Copyright by Goodheart-Willcox Co., Inc.
216 Manual Drive Trains and Axles
Side
gear
Thrust washer
Spider
gear
Pinion shaft
Side
gear
Snap ring
Spider
gear
Thrust
washer
Ring gear
Differential
case
Extension
housing
Front View
Clutch release
bearing
Clutch
release
fork
Front
of
vehicle Transmission
input shaft
Clutch
housing
Clutch release
shaft
Figure 10-20. This exploded view of a differential assembly
shows the differences that can exist between side gears. The
side gears have the familiar beveled-cut teeth, designed to mate
with the beveled spider gear teeth. (Chrysler)
Figure 10-21. This is the front view of a popular make of manual
transaxle used with a transverse engine. The clutch housing is
integral with the transaxle case. It is machined to precisely fit the
rear of the engine. Note the clutch release (throwout) bearing,
clutch release shaft and fork, and input shaft. The extension
housing contains an opening for one of the CV axles. (Chrysler)
which is located on the output shaft of the transaxle trans-
mission. The number of teeth on the ring and pinion gears
determines the final drive ratio of the transaxle.
The differential assembly shown in Figure 10-20 illus-
trates nonidentical side gears found on many transaxle
differential assemblies. Since the CV axles are of different
lengths or may have an intermediate shaft, different side
gear designs may provide the most efficient way to transfer
power. This is the main visual difference between many
transaxle differentials and differential assemblies used on
rear-wheel drive vehicles.
The differential assembly is often lubricated with the
same oil used to lubricate the transmission gears. Some
differentials, especially the hypoid types used with longitu-
dinal engines, may have a separate lubrication sump. This
type of differential usually uses a heavier grade of gear oil
than the transmission does.
Manual Transaxle Case
The manual transaxle case protects and aligns the
gears and other moving parts. The transaxle case also
contains transaxle lubricant and keeps dirt and water out of
the gears and bearings. The inboard ends of the CV axles
and the stationary parts of the transmission are mounted on
the case. Most of the bearings that support the gear and
axle shafts are mounted in the case.
There may be one or more sheet metal or cast
aluminum access covers on the transaxle case. These can
be removed for servicing the transaxle. In some instances,
these covers can be removed to service certain internal
parts without removing the transaxle from the vehicle.
Many transaxle cases are designed in two pieces. When
the transaxle requires service, the case can be split to gain
access to the internal parts.
Most manual transaxle cases of front-wheel drive
vehicles are made of aluminum. The case is machined to
precisely fit the rear, or output end, of the engine and to
accept the internal and external transaxle parts, Figure 10-21.
A spacer plate may be installed between the transaxle and
engine to strengthen the assembly. This is often done when
the transaxle is the mounting surface for the engine starter.
The clutch housing is usually cast as an integral part
of the transaxle case. Further, the housing for the differen-
tial portion of the transaxle is usually an integral part of the
case. Some differentials, however, especially those on
transaxles with conventionally mounted engines, have
separate housings. This allows for easier service of the
internal parts. Many separate differential housings are
made of cast iron for added strength.
Figure 10-22 shows three other views of the manual
transaxle featured in Figure 10-21. Notice that the housing
for the differential assembly is integral with the case, just as
the clutch housing is. This particular case has two sheet
metal covers, which can be removed to service the trans-
axle internal parts. Among other items, the case contains a
lubricant fill plug and vent.
Note that the openings in the transaxle case for the
input shaft and CV axles are equipped with lip seals. These
are used for preventing lubricant leakage. Stationary parts,
such as the transaxle case halves or covers, are sealed with
gaskets. Openings in the case for speedometer, linkage,
switches, and other parts may be sealed when these
components are threaded into the case. In some instances,
O-rings may be used on such components to help provide
a tight seal.