Pinion Depth Adjustment 8.6, 9.5 Inch Axles

Tools Required

Important: Make sure all of the tools, the differential side bearing bores, and the pinion bearing cups are clean before proceeding.

1. Lubricate the pinion bearings with axle lubricant. Refer to Fluid and Lubricant Recommendations in Maintenance and Lubrication.
2. Install the pinion bearings into the axle housing.



3. Assemble the following components into the axle housing:

•	For the 8.6 inch axle, assemble the J 21777-35 (1), the J 21777-43  (2), the J 21777-42  (3), and the J 21777-29 (4) as shown.

•	For the 9.5 inch axle, assemble the J 21777-8 (1), the J 21777-43  (2), the J 21777-42  (3), and the J 21777-85  (4) as shown.

4. While holding the J 21777-43 stationary, install an inch-pound torque wrench on the nut of the J 21777-43 and tighten the nut until a rotating torque of 1.7 N·m (15 lb in) is obtained.

Rotate the assembly several times in both directions in order to seat the pinion bearings.

5. Check the rotating torque of the assembly. If the torque is less than 1.7 N·m (15 lb in), tighten the nut on the J 21777-43 until a rotating torque of 1.7-2.3 N·m (15-20 lb in) is obtained.



6. Assemble the following components into the differential carrier bore of the axle housing:

•	For the 8.6 inch axle, assemble the J 21777-45 (1, 2) to the J 21777-1 (3) as shown.

•	For the 9.5 inch axle, assemble the J 21777-86 (1, 2) to the J 21777-1 (3) as shown.

7. Install the bearing caps.

Notice: Refer to Fastener Notice in the Preface section.

8. Install the bearing cap bolts.

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

9. Rotate the J 21777-1 within the J 21777-45 (8.6 inch axle), or the J 21777-86 (9.5 inch axle). The J 21777-1 must rotate back and forth freely within the discs. If the J 21777-1 does not rotate freely, disassemble the components, inspect for proper seating and/or mis-aligned components and re-assemble.



10. Align the plunger of the J 21777 -1 (1) to the 8.5 inch gauge block setting of the J 21777-29 (8.6 inch axle), or the J 21777-85 (9.5 in axle).
11. Install the J 8001 to the J 21777-1 as follows:

11.1.

Loosely clamp the J 8001 onto the stem on the J 21777-1.

11.2.

Place the contact pad of the J 8001 onto the mounting post of the J 21777-1.

11.3.

With the contact pad of the J 8001 touching the mounting post of the J 21777-1, loosen the lock nut on the J 8001 and push down on the J 8001 until the needle the J 8001 has turned 3/4 of a turn clockwise.

11.4.

Tighten the clamp on the J 8001 finger tight.

12. Move the plunger of the J 21777-1 back and forth until the needle of the J 8001 indicates the greatest deflection.

The deflection is the point where the needle changes direction.




13. At the greatest point of deflection, move the housing of the J 8001 until the needle indicates zero.
14. Move the plunger of the J 21777-1 back and forth again to verify the zero setting. Adjust the housing of the J 8001 1 as necessary to set the needle to zero.
15. Rotate the plunger of the J 21777-1 away from the J 21777-29 (8.6 inch axle) or the J 21777-85 (9.5 inch axle) until the J 21777-1 no longer touches the J 21777-29 (8.6 inch axle) or the J 21777-85 (9.5 inch axle).
16. The value indicated on the J 8001 is the thickness of the shim needed in order to set the depth of the pinion.
17. Select the shim that indicates the proper thickness. Measure the shim with a micrometer in order to verify that the thickness is correct.
18. Remove the pinion depth setting tools.
19. Remove the pinion bearings.
20. Install the pinion shim between the pinion gear and the inner pinion bearing. Refer to Drive Pinion Bearings Replacement .

Pinion Depth Adjustment 11 Inch Axle

Tools Required

Important: Make sure all of the tools, the differential side bearing bores, and the pinion bearing cups are clean before proceeding.

1. Assemble the J 41691 to the J 41692 .
2. Install the outer pinion bearing onto the J 41691 .
3. Install the inner pinion bearing onto the J 41690 .
4. Install the J 41691 , the outer pinion bearing and the J 41692 into the axle housing.
5. While holding the J 41691 , the outer pinion bearing and the J 41692 in place, install the J 41690 with the inner pinion bearing onto the J 41692 .
6. Install the J 41689 onto the J 41692 .
7. While holding the J 41689 stationary, tighten the J 41691 .

Tighten
Tighten the J 41691 to 1.7 N·m (15 lb in).

