Rear Drive Axle/Differential - Ford 8.8-Inch Ring Gear High Torque

Rear Drive Axle and Differential
The rear drive axle consists of the following:
^ The axle housing is a cast center section with 2 steel tube assemblies and a stamped differential housing cover
^ The differential housing cover uses silicone sealant as a gasket
^ The hypoid-design gearset (which is not serviced) consists of an 8.8-in ring gear and a drive pinion gear
^ Two opposed tapered roller bearings (drive pinion bearings) support the drive pinion in the axle housing
^ A drive pinion collapsible spacer, located on the differential pinion shaft, maintains drive pinion bearing preload
^ The pinion nut adjusts the drive pinion bearing preload
^ Differential bearing shims control the differential bearing preload and the differential ring gear backlash
^ Two opposed tapered roller bearings (differential bearings) support the differential assembly in the axle housing
^ Removable bearing caps retain the differential assembly in the axle housing
^ The differential case is a one-piece design with 2 openings to allow for lubricant flow
^ Inside the differential assembly, the differential pinion shaft supports 2 differential pinion gears
^ The pinion gears engage the differential side gears, to which the axle shafts are splined
^ The differential pinion shaft lock bolt retains the differential pinion shaft in the differential case
^ The semi-floating axle shafts are held in the housing by U-washers positioned in the slot on the axle shaft splined end
^ These U-washers also fit into a recess in the differential side gears within the differential case
^ Independent center spring in Traction-Lok(R) applications for clutch disc pressure

The 8.8-in high torque differential ring gear should not be removed from the differential flange. If directed to replace the differential ring and pinion gearset or differential case in the Diagnosis and Testing procedure, it will be necessary to replace the entire axle assembly. This includes the differential case internals such as side and pinion gears, Traction-Lok(R) discs and plates, thrust washers or ring gear bolts.

The rear axle assembly receives rotational input from the driveshaft through a piloted pinion flange. The drive pinion drives the ring which is bolted to the differential case. The design of the differential allows the side gears in the case to rotate at different speeds. The axle shafts are splined to the side gears permitting the vehicle to manipulate corners without sliding the inside tire. The weight of the vehicle is carried through the axle shaft bearing located in the tubes of the axle housing.

The axle identification tag identifies a particular axle design, a specific ratio and if it is a conventional or limited slip Traction-Lok(R) type. In addition, the plant code will not change as long as that particular axle assembly never undergoes an external design change. If, however, an internal design change takes place during the production life of the axle and that internal change affects parts interchangeability, a dash and numerical suffix is added to the plant code. This means that as an assembly, both axles are interchangeable; however, internally they are different. Therefore, each requires different internal parts at the time of repair.