Differential Assembly: Description and Operation

Rear Drive Axle and Differential

The rear drive axle consists of the following:

- A cast iron housing and a cast aluminum differential housing cover.
- Differential housing cover that uses silicone sealant as a gasket.
- The hypoid-design gearset consists of a 9.75-inch differential ring gear and a drive pinion gear.
- Two opposed pinion bearings support the drive pinion gear in the differential housing.
- A drive pinion collapsible spacer, located on the drive pinion gear shaft, maintains pinion bearing preload.
- The pinion nut adjusts the preload.
- Differential bearing shims, located between the differential bearing cups and the differential housing, adjust the differential ring gear backlash and the differential bearing preload.
- The differential case is a 1-piece design with 2 openings to allow for assembly of the internal components and lubricant flow.
- Two opposed differential bearings support the differential case in the differential housing.
- Removable differential bearing caps retain the differential assembly in the differential housing.
- A differential pinion shaft supports 2 differential pinion gears.
- A differential pinion shaft lock bolt retains the differential pinion shaft in the differential case.
- A circlip, located on the stub shaft, holds the halfshaft in the differential case. When installed, the circlip engages a groove in the differential side gear.
- The pinion gears engage the differential side gears, to which the halfshafts are splined.
- The rear axle requires SAE 75W-140 Synthetic Rear Axle Lubricant XY-75W140-QL (US); CXY-75W140-1L (Canada); or equivalent meeting Ford specification WSL-M2C192-A. If equipped with a Traction-Lok(R), 4 ounces of Friction Modifier XL-3 (US); CXL-3 (Canada); or equivalent meeting Ford specification EST-M2C118-A must be added.
- The rear axle ratio may be verified by checking the printed label on the axle housing. If worn or not visible, the Vehicle Identification Number (VIN) or the Vehicle Certification (VC) label may be used. For additional information, refer to Driveline System - General Information Description and Operation.

The rear drive axle receives rotational torque from the driveshaft through the pinion flange. The drive pinion turns the differential case. The differential case has a shaft with a pinion gear on each end. The shaft is bolted through the case and allows the pinion gears to roll with the differential side gears, providing the differential action letting the splined halfshafts drive at different speeds as needed when cornering.