Differential Assembly: Adjustments

DESCRIPTION
A drive pinion bearing adjustment shim 0.254 mm to 0.965 mm (0.010 to 0.038 inch) is used between the rear differential pinion bearing and pinion head. The correct drive pinion bearing adjustment shim size will locate the pinion for proper tooth contact with ring gear. Selecting correct drive pinion bearing adjustment shim when installing a new differential ring gear and pinion can be done by using Pinion Depth Gauge Set T79P-4020-A.





PROCEDURE
1. Refer to illustration and assemble the appropriate aligning adapter, gauge disc and gauge block to the screw.





2. Place differential pinion bearing (new, or used if in good condition) over aligning disc and insert into rear axle pinion bearing cup. Place front differential pinion bearing into the differential drive pinion bearing cup and assemble the tool handle into screw. Tighten to 2.26 Nm (20 inch lbs.).

NOTE: The gauge block must be offset to obtain an accurate reading.

3. Make sure the gauge handle adapter screw, aligning adapter, gauge disc and gauge block assembly are securely mounted between the front differential pinion bearing and rear differential pinion bearing. Check the tool handle torque prior to gauging to make sure bearings are properly seated. This can affect final shim selection when improperly assembled. Clean bearing cups and differential pedestal surfaces thoroughly. Apply only light oil film on bearing assemblies prior to gauging.
4. The gauge block should then be rotated several half-turns to make sure rollers are properly seated in bearing cups. Rotational torque on the gauge assembly should be 2.2 Nm (20 inch lbs.) with new bearings. Final position should be approximately 45° across gauge tube to make sure gauge block is in-line with gauge tube high point. This area should be used for pinion shim selection. Selection of drive pinion bearing adjustment shim with gauge block not lined up with tube high point will cause improper shim selection and may result in axle noise.
5. Use drive pinion bearing adjustment shims as the gauge for shim selection. This will minimize errors in attempting to stack feeler gauge stock together. It will also minimize simple addition errors in calculating correct shim thickness.

NOTE: Drive pinion bearing adjustment shims must be flat. Do not use dirty, bent, nicked or mutilated drive pinion bearing adjustment shims as a gauge.

6. It is important to feel a slight drag on the drive pinion bearing adjustment shim for correct selection. Do not attempt to force the drive pinion bearing adjustment shim between the gauge block and the gauge tube. This will minimize selection of a drive pinion bearing adjustment shim thicker than required which results in a deep tooth contact in final assembly of the axle.

NOTE: The same differential pinion bearing used in this procedure must be used in final assembly of the axle.

7. Place the drive pinion bearing adjustment shims on pinion shaft. Press differential pinion bearing until firmly seated on shaft.