Determining Drive Pinion Depth

Fig. 9 Rear axle pinion depth gauge:

Fig. 10 Pinion depth gauge block installation:

Prior to determining drive pinion depth, clean pinion bearing cups and differential bearing pedestals thoroughly to ensure an accurate reading. Apply only a light oil film to bearing assemblies to avoid false readings.
1. Assemble aligning adapter, gauge disc and gauge block to tool T79P-4020-A, Fig. 9.
2. Place rear pinion bearing over aligning adapter, then insert tool and bearing in rear pinion bearing cup in pinion housing bore. Place front pinion bearing over screw in front pinion bearing cup and assemble tool handle onto screw. Torque handle to 20 ft. lbs. Ensure tool is mounted securely between front and rear bearings.
3. Rotate gauge block several half turns to ensure bearings are seated properly. Rotational torque should be 20 ft. lbs. with new bearings. Set gauge block at an angle approximately 45 degrees from horizontal, Fig. 10.
4. Install gauge tube in differential bearing mounts, then install bearing caps and bearing cap bolts.
5. Use pinion shims to determine pinion depth by inserting shims between gauge block and gauge tube. The correct shim will fit with a slight drag. Do not attempt to force a shim between block and tube. Do not use shims that are bent, dirty, nicked or mutilated as a gauge.
6. Make note of proper shim size and remove tool from axle housing.
7. Using suitable arbor press and adapters, remove rear pinion bearing.
8. Install shim determined in step 5 above on pinion shaft, then reinstall bearing using arbor press. The rear pinion bearing used to determine drive pinion depth must be used in the final assembly of the axle.