Astro, Safari 1997-2005

Wheel Bearings

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Adjustment



  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. If equipped, remove the wheel/hub cover for access, then remove the dust cap from the hub.
  4.  
  5. Remove the cotter pin and loosen the spindle nut.
  6.  
  7. Spin the wheel forward by hand and torque the nut to 12 ft. lbs. (16 Nm) in order to fully seat the bearings and remove any burrs from the threads.
  8.  
  9. Back off the nut until it is just loose, then finger-tighten the nut.
  10.  
  11. Loosen the nut 1 / 4 - 1 / 2 turn until either hole in the spindle lines up with a slot in the nut, then install a new cotter pin. This may appear to be too loose, but it is the proper adjustment.
  12.  
  13. Proper adjustment creates 0.001-0.005 in. (0.025-0.127mm) end-play.
  14.  

The front wheel bearings on the 4WD vehicles are not adjustable. If the bearings become loose or make noise, they must be replaced.

Cleaning & Repacking



Before handling the bearings, there are a few things that you should remember to do and not to do.

Remember to DO the following:



Remove all outside dirt from the housing before exposing the bearing.
 
Treat a used bearing as gently as you would a new one.
 
Work with clean tools in clean surroundings.
 
Use clean, dry canvas or plastic gloves.
 
Clean solvents and flushing fluids are a must.
 
Use clean paper when laying out the bearings to dry.
 
Protect disassembled bearings from rust and dirt. Cover them up.
 
Use clean rags to wipe bearings.
 
Keep the bearings in oil-proof paper when they are to be stored or are not in use.
 
Clean the inside of the housing before replacing the bearing.
 

Do NOT do the following:



Don't work in dirty surroundings.
 
Don't use dirty, chipped or damaged tools.
 
Try not to work on wooden work benches or use wooden mallets.
 
Don't handle bearings with dirty or moist hands.
 
Do not use gasoline for cleaning; use a safe solvent.
 
Do not spin-dry bearings with compressed air. They will be damaged.
 
Do not spin dirty bearings.
 
Avoid using cotton waste or dirty cloths to wipe bearings.
 
Try not to scratch or nick bearing surfaces.
 
Do not allow the bearing to come in contact with dirt or rust at any time.
 


NOTE
The following procedures are made easier with the use of GM tools No. J-29117, J-8092, J-8850, J-8457 and J-9746-02 or their equivalents. Although the job can be done using a prybar, some a few LARGE sockets and some assorted drivers.

  1. Loosen the lug nuts on the front wheels.
  2.  
  3. Raise and safely support.
  4.  
  5. Remove the front tire and wheel assemblies.
  6.  
  7. Remove the caliper-to-steering knuckle bolts and the caliper from the steering knuckle. Using a wire, support the caliper from the vehicle; DO NOT disconnect the brake line.
  8.  
  9. Remove the dust cap at the center of the hub and disc assembly.
  10.  
  11. Remove the cotter pin, the spindle nut, the thrust washer and the outer bearing.
  12.  
  13. Grasping the hub and disc assembly firmly, pull the assembly from the axle spindle.
  14.  
  15. Using a small prybar or an inexpensive seal removal tool, pry the grease seal from the rear of the hub/disc assembly, then remove the inner bearing.
    NOTE
    DO NOT remove the bearing races from the hub, unless they show signs of damage.

  16.  
  17. If it is necessary to remove the wheel bearing races, use the GM front bearing race removal tool No. J-29117 to drive the races from the hub and disc assembly. If the tool is not available, you can use a prybar (if you take care not to damage the hub and disc assembly) or you can use a blunt drift from behind (the other side of the assembly).
    NOTE
    Wheel bearings and races which have been in service MUST remain together as matched sets. DO NOT switch bearings from side-to-side. ALSO, if the bearings are replaced, new races MUST be installed to insure the proper bearing operating life of the replacement parts.

  18.  
  19. Using solvent, clean the grease from all of the parts, then blow them dry with compressed air.
    NOTE
    DO NOT spin the dry bearings with the compressed air or damage will likely occur. If compressed air is not available, place the bearings on a clean, dry surface (clean, lint free rag or a plastic bag) and allow them to air dry.

  20.  
  21. Inspect all of the parts for scoring, pitting or cracking, replace the parts (if necessary).
  22.  

To install:

  1. If the bearing races were removed, perform the following procedures to the install the replacements:
    1. Using grease, lightly lubricate the inside of the hub/disc assembly.
    2.  
    3. Using the GM seal installation tools No. J8092 and J8850, drive the inner bearing race into the hub/disc assembly until it seats.
      NOTE
      When installing the bearing races, be sure to support the hub/disc assembly with GM tool No. J9746-02.

    4.  
    5. Using the GM seal installation tools No. J8092 and J8457, drive the outer race into the hub/disc assembly until it seats.
    6.  

