Adjustment Procedure

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NOTE:

The differential side bearing bores and the pinion bearing cups must be clean and free of any debris before proceeding with the pinion bearing adjustment.

Lubricate the pinion bearings with the proper axle lubricant. Refer to Fluid and Lubricant Recommendations .
Install the pinion bearings into the rear axle housing.

Fig 1: Special Tools In Axle Housing

Courtesy of GENERAL MOTORS CORP.

Install the J 21777-35 (1), the J 21777-43 (2), the J 21777-42 (3), and the J 21777-29 (4) in the rear axle housing.

NOTE:

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

Using a inch pound torque wrench and holding the J 21777-43, tighten the nut of the J 21777-43 until a rotating torque of 1.7 N.m (15 lb in) is obtained.
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: Assembling Special Tools In Differential Carrier Bore

Courtesy of GENERAL MOTORS CORP.

Install the J 21777-45 (1, 2) to the J 21777-1 (3) in the rear axle housing.
Install the differential bearing caps.

CAUTION:

Refer to Fastener Caution .

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

NOTE:

In the following service procedure, 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.

Rotate the J 21777-1 within the J 21777-45.

Fig 3: Aligning Special Tools

Courtesy of GENERAL MOTORS CORP.

Align the plunger of the J 21777-1 (1) to the gauge block setting of the J 21777-29.
Loosely clamp the J 8001 indicator on the stem on the J 21777-1.
Place the contact pad of the J 8001 indicator on the mounting post of the J 21777-1.
With the contact pad of the J 8001 indicator touching the mounting post of the J 21777-1, loosen the lock nut on the J 8001 indicator and push down on the J 8001 indicator until the needle the J 8001 indicatorh as turned 3/4 of a turn clockwise.
Tighten the clamp on the J 8001 indicator finger tight.

NOTE:

The deflection is the point where the needle changes direction.

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

Fig 4: Setting Pinion Depth

Courtesy of GENERAL MOTORS CORP.

At the greatest point of deflection, move the housing of the J 8001 indicator until the needle indicates zero.
Move the plunger of the J 21777-1 back and forth again to verify the zero setting. Adjust the housing of the J 8001 indicator as necessary to set the needle to zero.
Rotate the plunger of the J 21777-1 away from the J 21777-29 until it no longer touches the J 21777-29.
The value indicated on the J 8001 indicator is the thickness of the shim needed in order to set the depth of the pinion.

NOTE:

Measure the shim with a micrometer in order to verify that the thickness is correct.

Select the shim that indicates the proper thickness.
Remove the pinion depth setting tools.
Remove the pinion bearings.
Install the pinion shim between the pinion gear and the inner pinion bearing. Refer to Differential Drive Pinion Gear Bearing Replacement (8.6 Inch Axle) , Differential Drive Pinion Gear Bearing Replacement (10.5 Inch Axle) .