service JEEP GRAND CHEROKEE 2002 WJ / 2.G Owner's Manual

PINION GEAR/RING GEAR
REMOVAL
NOTE: The ring gear and pinion are serviced as a
matched set. Nevar replace one gear without replac-
ing the other matching gear.
(1) Raise and support vehicle
(2) Mark pinion companion flange and propeller
shaft for installation alignment.
(3) Remove propeller shaft from pinion companion
flange and tie propeller shaft to underbody.
(4) Remove differential from axle housing.
(5) Place differential case in a vise with soft metal
jaw (Fig. 51).
(6) Remove bolts holding ring gear to differential
case.
NOTE: On Veri-LokTdifferential the side bearing
and oil feed plenum must be removed before
removing the ring gear bolts.
(7) Driver ring gear off the differential case with a
rawhide hammer (Fig. 51).(8) With Spanner Wrench 6958 and a short length
of 1 in. pipe, hold pinion companion flange and
remove pinion nut and washer (Fig. 52).
(9) Remove pinion companion flange from pinion
shaft with Remover C-452 and Flange Wrench
C-3281.
Fig. 50 DIFFERENTIAL CASE BEARING
1 - INSTALLER
2 - HANDLE
Fig. 51 RING GEAR
1 - DIFFERENTIAL CASE
2 - RING GEAR
3 - HAMMER
Fig. 52 Pinion Flange
1 - PINION FLANGE
2 - FRONT AXLE
3 - SPANNER WRENCH
WJFRONT AXLE - 186FBI 3 - 45
DIFFERENTIAL CASE BEARINGS (Continued)

REAR AXLE - 198RBI
TABLE OF CONTENTS
page page
REAR AXLE - 198RBI
DESCRIPTION.........................50
OPERATION...........................50
DIAGNOSIS AND TESTING................51
REMOVAL.............................55
INSTALLATION.........................56
ADJUSTMENTS........................56
SPECIFICATIONS.......................65
SPECIAL TOOLS.......................66
AXLE SHAFTS
REMOVAL.............................69
INSTALLATION.........................69
AXLE BEARINGS/SEALS
REMOVAL.............................69
INSTALLATION.........................70
PINION SEAL
REMOVAL.............................71
INSTALLATION.........................71
COLLAPSIBLE SPACER
REMOVAL.............................73INSTALLATION.........................73
DIFFERENTIAL
REMOVAL.............................75
DISASSEMBLY.........................77
ASSEMBLY............................77
INSTALLATION.........................77
DIFFERENTIAL-TRAC-LOC
DIAGNOSIS AND TESTING................79
DISASSEMBLY.........................79
CLEANING............................82
INSPECTION..........................82
ASSEMBLY............................82
DIFFERENTIAL CASE BEARINGS
REMOVAL.............................83
INSTALLATION.........................84
PINION GEAR/RING GEAR
REMOVAL.............................84
INSTALLATION.........................86
REAR AXLE - 198RBI
DESCRIPTION
The Rear Beam-design Iron (RBI) axle housing has
an iron center casting with axle shaft tubes extend-
ing from either side. The tubes are pressed into and
welded to the differential housing to form a one-piece
axle housing. The axles has semi-floating axle shafts,
meaning that loads are supported by the axle shaft
and bearings. The axle shafts are retained by bearing
retainer plates on the axles which are bolted to
flanges at the outboard end of the axle tubes.
The differential case is a one-piece design. Differ-
ential bearing preload and ring gear backlash is
adjusted by the use of selective spacer shims. Pinion
bearing preload is set and maintained by the use of a
collapsible spacer. A differential cover provides a
means for inspection and service.
Axles with optional Trac-Loktdifferential have a
one-piece differential case, and the same internal
components as a standard differential, plus two
clutch disc packs.
OPERATION
The axle receives power from the transmission/
transfer case through the rear propeller shaft. Therear propeller shaft is connected to the pinion gear
which rotates the differential through the gear mesh
with the ring gear bolted to the differential case. The
engine power is transmitted to the axle shafts
through the pinion mate and side gears. The side
gears are splined to the axle shafts.
STANDARD DIFFERENTIAL
During straight-ahead driving, the differential pin-
ion gears do not rotate on the pinion mate shaft. This
occurs because input torque applied to the gears is
divided and distributed equally between the two side
gears. As a result, the pinion gears revolve with the
pinion mate shaft but do not rotate around it (Fig. 1).
When turning corners, the outside wheel must
travel a greater distance than the inside wheel to
complete a turn. The difference must be compensated
for to prevent the tires from scuffing and skidding
through turns. To accomplish this, the differential
allows the axle shafts to turn at unequal speeds (Fig.
2). In this instance, the input torque applied to the
pinion gears is not divided equally. The pinion gears
now rotate around the pinion mate shaft in opposite
directions. This allows the side gear and axle shaft
attached to the outside wheel to rotate at a faster
speed.
3 - 50 REAR AXLE - 198RBIWJ

