Rzeppa-type CV joints—allow each wheel to move inde-
pendently of the vehicle body and of each other.
A typical independently suspended drive axle
arrangement is shown in Figure 16-38. Although they look
different, these axles transfer power in much the same
manner as solid drive axles.
Figure 16-39 is an example of how an independently
suspended drive axle and wheel hub are assembled. The
hub is firmly attached to the suspension control arm. The
inner portion of the hub rotates inside of a bearing and acts
as a mounting flange for the wheel and brake assembly.
The stub axle is splined to the hub and drives it. The
universal joint allows free movement of the suspension
control arm. Some splined axles can slide to compensate
for changes in axle length when the rear suspension moves
up and down.
Summary
All rear axle assemblies have the same basic design
and operate by the same principles. Rear end variations
depend on whether the vehicle has a solid-axle or inde-
pendent rear suspension, a removable or integral carrier,
semi-floating or full-floating axles, and a standard or limited-
slip differential.
The major parts of the rear axle assembly are the dif-
ferential assembly, rear axle housing, drive axles, bearings,
and seals. Engine power enters the drive pinion gear
through the differential pinion yoke and drive shaft assem-
bly. The drive pinion gear turns the ring gear. The
interaction of the ring and pinion assembly turns the power
at a 90° angle and reduces its speed. The ring gear is bolt-
ed to the differential case. Power flows from the ring gear
into the differential case, which transfers the power to the
spider gears. The spider gears transfer the power to side
gears, which then transfer the power to the drive axles and
rear wheels.
The differential assembly has three purposes. It redi-
rects the drive shaft rotation in a 90° angle, reduces rotat-
ing speed to increase power, and allows the vehicle to
make turns without wheel hop or axle breakage.
The relative positions of the ring and drive pinion
gears must be set exactly, or the gears will be noisy and
wear out prematurely. The position of the ring and drive
pinion gears in the case and in relation to each other must
be carefully adjusted.
The differential case assembly allows the vehicle to make
turns without wheel hop. It has an arrangement of gears that
allows the rear wheels to turn at different speeds. There are two
kinds of differential case assemblies, standard and locking.
The standard differential is composed of meshing spi-
der and side gears, enclosed in a differential case. The ring
gear is bolted to the case. Power flow is through the case,
into the spider gears, and on to the side gears. The side
gears are splined to the drive axles. They transfer power to
the drive axles and rear wheels.
When driving on slippery surfaces, the rear wheels of
a vehicle with a standard differential will often slip. This is
because the differential will always drive the wheel with
the least traction. To overcome this problem, various kinds
of locking differentials are used. They increase traction by
sending power to the wheel with the most traction.
330 Manual Drive Trains and Axles
Wheel
bearings
Rear drive axle
(central shaft)
Differential
has been
rotated (top view)
Stub axle
CV joint
Differential
Stub
axle CV joint
Independent
rear suspension
CV joint
Figure 16-38. The drive axle of a vehicle with an independent rear suspension consists of three shafts and two U-joints. The central
shaft is connected through the U-joints to a short shaft, or stub axle, on either side. Stub axles are splined to the wheel hub and
side gears. Note that the differential has been rotated 90° for the purpose of illustration.