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Disc Brake System: Other Chevrolet Uplander I

Mechanical - Hydraulic ~2887 words

Brake Rotor Thickness Measurement

  1. Clean the brake pad lining contact surface of the brake rotor with denatured alcohol or an equivalent brake cleaner.
  2. Using a micrometer calibrated in ten-thousandths of an inch, measure and record the lowest thickness of the brake rotor at 4 or more points, equally spaced around the rotor. Ensure that the measurements are only taken within the brake pad lining contact area and that the micrometer is positioned the same distance from the outside edge of the rotor for each measurement.
  3. Compare the lowest thickness measurement recorded to the following specifications: Specification: Front brake rotor minimum allowable thickness after refinishing - 31.08 mm (1.22 in). Rear brake rotor minimum allowable thickness after refinishing - 10.8 mm (0.425 in).
  4. If the lowest thickness measurement of the brake rotor is above the minimum allowable thickness after refinishing specification, the rotor may be able to be refinished, depending upon surface and wear conditions which may be present.
  5. If the lowest thickness measurement of the brake rotor is at or below the minimum allowable thickness after refinishing specification, the rotor may not be refinished.
  6. Compare the lowest thickness measurement recorded to the following specifications: Specification: Front brake rotor discard thickness - 30.7 mm (1.21 in). Rear brake rotor discard thickness - 10.5 mm (0.413 in).
  7. If the lowest thickness measurement of the brake rotor is at or below the discard thickness specification, the rotor requires replacement.

Brake Rotor Thickness Variation Measurement

CAUTIONRefer to Brake Dust Caution in Cautions and Notices.
IMPORTANTAny disc brake rotor that exhibits thickness variation exceeding the maximum acceptable level must be refinished or replaced. Thickness variation exceeding the maximum acceptable level can cause brake pulsation.
  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»(ref-241732-S31783163252006081100000) and/or «Brake Pads Replacement - Rear (J65, JL9)»(ref-241732-S39614569842006081100000) , if equipped.
  2. Clean the friction surfaces of the brake rotor with denatured alcohol or an equivalent approved brake cleaner.
  3. Using a micrometer calibrated in thousanths-of-a-millimeter or ten-thousanths-of-an-inch, measure and record the thickness of the brake rotor at four or more points, evenly spaced around the rotor. Ensure that the measurements are only taken within the friction surfaces and that the micrometer is positioned the same distance from the outer edge of the rotor, about 13 mm (0.5 in), for each measurement.
  4. Calculate the difference between the highest and lowest thickness measurements recorded to obtain the amount of thickness variation.
  5. Compare the thickness variation measurement to the following specification: Specification: Brake rotor maximum allowable thickness variation: 0.025 mm (0.001 in)
  6. If the brake rotor thickness variation measurement exceeds the specification, the rotor requires refinishing or replacement.

Tools Required

  1. J 39544-KIT Torque-Limiting Socket Set or equivalent. See «Special Tools»(ref-241732-S25412513332006081100000) .
  2. J 41013 Rotor Resurfacing Kit. See «Special Tools»(ref-241732-S25412513332006081100000) .
  3. J 42450-A Wheel Hub Resurfacing Kit. See «Special Tools»(ref-241732-S25412513332006081100000) .
  4. J 45101 Hub and Wheel Runout Gage. See «Special Tools»(ref-241732-S25412513332006081100000) .
  5. J 45101-100 Conical Brake Rotor Washers. See «Special Tools»(ref-241732-S25412513332006081100000) .

