Jeep Cherokee (XJ): Diagnosis and testing
Axle bearing problem conditions are usually caused
by: Axle gear problem conditions are usually the result
of: Axle component breakage is most often the result
of: DIAGNOSTIC CHART Condition Possible Causes Correction Axle gear noise can be caused by insufficient lubricant,
incorrect backlash, tooth contact, worn/damaged
gears, or the carrier housing not having the proper
offset and squareness.
Gear noise usually happens at a specific speed
range. The noise can also occur during a specific type
of driving condition. These conditions are acceleration,
deceleration, coast, or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then accelerate
the vehicle to the speed range where the noise is
the greatest. Shift out-of-gear and coast through the
peak-noise range. If the noise stops or changes
greatly: Differential side gears and pinions can be checked
by turning the vehicle. They usually do not cause
noise during straight-ahead driving when the gears
are unloaded. The side gears are loaded during vehicle
turns. A worn pinion mate shaft can also cause a
snapping or a knocking noise. The axle shaft, differential and pinion bearings can
all produce noise when worn or damaged. Bearing
noise can be either a whining, or a growling sound.
Pinion bearings have a constant-pitch noise. This
noise changes only with vehicle speed. Pinion bearing
noise will be higher pitched because it rotates at a
faster rate. Drive the vehicle and load the differential.
If bearing noise occurs, the rear pinion bearing
is the source of the noise. If the bearing noise is
heard during a coast, the front pinion bearing is the
source.
Worn or damaged differential bearings usually produce
a low pitch noise. Differential bearing noise is
similar to pinion bearing noise. The pitch of differential
bearing noise is also constant and varies only
with vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph. Low speed knock Low speed knock is generally caused by a worn
U-joint or by worn side-gear thrust washers. A worn
pinion shaft bore will also cause low speed knock. Vibration at the rear of the vehicle is usually
caused by a: Check for loose or damaged front-end components
or engine/transmission mounts. These components
can contribute to what appears to be a rear-end
vibration. Do not overlook engine accessories, brackets
and drive belts.
All driveline components should be examined
before starting any repair.
Refer to Group 22, Wheels and Tires, for additional
vibration information. A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged), can be caused by: The source of a snap or a clunk noise can be determined
with the assistance of a helper. Raise the vehicle
on a hoist with the wheels free to rotate. Instruct
the helper to shift the transmission into gear. Listen
for the noise, a mechanics stethoscope is helpful in
isolating the source of a noise. The most common problem is a chatter noise when
turning corners. Before removing a Trac-loky unit
for repair, drain, flush and refill the axle with the
specified lubricant. Refer to Lubricant change in this
Group.
A container of Mopart Trac-loky Lubricant (friction
modifier) should be added after repair service or
during a lubricant change.
After changing the lubricant, drive the vehicle and
make 10 to 12 slow, figure-eight turns. This maneuver
will pump lubricant through the clutches. This
will correct the condition in most instances. If the
chatter persists, clutch damage could have occurred WARNING: WHEN SERVICING VEHICLES WITH A
TRAC-LOKY DIFFERENTIAL DO NOT USE THE
ENGINE TO TURN THE AXLE AND WHEELS. BOTH
REAR WHEELS MUST BE RAISED AND THE VEHICLE
SUPPORTED. A TRAC-LOKY AXLE CAN
EXERT ENOUGH FORCE IF ONE WHEEL IS IN CONTACT
WITH A SURFACE TO CAUSE THE VEHICLE
TO MOVE.
The differential can be tested without removing the
differential case by measuring rotating torque. Make
sure brakes are not dragging during this measurement.
(1) Place blocks in front and rear of both front
wheels.
(2) Raise one rear wheel until it is completely off
the ground.
(3) Engine off, transmission in neutral, and parking
brake off.
(4) Remove wheel and bolt Special Tool 6790 to
studs.
(5) Use torque wrench on special tool to rotate
wheel and read rotating torque (Fig. 6).
1 - SPECIAL TOOL 6790 WITH BOLT IN CENTER HOLE (6) If rotating torque is less than 22 N·m (30 ft.
lbs.) or more than 271 N·m (200 ft. lbs.) on either
wheel the unit should be serviced.General information
Wheel Noise
Axle Shaft Noise
Axle Shaft Broke
Differential Cracked
Differential Gears Scored
Loss Of Lubricant
Axle Overheating
Gear Teeth Broke
Axle Noise
Gear noise
Bearing noise
Vibration
Driveline snap
Trac-lok differential noise
Trac-lok test
Fig. 6 Trac-lokY Test -Typical
2 - TORQUE WRENCH
Service procedures. Removal and installation. Disassembly and assembly
Other materials:
Specifications
Body lubricants
Weld locations
UPPER COWL
UPPER COWL
COWL
A-PILLAR
B-PILLAR
D-PILLAR
FUEL FILLER OPENING
CARGO AREA FLOOR PAN
ROOF AND D-PILLAR
LIFTGATE OPENING
ROOF
FRAME RAIL
REINFORCEMENT
FRONT INNER FENDER
FRONT INNER FENDER A ...