Pinion Depth Adjustment

Tools Required

• J 21777-85  Gage and Plate. See Special Tools .
• J 21777-86  Side Bearing Disc, 2 Required. See Special Tools .
• J 34925  Pinion Setting Gage and Components

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. Use the proper fluid. Refer to Fluid and Lubricant Recommendations .
Fig 1: Assembling Special Tools In Axle Housing
Courtesy of GENERAL MOTORS CORP.
2. Assemble the following components into the axle housing:
   1. Install the pinion bearings into the axle housing.
   2. Assemble the J 21777-8 (1), the J 21777-43 (2), the J 21777-42 (3), and the J 21777-85 (4) as shown.
3. While holding the J 21777-43 stationary, slowly tighten the nut of the J 21777-43 until a rotating torque of approximately 1.1-2.2 N.m (10-20 lb in) is obtained.
4. Rotate the assembly several times in both directions in order to seat the pinion bearings.
5. Measure the rotating torque of the assembly using an inch-pound torque wrench.

   Specification:  The rotating torque of the assembly should be 1.1-2.3 N.m (10-20 lb in).

6. If the rotating torque of the assembly is less than 1.1N.m (10 lb in), continue to tighten the nut on the J 21777-43 until a rotating torque of 1.1-2.3 N.m(10-20 lb in) is obtained.
Fig 2: Assembling Special Tools In Differential Carrier Bore
Courtesy of GENERAL MOTORS CORP.
7. Assemble the J 21777-86 (1, 2) to the J 21777-1 (3) and install into the differential carrier bore of the axle housing as shown.
8. Install the bearing caps.
NOTE: Refer to Fastener Notice .
9. Install the bearing cap bolts.

   Tighten:  Tighten the bearing cap bolts to 85 N.m (63 lb ft).

10. Rotate the J 21777-1 within the J 21777-86. 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.
Fig 3: J 21777-1 & J 44416-3
Courtesy of GENERAL MOTORS CORP.
11. Align the plunger of the J 21777-1 (1) to the J 21777-85  (2). See Special Tools .
12. Install the J 8001-3 to the J 21777-1 as follows:
    1. Loosely clamp the J 8001-2 onto the stem on the J 21777-1.
    2. Install the J 8001-3 onto the J 8001-2.
    3. Place the contact pad of the J 8001-3 onto the mounting post of the J 21777-1.
    4. With the contact pad of the J 8001-3 touching the mounting post of the J 21777-1, loosen the lock nut on the J 8001-2 and push down on the J 8001-3 until the needle the J 8001-3 has turned 3/4 of a turn clockwise.
    5. Tighten the clamp on the J 8001-2 finger tight.
13. Move the plunger of the J 21777-1 back and forth until the needle of the J 8001-3 indicates the greatest amount of deflection.

    The greatest amount of deflection is the point where the needle changes direction.

Fig 4: Moving The Housing J 8001
Courtesy of GENERAL MOTORS CORP.
14. At the greatest point of deflection, move the housing of the J 8001-3 until the needle indicates ZERO.
15. Move the plunger of the J 21777-1 back and forth again to verify the ZERO setting. Adjust the housing of the J 8001-3 as necessary to set the needle to ZERO.
16. Rotate the plunger of the J 21777-1 away from the J 21777-85 until it no longer touches the J 21777-85.
17. The value indicated on the J 8001-3 is the thickness of the shim needed in order to set the depth of the pinion.
18. Select the shim that indicates the proper thickness. Measure the shim with a micrometer in order to verify that the thickness is correct.
19. Remove the pinion depth setting tools.
20. Remove the pinion bearings.
21. Install the pinion shim between the pinion gear and the inner pinion bearing. Refer to Drive Pinion Bearings Replacement .