Audi Cars 1999-05

Wheel Bearings

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On 1996 and earlier front wheel drive vehicles, the rear wheel bearings are of the standard tapered-roller design. Periodic lubrication and adjustment is necessary to prevent premature bearing failure.

Although the manufacturer does not have a recommended lubrication interval, any time the rear brakes are replaced the wheel bearing grease and adjustment should be checked and repacked or adjusted as necessary.

On all vehicles equipped with All Wheel Drive (AWD) and 1997 and later vehicles equipped with sealed rear wheel bearings pressed into the hub, the wheel bearings are sealed units, and lubrication is not possible.

Adjustment



  1. Tighten the bearing nut while turning the drum or disc. Torque the nut to 88 inch lbs. (10 Nm) to seat the bearing, and then loosen it again.
  2.  
  3. When tightening adjusting the nut again, move the thrust washer side to side with a screwdriver. The thrust washer must still be movable with light effort when adjustment is complete.
  4.  
  5. When installing the locking ring, keep trying different positions of the ring on the nut until the cotter pin goes through it and into the hole. Don't turn the nut to align the locking ring with the hole in the axle. Use a new cotter pin.
  6.  


WARNING
Do NOT tighten the wheel bearing such that the bearing is preloaded. If the bearing is preloaded it will wear prematurely because the bearing expands from the heat generated when it is in use.

Front Wheel Drive (FWD) Vehicles
  1. Block the front wheels. On models with automatic transmission, select Park. On models with manual transmission, select first gear.
  2.  
  3. Raise and support the vehicle safely.
  4.  
  5. If the wheel must be removed to access the dust cap, remove the cap.
  6.  
  7. Release the parking brake.
  8.  
  9. Remove the grease cap.
  10.  
  11. Remove the cotter pin and the locking cap.
  12.  
  13. Lightly tighten the adjusting nut. Do NOT use excessive force.
  14.  
  15. While backing of the nut, use a suitable flat blade screwdriver and attempt to slide the thrust washer side to side. Use the thrust washer as if it were a feeler gauge. When the washer can be moved side to side smoothly, without excessive force install the locking cap using a new cotter key, and then install the dust cap.
  16.  
  17. If removed, install the wheel, tightening the lug bolts by hand.
  18.  
  19. Check the wheel bearing by attempting to rock the top or bottom of the wheel in and out toward the center of the vehicle.
  20.  


NOTE
If the top or bottom of the wheel can be moved in and out toward the center of the vehicle with the bearings properly adjusted, the bearings may be worn and should be replaced.


WARNING
Do NOT preload the wheel bearings adjustment nut to compensate for worn bearings. The heat generated during operation will allow the bearings to expand and ultimately seize.

  1. The balance of the procedure is in reverse order of checking and adjusting.
  2.  
  3. If removed, torque the lug bolts in a crisscross pattern to:
  4.  


    M 12 x 1.5 Wheel lug bolts: 81 ft. lbs. (110 Nm)
     
    M 14 x 1.5 Wheel lug bolts: 89 ft. lbs. (120 Nm)
     


Non-Quattro Models
  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:

    Grease cap
     
    Cotter pin and the locking nut
     

  4.  
  5. While turning the wheel, so the wheel bearing does not jam, tighten the adjusting nut firmly.
  6.  
  7. Back the nut off slightly. The nut is properly adjusted when it is possible to pry the thrust washer side to side with some drag but using light pressure on the tool.
  8.  
  9. Install the locking nut and a new cotter pin.
  10.  
  11. When installing the cap, be sure it is securely in place.
  12.  

Quattro Models

The wheel bearings are sealed; no adjustment is necessary or possible. If the bearings are found to be loose or noisy, they must be replaced.

Removal & Installation



  1. Raise and safely support the vehicle, and remove the rear wheels.
  2.  
  3. On vehicles with rear drum brakes, insert a small pry tool through a wheel bolt hole and push up on the spring tensioned adjusting wedge to slacken the rear brake adjustment.
  4.  
  5. On vehicles with rear disc brakes, remove the two 8mm Allen® bolts that secure the caliper to the axle. Hang the caliper from the spring with wire; Do NOT let it hang by the hydraulic hose.
  6.  
  7. Pry off the grease cap, then remove the cotter pin, locking ring, axle nut and thrust washer. Carefully remove the bearing without dropping it.
  8.  
  9. Remove the brake drum or rotor and pry the bearing seal out of the hub. The seal will be destroyed, but be careful not to pry on the bearing.
  10.  
  11. Clean the bearings in solvent, and wipe the inside of the drum/rotor. Examine the bearings and inner races for discoloration, wear or damage.
  12.  
  13. Pack the bearings with new wheel bearing grease. Coat the bearing races in the hub with grease and partially fill the inside of the drum/rotor with bearing grease as well. Keep in mind that the grease not only lubricates the bearings, but also provides a means of cooling.
  14.  
  15. Place the freshly packed inner wheel bearing in the drum/rotor. Before installing the seal, make sure the seal and the seal's mating surface in the drum or rotor are clean, dry and free of any grease or debris. Using a flat block of wood or other suitable seal driver, install the wheel bearing grease seal into the drum/rotor.
  16.  


NOTE
Do NOT attempt to drive the seal in place with a hammer, it will be damaged.

