Section 29 (Drive Axle - Rear (AWD)): Description

All-Wheel Drive (AWD) is available on all models equipped with 3.3L engine and A604 transaxle. AWD system consists of rear carrier, torque tube, overrunning clutch assembly, a vacuum operated dog clutch and a viscous coupling in one unit called the Rear Driveline Module (RDLM) . Power is supplied by a Power Transfer Unit (PTU) that sits in place of the extension housing on the transmission.

Rear carrier contains conventional open differential with hypoid ring and pinion gear set. See Fig 1 . Hypoid gears are lubricated by SAE 85W-90 gear oil.

Torque tube assembly attaches to overrunning clutch case. See Fig 2 . A drive shaft and a sealed front bearing assembly are located inside torque tube housing. A vacuum reservoir and solenoid assembly are bolted to top of torque tube.

Overrunning clutch allows rear wheels to overrun front wheels during rapid front wheel braking. Overrunning clutch prevents feedback of front wheel braking torque to rear wheels and allows braking behavior similar to FWD models. Overrunning clutch has separate oil sump and is filled independently from differential. See LUBRICATION  .

Dog clutch provides AWD action in reverse by bridging and locking out overrunning clutch. Dog clutch is operated by double-acting servo using manifold vacuum. Two vacuum solenoids, controlled by back-up light switch, engage and disengage dog clutch. Spring in servo disengages dog clutch if vacuum supply is lost.

Viscous coupling controls and distributes torque to rear wheels. Coupling is similar to a multiplate clutch. Alternating plates are indexed to front and rear drive units and operate in a silicone fluid. Unit is sealed and requires no maintenance or adjustment.

Rear axle shafts are similar to FWD axle and are serviced using FWD procedures. See AXLE SHAFTS - FRONT article in DRIVE AXLES.

Fig 1: Exploded View of Rear Carrier Assembly

Courtesy of CHRYSLER MOTORS.