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GENE
GENE, AUTO MECHANIC
Category: Chevy
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Experience:  40 YEARS AS A AUTOMOBILE TECH,ASE MASTER CERTIFIED, GM CERTIFIED
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how to replace rear axle seal on my 3/4 ton chevy 4x4 1978

Customer Question

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Submitted: 6 years ago.
Category: Chevy
Expert:  GENE replied 6 years ago.

hope this helps

gene

Ton Trucks

EXCEPT 1974-79 WITH LOCKING DIFFERENTIAL

See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10

Click image to see an enlarged view
Fig. 1: Drain the rear differential into a suitable container

 

Click image to see an enlarged view
Fig. 2: Remove the differential cover

 

Click image to see an enlarged view
Fig. 3: Clean the gasket material from the mating surfaces

 

Click image to see an enlarged view
Fig. 4: Turn the differential until you can relach the shaft lockscrew

 

Click image to see an enlarged view
Fig. 5: Remove the lockscrew ...

 

Click image to see an enlarged view
Fig. 6: ... then remove the pinion shaft

 

Click image to see an enlarged view
Fig. 7: Remove the C-lock from the bottom end of the shaft

 

Click image to see an enlarged view
Fig. 8: When removing the axle shaft, be careful not to damage the oil seal

 

Click image to see an enlarged view
Fig. 9: A suitable wheel bearing puller can usually be rented from an automotive tool rental shop

 

Click image to see an enlarged view
Fig. 10: Correct bearing installation

 

  1. Support the axle on jackstands.

  2. Remove the wheels and brake drums.

  3. Clean off the differential cover area, loosen the cover to drain the lubricant, and remove the cover.

  4. Turn the differential until you can reach the differential pinion shaft lockscrew. Remove the lockscrew and the pinion shaft.

  5. Push in on the axle end. Remove the C-lock from the inner (bottom) end of the shaft.

  6. Remove the shaft, being careful of the oil seal.

  7. You can pry the oil seal out of the housing by placing the inner end of the axle shaft behind the steel case of the seal, then prying it out carefully.

  8. A puller or a slide hammer is required to remove the bearing from the housing.

To install:

  1. Pack the new or reused bearing with wheel bearing grease and lubricate the cavity between the seal lips with the same grease.

  2. The bearing has to be driven into the housing. Don't use a drift, you might cock the bearing in its bore, use a large socket instead. Drive only on the outer bearing race. In a similar manner, drive the seal in flush with the end of the tube.

  3. Slide the shaft into place, turning it slowly until the splines are engaged with the differential. Be careful of the oil seal.

  4. Install the C-lock on the inner axle end. Pull the shaft out so that the C-lock seats in the counterbore of the differential side gear.

  5. Position the differential pinion shaft through the case and the pinion gears, aligning the lockscrew hole. Install the lockscrew.

  6. Install the cover with a new gasket and tighten the bolts evenly in a crisscross pattern.

  7. Fill the axle with lubricant.

  8. Replace the brake drums and wheels.

1974-79 WITH LOCKING DIFFERENTIAL

See Figures 11, 12, 13, 14, 15 and 16

Click image to see an enlarged view
Fig. 11: Removing the lockscrew

 

Click image to see an enlarged view
Fig. 12: Positioning the differential case for best clearance for pinion shaft removal - 1974-79 vehicles with locking differential

 

Click image to see an enlarged view
Fig. 13: Push the axle shaft inward to remove the C-lock

 

Click image to see an enlarged view
Fig. 14: Rear wheel bearing installation tool

 

Click image to see an enlarged view
Fig. 15: Correct C-clock positioning - 1974-79 vehicles with locking differential

 

Click image to see an enlarged view
Fig. 16: Installing the seal using the proper tool

 

This axle uses a thrust block on the differential pinion shaft.

  1. Follow Steps 1-3 of the proceeding procedure.

  2. Rotate the differential case so that you can remove the lockscrew and support the pinion shaft so it can't fall into the housing. Remove the differential pinion shaft lockscrew.

  3. Carefully pull the pinion shaft partway out and rotate the differential case until the shaft touches the housing at the top.

  4. Use a drift pin to position the C-lock with its open end directly inward. You can't push in the axle shaft till you do this.

  5. Push the axle shaft in and remove the C-lock.

  6. Follow Steps 6-11 of the proceeding procedure.

  7. Keep the pinion shaft partway out of the differential case while installing the C-lock on the axle shaft. Put the C-lock on the axle shaft and carefully pull out on the axle shaft until the C-lock is clear of the thrust block.