8. Assemble the J 41789 (2 required) to the J 39702 .



9. Install the J 41789 (1) and the J 39702 (2) into the axle housing.




Important: Corresponding letters are stamped on the bearing caps and axle housing. The bearing caps must be reassembled in the same position as removed.

10. Install the bearing caps.

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.

11. Install the bearing cap bolts.

Tighten
Tighten the bearing cap bolts finger tight. Do not torque the bolts to specification at this time.

12. Rotate the J 39702 within the J 41789 . The J 39702 must rotate freely within the discs. If the J 39702 does not rotate freely, disassemble the components, inspect for proper seating and/or mis-aligned components and re-assemble.



13. Install the J 26900-12 (2) onto the J 39704 (1).



14. Place the J 26900-12 (1) and the J 39704 (2) onto the J 41689 (3).
15. While holding the J 26900-12 and the J 39704 on the J 41689 , turn the face of the J 26900-12 until the needle and the zero are aligned.



16. Once the needle and the zero of the are aligned, slide the J 26900-12 (1) and the J 39704 (2) on the J 41689 (3) towards the J 39702 (4) until the needle of the J 26900-12 indicates the greatest value.

Repeat this step several times in order to verify the reading.

The value indicated is the amount of pinion preload shim thickness, in millimeters, required for a nominal pinion setting.

17. In order to adjust the pinion preload shim thickness for the pinion that is to be installed, do the following:

17.1.

Read the number on the button end of the pinion.

If the number on the button end of the pinion is "0", no adjustment of the pinion preload shim pack is necessary.

17.2.

If the number is not "0", the number will also have a corresponding "+" or "-" in front of it.

The "+" or "-" indicates the amount of pinion preload shim thickness that either needs to be added to or subtracted from the amount determined in step 19 in order to the drive pinion gear to be positioned properly within the axle housing.

•

For example, if the number on the button end of the pinion is a "+3", this indicates that 0.0762 mm (0.003 in) of shim thickness will need to be subtracted from the value determined in step 19 in order to place the teeth of the pinion in the best running position with the teeth of the ring gear. Refer to the table below.

•

If the number on the button end of the pinion is a "-3", this indicates that 0.0762 mm (0.003 in) of shim thickness will need to be added to the value determined in step 19 in order to place the teeth of the pinion in the best running position with the teeth of the ring gear. Refer to the table below.

18. Remove the pinion depth setting tools.
19. Install the pinion position shim onto the drive pinion.

Measure the thickness of the shim with a micrometer in order to verify the thickness.




20. Install the inner pinion bearing onto the drive pinion using the J 44412 .
21. Install the original pinion preload shim thickness onto the drive pinion. If the original shim thickness is not available, assemble 1.52 mm (0.060 in) of pinion preload shims.

Measure each shim separately with a micrometer and add the thickness together to determine the total shim pack size.

22. Install the drive pinion with the inner pinion bearing and the pinion preload shims into the axle housing.
23. Install the outer pinion bearing.
24. Install the thrust washer.
25. Seat the pinion yoke onto the pinion shaft by tapping it with a soft-faced hammer until a few pinion shaft threads show through the yoke.
26. Install the pinion yoke nut washer.
27. Install the pinion yoke nut.

Tighten
Tighten the pinion yoke nut to 339 N·m (250 lb ft).

28. Measure the rotating torque of the drive pinion using an inch-pound torque wrench.

Specification
The rotating torque of the drive pinion should be between 2.8-4.0 N·m (25-35 lb in).

29. If the rotating torque of the drive pinion is not within specifications, adjust the pinion preload shim thickness by doing the following:

29.1.

Install the J 8614-01 to the pinion yoke.

29.2.

Remove the pinion nut while holding the J 8614-01 .

29.3.

Remove the washer.





29.4.

Install the J 8614-2 (2) and the J 8614-3 (3) into the J 8614-01 (1) as shown.

29.5.

Remove the pinion yoke by turning the J 8614-3 (3) clockwise while holding the J 8614-01 (1).

29.6.

Remove the thrust washer.

29.7.

Remove the outer pinion bearing.

29.8.

Remove the drive pinion using a soft-faced hammer.

29.9.

Remove the pinion preload shims.

29.10.

Adjust the amount of pinion preload shim thickness by doing the following:

Important: Removing approximately 0.0254 mm (0.001 in) of shim thickness will increase the rotating torque by approximately 71-89 N·m (8-10 lb in).

•	If the rotating torque is too low, remove the appropriate amount of shim thickness from the shim thickness pack using the guideline above.

