VW Passat & Audi A4 1990-2000

Pinion Seal

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REMOVAL & INSTALLATION
1998-00 Passat Models

WARNING
Exercise great care if removing the drive flange and the mounting nut from the differential pinion shaft as the amount of torque applied will change the preload of the differential bearings and the mesh of the final drive gears. Improper assembly could result in severe internal damage.

  1. Raise and safely support the vehicle.
  2.  
  3. Matchmark the driveshaft to the drive flange with paint, then remove the drive shaft and support it out of the way.
  4.  
  5. Support the differential with a suitable transmission jack.
  6.  
  7. Remove the front support bracket fasteners and carefully lower the front of the differential until the flange nut is accessible.
  8.  
  9. Matchmark the flange lock nut with paint.
  10.  


WARNING
The flange nut MUST be matchmarked with paint otherwise its original installation position will be lost!

  1. Measure the distance of the topmost portion of the flange nut to the flat surface of the drive flange and write the measurement down.
  2.  
  3. Measure the distance of the top of the flank of the flange nut to the flat surface of the drive flange and write the measurement down.
  4.  


NOTE
The flange nut must be reused for proper installation.

  1. Using Tool No. 3028, or its equivalent, support the flange and remove the nut. Loosen and remove the nut by hand.
  2.  
  3. Place a suitable drain pan under the differential and remove the drive flange using Tool No. VW391, or its equivalent.
  4.  
  5. Remove the oil seal, and then remove the O-ring from the splined shaft.
  6.  



Click image to see an enlarged view

Fig. Proper installation of the flange lock nut is critical. Compare the measurements before and after installation

To install:

  1. Install a new O-ring lubricated with gear oil on the splined shaft.
  2.  
  3. Install a new seal into the housing until it is fully seated, then coat between the inner sealing and dust lips of the seal with a light coating of multi-purpose grease. Do NOT use wheel bearing grease.
  4.  
  5. Carefully seat the drive flange onto the splined shaft.
  6.  
  7. Clean the threads of the lock nut and splined shaft thoroughly with rubbing alcohol or brake cleaner and allow to dry.
  8.  
  9. Apply a light coating of a locking agent, such as Part No. D 000 600.
  10.  
  11. Install the lock nut and tighten to its original position.
  12.  
  13. Repeat the measurements taken between the of the topmost portion of the flange nut to the flat surface of the drive flange and the top of the flank of the flange nut to the flat surface of the drive flange and write the measurements down. The measurements must not differ by more than 0.02 inches (0.5mm).
  14.  
  15. Secure the nut by staking the outer surface with the splined shaft.
  16.  
  17. The balance of the installation is in reverse order of removal noting the following:
  18.  
  19. Observe the following torque specifications:
  20.  
  21. Differential-to-front mount: 30 ft. lbs. (40 Nm)
  22.  
  23. Driveshaft-to-differential: 41 ft. lbs. (55 Nm)
  24.  
  25. Upon completion, check and top off the differential fluid level using an approved lubricant.
  26.  

A4 Models

The differential will require partial disassembly and the torque tube housing and bearing must be replaced during disassembly.

  1. Raise and safely support the vehicle.
  2.  
  3. Remove the rear portion of the exhaust system.
  4.  
  5. Remove the heat shield over the driveshaft, matchmark the driveshaft to the final drive, then remove, and support the drive shaft.
  6.  
  7. Drain the differential oil into a suitable container.
  8.  
  9. Support the differential with a suitable transmission jack.
  10.  
  11. Remove the front differential crossmember-to-body mounting bolts.
  12.  
  13. Remove the four mounting bolts for the torque tube extension housing from the main differential housing.
  14.  
  15. Using a suitable slide hammer attached to the drive flange, carefully remove the housing along with the drive from the differential.
  16.  
  17. Clamp the housing in a sturdy and suitable vise, and using a suitable three-jaw gear puller, remove the sleeve from the splined end of the drive flange.
  18.  
  19. Remove the circlip at the rear of the housing near the drive flange, then thread an 8mm bolt into the sealing plug and remove using a slide hammer.
  20.  
  21. Using an angled external snap-ring pliers, expand the snap ring and slide it down the shaft.
  22.  
  23. Attach a suitable slide hammer to the flange, and remove the flange from the housing.
  24.  
  25. Remove the seal from the end of the housing, and then remove the snap-ring behind the seal.
  26.  
  27. Using an internally expanding gear puller and a slide hammer, remove the bearing.
  28.  
  29. If the backing plate is damaged, replace the backing plate, making sure if replaced, the plate is fully seated.
  30.  



Click image to see an enlarged view

Fig. The front torque tube housing must be removed from the differential to replace the pinion seal on A4 models

To install:

  1. Press a new bearing into the housing and install its snap ring.
  2.  
  3. Coat the inner lips of a new seal with gear oil and install the seal.
  4.  
  5. While expanding the drive flange shaft retainer, press the drive flange into the housing making sure to fully seat the circlip.
  6.  
  7. Support the drive flange and press the sleeve over the splined shaft
  8.  
  9. Install the access cap along with its seal into the end of the housing and install its retaining clip.
  10.  
  11. Install the housing onto the differential using a new O-ring.
  12.  
  13. Tighten the housing M10 fasteners to 26 ft. lbs. (35 Nm).
  14.  
  15. The balance of the installation is in reverse order of removal noting the following:
  16.  
  17. Fill the differential with the recommended type and amount of gear oil. For additional information, please refer to the following topic(s): General Information And Maintenance, Fluids And Lubricants.
  18.  

 
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