GM Full Size Vans 1987-1997 Repair Guide

Pinion Seal

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REMOVAL & INSTALLATION



Semi-Floating Axles

See Figures 1 through 5

  1. Raise and support the truck on jackstands. It would help to have the front end slightly higher than the rear to avoid fluid loss.
  2.  
  3. Matchmark and remove the driveshaft.
  4.  
  5. Release the parking brake.
  6.  
  7. Remove the rear wheels. Rotate the rear wheels by hand to make sure that there is absolutely no brake drag. If there is brake drag, remove the drums.
  8.  
  9. Using a torque wrench on the pinion nut, record the force needed to rotate the pinion.
  10.  



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Fig. Fig. 1: Measuring the pinion rotating torque - semi-floating axles



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Fig. Fig. 2: Scribed marks - semi-floating axles



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Fig. Fig. 3: Removing the drive pinion nut - semi-floating axles



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Fig. Fig. 4: Removing the drive pinion flange - semi-floating axles



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Fig. Fig. 5: Installing the pinion seal - semi-floating axles

  1. Matchmark the pinion shaft, nut and flange. Count the number of exposed threads on the pinion shaft.
  2.  
  3. Install a holding tool on the pinion. A very large adjustable wrench will do, or, if one is not available, put the drums back on and set the parking brake as tightly as possible.
  4.  
  5. Remove the pinion nut.
  6.  
  7. Slide the flange off of the pinion. A puller may be necessary.
  8.  
  9. Centerpunch the oil seal to distort it and pry it out of the bore. Be careful to avoid scratching the bore.
  10.  

To install:
  1. Pack the cavity between the lips of the seal with lithium-based chassis lube.
  2.  
  3. Position the seal in the bore and carefully drive it into place. A seal installer is VERY helpful in doing this.
  4.  
  5. Pack the cavity between the end of the pinion splines and the pinion flange with Permatex No.2® sealer, or equivalent non-hardening sealer.
  6.  
  7. Place the flange on the pinion and push it on as far as it will go.
  8.  
  9. Install the pinion washer and nut on the shaft and force the pinion into place by turning the nut.
  10.  


WARNING
Never hammer the flange into place!

  1. Tighten the nut until the exact number of threads previously noted appear and the matchmarks align.
  2.  
  3. Measure the rotating torque of the pinion under the same circumstances as before. Compare the two readings. As necessary, tighten the pinion nut in VERY small increments until the torque necessary to rotate the pinion is 3 inch lbs. higher than the originally recorded torque.
  4.  
  5. Install the driveshaft.
  6.  

Full Floating Axles
  1. Raise and support the truck on jackstands. It would help to have the front end slightly higher than the rear to avoid fluid loss.
  2.  
  3. Matchmark and remove the driveshaft.
  4.  
  5. Matchmark the pinion shaft, nut and flange. Count the number of exposed threads on the pinion shaft.
  6.  
  7. Install a holding tool on the pinion. A very large adjustable wrench will do, or, if one is not available, set the parking brake as tightly as possible.
  8.  
  9. Remove the pinion nut.
  10.  
  11. Slide the flange off of the pinion. A puller may be necessary.
  12.  
  13. Centerpunch the oil seal to distort it and pry it out of the bore. Be careful to avoid scratching the bore.
  14.  

To install:
  1. Pack the cavity between the lips of the seal with lithium-based chassis lube.
  2.  
  3. Position the seal in the bore and carefully drive it into place. A seal installer is VERY helpful in doing this.
  4.  
  5. Place the flange on the pinion and push it on as far as it will go.
  6.  
  7. Install the pinion washer and nut on the shaft and force the pinion into place by turning the nut.
  8.  


WARNING
Never hammer the flange into place!

  1. Tighten the nut until the exact number of threads previously noted appear and the matchmarks align.
  2.  
  3. Install the driveshaft.
  4.  

 
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