•	Measure each shim separately with a micrometer and add the thickness together to determine the total shim pack size.

Important: Adding approximately 0.0254 mm (0.001 in) of shim thickness will decrease the rotating torque by approximately 71-89 N·m (8-10 lb in).

•	If the rotating torque is too high, add the appropriate amount of shim thickness to the shim thickness pack using the guideline above.

•	Measure each shim separately with a micrometer and add the thickness together to determine the total shim pack size.

30. Install the new pinion preload shim pack onto the drive pinion.
31. Install the drive pinion with the inner pinion bearing and the pinion preload shims into the axle housing.
32. Install the outer pinion bearing.
33. Install the thrust washer.
34. Seat the pinion yoke onto the pinion shaft by tapping it with a soft-faced hammer until a few pinion shaft threads show through the yoke.
35. Install the pinion yoke nut washer.
36. Install the pinion yoke nut.

Tighten
Tighten the pinion yoke nut to 339 N·m (250 lb ft).

37. Measure the rotating torque of the drive pinion using an inch-pound torque wrench.

Specification
The rotating torque of the drive pinion should be between 2.8-4.0 N·m (25-35 lb in).

38. If the rotating torque of the drive pinion is not within specification, adjust the pinion bearing preload shim pack as necessary following the steps above.



39. If the rotating torque is within specifications, install the J 8614-01 to the pinion yoke.
40. Remove the pinion nut while holding the J 8614-01 .
41. Remove the washer.



42. Install the J 8614-2 (2) and the J 8614-3 (3) into the J 8614-01 (1) as shown.
43. Remove the pinion yoke by turning the J 8614-3 (3) clockwise while holding the J 8614-01 (1).
44. Apply a light coat of axle lubricant (GM P/N 12346140 or equivalent) to lip of the pinion seal.



45. Install the new pinion oil seal using the J 41696 .
46. Seat the pinion yoke onto the pinion shaft by tapping it with a soft-faced hammer until a few pinion shaft threads show through the yoke.
47. Install the pinion yoke nut washer.
48. Install the new pinion yoke nut.

Tighten
Tighten the pinion yoke nut to 637 N·m (470 lb ft).

49. Measure the rotating torque of the drive pinion using an inch-pound torque wrench.

Specification
The rotating torque of the drive pinion should be between 2.8-5.1 N·m (25-45 lb in).

50. Install the differential assembly. Refer to Differential Replacement .

Pinion Depth Adjustment 10.5 Inch Axle

1. Install the differential, if necessary. Refer to Differential Replacement.

Important: Measure and record the thickness of the pinion gear bearing retainer shim before any service procedures are performed to the pinion gear bearing retainer assembly.

2. Install the original shim to the pinion bearing retainer. If the original shim is not available, install a 0.41 mm (0.016 in) shim to build pinion depth.

Important:  Do not apply sealant to the pinion gear bearing retainer at this time.

3. Install the pinion gear bearing retainer.

Notice: Refer to Fastener Notice in the Preface section.

4. Install the pinion gear bearing retainer bolts.

Tighten
Tighten the pinion gear bearing retainer bolts to 88 N·m (65 lb ft).

5. Adjust the backlash. Refer to Backlash Adjustment.
6. Perform a gear tooth pattern check on the pinion and the ring gear. Refer to Gear Tooth Contact Pattern Inspection.
7. If the gear tooth contact pattern indicates a high or a low flank contact pattern, adjust the pinion depth by doing the following:

7.1.	Remove the pinion gear bearing retainer bolts.

7.2.	Remove the pinion gear bearing retainer.

7.3.	Remove the shim.

•	If the gear tooth contact pattern shows a high flank contact pattern, install a shim one size larger.

•	If the gear tooth contact pattern shows a low flank contact pattern, install a shim one size smaller.

7.4.	Install the new shim to the pinion gear bearing retainer.

7.5.	Install pinion gear bearing retainer.

7.6.	Install pinion gear bearing retainer bolts.

Tighten
Tighten the pinion gear bearing retainer bolts to 88 N·m (65 lb ft).

7.7.	Inspect the gear tooth contact pattern of the pinion and the ring gear. Refer to Gear Tooth Contact Pattern Inspection.

7.8.	If the gear tooth pattern is still incorrect, adjust the shim thickness as necessary and recheck the gear tooth pattern of the pinion and the ring gear.

8. Inspect the backlash between the pinion and the ring gear and adjust, if necessary. Refer to Backlash Adjustment.

The pinion shims are available in the following sizes:

Shim Sizes