Rear Drive Axle and Differential - Overview
The 9.75-inch ring gear rear axle has SRW (Single Rear Axle), SRW Jumbo, DRW (Dual Rear Wheel) and DRW 5 Ton versions dependant on load capacity. All versions have full floating axles. The SRW has 3.31, 3.73, and 4.10 gear ratio versions. The SRW Jumbo has 3.73 and 4.10 gear ratio versions. The DRW has 3.73 and 4.10 gear ratio versions. DRW with 5 Ton has 3.73 gear ratio versions.
The rear axle assembly consists of the following:
- Integral-type housing hypoid gear design (center of the pinion set below the centerline of the ring gear)
- Hypoid differential ring gear and pinion consisting of a 9.75-inch ring gear and an overhung drive pinion that is supported by 2 opposed tapered roller bearings
- Pinion bearing preload that is maintained by a drive pinion collapsible spacer on the differential pinion shaft and adjusted by the pinion nut
- Cast center section with 2 steel tube assemblies and a stamped differential housing cover
- Differential housing cover using silicone rubber based sealant as a gasket
- Differential pinion shaft that is retained by a threaded differential pinion shaft lock bolt attached to the differential case
- Differential case that is mounted in the rear axle housing between 2 opposing differential bearings that are retained in the rear axle housing by 2 removable bearing caps
- Differential bearing preload and ring gear backlash which are adjusted by differential bearing shims that are located between the differential bearing cups and the rear axle housing
- Full floating axle shafts
The rear drive axle receives rotational torque from the driveshaft. The direction of the rotation determines movement of the vehicle. The rotation enters the rear drive axle through the drive pinion flange, turning the drive pinion and rotating the ring gear. The ring gear is bolted to the differential case. The differential case houses the pinion shaft upon which the differential pinion gears ride. The pinion gears are in mesh with the differential side gears to which the axle shafts are splined. It is the unique arrangement of the differential that allows the axle shafts to be driven at different speed when needed, such as when driving around corners. The Limited-Slip differential is available that introduces a series of clutch plates and discs behind the differential side gears to deliver as much torque as possible to each axle shaft when the traction at the rear wheels is not equal. The Limited-Slip differential requires a friction modifier that must be installed with the axle lubricant for the plates and discs to be functional.