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Home >> GMC Truck >> 1999 >> S15/T15 Sonoma P/U 4WD V6-4.3L VIN X >> Repair and Diagnosis >> Brakes and Traction Control >> Disc Brake System >> Testing and Inspection >> Component Tests and General Diagnostics >> Brake Rotor Assembled Lateral Runout (LRO) Measurement >> Lateral Runout (LRO) - Front

Lateral Runout (LRO) - Front

Check the rotor for lateral runout using the following procedure:

^ Tools Required
- J8001 Dial Indicator Set

1. Remove the tire and the wheel.
2. Tighten the wheel nuts so that the rotor is tight against the hub (JC1 system only).
3. Adjust the wheel bearings in order to eliminate excessive free play (RWD pickups only).
4. Clean the rotor surface.





5. Install the J8001 Dial Indicator so that the dial indicator button contacts the rotor surface about 25 mm (1.0 inch) from the outer edge.
6. Set the dial indicator to zero.
7. Turn the rotor one complete revolution and observe the lateral runout on the dial indicator. The Total Indicator Runout (TIR) should not exceed 0.08 mm (0.003 inch).
8. If lateral runout is not within specifications refinish or replace the rotor (RWD pickups only).
9. In some cases, excessive lateral runout can be rectified by indexing the rotor. Move the rotor one or two wheel bolt positions from the original position (JC1 system only).
10. If the lateral runout still exceeds 0.08 mm (0.003 inch), check the hub for excessive lateral runout, or looseness (JC1 system only).
10.1. Remove the brake rotor.
10.2. Reposition the J8001 Dial Indicator so that the button contacts the surface of the hub.
10.3. Set the dial indicator to zero.
10.4. Rotate the hub one complete revolution.
10.5. Note the lateral runout.
10.6. If the hub lateral runout exceeds, replace the hub. Refer to Wheel Hub, Bearing, and Seal Replacement (4WD Pickup and Utilities) in Front Suspension.
10.7. If the hub lateral runout is within specifications, refinish or replace the rotor.
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