Condition Possible Causes Correction
Differential Gears Scored 1. Insufficient lubrication. 1. Replace scored gears. Fill
differential with the correct fluid type
and quantity.
2. Improper grade of lubricant. 2. Replace scored gears. Fill
differential with the correct fluid type
and quantity.
3. Excessive spinning of one
wheel/tire.3. Replace scored gears. Inspect all
gears, pinion bores, and shaft for
damage. Service as necessary.
Loss Of Lubricant 1. Lubricant level too high. 1. Drain lubricant to the correct
level.
2. Worn axle shaft seals. 2. Replace seals.
3. Cracked differential housing. 3. Repair as necessary.
4. Worn pinion seal. 4. Replace seal.
5. Worn/scored yoke. 5. Replace yoke and seal.
6. Axle cover not properly sealed. 6. Remove, clean, and re-seal
cover.
Axle Overheating 1. Lubricant level low. 1. Fill differential to correct level.
2. Improper grade of lubricant. 2. Fill differential with the correct
fluid type and quantity.
3. Bearing pre-loads too high. 3. Re-adjust bearing pre-loads.
4. Insufficient ring gear backlash. 4. Re-adjust ring gear backlash.
Gear Teeth Broke 1. Overloading. 1. Replace gears. Examine other
gears and bearings for possible
damage.
2. Erratic clutch operation. 2. Replace gears and examine the
remaining parts for damage. Avoid
erratic clutch operation.
3. Ice-spotted pavement. 3. Replace gears and examine
remaining parts for damage.
4. Improper adjustments. 4. Replace gears and examine
remaining parts for damage. Ensure
ring gear backlash is correct.
3 - 54 REAR AXLE - 198RBIWJ
REAR AXLE - 198RBI (Continued)

PINION DEPTH MEASUREMENT
Measurements are taken with pinion bearing cups
and pinion bearings installed in the housing. Take
measurements with Pinion Gauge Set and Dial Indi-
cator C-3339 (Fig. 8).
(1) Assemble Pinion Height Block 6739, Pinion
Block 6735 and rear pinion bearing onto Screw 6741
(Fig. 8).
(2) Insert assembled height gauge components,
rear bearing and screw into the housing through pin-
ion bearing cups (Fig. 9).
(3) Install front pinion bearing and Cone-nut 6740
hand tight (Fig. 8).
(4) Place Arbor Disc 6732 on Arbor D-115-3 in posi-
tion in the housing side bearing cradles (Fig. 10).
Install differential bearing caps on Arbor Discs and
tighten cap bolts to 41 N´m (30 ft. lbs.).
NOTE: Arbor Discs 6732 has different step diame-
ters to fit other axles. Choose proper step for axle
being serviced.
(5) Assemble Dial Indicator C-3339 into Scooter
Block D-115-2 and secure set screw.(6) Place Scooter Block/Dial Indicator in position
in the housing so dial probe and scooter block are
flush against the rearward surface of the pinion
height block (Fig. 8). Hold scooter block in place and
zero the dial indicator face to the pointer. Tighten
dial indicator face lock screw.
(7) With scooter block still in position against the
pinion height block, slowly slide the dial indicator
probe over the edge of the pinion height block.
Fig. 8 PINION GEAR DEPTH GAUGE TOOLS
1 - DIAL INDICATOR
2 - ARBOR
3 - PINION HEIGHT BLOCK
4 - CONE
5 - SCREW
6 - PINION BLOCK
7 - SCOOTER BLOCK
8 - ARBOR DISC
Fig. 9 PINION HEIGHT BLOCK
1 - PINION BLOCK
2 - PINION HEIGHT BLOCK
Fig. 10 GAUGE TOOLS IN HOUSING
1 - ARBOR DISC
2 - PINION BLOCK
3 - ARBOR
4 - PINION HEIGHT BLOCK
3 - 58 REAR AXLE - 198RBIWJ
REAR AXLE - 198RBI (Continued)

