Drive/Propeller Shafts, Bearings and Joints: Description and Operation
Driveline System
The driveline system consists of the following components:
- Center support bearing
- Driveshaft assembly
- Front halfshafts
- Rear halfshafts
- Active torque coupling/rear axle
On Front Wheel Drive (FWD) vehicles, the transaxle transmits power from the engine to the halfshafts.
On All-Wheel Drive (AWD) vehicles, power is transmitted from the engine through the transaxle to the Power Transfer Unit (PTU). The PTU transfers engine power from the transaxle to the front halfshafts, and through the driveshaft to the active torque coupling/rear axle and halfshafts. For information on the PTU, refer to Transfer Case.
The engine angle is built into the engine mounts. If the engine angle is out of specification, the engine mounts must be inspected for damage. Refer to Engine.
Vehicle Certification (VC) Label Example
The Vehicle Certification (VC) label is located in the driver door jamb. The axle code is on the VC label. Refer to Vehicle Identification Codes.
The axle ratio is 2.93 and the ring gear has a diameter of 174 mm (6.85 in).
The wheel speed sensor rings for FWD vehicles are located on the front halfshafts and are mounted to the rear inner spindles.
The wheel speed sensor rings are located on the front and rear halfshafts for AWD vehicles.
Driveshaft
The driveshaft is a 3-piece shaft with rubber-isolated center bearings.
The driveshaft has traditional balance weights attached (spot-welded) by the manufacturer.
U-joints
The CV and U-joints are installed new with the driveshaft.
The front CV joint is:
- lubricated with a special lubricant and requires no additional lubrication.
The center U-joints are:
- a lubed-for-life design that requires no periodic lubrication.
- equipped with nylon thrust washers located at the base of each bearing cup which control end play, position the needle bearings and improve grease movement.
Rear Drive Unit
The active torque coupling/Rear Drive Unit (RDU) is serviced as an assembly.
The RDU housing cover uses a silicone sealant rather than a gasket.
Each halfshaft is held in the RDU case by a halfshaft circlip that is located on the inner CV joint stub shaft pilot bearing housing. When each halfshaft is installed, the halfshaft circlip engages a slot in the differential side gear.
The RDU operates as follows:
- The RDU pinion receives power from the engine through the transaxle, PTU, driveshaft and active torque coupling, and is always engaged.
- The pinion gear rotates the differential case, which is bolted to the differential case outer flange.
- Inside the differential case, 2 differential pinion gears are mounted on a differential pinion shaft that is pinned to the differential case.
- These differential pinion gears are engaged with the differential side gears, to which the halfshafts are splined.
- As the differential case turns, it rotates the halfshafts and rear wheels.
- When it is necessary for one wheel and halfshaft to rotate faster than the other, the faster turning differential side gear causes the differential pinion gears to roll on the slower turning differential side gear. This allows differential action between the 2 halfshafts.
Halfshafts
The drive halfshafts consist of the following components:
- Inner CV joints
- Outer CV joints
- CV joint boot clamps
- CV joint boots
- Tripod joint housings
- Retainer circlips
- Front intermediate shaft bearing
The front intermediate shaft bearing is pressed on and is only serviced as an assembly with the intermediate shaft.
NOTICE: An inspection of the outer and inner Constant Velocity (CV) joint boots is necessary so that if damage or grease leakage is evident, installation of a new halfshaft can take place immediately. Continued operation with damage or grease leakage will result in CV joint wear and noise due to contamination and loss of the CV joint grease.
- The inner and outer CV joints connect to a splined shaft. A circlip holds the cross groove inner race assembly (inner CV joint) together.
- A circlip retains the splined inner CV joint. Install a new axle circlip each time the halfshaft is removed from the vehicle.
- A wheel hub nut secures the side shaft assembly (interconnecting shaft and outer CV joint) to the wheel hub. Install a new wheel hub nut each time the halfshaft is removed from the vehicle.
Halfshaft Handling
NOTICE: Handle the halfshaft only by the interconnecting shaft to avoid pull-apart and potential damage to the Constant Velocity (CV) joints. Damage will occur to an assembled inner CV joint if it is over-plunged outward from the joint housing or over angled.
Handle all halfshaft components carefully during removal and installation procedures. Never use a hammer to remove or install the halfshafts. Never use the halfshaft assembly as a lever to position other components. Always support the free end of the halfshaft. Do not allow the boots to contact sharp edges or hot exhaust components. Do not drop assembled halfshafts. The impact may cut the boots from the inside without evidence of external damage.