Pinion Depth Adjustment (8.6, 9.5, 9.5LD Inch Axles)

Tools Required

• J 21777-85  Gage and Plate, 9. See Special Tools .5/9.5LD inch axle
• J 21777-86  Side Bearing Disc, 9. See Special Tools .5/9.5LD inch axle, 2 Required
• J 34925  Pinion Setting Gage and Components. See Special Tools .
• J 8001  Dial Indicator Set

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.
Fig 1: Installed View Of J 21777-35, J 21777-43, J 21777-42 & J 45230 In Axle Housing
Courtesy of GENERAL MOTORS CORP.
3. Assemble the following components into the axle housing:
   • For the 8.6 in 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 9.5/9.5LD in 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.
Fig 2: View Of J 21777-45 & J 21777-1 Installed Into Axle Housing
Courtesy of GENERAL MOTORS CORP.
6. Assemble the following components into the differential carrier bore of the axle housing:
   • For the 8.6 in axle, assemble the J 21777-45 (1, 2) to the J 21777-1 (3) as shown.
   • For the 9.5/9.5LD in axle, assemble the J 21777-86 (1, 2) to the J 21777-1 (3) as shown.
7. Install the bearing caps.
NOTE: Refer to Fastener Notice in Cautions and Notices.
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. See Special Tools .5/9.5LD 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.
Fig 3: View Of J 21777-1 & J 44416-3
Courtesy of GENERAL MOTORS CORP.
10. Align the plunger of the J 21777-1 (1) to the 8.5 inch gage block setting of the J 21777-29, 8.6 inch axle, or the J 21777-85  , 9. See Special Tools .5/9.5LD inch axle (2).
11. Install the J 8001  to the J 21777-1 as follows:
    1. Loosely clamp the J 8001  onto the stem on the J 21777-1.
    2. Place the contact pad of the J 8001  onto the mounting post of the J 21777-1.
    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.
    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.

Fig 4: Measuring Shim Thickness Using J 8001
Courtesy of GENERAL MOTORS CORP.
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  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. See Special Tools .5/9.5LD inch axle, until it no longer touches the J 21777-29 or the J 21777-85  . See Special Tools .
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 .