(12) Install cover and tighten bolts in a criss-cross
pattern to 41 N´m (30 ft. lbs.).
(13) Refill the differential with Mopar Hypoid
Gear Lubricant or equivalent to bottom of the fill
plug hole.
(14) Install fill hole plug.
(15) Remove support and lower the vehicle.
DIFFERENTIAL-TRAC-LOC
DIAGNOSIS AND TESTING
The most common problem is a chatter noise when
turning corners. Before removing the unit for repair,
drain, flush and refill the axle with the specified
lubricant. A container of Mopar Trac-loktLubricant
(friction modifier) should be added after repair ser-
vice or during a lubricant change.
After changing the lubricant, drive the vehicle and
make 10 to 12 slow, figure-eight turns. This maneu-
ver will pump lubricant through the clutches. This
will correct the condition in most instances. If the
chatter persists, clutch damage could have occurred.
DIFFERENTIAL TEST
The differential can be tested without removing the
differential case by measuring rotating torque. Make
sure brakes are not dragging during this measure-
ment.
(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 park-
ing brake off.
(4) Remove wheel and bolt Special Tool 6790 or
equivalent tool to studs.
(5) Use torque wrench on special tool to rotate
wheel and read rotating torque (Fig. 56).
(6) If rotating torque is less than 41 N´m (56 ft.
lbs.) or more than 271 N´m (200 ft. lbs.) on either
wheel the unit should be serviced.
DISASSEMBLY
(1) Clamp side gear Holding Fixture 6965 in a vise
and position the differential case on the Holding Fix-
ture (Fig. 57).
Fig. 56 ROTATING TORQUE TEST
1 - SPECIAL TOOL WITH BOLT IN CENTER HOLE
2 - TORQUE WRENCH
Fig. 57 DIFFERENTIAL CASE FIXTURE
1 - HOLDING FIXTURE
2 - VISE
3 - DIFFERENTIAL
WJREAR AXLE - 198RBI 3 - 79
DIFFERENTIAL (Continued)

(2) Remove ring gear if the ring gear is to be
replaced. The Trac-loktdifferential can be serviced
with the ring gear installed.
(3) Remove the pinion gear mate shaft lock screw
(Fig. 58).
(4) Remove pinion gear mate shaft with a drift and
hammer (Fig. 59).(5) Install and lubricate Step Plate C-6960-3 (Fig.
60).
(6) Assemble Threaded Adapter C-6960-1 into top
side gear. Thread Forcing Screw C-6960-4 into
adapter until it becomes centered in adapter plate.
(7) Position a small screw driver in slot of
Threaded Adapter Disc C-6960-1 (Fig. 61) to prevent
adapter from turning.
(8) Install Forcing Screw C-6960-4 and tighten
screw to 122 N´m (90 ft. lbs.) maximum to compress
Belleville springs in clutch packs (Fig. 62).
(9) With a feeler gauge remove thrust washers
from behind the pinion gears (Fig. 63).
(10) Insert Turning Bar C-6960-2 into the pinion
mate shaft hole in the case (Fig. 64).
(11) Loosen the Forcing Screw in small increments
until the clutch pack tension is relieved and the dif-
ferential case can be turned using Turning Bar.
(12) Rotate differential case until the pinion gears
can be removed.
(13) Remove pinion gears from differential case.
(14) Remove Forcing Screw, Step Plate and
Threaded Adapter.
Fig. 58 MATE SHAFT LOCK SCREW
1 - LOCK SCREW
2 - PINION GEAR MATE SHAFT
Fig. 59 PINION MATE SHAFT
1 - PINION MATE SHAFT
2 - SIDE GEAR
3 - DRIFT
4 - PINION MATE GEAR
Fig. 60 Step Plate
1 - LOWER SIDE GEAR
2 - DIFFERENTIAL CASE
3 - STEP PLATE
3 - 80 REAR AXLE - 198RBIWJ
DIFFERENTIAL-TRAC-LOC (Continued)