Measuring Procedure

CAUTIONRefer to Brake Dust Caution in Cautions and Notices.
IMPORTANTBrake 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 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.
  2. Inspect the mating surface of the hub/axle flange and the brake rotor to ensure that 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: Remove the brake rotor from the vehicle. Refer to «Brake Rotor Replacement - Front»(ref-241732-S40518848452006081100000) and/or «Brake Rotor Replacement - Rear»(ref-241732-S18618561732006081100000) , if equipped. Using the J 42450-A , thoroughly clean any rust or corrosion from the mating surface of the hub/axle flange. See «Special Tools»(ref-241732-S25412513332006081100000) . Using the J 41013 , thoroughly clean any rust or corrosion from the mating surface of the brake rotor. See «Special Tools»(ref-241732-S25412513332006081100000) . 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 J 45101-100 (1) and one lug nut (2) onto the upper-most wheel stud. See «Special Tools»(ref-241732-S25412513332006081100000) .
  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. See «Special Tools»(ref-241732-S25412513332006081100000) .
  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. See «Special Tools»(ref-241732-S25412513332006081100000) . Refer to «Tire and Wheel Removal and Installation»(ref-241703-S14581567662006081100000) in Tires and Wheels.
  8. If the brake rotor has been REFINISHED or REPLACED with a new rotor, proceed to step 14.
  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 45101 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. See «Special Tools»(ref-241732-S25412513332006081100000) .5 in) from the outer edge of the rotor.
  11. Measure and record the assembled LRO of the brake rotor. Rotate the rotor until the lowest reading is displayed on the indicator dial, then set the dial to zero. Rotate the rotor until the highest reading is displayed on the dial. Mark the location of the high spot relative to the nearest wheel stud or studs. 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) Rear brake rotor maximum allowable assembled lateral runout: 0.06 mm (0.002 in)
  13. If the brake rotor assembled LRO is within specifications, proceed to step 18. If the brake rotor assembled LRO exceeds the specification, refinish the rotor to ensure true parallelism, refer to «Brake Rotor Refinishing»(ref-241732-S21618933572006081100000) . After refinishing the rotor, proceed to step 14.
  14. Mount a dial indicator, J 45101 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. See «Special Tools»(ref-241732-S25412513332006081100000) .5 in) from the outer edge of the rotor.
  15. Measure and record the assembled LRO of the brake rotor. Rotate the rotor until the lowest reading is displayed on the indicator dial, then set the dial to zero. Rotate the rotor until the highest reading is displayed on the dial. Mark the location of the high spot relative to the nearest wheel stud or studs. 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) Rear brake rotor maximum allowable assembled lateral runout: 0.06 mm (0.002 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»(ref-241732-S40987518142006081100000) .
  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 J 45101-100 and the lug nuts. See «Special Tools»(ref-241732-S25412513332006081100000) .

Burnishing Pads and Rotors

CAUTIONRoad test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.
CAUTIONRefer to Brake Dust Caution in Cautions and Notices.

Burnishing the brake pads and brake rotors is necessary in order to ensure that the braking surfaces are properly prepared after service has been performed on the disc brake system.

This procedure should be performed whenever the disc brake rotors have been refinished or replaced, and/or whenever the disc brake pads have been replaced.

  1. Select a smooth road with little or no traffic.
  2. Accelerate the vehicle to 48 km/h (30 mph). IMPORTANT: Use care to avoid overheating the brakes while performing this step.
  3. Using moderate to firm pressure, apply the brakes to bring the vehicle to a stop. Do not allow the brakes to lock.
  4. Repeat steps 2 and 3 until approximately 20 stops have been completed. Allow sufficient cooling periods between stops in order to properly burnish the brake pads and rotors.

J 28662 Brake Pedal Effort Gage

J 35777 Caliper Piston Seal Installer. See Special Tools .

  1. J 41013 Rotor Resurfacing Kit. See «Special Tools»(ref-241732-S25412513332006081100000) .
  2. J 42450-A Wheel Hub Resurfacing Kit. See «Special Tools»(ref-241732-S25412513332006081100000) .
  1. J 41013 Rotor Resurfacing Kit. See «Special Tools»(ref-241732-S25412513332006081100000) .
  2. J 42450-A Wheel Hub Resurfacing Kit. See «Special Tools»(ref-241732-S25412513332006081100000) .
  1. J 39544-KIT Torque-Limiting Socket Set or equivalent. See «Special Tools»(ref-241732-S25412513332006081100000) .
  2. J 45101-100 Conical Brake Rotor Washers. See «Special Tools»(ref-241732-S25412513332006081100000) .

Indexing Procedure

CAUTIONRefer to Brake Dust Caution in Cautions and Notices.
IMPORTANTBrake 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 . 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). Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement .
  1. Remove the J 45101-100 and the lug nuts that were installed during the assembled LRO measurement procedure. See «Special Tools»(ref-241732-S25412513332006081100000) .
  2. Inspect the mating surface of the hub/axle flange and the brake rotor to ensure that there are no foreign particles or debris remaining.
  3. Index the brake rotor in a different orientation to the hub/axle flange.
  4. Hold the rotor firmly in place against the hub/axle flange and install one of the J 45101-100 (1) and one lug nut (2) onto the upper-most wheel stud. See «Special Tools»(ref-241732-S25412513332006081100000) .
  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. See «Special Tools»(ref-241732-S25412513332006081100000) .
  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. See «Special Tools»(ref-241732-S25412513332006081100000) . Refer to «Tire and Wheel Removal and Installation»(ref-241703-S14581567662006081100000) in Tires and Wheels.
  8. Measure the assembled LRO of the brake rotor. Refer to «Brake Rotor Assembled Lateral Runout (LRO) Measurement»(ref-241732-S00374773892006081100000) .
  9. Compare the amount of change between this measurement and the original measurement.
  10. If this measurement is within specifications, proceed to step 14.
  11. If this measurement still exceeds specifications, repeat steps 1-9 until the best assembled LRO measurement is obtained.
  12. Matchmark the final location of the rotor to the wheel studs if the orientation is different than it was originally.
  13. If the brake rotor assembled LRO measurement still exceeds the maximum allowable specification, refer to «Brake Rotor Assembled Lateral Runout (LRO) Correction»(ref-241732-S40987518142006081100000) .
  14. If the brake rotor assembled LRO is within specification, install the brake caliper and depress the brake pedal several times to secure the rotor in place before removing the J 45101-100 and the lug nuts. See «Special Tools»(ref-241732-S25412513332006081100000) .
  1. J 39544-KIT Torque-Limiting Socket Set or equivalent. See «Special Tools»(ref-241732-S25412513332006081100000) .
  2. J 45101-100 Conical Brake Rotor Washers. See «Special Tools»(ref-241732-S25412513332006081100000) .