  2.  
  3. Using wheel bearing grease, lubricate the bearings, the races and the spindle; be sure to place a gob of grease (inside the hub/disc assembly) between the races to provide an ample supply of lubricant.
    NOTE
    To lubricate each bearing, Use a wheel bearing greaser or place a gob of grease in the palm of the hand, then scoop the bearing through the grease to force grease between the rollers and cage. Be sure to thoroughly fill the bearing around the entire circumference from the top and bottom of the assembly, then roll the bearing through the grease to assure it is well lubricated.

  4.  
  5. Place the inner wheel bearing into the hub/disc assembly. Using a smooth flat driver, length of pipe or a large socket, drive the new grease seal into the rear of the hub and disc assembly until it is flush with the outer surface.
  6.  
  7. Position the hub and disc assembly onto the spindle, then install the outer bearing, thrust washer and the hub nut.

    Click image to see an enlarged view

    Fig. Exploded view of the front wheel hub and bearing assembly-2-wheel drive without ABS shown (ABS similar but with a speed sensor assembly on the shield and a reluctor ring on the back of the hub)



    Click image to see an enlarged view

    Fig. Remove the dust cap from the center of the hub and disc assembly



    Click image to see an enlarged view

    Fig. If the cap is stuck use a thin chisel to drive it away from the disc . . .



    Click image to see an enlarged view

    Fig. . . . then pry the cap free, but be careful not to deform and ruin the cap



    Click image to see an enlarged view

    Fig. Once loosened, remove the cap for access to the bearing retainer (cotter pin, washer and nut)



    Click image to see an enlarged view

    Fig. Bend the ends outward and pull or lever the cotter pin from the spindle . . .



    Click image to see an enlarged view

    Fig. " If difficulty is encountered, gently tap on the pliers with a hammer to help free the cotter pin



    Click image to see an enlarged view

    Fig. . . . then loosen and remove the castellated spindle nut



    Click image to see an enlarged view

    Fig. Withdraw the thrust washer . . .



    Click image to see an enlarged view

    Fig. . . . then remove the outer bearing, freeing the hub and disc assembly



    Click image to see an enlarged view

    Fig. Pull the hub/disc assembly from the spindle and face downward on a clean working surface



    Click image to see an enlarged view

    Fig. Remove the inner wheel bearing seal using a seal puller (this really makes the job easier) . . .



    Click image to see an enlarged view

    Fig. On ABS equipped vehicles a puller removes the seal WITHOUT damaging the reluctor ring (the visible teeth)



    Click image to see an enlarged view

    Fig. With the seal removed, the inner wheel bearing may be lifted from the back of the hub



    Click image to see an enlarged view

    Fig. Removing the bearings races from the hub and disc assembly



    Click image to see an enlarged view

    Fig. Installing the inner wheel bearing race to the hub and disc



    Click image to see an enlarged view

    Fig. Installing the outer wheel bearing race to the hub and disc



    Click image to see an enlarged view

    Fig. Thoroughly pack the bearing with fresh, high temperature wheel-bearing grease before installation



    Click image to see an enlarged view

    Fig. Apply a thin coat of fresh grease to the new inner bearing seal lip



    Click image to see an enlarged view

    Fig. Though a driver is preferred, any circular tool (pipe or socket) of similar size can install the seal

  8.  
  9. While turning the wheel, torque the hub nut to 12 ft. lbs. (16 Nm) until the bearings seat. Back off the nut to the "just loose'' position, then retighten it by hand. Back the nut off until the nearest nut slot aligns with the spindle hole. The nut should not be turned back more than 1 / 2 of a nut flat.
  10.  
  11. Install a new cotter pin through the nut and the spindle, then bend the ends and cut off the excess pin (one outward over the end of the spindle, and the other downward around the spindle). Install the grease cap.
  12.  
  13. If possible, use a dial indicator to the check the rotor end-play. The end-play should be 0.001-0.005 in. (0.03-0.13mm) when the bearings are properly adjusted. If not, readjust the hub/disc assembly.
  14.  
  15. Install the caliper onto the steering knuckle.
  16.  
  17. Install the tire and wheel assembly.
  18.  
  19. Carefully lower the vehicle.
  20.  
  21. Tighten the lug nuts, then road test the vehicle.
  22.  

The all wheel drive front wheel bearings are the sealed type that require no periodic adjusting or repacking. The bearing and hub is a 1 piece assembly requiring replacement if the bearings are defective. For removal and installation information refer to the Wheel Bearing procedure in this section.

Removal & Installation



  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove wheel.
  4.  
  5. Remove brake caliper with the pads without disconnecting the brake line.
  6.  
  7. Remove grease cap.
  8.  
  9. Remove cotter pin, spindle nut and washer.
  10.  
  11. Remove hub.
    WARNING
    Be careful not to drop the outer wheel bearing. As the hub is pulled forward, the outer wheel bearings will often fall forward and they may easily be removed at this time.

