification, install the brake caliper and depress the brake pedal several times to secure the rotor in place before removing the J45101-100 and the lug nuts.
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