Procedure

CAUTIONRefer to Brake Dust Caution in Cautions and Notices.
IMPORTANTBrake 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 . 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). Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement .
  1. Rotate the brake rotor to position the high spot, identified and marked during the brake rotor assembled LRO measurement procedure, to face upward.
  2. Remove the J 45101-100 and the lug nuts that were installed during the assembled LRO measurement procedure and/or the indexing correction procedure. See «Special Tools»(ref-241732-S25412513332006081100000) .
  3. Inspect the mounting surface of the hub/axle flange and the brake rotor to ensure that there are no foreign particles or debris remaining.
  4. Select the correction plate, following the manufacturer's instructions, which has a specification closest to the assembled LRO measurement. For example: If the assembled LRO measurement was 0.076 mm (0.003 in), the 0.076 mm (0.003 in) correction plate would be used. If the measurement was 0.127 mm (0.005 in), the 0.152 mm (0.006 in) correction plate would be used.
  5. Determine the positioning for the correction plate (1) using the high spot mark (3) made during the brake rotor assembled LRO measurement procedure.
  6. Install the correction plate (1) onto the hub/axle flange, with the V-shaped notch (2) orientated to align with the high spot mark (3), that was positioned to face upward.
  7. Install the brake rotor to the hub/axle flange. Use the matchmark made prior to removal for proper orientation to the flange.
  8. Hold the rotor firmly in place against the hub/axle flange and install one of the J 45101-100 (1) and one lug nut (2) onto the upper-most wheel stud. See «Special Tools»(ref-241732-S25412513332006081100000) .
  9. Continue to hold the rotor secure and tighten the lug nut firmly by hand.
  10. Install the remaining J 45101-100 and lug nuts onto the wheel studs and tighten the nuts firmly by hand in a star-pattern. See «Special Tools»(ref-241732-S25412513332006081100000) .
  11. Using the J 39544-KIT or equivalent, tighten the lug nuts in a star-pattern to specification, in order to properly secure the rotor. See «Special Tools»(ref-241732-S25412513332006081100000) . Refer to «Tire and Wheel Removal and Installation»(ref-241703-S14581567662006081100000) in Tires and Wheels.
  12. Measure the assembled LRO of the brake rotor. Refer to «Brake Rotor Assembled Lateral Runout (LRO) Measurement»(ref-241732-S00374773892006081100000) .
  13. If the brake rotor assembled LRO measurement still exceeds the maximum allowable specification, refer to «Brake Rotor Assembled Lateral Runout (LRO) Correction»(ref-241732-S40987518142006081100000) .
  14. 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 J 45101-100 and the lug nuts. See «Special Tools»(ref-241732-S25412513332006081100000) .

J 45101-100 Conical Brake Rotor Washers. See Special Tools .

CAUTIONRefer to Brake Dust Caution in Cautions and Notices.
IMPORTANTBrake 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 . 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). Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement .
  1. Ensure that the caliper and caliper bracket that are already being supported, are clear from contacting any rotating components, such as the brake rotor.
  2. Remove the J 45101-100 and the lug nuts that were installed during the assembled LRO measurement procedure and/or the indexing correction procedure. See «Special Tools»(ref-241732-S25412513332006081100000) .
  3. Inspect the mounting surface of the hub/axle flange and the brake rotor to ensure that there are no foreign particles or debris remaining.
  4. Set up the lathe, following the manufacturer's instructions.
  5. Refinish the brake rotor, following the brake lathe manufacturer's instructions.
  6. After each successive cut, inspect the brake rotor thickness. Refer to «Brake Rotor Thickness Measurement»(ref-241732-S23568694432006081100000) .
  7. If at any time the brake rotor exceeds the minimum allowable thickness after refinish specification, the brake rotor must be replaced. After replacing the rotor, proceed to step 10.
  8. After refinishing the brake rotor, use the following procedure in order to obtain the desired non-directional finish: Follow the brake lathe manufacturer's recommended speed setting for applying a non-directional finish Using moderate pressure, apply the non-directional finish: If the lathe is equipped with a non-directional finishing tool, apply the finish with 120 grit aluminum oxide sandpaper If the lathe is not equipped with a non-directional finishing tool, apply the finish with a sanding block and 150 grit aluminum oxide sandpaper After applying a non-directional finish, clean each friction surface of the brake rotor with denatured alcohol or an equivalent approved brake cleaner
  9. Remove the lathe from the vehicle.
  10. Measure the assembled LRO of the brake rotor. Refer to «Brake Rotor Assembled Lateral Runout (LRO) Measurement»(ref-241732-S00374773892006081100000) .
  11. If the brake rotor assembled LRO measurement still exceeds the maximum allowable specification, refer to «Brake Rotor Assembled Lateral Runout (LRO) Correction»(ref-241732-S40987518142006081100000) .
  12. If the brake rotor assembled LRO is within specification, install the brake caliper and depress the brake pedal several times to secure the rotor in place before removing the J 45101-100 and the lug nuts. See «Special Tools»(ref-241732-S25412513332006081100000) .
  1. J 41013 Rotor Resurfacing Kit. See «Special Tools»(ref-241732-S25412513332006081100000) .
  2. J 42450-A Wheel Hub Resurfacing Kit. See «Special Tools»(ref-241732-S25412513332006081100000) .

