Land Rover Discovery: Rear Differential

Rear Differential Section View

1. Active on-demand coupling
2. Pinion shaft
3. Taper roller bearings
4. Pinion gear
5. Side gear - right halfshaft
6. Pinion gear
7. Crosspin shaft
8. Differential carrier
9. Angular contact ball bearings
10. Side gear - left halfshaft
11. Crown wheel drive gear
12. Collapsible spacer
13. Active on-demand coupling hydraulic fluid reservoir

The rear differential is a hypoid spiral bevel design. The crown wheel gearing provides an output ratio of 2.58:1.

The rear differential is located in the rear subframe, supported on four rubber mountings. Two mountings on the rear differential casing are located at the rear of the rear subframe. A bracket, which is bolted to the differential casing, locates the forward two mountings in the rear subframe.

The rear differential comprises differential casing which locates a pinion shaft and hypoid pinion-gear and a crown wheel drive-gear with an integral differential carrier, which houses two pinion gears. Two sun gears are also located in the differential carrier and pass the rotational drive to the halfshafts. The cast differential casing has a pinion housing bolted on the left side, which allows access to the internal components.

The pinion shaft is mounted on two opposed taper roller bearings, with a collapsible spacer located between them. The spacer is used to hold the bearings in alignment and also collapses under the pressure applied to the pinion flanged nut. This allows the flanged nut to be tightened to a predetermined torque, which collapses the spacer, setting the correct bearing preload.

The pinion shaft has an externally splined outer end which locates in the splined bore of the active on-demand coupling clutch drum and also locates in a needle roller bearing in the clutch drum. An oil seal is pressed into the casing and seals the pinion shaft to the differential casing.

The pinion shaft has a hypoid gear at its inner end, which mates with a crown wheel drive gear. The crown wheel drive gear is located on the differential carrier and secured with screws. The differential carrier is mounted on angular contact ball bearings located in machined bores on each side of the differential casing.

Shims are retained in the casing behind the bearing cups, the shim thickness is selected to apply the correct bearing preload and hypoid backlash. The differential carrier has a through hole, which provides location for a crosspin shaft. The crosspin shaft supports the pinion gears.

Each halfshaft is supported by a sun gear and the angular contact ball bearings. The halfshaft is fitted with a snap ring at one end, which locates in a machined groove in the sun gear, locking the halfshaft in position.

The sun gears are located in pockets in the differential carrier and mesh with the pinion gears. Spacers are fitted between the sun gears and the differential carrier and set the correct mesh contact between the pinion gears and the sun gears.

Oil seals are pressed into each side of the pinion housing and seal the halfshaft to the housing.

The plastic fluid reservoir on the side of the rear differential contains the hydraulic fluid for the active on-demand coupling. This is a separate reservoir to that of the rear differential which has its own oil. Both the rear differential and the active on-demand coupling fluids are fill for life. A level and drain plug is supplied in the plastic fluid reservoir for the on-demand coupling. The rear differential has a level plug in the side cover and a drain plug on the underside of the unit.

Rear Drive Axle- differential - Vehicles without- Active Driveline/  Description and OperationActive on-demand Coupling

READ NEXT: