Rear Drive Axle and Differential

WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.

The 9.75-inch ring gear rear conventional differential has 3.31 and 3.73 gear ratio versions.

The 9.75-inch ring gear rear differential with eLSD has 3.73 gear ratio.

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
A cast iron housing and carrier and a cast aluminum differential housing cover
A cast aluminum differential housing cover and HCU
Differential housing cover that uses silicone 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
Optional eLSD

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 eLSD system directs torque, enabling the vehicle to drive over terrain and road conditions that a conventional axle cannot. The system is active at all times and requires no input from the driver. The eLSD is not equipped with a lock button which enables the Locking function of the rear drive axle.

The eLSD system consists of the following components:

HCU
Hydraulic Actuator
HCU Clutches
HCU Carrier
DCMR

The Drive Mode Selection

The Drive Mode Select system provides varying driving experiences through a suite of sophisticated electronic vehicle systems. The system allows selection of different modes for the vehicle to operate. The associated drive mode select switch allows the driver to select the mode best suited to the driving conditions. Each mode changes a number of the vehicle parameters within the engine, transmission, traction control and drive systems. The system is controlled by rotary type switch located on the center console. The system provides a single location to control multiple systems performance settings.

Changing the drive mode automatically changes the functionality of the following systems:

EPAS system adjusts steering effort and feel based on the selected drive mode.
Electronic stability control and traction control maintains vehicle control in adverse conditions or high performance driving.
Electronic throttle control enhances the powertrain response to driver inputs.
Transmission controls are optimized with shift schedules tuned to each mode.
Transfer case automatically engages specific 4WD modes.
eLSD engages automatically in certain drive modes.