  12.  
  13. Remove outer roller bearing assembly.
  14.  
  15. Remove inner seal by prying it out of the hub and discard it.
  16.  
  17. Remove inner bearing assembly.
  18.  

To install:

Click image to see an enlarged view

Fig. Wheel bearings, races and related components-2WD vehicles

  1. Clean all parts in solvent and allow to air dry, then check for excessive wear or damage. Inspect all of the parts for scoring, pitting or cracking and replace if necessary.
    NOTE
    DO NOT remove the bearing races from the hub, unless they show signs of damage.

  2.  
  3. If it is necessary to remove the wheel bearing races, use the GM Front Bearing Race Removal tool J-29117 to drive the races from the hub/disc assembly. A hammer and brass drift may also be used to drive the races from the hub, but the race removal tool is quicker.
  4.  
  5. If the bearing races were removed, position the replacement races in the freezer for a few minutes and then install them to the hub:
    1. Lightly lubricate the inside of the hub/disc assembly using wheel bearing grease.
    2.  
    3. Using the GM Seal Installation tools J-8092 and J-8850, drive the inner bearing race into the hub/disc assembly until it seats. Be sure the race is properly seated against the hub shoulder and is not cocked.
      NOTE
      When installing the bearing races, be sure to support the hub/disc assembly with GM tool J-9746-02.

    4.  
    5. Using the GM Seal Installation tools J-8092 and J-8457, drive the outer race into the hub/disc assembly until it seats.
    6.  

  6.  
  7. Using a high melting point wheel bearing grease, lubricate the bearings, races and spindle; be sure to place a gob of grease (inside the hub/disc assembly) between the races to provide an ample supply of lubricant.
    NOTE
    To lubricate each bearing, place a gob of grease in the palm of the hand, then scoop the bearing through the grease until it is well lubricated.

  8.  
  9. Place the inner bearing in the hub, then apply a thin coating of grease to the sealing lip and install a new inner seal, making sure the seal flange faces the bearing cup.
    NOTE
    Although a seal installation tool is preferable, a section of pipe with a smooth edge or a suitably sized socket may be used to drive the seal into position. Be sure the seal is flush with the outer surface of the hub assembly.

  10.  
  11. Install wheel hub over the spindle.
  12.  
  13. Install outer bearing into the hub by hand.
  14.  
  15. Install spindle washer and nut.
  16.  
  17. Install brake caliper.
  18.  
  19. Install wheel.
  20.  
  21. Properly adjust the wheel bearings.
  22.  
  23. Install new cotter pin.
  24.  
  25. Install dust cap.
  26.  
  27. Install wheel cover.
  28.  

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Install Torsion Bar Unloading tool J-36202 on the torsion bar adjusting bolt and remove the bolt. To aid during installation, count the number of turns required to remove the bolt.

    Click image to see an enlarged view

    Fig. Use Torsion Bar Unloading tool J-36202 to remove the adjusting bolt and unload the torsion bar

  4.  
  5. Remove the wheel.
  6.  
  7. Install an axle shaft boot seal protector to the Tri-Pod axle joint.
  8.  
  9. Remove cotter pin and retainer.
  10.  
  11. Remove castle nut and the thrust washer.
  12.  
  13. Remove brake caliper and support it aside using wire or a coat hanger.
    NOTE
    Be sure the brake line is not stretched or damaged.

  14.  
  15. Remove brake disc from the wheel hub.
  16.  
  17. Remove halfshaft from the hub/bearing assembly, using a Spindle Remover tool J-28733-A to prevent damage to the shaft or hub/bearing assembly.
  18.  
  19. Remove hub/bearing assembly from the knuckle.
  20.  
  21. Clean and inspect the parts for nicks, scores and/or damage, then replace them as necessary.
  22.  

To install:

  1. Install hub and bearing assembly by aligning the threaded holes. Torque the bolts to 77 ft. lbs. (105 Nm).
  2.  
  3. Install tie rod end to the steering knuckle using the retaining nut.
  4.  
  5. Install new cotter pin.
  6.  
  7. Install brake assembly.
  8.  
  9. Install halfshaft nut. Tighten the nut to 180 ft. lbs. (245 Nm).
  10.  
  11. Install retainer and a new cotter pin but DO NOT back off specification in order to insert the cotter pin.
  12.  
  13. Remove the torsion bar unloader tool and the drive axle boot protector.
  14.  
  15. Install the wheel.
  16.  
  17. Check and/or adjust the vehicle trim height, as necessary.

    Click image to see an enlarged view

    Fig. Hub and bearing assembly-4WD vehicles

  18.  

 
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