GM Full-Size Trucks 1988-1998 Repair Information

Brake Disc (Rotor)

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REMOVAL & INSTALLATION



Front
R-Series and C-Series

See Figure 1

  1. Remove the brake caliper as previously outlined.
  2.  
  3. Remove the outer wheel bearing.
  4.  
  5. Remove the rotor from the spindle.
  6.  
  7. Reverse procedure to install. Adjust the bearings.
  8.  



Click image to see an enlarged view

Fig. Fig. 1: Remove the wheel and outer wheel bearing so that the rotor can be removed from the vehicle

V-Series

Before starting, you'll need a special wheel bearing nut socket for your1/2inch drive ratchet. These sockets are available through auto parts stores and catalogs. You can't do this job properly without it.

  1. Raise and support the front end on jackstands.
  2.  
  3. Remove the wheels.
  4.  
  5. Remove the hubs.
  6.  
  7. Wipe the inside of the hub to remove as much grease as possible.
  8.  
  9. Using your bearing nut socket, remove the locknut from the spindle.
  10.  
  11. With the locknut off you'll be able to see the locking ring on the adjusting nut. Remove the locking ring. A tool such as a dental pick will make this easier.
  12.  
  13. Using the special socket, remove the bearing adjusting nut.
  14.  

You'll notice that the adjusting nut and the locknut are almost identical. The difference is, the adjusting nut has a small pin on one side which indexes with a hole in the locking ring. DO NOT CONFUSE THE TWO NUTS!

  1. Dismount the brake caliper and suspend it out of the way, without disconnecting the brake line.
  2.  
  3. Pull the hub off of the spindle. The outer bearing will tend to fall out as soon as it clears the spindle, so have a hand ready to catch it.
  4.  

The minimum wear thickness, 1.215 in. (30.86mm), is cast into each disc hub. This is a minimum wear dimension and not a refinish dimension. If the thickness of the disc after refinishing will be 1.230 in. (31.2mm) or less, it must be replaced. Refinishing is required whenever the disc surface shows scoring or severe rust scale. Scoring not deeper than 0.015 in. (0.38mm) in depth can be corrected by refinishing.

Some discs have an anti-squeal groove. This should not be mistaken for scoring.

To install:
  1. Carefully place the hub assembly on the spindle. Take care to avoid damaging the seal on the spindle threads. Make sure the hub is all the way on the spindle.
  2.  
  3. Place the outer bearing on the spindle and slide it into place in its race.
  4.  
  5. Thread the adjusting nut on the spindle until it contacts the outer bearing.
  6.  


WARNING
Make sure you are using the adjusting nut. Remember, it has a small pin on one side. That pin must face outwards, towards you!

  1. Using the special socket and the torque wrench:
    1. Tighten the adjusting nut to 50 ft. lbs. (68 Nm) while rotating the hub.
    2.  
    3. Back off the adjusting nut until it is loose.
    4.  
    5. While rotating the hub, tighten the adjusting nut to 35 ft. lbs. (47 Nm) for automatic locking hubs or 50 ft. lbs. (68 Nm) for manual locking hubs.
    6.  
    7. Back off the adjusting nut 1 / 4 to 3 / 8 of a turn for automatic hubs or 1 / 4 turn for manual hubs.
    8.  

  2.  
  3. Coat the locking ring with wheel bearing grease. Place the locking ring on the spindle. There is a tab on the inner diameter of the ring which must fit in the slot on the top of the spindle. Slide the locking ring in until it contacts the adjusting nut. The pin on the adjusting nut must enter one of the holes in the locking ring. You can tell that the locking ring is seated properly when you see the grease on the ring get pushed out of one of the holes by the pin, and the ring does not rock from side-to-side when you press on either side with your finger. If the locking ring and pin don't index, take note of how far off they are, pull the ring off the spindle and turn the nut, either by hand or with the socket, just enough for a good fit. Try the locking ring again.
  4.  
  5. When the locking ring engages the adjusting nut pin properly, your bearing adjustment is set. Thread the locknut onto the spindle until it contacts the locking ring.
  6.  
  7. Tighten the locknut to at least 160 ft. lbs. (217 Nm). This locknut ensures that the locking ring and adjusting nut don't move. Over-tightening the locknut has no effect on the bearing adjustment.
  8.  
  9. Install the locking hub.
  10.  
  11. Install the caliper and then install the wheel.
  12.  