Refinishing Procedure

CAUTIONRefer to Brake Dust Caution in Cautions and Notices.
IMPORTANTThe disc brake rotors do not require refinishing as part of routine brake system service. New disc brake rotors do not require refinishing. Do not refinish disc brake rotors in an attempt to correct the following conditions: Brake system noise - squeal, growl, groan Uneven and/or premature disc brake pad wear Superficial or cosmetic corrosion/rust of the disc brake rotor friction surface Scoring of the disc brake rotor friction surface less than the maximum allowable specification Before refinishing a brake rotor, the rotor MUST first be checked for adequate thickness to allow the rotor to be refinished and remain above the minimum allowable thickness after refinish specification. Refer to Brake Rotor Thickness Measurement . Disc brake rotors should only be refinished if they have adequate thickness to be refinished and if one or more of the following conditions exist: Thickness variation in excess of the maximum allowable specification Excessive corrosion/rust and/or pitting Cracks and/or heat spots Excessive blueing discoloration Scoring of the disc brake rotor surface in excess of the maximum allowable specification Disc brake rotors may need to be refinished as part of the process for correcting brake rotor assembled lateral runout (LRO) that exceeds the maximum allowable specification.
  1. Using the J 42450-A , thoroughly clean any rust or corrosion from the mating surface of the hub/axle flange. See «Special Tools»(ref-241732-S25412513332006081100000) .
  2. Using the J 41013 , thoroughly clean any rust or corrosion from the mating surface and mounting surface of the brake rotor. See «Special Tools»(ref-241732-S25412513332006081100000) .
  3. Inspect the mating surfaces of the hub/axle flange and the rotor to ensure that there are no foreign particles or debris remaining.
  4. Mount the brake rotor to the brake lathe according to the lathe manufacturer's instructions, ensuring that all mounting attachments and adapters are clean and free of debris.
  5. Ensure that any vibration dampening attachments are securely in place.
  6. With the brake lathe running, slowly bring in the cutting tools until they just contact the brake rotor friction surfaces.
  7. Observe the witness mark on the brake rotor. If the witness mark extends approximately three-quarters or more of the way around the brake rotor friction surface on each side, the brake rotor is properly mounted to the lathe.
  8. If the witness mark does not extend three-quarters or more of the way around the brake rotor, re-mount the rotor to the lathe.
  9. Following the brake lathe manufacturer's instructions, refinish the brake rotor.
  10. After each successive cut, inspect the brake rotor thickness. Refer to «Brake Rotor Thickness Measurement»(ref-241732-S23568694432006081100000) .
  11. If at any time the brake rotor exceeds the minimum allowable thickness after refinish specification, the brake rotor must be replaced.
  12. After refinishing the brake rotor, use the following procedure in order to obtain the desired non-directional finish: Follow the brake lathe manufacturer's recommended speed setting for applying a non-directional finish Using moderate pressure, apply the non-directional finish: If the lathe is equipped with a non-directional finishing tool, apply the finish with 120 grit aluminum oxide sandpaper If the lathe is not equipped with a non-directional finishing tool, apply the finish with a sanding block and 150 grit aluminum oxide sandpaper After applying a non-directional finish, clean each friction surface of the brake rotor with denatured alcohol or an equivalent approved brake cleaner
  13. Remove the brake rotor from the brake lathe.
  14. Measure the assembled lateral runout (LRO) of the brake rotor to ensure optimum performance of the disc brakes. Refer to «Brake Rotor Assembled Lateral Runout (LRO) Measurement»(ref-241732-S00374773892006081100000) .
  15. 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»(ref-241732-S40987518142006081100000) .

More articles — Disc Brake System