Differential Assembly: Description and Operation

Rear Carrier Component Identification:

Torque Tube And Overrunning Clutch:

DESCRIPTION
The rear drive line module assembly consists of five main parts: the rear carrier, torque tube, overrunning clutch assembly, a vacuum operated dog clutch, and a viscous coupling.

The primary benefit of All Wheel Drive is:
- Superior straight line acceleration, and comering on all surfaces
- Better traction and handling under adverse conditions, resulting in improved hill climbing ability and safer driving.

The heart of the system is an inter-axle viscous coupling. The vehicle retains predominantly front wheel drive characteristics, but the All Wheel Drive capability takes effect when the front wheels start to slip. Under normal level road, straight line driving, 90% of the torque is allocated to the front wheels. The viscous coupling allows more torque to the rear wheels in accordance with the amount of the slippage at the front wheels. The variable torque distribution is automatic with no driver inputs required.

The rear carrier contains a conventional open differential with hypoid ring gear and pinion gear set. The hypoid gears are lubricated by SAE 80W-90 gear lubricant.

The torque tube assembly attaches to the overrunning clutch case. The front torque shaft bearing is located in the torque tube. The front torque shaft bearing is permanently sealed and does not require maintenance. The torque shaft is located within the torque tube assembly. The vacuum reservoir and solenoid assembly are attached to the top of the torque tube.

The overrunning clutch allows the rear wheels to overrun the front wheels during a rapid front wheel lock braking maneuver. The overrunning action prevents any feed-back of front wheel braking torque to the rear wheels. It also allows the braking system to control the braking behavior as a two wheel drive (2WD) vehicle.

The overrunning clutch has a separate oil sump and is filled independently from the differential. The fill plug is located on the side of the overrunning clutch case. When filling the overrunning clutch with lubricant use Mopar(R) Type 7176 Automatic Transmission fluid or equivalent.

The dog-clutch provides All Wheel Drive in reverse by bridging and locking out the overrunning clutch. The dog-clutch is operated by a double-acting servo using intake manifold vacuum as its power source. Two vacuum solenoids, controlled by the back up light switch, engage and disengage the dog-clutch. A spring in the vacuum servo disengages the dog clutch if vacuum is lost.

Located in front of the torque tube is the viscous coupling. The viscous coupling controls and distributes torque/power to the rear wheels. The coupling is similar to a multi-plate clutch. It consists of a series of closely spaced discs. The discs are alternately connected to the front and rear drive units, which operate in silicone fluid. The unit is totally sealed and partially filled with silicone fluid. There is no adjustment, maintenance or fluid checks required during the life of the unit.