INSTALLATION
NOTE: If differential side bearings or differential
case are replaced, differential side bearing shim
requirements may change. Refer to Adjustments
(Differential Bearing Preload and Gear Backlash) for
procedures.
(1) Install differential side bearings with Installer
C-3716-A and Handle C-4171 (Fig. 70).
(2) Install differential in axle housing.
(3) Remove support and lower vehicle.
PINION GEAR/RING GEAR
REMOVAL
NOTE: The ring and pinion gears are serviced as a
matched set. Never replace one gear without the
other gear.
(1) Raise and support vehicle.
(2) Mark pinion yoke and propeller shaft for
installation reference.
(3) Disconnect propeller shaft from pinion yoke
and tie shaft to underbody.
(4) Remove differential from the housing.
(5) Place differential case in a vise with soft metal
jaw.(6) Remove bolts holding ring gear to differential
case.
(7) Drive ring gear from differential case with a
rawhide hammer (Fig. 71).
(8) Hold the pinion yoke with Spanner Wrench
6958 and remove the pinion yoke nut and washer
(Fig. 72).
Fig. 70 Differential Side Bearing
1 - INSTALLER
2 - HANDLE
Fig. 71 RING GEAR
1 - DIFFERENTIAL CASE
2 - RING GEAR
3 - HAMMER
Fig. 72 PINION YOKE HOLDER
1 - 1 in. PIPE
2 - PINION YOKE
3 - HOLDER
4 - LOWER CONTROL ARM
3 - 84 REAR AXLE - 198RBIWJ
DIFFERENTIAL CASE BEARINGS (Continued)

REAR AXLE - 226RBA
TABLE OF CONTENTS
page page
REAR AXLE - 226RBA
DESCRIPTION.........................90
OPERATION...........................90
DIAGNOSIS AND TESTING................92
REMOVAL.............................95
INSTALLATION.........................96
ADJUSTMENTS........................97
SPECIFICATIONS......................105
SPECIAL TOOLS.......................106
AXLE SHAFTS
REMOVAL............................109
INSTALLATION........................109
AXLE BEARINGS/SEALS
REMOVAL............................109
INSTALLATION........................110
PINION SEAL
REMOVAL............................111
INSTALLATION........................112
COLLAPSIBLE SPACER
REMOVAL............................113INSTALLATION........................114
DIFFERENTIAL
REMOVAL............................115
DISASSEMBLY........................117
ASSEMBLY...........................117
INSTALLATION........................117
DIFFERENTIAL - TRAC-LOK
DIAGNOSIS AND TESTING...............119
DISASSEMBLY........................119
CLEANING...........................121
INSPECTION.........................121
ASSEMBLY...........................121
DIFFERENTIAL CASE BEARINGS
REMOVAL............................123
INSTALLATION........................123
PINION GEAR/RING GEAR
REMOVAL............................124
INSTALLATION........................126
REAR AXLE - 226RBA
DESCRIPTION
The Rear Beam-design Aluminum (RBA) axle hous-
ing has an aluminum center casting (differential
housing) with axle shaft tubes extending from either
side. The tubes are pressed into the differential hous-
ing to form a one-piece axle housing. The axle has
semi-floating axle shafts, meaning that vehicle load
is supported by the axle shaft and bearings.
The differential case is a one-piece design. Differen-
tial bearing preload and ring gear backlash is adjusted
with selective shims. Pinion bearing preload is set and
maintained by the use of a collapsible spacer. The cover
provides a means for inspection and service.
Optional Trac-Loktdifferential differential has a
one-piece differential case, and the same internal
components as a standard differential, plus two
clutch disc packs.
Optional Vari-Loktdifferential has a one-piece dif-
ferential case which contains the gerotor pump
assembly and the clutch mechinism. The unit is ser-
viced only as an assembly.
OPERATION
The axle receives power from the transfer case
through the front propeller shaft. The front propellershaft is connected to the pinion gear which rotates
the differential through the gear mesh with the ring
gear bolted to the differential case. The engine power
is transmitted to the axle shafts through the pinion
mate and side gears. The side gears are splined to
the axle shafts.
STANDARD DIFFERENTIAL
During straight-ahead driving the differential pin-
ion gears do not rotate on the pinion mate shaft. This
occurs because input torque applied to the gears is
divided and distributed equally between the two side
gears. As a result, the pinion gears revolve with the
pinion mate shaft but do not rotate around it (Fig. 1).
When turning corners, the outside wheel must travel
a greater distance than the inside wheel to complete a
turn. The difference must be compensated for to prevent
the tires from scuffing and skidding through turns. To
accomplish this, the differential allows the axle shafts
to turn at unequal speeds (Fig. 2). In this instance, the
input torque applied to the pinion gears is not divided
equally. The pinion gears now rotate around the pinion
mate shaft in opposite directions. This allows the side
gear and axle shaft attached to the outside wheel to
rotate at a faster speed.
3 - 90 REAR AXLE - 226RBAWJ

