2004 GMC 2500 Step-By-Step Axle Gear Swap - Diesel Tech

1) Eric Brusman and Justin Hustead were in charge of the gear swap. Hustead started by removing the rear driveshaft.

2) Then the Mag-Hytec differential cover was removed so the old gear lube could be drained.

3) Next, the wheel center caps were removed to expose the axleshaft flange. After removing the bolts, Hustead removed the axleshafts from the truck.

4) Brusman then marked the carrier caps' position so that they could be reinstalled in the exact same location. The four bolts that retain the carrier caps were removed, and care was taken to ensure that the carrier did not fall out of the axlehousing.

5) When the carrier was removed, the pinion gear became visible.

6) Hustead removed the pinion gear nut with an impact gun, and then used a three-bolt puller to drive the pinion gear forward into the differential to separate the pinion gear from the driveshaft yoke.

7) Brusman grabbed the pinion gear as Hustead pushed it through. Technicians will often use an air hammer to drive the pinion gear out of the axlehousing, but doing so increases the chance of damaging the pinion. If you think there's a chance you might reuse the stock gears, use care when you remove the old parts.

8) Although the Yukon Gear installation kit came with new shims, Brusman used a hydraulic press to push the inner pinion bearing off the old pinion gear so that he could get the factory shim.

9) Brusman chose to reuse the old shim (arrow) with the new bearings and pinion gear, as he told us in most cases this gives him the correct pinion depth on the first try.

10) The change from 3.73 to 4.56 gears gives the engine a more of a mechanical advantage to move the truck. In this case, the stock 3.73 pinion gear (right) had 11 teeth, and the new 4.56 pinion gear (left) only has 9 teeth.

11) With the old pinion shim in place, a new bearing (A) was pressed onto the new pinion gear. The bearing was then coated in grease and a new crush sleeve (B) was installed onto the pinion gear. This crush sleeve is designed to be "crushed" as the pinion gear nut is tightened. How much it gets crushed determines the preload on the pinion bearings.

12) The inside of the axlehousing was cleaned with brake cleaner to remove all the old grime. When everything was spotless, the pinion gear bearing races in the axlehousing were replaced, and the new pinion gear was installed with the old pinion shim, new inner pinion bearing, and new crush sleeve.