Rio L4-1.6L (2004)
Axle Shaft Assembly: Description and Operation
DESCRIPTION AND OPERATION
The halfshafts are the mechanical link that transfer the engine torque from the transaxle and differential to the front wheels. At the transaxle end, the
halfshafts are splined to the differential side gears. Disengagement of the shaft from the gear is prevented by an expanding spring steel circlip. During
the installation, the clip compresses around the shaft as it enters the gear. Once through the differential gear, the clip expands into a counterbore
machined into the back side of the gear.
The wheel end of the halfshafts are splined to the wheel hubs which are supported on the opposed tapered wheel bearings. Disengagement of the shaft
from the wheel hub is prevented by a washer and an attaching nut.
A backlash between the wheel hub and halfshaft is eliminated by the splines. The wheel hub splines are machined straight while the halfshaft splines
are machined with a slight helical cut.
Constant Velocity (CV) joints are installed at both ends of the halfshafts.
Two different types of CV joints are used. The inboard CV joints are repairable tripod CV joints. The outboard CV joints are non-repairable Birfield
CV joints.
Tripod CV joints are used to prevent the transfer of engine vibration through the halfshafts to the vehicle body. Additional reduction of vibration is
provided by a dynamic damper installed approximately in the middle of the right halfshaft.
CV joints are necessary because the halfshaft is required to transmit torque while compensating for front suspension movement. As the suspension
moves, the CV joints allow the halfshaft to change length and operate smoothly through varying angles.
For the necessary flexibility, Birfield CV joints use ball bearings positioned by a cage. The tripod CV joint uses three balls mounted on needle
bearings and a spider. In both types of joints, the outer race is machined into the CV joint housing.
The tripod CV joints can be disassembled and serviced. Other than the CV joint boot, the outboard Birfield CV joint is serviced only as an assembly
with the shaft.