and therefore creates pressure in the pump. The tun-
ing of the front and rear axle orifices and valves
inside the gerotor pump is unique and each system
includes a torque-limiting pressure relief valve to
protect the clutch pack, which also facilitates vehicle
control under extreme side-to-side traction varia-
tions. The resulting pressure is applied to the clutch
pack and the transfer of torque is completed.
Under conditions in which opposite wheels are on
surfaces with widely different friction characteristics,
Vari-loktdelivers far more torque to the wheel on
the higher traction surface than do conventional
Trac-loktsystems. Because conventional Trac-lokt
differentials are initially pre-loaded to assure torque
transfer, normal driving (where inner and outer
wheel speeds differ during cornering, etc.) produces
torque transfer during even slight side-to-side speed
variations. Since these devices rely on friction from
this preload to transfer torque, normal use tends to
cause wear that reduces the ability of the differential
to transfer torque over time. By design, the Vari-lokt
system is less subject to wear, remaining more con-
sistent over time in its ability to transfer torque. The
coupling assembly is serviced as a unit. From a ser-
vice standpoint the coupling also benefits from using
the same lubricant supply as the ring and pinion
gears.
DIAGNOSIS AND TESTING
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, 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 accelera-
tion, deceleration, coast, or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then acceler-
ate 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:
²Check for insufficient lubricant.
²Incorrect ring gear backlash.
²Gear damage.
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 vehi-
cle turns. A worn pinion mate shaft can also cause a
snapping or a knocking noise.
BEARING 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 differen-
tial. 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 pro-
duce a low pitch noise. Differential bearing noise is
similar to pinion bearing noise. The pitch of differen-
tial 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
Vibration at the rear of the vehicle is usually
caused by a:
²Damaged drive shaft.
²Missing drive shaft balance weight(s).
²Worn or out-of-balance wheels.
²Loose wheel lug nuts.
²Worn U-joint(s).
²Loose/broken springs.
²Damaged axle shaft bearing(s).
²Loose pinion gear nut.
²Excessive pinion yoke run out.
²Bent axle shaft(s).
Check for loose or damaged front-end components
or engine/transmission mounts. These components
can contribute to what appears to be a rearend vibra-
tion. Do not overlook engine accessories, brackets
and drive belts.
All driveline components should be examined
before starting any repair.
(Refer to 22 - TIRES/WHEELS - DIAGNOSIS AND
TESTING)
3 - 92 REAR AXLE - 226RBAWJ
REAR AXLE - 226RBA (Continued)

Condition Possible Causes Correction
Differential Cracked 1. Improper adjustment of the
differential bearings.1. Replace case and inspect gears
and bearings for further damage.
Set differential bearing pre-load
properly.
2. Excessive ring gear backlash. 2. Replace case and inspect gears
and bearings for further damage.
Set ring gear backlash properly.
3. Vehicle overloaded. 3. Replace case and inspect gears
and bearings for further damage.
Avoid excessive vehicle weight.
4. Erratic clutch operation. 4. Replace case and inspect gears
and bearings for further damage.
Avoid erratic use of clutch.
Differential Gears Scored 1. Insufficient lubrication. 1. Replace scored gears. Fill
differential with the correct fluid type
and quantity.
2. Improper grade of lubricant. 2. Replace scored gears. Fill
differential with the correct fluid type
and quantity.
3. Excessive spinning of one
wheel/tire.3. Replace scored gears. Inspect all
gears, pinion bores, and shaft for
damage. Service as necessary.
Loss Of Lubricant 1. Lubricant level too high. 1. Drain lubricant to the correct
level.
2. Worn axle shaft seals. 2. Replace seals.
3. Cracked differential housing. 3. Repair as necessary.
4. Worn pinion seal. 4. Replace seal.
5. Worn/scored yoke. 5. Replace yoke and seal.
6. Axle cover not properly sealed. 6. Remove, clean, and re-seal
cover.
Axle Overheating 1. Lubricant level low. 1. Fill differential to correct level.
2. Improper grade of lubricant. 2. Fill differential with the correct
fluid type and quantity.
3. Bearing pre-loads too high. 3. Re-adjust bearing pre-loads.
4. Insufficient ring gear backlash. 4. Re-adjust ring gear backlash.
3 - 94 REAR AXLE - 226RBAWJ
REAR AXLE - 226RBA (Continued)