  1. Pack about 1 oz. of grease into the hub and fit the drum or disc onto the axle.
  2.  
  3. Pack the outer bearing with grease and fit the bearing, thrust washer and nut onto the axle. Adjust as outlined, the bearing pre-load and install the locking ring, cotter pin and grease cap.
  4.  
  5. Install the brake caliper, if removed.
  6.  

  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:
    NOTE
    The wheel hub assembly and wheel bearing are an integral unit. The wheel bearing cannot be replaced separately. If the wheel hub assembly can be pulled from the wheel bearing housing by hand, it is okay and can be reinstalled. If not okay, wheel hub assembly must be replaced.



    Rear wheel
     
    Brake caliper, without disconnecting the hydraulic line and suspend it on a wire.
     
    Brake rotor
     
    Dust cap
     
    Center hub bolt
     
    Speed sensor
     
    Collared bolt securing wheel bearing housing to rear shock absorber (mark position for proper reinstallation)
     
    Shock absorber, if necessary
     
    Wheel bearing housing
     
    Wheel hub
     

  4.  

To install:

  1. Clean and inspect mating surfaces for bearing races.
  2.  
  3. Install in reverse of the removal procedure, noting the following:
    NOTE
    If shock absorber was removed, torque upper mounting bolts to 27 ft. lbs. (36 Nm).






    Center hub bolt to 140 ft. lbs. (190 Nm), plus an additional 180° with wheel raised off ground; when vehicle is returned to ground, loosen bolt by 90°
     
    Wheel bearing housing to shock absorber new bolt. Torque self-locking nut to 118 ft. lbs. (160 Nm), plus an additional 90°, with vehicle standing on ground.
     

  4.  
  5. Check the brakes for proper operation.

    Click image to see an enlarged view

    Fig. Exploded view of the rear wheel bearing-A4 with front wheel drive vehicles



    Click image to see an enlarged view

    Fig. Exploded view of the rear wheel bearing housing-A4 Quattro models

  6.  

  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:

    Wheel(s)
     
    Brake caliper (suspend by wire from body)
     
    Rotor
     
    Wheel speed sensor bracket
     
    Speed sensor
     
    Wheel hub/bearing assembly bolts
     
    Wheel hub/bearing assembly with backing plate
     

  4.  

To install:


NOTE
Wheel hub and bearing assembly is an integral unit. The wheel bearing cannot be replaced separately. If the wheel hub and bearing assembly is replaced, also replace the wheel speed sensor.

  1. Installation is the reverse of the removal procedure, noting the following:

    Wheel hub/bearing bolts: torque to 44 ft. lbs. (60 Nm)
     
    Brake caliper bolts: torque to 26 ft. lbs. (35 Nm)
     
    Wheel bolts: torque to 89 ft. lbs. (120 Nm)

    Click image to see an enlarged view

    Fig. Exploded view of rear wheel hub/bearing assembly-A6 models with front wheel drive

     

  2.  

  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:

    Wheel assembly
     
    Caliper (hang by wire from body)
     
    Backing plate
     
    Brake rotor
     
    ABS wheel speed sensor from the wheel bearing housing
     
    Coupling rod bolt
     
    Tie rod bolt (mark position of eccentric bolt before removal)
     
    Control arm bolt
     
    Wheel bearing housing from drive axle
     

  4.  
  5. Remove the wheel bearing by pressing it from the hub.
  6.  

To install:

Click image to see an enlarged view

Fig. Exploded view of the rear wheel bearing housing and related components-A6 Quattro models

  1. Installation is the reverse of the removal procedure, noting the following torque specifications:

    Tie rod to wheel bearing housing bolt: 70 ft. lbs. (95 Nm)
     
    Upper control arm to wheel bearing housing bolt: 52 ft. lbs. (70 Nm) plus 90°
     
    Wheel bearing housing to lower control arm new self-locking nut: 74 ft. lbs. (100 Nm)
     
    Coupling rod to wheel bearing housing bolt: 41 ft. lbs. (55 Nm)
     
    Backing plate to control arm bolt: 7 ft. lbs. (10 Nm)
     
    Shock absorber to control arm bolt: 52 ft. lbs. (70 Nm) plus 90°
     
    Drive axle socket head bolts: M8 to 30 ft. lbs. (40 Nm) or M10 to 52 ft. lbs. (70 Nm)
     

  2.  
  3. Check and/or adjust the wheel alignment.
  4.  

  1. Before servicing the vehicle, refer to the precautions section.

    Wheel
     
    Brake caliper, without disconnecting the hydraulic line and suspend it on a wire.
     
    Grease cap
     
    Cotter pin, nut and washer
     
    Outer bearing
     
    Brake rotor
     
    Bearing inner bearing and seal from the rotor hub, using a soft drift or press
     
    Bearing inner and outer race(s) from the rotor, using a soft drift or press
     

  2.  

To install:

  1. Clean and inspect mating surfaces for bearing races.
  2.  
  3. Install or connect the following:

    New races using soft drift or press
     
    New bearing packed with grease and set it into the inner race
     
    Seal, making sure it is square in the rotor hub
     
    Rotor, outer bearing, washer, and nut and adjust bearing play
     
    Cotter pin and dust cap
     
    Brake caliper
     

  4.  
  5. If hydraulic lines were removed, install and bleed brakes.
  6.  
  7. If parking brake cable has been remove, install and adjust as necessary.
  8.  
  9. Install the wheel .
  10.  
  11. Check the brakes for proper operation.
  12.  

 
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