How-To Install and Setup Axle Ring and Pinion Gears
Good gear men are like voodoo priests. They are the keepers of the dark art. There are two things that will strike fear into the average mechanic, and setting up a diff is one of them. Setting up a differential is probably one of the most under-rated jobs that a mechanic can tackle. "Setting up" a rear end involves much more than merely replacing parts and installing them without any regard to the tolerances that the components must be held to. Proper setup requires patience, cleanliness, and attention to detail.
Upon removing the diff cover and draining the gear oil from the axle, mark the position of the differential bearing caps with a center punch or letter stamp set to insure proper location and orientation during reassembly. Remove the differential carrier from the housing (it may be a tight fit due to carrier bearing preload).
Note the position of any shims and their location. Remove the pinion nut and strike the pinion out of the housing. Remove the pinion bearing races from the rear end housing. Remove the carrier bearings from the differential carrier and the pinion bearings from the pinion gear.
Inspect the rear end housing closely in the area where the pinion bearing races are pressed in and where the bearing caps hold the differential bearing races. Look for signs of the bearing races spinning. Check the differential carrier and the pinion gear for signs of loose fitting bearings or spinning bearings. If the rear-end housing does not pass inspection, a replacement should be found or the housing may be repaired by a reputable machine shop. If the carrier or the pinion gear are found to be damaged, a replacement should be seriously considered.
Install the new bearing races...