K1 and 2-Series
  1. Raise and support the front end on jackstands.
  2.  
  3. Remove the wheel.
  4.  
  5. Remove the caliper. Do not disconnect the brake hose from the caliper. Use a piece of wire to support the caliper, do not let it hang on the hose.
  6.  
  7. Remove the rotor.
  8.  
  9. Installation is the reverse of removal.
  10.  

K3-Series
  1. Raise and support the front end on jackstands.
  2.  
  3. Remove the wheel.
  4.  
  5. Remove the hub nut and washer. Insert a long drift or dowel through the vanes in the brake rotor to hold the rotor while loosening the nut.
  6.  
  7. Using a puller, force the outer end of the axle shaft out of the hub. Remove the hub/rotor.
  8.  

To install:
  1. Position the shaft in the hub and install the washer and hub nut. Leave the drift in the rotor vanes and tighten the hub nut to 173 ft. lbs. (235 Nm).
  2.  
  3. Remove the drift.
  4.  
  5. Install the wheel and lower the vehicle.
  6.  

Rear
  1. Raise and support the rear end on jackstands.
  2.  
  3. Remove the wheel.
  4.  
  5. Remove the axle shaft. Refer to Drive Train for this procedure.
  6.  
  7. Using wheel bearing nut wrench, remove the outer lock nut. If equipped, remove the retaining ring.
  8.  
  9. Remove the lock or key washer.
  10.  
  11. Remove the bearing adjusting nut and washer.
  12.  
  13. Remove the hub and rotor assembly.
  14.  

To install:
  1. Install the hub and rotor assembly making sure the bearings and the oil seal are positioned properly.
  2.  
  3. Apply alight coating of high melting point wheel bearing lubricant to the contact surfaces outside diameter of the axle housing tube.
  4.  
  5. Install the washer making sure the tang is engaged in the keyway.
  6.  
  7. Install the bearing adjusting nut and tighten as follows:
    1. Tighten the nut to 50 ft. lbs. (68 Nm) while turning the hub.
    2.  
    3. Back off the nut and retighten to 30-40 ft. lbs. (40-54 Nm) while rotating the hub.
    4.  
    5. Back the nut off 135-150°.
    6.  

  8.  
  9. Install the lockwasher and the locknut. Bend one ear of the lockwasher over the inner nut a minimum of 30° and one ear of the lockwasher over the outer nut a minimum of 60°.
  10.  
  11. Tighten the nut to 65 ft. lbs. (88 Nm).
  12.  
  13. Install the axle shaft, the tire and wheel assembly and lower the vehicle.
  14.  

INSPECTION



  1. Using a brake rotor micrometer measure the rotor thickness in several places around the rotor.
  2.  
  3. If the disc brake rotor minimum thickness varies more than 0.0005 inch (0.013mm) from point-to-point, refinish or replace the rotor
  4.  
  5. Mount a magnetic base dial indicator to the strut member and zero the indicator stylus on the face of the rotor. Rotate the rotor 360 degrees by hand and record the run-out.
  6.  

If the wheel has to be removed to check run-out, install the wheel lugs and tighten them to specification to hold the rotor in place.

  1. Refer to the brake specifications chart at the end of this section for the rotor run-out specification. If the run-out exceeds specification, it should be replaced.
  2.  


CAUTION
Older brake pads or shoes may contain asbestos, which has been determined to be a cancer causing agent. Never clean the brake surfaces with compressed air! Avoid inhaling any dust from any brake surface! When cleaning brake surfaces, use a commercially available brake cleaning fluid.

 
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