  8. Follow steps 13-16 of the previous procedure.

 

Except Half Ton Trucks

These models all use axles of full floating design. The procedures are the same for locking and non-locking axles. Some 1970-72 trucks use Dana axles, but the same procedures should be used.

The best way to remove the bearings from the wheel hub is with an arbor press. Use of a press reduces the chances of damaging the bearing races, cocking the bearing in its bore, or scoring the hub walls. A local machine shop is probably equipped with the tools to remove and install bearings and seals. However, if one is not available, the hammer and drift method outlined can be used.

  1. Support the axle on jacking stands.

  2. Remove the wheels.

  3. Remove the bolts and lock washers that attach the axle shaft flange to the hub.

  4. On 1970-72 trucks, install two 1/2 in. by 13 in. bolts in the threaded holes provided in the axle shaft flange. By turning these bolts alternately the axle shaft may be easily started and then removed from the housing.

  5. On 1973 and later trucks, rap on the flange with a soft faced hammer to loosen the shaft. Grip the rib on the end of the flange with a pair of locking pliers and twist to start shaft removal. Remove the shaft from the axle tube.

  6. The hub and drum assembly must be removed to remove the bearings and oil seals. You will need a large socket to remove and later adjust the bearing adjustment nut.

  7. Remove the locknut retainer, then the locknut.

  8. Remove the adjusting nut from the housing tube.

  9. Remove the thrust washer from the housing tube.

  10. Pull the hub and drum straight off the axle housing.

  11. Remove the oil seal and discard.

  12. Use a hammer and a long draft pin to knock the inner bearing, cup, and oil seal from the hub assembly.

  13. Remove the outer bearing snapring with a pair of pliers. It may be necessary to tap the bearing outer race away from the retaining ring slightly by tapping on the ring to remove the ring.

  14. Drive the outer bearing from the hub with a hammer and drift pin.

  15. To reinstall the bearings, place the outer bearing into the hub. The larger outside diameter of the bearing should face the outer end of the hub. Drive the bearing into the hub using a washer that will cover both the inner and outer races of the bearing. Place a socket on the top of this washer, then drive the bearing into place with a series of light taps. If available, an arbor press should be used for this job.

  16. Drive the bearing past the snapring groove, and install the snapring. Then, turning the hub assembly over, drive the bearing back against the snapring. Again, protect the bearing by placing a washer on top of it. You can use the thrust washer that fits between the bearing and the adjusting nut for this job.

  17. Place the inner bearing into the hub. The thick edge should be toward the shoulder in the hub. Press the bearing into the hub until it seats against the shoulder, using a washer and socket as outlined earlier. Make certain that the bearing is not cocked and that it is fully seated on the shoulder.

  18. Pack the wheel bearings with the grease, and lightly coat the inside diameter of the hub bearing contact surface and the outside diameter of the axle housing tube.

  19. Make sure that the inner bearing, oil seal, axle housing oil deflector, and outer bearing are properly positioned. Install the hub and drum assembly on the axle housing, exercising care so as not to damage the oil seal or dislocate other internal components.

  20. Install the thrust washer so that the tang on the inside diameter of the washer is in the keyway on the axle housing.

  21. Install the adjusting nut. Tighten to 50 ft. lbs. (68 Nm), at the same time rotating the hub to make sure that all the bearing surfaces are in contact. Back off the nut and retighten to 35 ft. lbs. (47 Nm), then back off 1/4 of a turn.

  22. Install the tanged retainer against the inner adjusting nut. Align the adjusting nut so that the short tang of the retainer will engage the nearest slot on the adjusting nut.

  23. Install the outer locknut and tighten to 65 ft. lbs. (88 Nm) Bend the long tang of the retainer into the slot of the outer nut. This method of adjustment should provide 0.001-0.010 in. of end-play.

  24. Place a new gasket over the axle shaft and position the axle shaft in the housing so that the shaft splines enter the differential side gear. Position the gasket so that the holes are in alignment, and install the flange-to-hub attaching bolts. Tighten to 90 ft. lbs. (122 Nm) for vehicles through 1975. For 1976-79 vehicles, tighten to 115 ft. lbs. (156 Nm).

To prevent lubricant from leaking through the flange holes, apply a non-hardening sealer to the bolt threads. Use the sealer sparingly.

  1. Install the wheel and tire assembly.

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