GM Full Size Vans 1987-1997 Repair Guide

Brake Disc (Rotor)

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REMOVAL & INSTALLATION



See Figure 1

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



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Fig. Fig. 1: Remove the rotor from the vehicle

INSPECTION



  1. Raise and support the front of the van with jackstands, then remove the wheel assemblies.
  2.  
  3. To check the disc run-out, perform the following procedures:
    1. Using a dial indicator, secure and position it so that the button contacts the disc about 1 in. (25 mm) from the outer edge.
    2.  
    3. Rotate the disc. The lateral run-out should not exceed 0.004 in. (0.10mm) on 1987-95 models. On 1996-97 models the run-out should not exceed 0.003 in. (0.08mm) or 0.010 in. (0.25mm) on 3500 models. If the reading is excessive, recondition or replace the rotor.
    4.  

  4.  
  5. To check the thickness variation, perform the following procedures:
    1. Using a micrometer, check the thickness at four (4) locations around the disc, at the same distance from the edge.
    2.  
    3. The thickness should not vary by more than 0.0005 in. (0.013mm). If the reading is excessive, recondition or replace the rotor.
    4.  

  6.  
  7. The surface finish must be relatively smooth to avoid pulling and erratic performance, also, to extend the lining life. Light rotor scoring of up to 0.06 in. (1.5mm) in depth, can be tolerated. if the scoring depths are excessive, recondition or replace the rotor.
  8.  

 
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