GM Full-Size Trucks 1970-1979 Repair Guide

Disc Brake Rotor

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REMOVAL & INSTALLATION



2-Wheel Drive Vehicles

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the 2WD steering knuckle and hub assembly showing the inner and outer wheel bearings

  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.
  8.  

4-Wheel Drive Vehicles

See Figure 2



Click image to see an enlarged view

Fig. Fig. 2: Removing the front disc brake rotor - 1977 4WD truck shown

  1. Remove the locking hubs.
  2.  
  3. Remove the wheel bearing outer locknut, retainer and and wheel bearing inner adjusting nut.
  4.  
  5. Remove the hub and disc assembly and outer wheel bearing.
  6.  
  7. Remove the oil seal and inner bearing cone from the hub using a brass drift and tapping with a hammer. Discard the oil seal.
  8.  
  9. Remove the inner and outer bearing cups using a brass drift and a hammer.
  10.  
  11. Clean, inspect and lubricate all parts as require with a high speed grease.
  12.  


WARNING
Lubrication must be applied to prevent deterioration before the unit is placed in service.

  1. Assemble the outer wheel bearing cup into the wheel hub using Tool J-6368 and Driver Handle J-8092.
  2.  
  3. Assemble the inner wheel bearing cup into the wheel hub using Tool J-23448 and Driver Handle J-8092.
  4.  
  5. Pack the wheel bearing cone with a high melting point type wheel bearing grease and insert the cone into the cup.
  6.  
  7. Install the hub and disc and wheel bearings on the spindle.
  8.  
  9. Adjust the wheel bearings.
  10.  

INSPECTION



See Figure 3



Click image to see an enlarged view

Fig. Fig. 3: Measure rotor runout using a suitable dial indicator

The minimum wear thickness, 1.215 in., 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. 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. in depth can be corrected by refinishing.

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

 
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