Tools Required

1. Install the outer pinion bearing cup using the J 7818 (7.6 inch axle) or the J 8611-01 (8.6 inch axle) (2) and the J 8092  (1).



2. Install the inner pinion bearing cup using the J 29609 (7.6 inch axle) or the J 8608 (8.6 inch axle) (1) and the J 8092  (2).
3. Determine the selective shim thickness for the pinion. Refer to Pinion Depth Adjustment .



4. Install the selective shim between the inner pinion bearing and the shoulder on the gear.
5. Install the inner pinion bearing using the J 5590 (7.6 inch axle) or the J 24433 (8.6 inch axle).

Press the bearing on until the cone seats on the pinion shim.

6. Install a new collapsible spacer.
7. Lubricate the pinion bearings with axle lubricant. Use the proper fluid. Refer to Fluid and Lubricant Recommendations in Maintenance and Lubrication.
8. Install the pinion into the axle housing.
9. Install the outer pinion bearing onto the pinion.



10. On the 7.6 inch axle, determine the type of pinion oil seal is used on the axle.

On early production axles, a 2 lip pinion seal was used. The seal can be identified by the short deflector (1) used on the pinion flange/yoke.

On late production axles, a 3 lip pinion seal was used. The seal can be identified by the long deflector (2) used on the pinion flange/yoke.





Important: When replacing the pinion oil seal and/or the pinion flange/yoke on the 7.6 inch axle, observe the following guidelines:

•	When replacing only the pinion oil seal, the same style pinion oil seal must be used.

•	If replacing both the pinion oil seal and the pinon flange/yoke, the same style of the pinion oil seal and pinion flange/yoke must be used.

•	The 2 lip and the 3 lip style pinion oil seals and pinion flange/yokes are not interchangeable.

11. For the 7.6 inch axle, install the new pinion gear oil seal. For the 2 lip style pinion oil seal, use the J 23911 . For the 3 lip style pinion oil seal, use the J 33782 .

For the 8.6 inch axle, install the new pinion oil seal using the J 22388 .

12. Apply sealant, GM P/N 12346004 or equivalent, to the splines of the pinion flange/yoke.

Important: Install the pinion gear flange/yoke to the pinion gear shaft in the same position as marked during removal in order to maintain correct driveline balance.

13. Install the pinion flange/yoke.

Align the marks make during removal.

Notice: Do not hammer the pinion flange/yoke onto the pinion shaft. Pinion components may be damaged if the pinion flange/yoke is hammered onto the pinion shaft.

14. Seat the pinion flange/yoke onto the pinion shaft by tapping it with a soft-faced hammer until a few pinion shaft threads show through the flange/yoke.
15. Install the washer and a new pinion nut.



16. Install the J 8614-01 onto the pinion flange/yoke as shown.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

Important: If the rotating torque is exceeded, the pinion will have to be removed and a new collapsible spacer installed.

17. Tighten the pinion nut while holding the J 8614-01 .

Tighten
Tighten the nut until the pinion end play is just taken up. Rotate the pinion while tightening the nut to seat the bearings.




18. Measure the rotating torque of the pinion. Compare this measurement with the rotating torque recorded during removal.

Tighten
Tighten the nut in small increments, as needed, until the rotating torque is 1.1-2.8 N·m (10-25 lb in) (used bearings) or 1.7-3.4 N·m (15-30 lb in) (new bearings).

19. Once the specified torque is obtained, rotate the pinion several times to ensure the bearings have seated. Recheck the rotating torque and adjust if necessary.
20. Lubricate the differential side bearings with axle lubricant. Use the proper fluid. Refer to Fluid and Lubricant Recommendations in Maintenance and Lubrication.



21. Place the differential case, with the bearing cups installed, into the axle housing.



22. Install the bearing caps and the bolts.

Do not torque the bearing cap bolts at this time.

23. Adjust the differential side bearing preload. Refer to Differential Carrier Bearing Preload Adjustment .



24. Measure the rotating torque of the pinion and the ring gear. Compare this measurement with the rotating torque recorded during removal.

Specification
The rotating torque of the pinion and the ring gear should be 2.8-5.6 N·m (25-50 lb in) (used bearings) or 3.9-6.2 N·m (30-55 lb in) (new bearings).

25. If the rotating torque of the pinion and the ring gear is not within specifications, adjust the differential side bearing preload or the pinion bearing preload as necessary.
26. Once the specified torque is obtained, rotate the pinion several times to ensure the bearings have seated. Recheck the rotating torque and adjust if necessary.
27. Adjust the backlash. Refer to Backlash Adjustment .
28. Perform a gear tooth contact pattern check. Refer to Gear Tooth Contact Pattern Inspection .
29. Tighten the bearing cap bolts

Tighten
Tighten the bearing cap bolts to 75 N·m (55 lb ft).




30. Install the axle shaft bearing using the J 23765 (7.6 inch axle) or the J 23690 (8.6 inch axle) (1) and the J 8092  (2).
31. Drive the axle shaft bearing into the axle housing until the tool bottoms against the tube.



32. Install the axle shaft seal using the J 23771 (7.6 inch axle) or the J 21128 (8.6 inch axle).
33. Drive the tool into the bore until the axle shaft seal bottoms flush with the tube.

Important: Carefully insert the axle shaft in order to not damage the seal.




34. Install the axle shaft (1) into the housing (5).
35. Slide the axle shaft (1) into place allowing the splines to engage the differential side gear.
36. On axles without a locking differential, place the lock (4) on the button end of the axle shaft (1).
37. On axles with a locking differential, keep the pinion shaft partially withdrawn.



38. On axles with a locking differential, place the lock (1) on the axle shaft (3) so that the ends are flush with the thrust block (2).
39. Pull the shaft flange outward in order to seat the lock in the differential gear.



40. Align the hole in the pinion shaft with the bolt hole in the differential case.
41. Install the new pinion shaft locking bolt.

Tighten

•	Tighten the pinion shaft locking bolt to 34 N·m (25 lb ft) (7.6 inch axle).

•	Tighten the pinion shaft locking bolt to 36 N·m (27 lb ft) (8.6 inch axle).




42. Install the rear axle housing cover (2) and a new gasket.
43. Install the rear axle housing cover bolts (1).

Tighten

•	Tighten the rear housing cover bolts in a crosswise pattern to 30 N·m (20 lb ft) (7.6 inch axle).

•	Tighten the rear housing cover bolts in a crosswise pattern to 39 N·m (29 lb ft) (8.6 inch axle).




44. Install the drain plug (8.6 inch axle only).

Tighten
Tighten the drain plug to 33 N·m (24 lb ft).

45. Fill the axle using the proper fluid. Refer to Approximate Fluid Capacities and Fluid and Lubricant Recommendations in Maintenance and Lubrication.



46. Install the fill plug.

Tighten
Tighten the fill plug to 33 N·m (24 lb ft).