Isuzu Trooper (2000 year). Manual - part 80

4A2–2

DIFFERENTIAL (REAR)

In case of Work Shop Manual;

A-type: Refer to ’98 UBS Work Shop Manual.
B-type: Described in ’00UBS Work Shop Manual.

425RY00018

DIFFERENTIAL (REAR)

4A2–3

General Description

The rear axle assembly is of the semi–floating type in
which the vehicle weight is carried on the axle housing .
The center line  of the pinion gear is below the center line
of the ring gear (hypoid drive).
All parts necessary to transmit power from the propeller
shaft to the rear wheels are enclosed in a banjo type axle
housing.
The 9.61 inch ring gear rear axle uses a conventional ring
and pinion gear set to transmit the driving force of the
engine to the rear wheels. This gear set transfers this

driving force at a 90 degree angle from the propeller shaft
to the drive shafts.
The axle shafts are supported at the wheel end of the
shaft by a roller bearing.
The pinion gear is supported by two tapered roller
bearings. The pinion depth is set by a shim pack located
between the gear end of the pinion and the roller bearing
that is pressed onto the pinion.  The pinion bearing
preload is set by crushing a collapsible spacer between
the bearings in the axle housing.

420RY00003

The ring gear is bolted onto the differential cage with 12
bolts.
The differential cage is supported in the axle housing by
two tapered roller bearings. The differential and ring gear
are located in relationship to the pinion by using selective
shims and spacers between the bearing and the axle
housing. To move the ring gear, shims are deleted from
one side and an equal amount are added to the other side.
These shims are also used to preload the bearings which

are pressed onto the differential cage. Two bearing caps
are used to hold the differential into the rear axle housing.
The differential is used to allow the wheels to turn at
different rates of speed while the rear axle continues to
transmit the driving force.  This prevents tire scuffing
when going around corners and prevents premature wear
on internal axle parts.
The rear axle is sealed with a pinion seal, a seal at each
axle shaft end, and by a liquid gasket between the
differential carrier and the axle housing.

4A2–4

DIFFERENTIAL (REAR)

Diagnosis

Many noises that seem to come from the rear axle
actually originate from other sources such as tires, road
surface, wheel bearings, engine, transmission, muffler, or
body drumming.  Investigate to find the source of the
noise before disassembling the rear axle.  Rear axles, like
any other mechanical device, are not absolutely quiet but
should be considered quiet unless some abnormal noise
is present.
To make a systematic check for axle noise, observe the
following:

1. Select a level asphalt road to reduce tire noise and

body drumming.

2. Check rear axle lubricant level to assure correct level,

and then drive the vehicle far enough to thoroughly
warm up the rear axle lubricant.

3. Note the speed at which noise occurs. Stop the

vehicle and put the transmission in neutral. Run the
engine speed slowly up and down to determine if the
noise is caused by exhaust, muffler noise, or other
engine conditions.

4. Tire noise changes with different road surfaces; axle

noises do not. Temporarily inflate all tires to 344 kPa
(50 psi) (for test purposes only). This will change
noise caused by tires but will not affect noise caused
by the rear axle.
Rear axle noise usually stops when coasting at
speeds under 48 km/h (30 mph); however, tire noise
continues with a lower tone. Rear axle noise usually
changes when comparing pull and coast, but tire
noise stays about the same.
Distinguish between tire noise and rear axle noise by
noting if the noise changes with various speeds or
sudden acceleration and deceleration. Exhaust and
axle noise vary under these conditions, while tire
noise remains constant and is more pronounced at
speeds of 32 to 48 km/h (20 to 30 mph). Further check
for tire noise by driving the vehicle over smooth
pavements or dirt roads (not gravel) with the tires at
normal pressure. If the noise is caused by tires, it will
change noticeably with changes in road surface.

5. Loose or rough front wheel bearings will cause noise

which may be confused with rear axle noise; however,
front wheel bearing noise does not change when
comparing drive and coast. Light application of the
brake while holding vehicle speed steady will often
cause wheel bearing noise to diminish. Front wheel
bearings may be checked for noise by jacking up the
wheels and spinning them or by shaking the wheels to
determine if bearings are loose.

6. Rear suspension rubber bushings and spring

insulators dampen out rear axle noise when correctly
installed. Check to see that there is no link or rod
loosened or metal–to–metal contact.

7. Make sure that there is no metal–to–metal contact

between the floor and the frame.

After the noise has been determined to be in the axle, the
type of axle noise should be determined, in order to make
any necessary repairs.

Gear Noise

Gear noise (whine) is audible from 32 to 89 km/h (20 to 55
mph) under four driving conditions.

1. Driving under acceleration or heavy pull.
2. Driving under load or under constant speed.
3. When using enough throttle to keep the vehicle from

driving the engine while the vehicle slows down
gradually (engine still pulls slightly).

4. When coasting with the vehicle in gear and the throttle

closed.  The gear noise is usually more noticeable
between 48 and 64 km/h (30 and 40 mph) and 80 and
89 km/h (50 and 55 mph).

Bearing Noise

Bad bearings generally produce a rough growl or grating
sound, rather than the whine typical of gear noise.
Bearing noise frequently “wow–wows” at bearing rpm,
indicating a bad pinion or rear axle side bearing.  This
noise can be confused with rear wheel bearing noise.

Rear Wheel Bearing Noise

Rear wheel bearing noise continues to be heard while
coasting at low speed with transmission in neutral. Noise
may diminish by gentle braking. Jack up the rear wheels,
spin them by hand and listen for noise at the hubs.
Replace any faulty wheel bearings.

Knock At Low Speeds

Low speed knock can be caused by worn universal joints
or a side gear hub counter bore in the cage that is worn
oversize.  Inspect and replace universal joints or cage and
side gears as required.

Backlash Clunk

Excessive clunk on acceleration and deceleration can be
caused by a worn rear axle pinion shaft, a worn cage,
excessive clearance between the axle and the side gear
splines, excessive clearance between the side gear hub
and the counterbore in the cage, worn pinion and side
gear teeth, worn thrust washers, or excessive drive pinion
and ring gear backlash. Remove worn parts and replace
as required. Select close–fitting parts when possible.
Adjust pinion and ring gear backlash.

DIFFERENTIAL (REAR)

4A2–5

Axle Housing

Axle Housing and Associated Parts

420RY00001

Legend

(1) Coil Spring and Insulator
(2) Axle Housing Assembly
(3) ABS Speed Sensor and Harness
(4) Nut
(5) Parking Brake Cable
(6) Bolt and Nut
(7) Antilock Brake System (ABS) Connector and

Bracket

(8) Bolt and Nut

(9) Nut

(10) Differential Assembly

(11) Axle Shaft Assembly

(12) Brake Disc
(13) Brake Pipe
(14) Brake Caliper
(15) Nut
(16) Breather Hose
(17) Flare Nut

Removal

1. Raise the vehicle and support it with suitable safety

stands.
The hoist must remain under the rear axle housing.

2. Remove brake fluid.  Refer to Hydraulic Brakes in

Brake section.

3. Remove rear wheels and tires.  Refer to Wheel in

Suspension section.

4. Remove propeller shaft.  Refer to Rear Propeller

Shaft in this section.

5. Drain the rear axle oil into a proper container.
6. Remove parking brake cable, release the connection

between the cable fixing clip equalizer.  Refer to
Parking Brakes in Brake section.

7. Move the clip aside and pull out the breather hose.