Determining Total Shim Pack Size

NOTICE:
- Both methods for setting differential bearing preload and gear backlash are described. All Model 80 axle assemblies can be serviced by using the outboard selective shim method.
- If the original axle assembly has the outboard selective shims, it should not be serviced using the inboard shims for preload/backlash adjustment. In other words, if you have outboard selective shims, you must stay with that method. If the axle assembly uses inboard shims and outboard spacers (non-selective), you may use the outboard selective shim method for service.
- If your axle assembly has selective outboard spacers and one 0.76 mm (0.030 inch) shim (each side) between the differential case and bearing cone. Make your measurements with the outboard spacers removed, but with the 0.76 mm (0.030 inch) shim assembled on the differential case trunnion placed between the case and the master differential bearings. The selective outboard spacers are available in sizes (thickness) from 5.18 mm (0.2040 inch) to 6.10 mm (0.2400 inch), in 0.08 mm (0.003 inch) increments. The dial indicator should have the capability of making measurements up to 12.7 mm (0.500 inch).
- If your axle assembly has outboard spacers, but controls the preload and backlash by using selective shims (each side) between the differential case and bearing cone. Make the measurements with the outboard spacers installed in the housing, but do not place any shims on the differential case hubs between the case and master differential bearings. The selective shims placed between the bearing cone and differential case are available in 0.08, 0.13, 0.25, 0.76 mm (0.003, 0.005, 0.010, 0.030 inch) sizes. The dial indicator should have the capability of making measurements up to 3.81 mm (0.150 inch).

1. Assemble the case to the axle housing. The pinion must not be installed.





2. Mount a dial indicator having a minimum travel of 5 mm (0.200 inch) with a magnetic base on the ring gear bolt side of the housing.
3. Force the differential assembly as far as possible in the direction toward the indicator.
4. Preload the dial indicator one half of its travel. Place the tip of the indicator on a flat surface on the differential, next to a ring gear bolt. Mark this location with a piece of chalk.
5. Zero the dial indicator.
6. Force the differential case in the opposite direction as far as it will go. Repeat this Step until the same reading is obtained. Record the number of thousandths that the dial indicator traveled, not the reading on the dial. This will be the measurement of the shim pack without the bearing preload (which will be added later).
7. Remove the dial indicator.
8. Remove the differential from the housing.
- Do not remove the master bearings from the differential.
9. Remove the spacers from the housing, if used.
- Spacers are removed to prevent them from falling out while installing the pinion gear. Tag spacers and indicate from which side they were removed. They must be reassembled as removed or the reading taken in Step 6 will not be correct.