2002 JEEP GRAND CHEROKEE set 1 2

TRAC-LOKTDIFFERENTIAL
This differentials clutches are engaged by two con-
current forces. The first being the preload force
exerted through Belleville spring washers within the
clutch packs. The second is the separating forces gen-
erated by the side gears as torque is applied through
the ring gear (Fig. 3).
This design provides the differential action needed
for turning corners and for driving straight ahead
during periods of unequal traction. When one wheel
looses traction, the clutch packs transfer additional
torque to the wheel having the most traction. This
differential resist wheel spin on bumpy roads and
provide more pulling power when one wheel looses
traction. Pulling power is provided continuously until
both wheels loose traction. If both wheels slip due to
unequal traction, Trac-lokŸ operation is normal. Inextreme cases of differences of traction, the wheel
with the least traction may spin.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
Fig. 1 STRAIGHT AHEAD DRIVING
1 - WHEELS ROTATE AT CASE SPEED
2 - PINION GEAR
3 - SIDE GEAR
4 - PINION GEARS ROTATE WITH CASE
Fig. 2 DIFFERENTIAL ON TURNS
1 - PINION GEARS ROTATE ON PINION SHAFT
Fig. 3 TRAC-LOK LIMITED SLIP DIFFERENTIAL
1 - CASE
2 - RING GEAR
3 - DRIVE PINION
4 - PINION GEAR
5 - MATE SHAFT
6 - CLUTCH PACK
7 - SIDE GEAR
8 - CLUTCH PACK
WJREAR AXLE - 198RBI 3 - 51
REAR AXLE - 198RBI (Continued)

DIAGNOSTIC CHART
Condition Possible Causes Correction
Wheel Noise 1. Wheel loose. 1. Tighten loose nuts.
2. Faulty, brinelled wheel bearing. 2. Replace bearing.
Axle Shaft Noise 1. Misaligned axle tube. 1. Inspect axle tube alignment.
Correct as necessary.
2. Bent or sprung axle shaft. 2. Inspect and correct as necessary.
3. End-play in pinion bearings. 3. Refer to pinion pre-load
information and correct as
necessary.
4. Excessive gear backlash
between the ring gear and pinion.4. Check adjustment of the ring
gear and pinion backlash. Correct
as necessary.
5. Improper adjustment of pinion
gear bearings.5. Adjust the pinion bearings
pre-load.
6. Loose pinion yoke nut. 6. Tighten the pinion yoke nut.
7. Scuffed gear tooth contact
surfaces.7. Inspect and replace as
necessary.
Axle Shaft Broke 1. Misaligned axle tube. 1. Replace the broken shaft after
correcting tube mis-alignment.
2 Vehicle overloaded. 2. Replace broken shaft and avoid
excessive weight on vehicle.
3. Erratic clutch operation. 3. Replace broken shaft and avoid
or correct erratic clutch operation.
4. Grabbing clutch. 4. Replace broken shaft and inspect
and repair clutch as necessary.
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.
WJREAR AXLE - 198RBI 3 - 53
REAR AXLE - 198RBI (Continued)

(13) Separate rear axle ball joint from the upper
suspension arm with Remover 8278 (Fig. 4).
(14) Disconnect shock absorbers from axle.
(15) Disconnect track bar.
(16) Disconnect lower suspension arms from the
axle brackets.
(17) Separate the axle from the vehicle.
INSTALLATION
CAUTION: The weight of the vehicle must be sup-
ported by the springs before suspension arms and
track bar fasteners are tightened. If springs are not
at their normal ride position, vehicle ride height and
handling could be affected.
(1) Raise axle with lift and align coil springs.
(2) Install lower suspension arms in axle brackets.
Install nuts and bolts, do not tighten bolts at this
time.
(3) Install upper suspension arm on rear axle ball
joint.
(4) Install rear axle ball joint nut and tighten to
122 N´m (90 ft.lbs.) (Fig. 5).
(5) Install track bar and attachment bolts, do not
tighten bolts at this time.
(6) Install shock absorbers and tighten nuts to 60
N´m (44 ft. lbs.).(7) Install stabilizer bar links and tighten nuts to
36 N´m (27 ft. lbs.).
(8) Install wheel speed sensors.
(9) Connect parking brake cable to brackets and
lever.
(10) Install brake rotors and calipers.
(11) Install the brake hose to the axle junction
block.
(12) Install axle vent hose.
(13) Align propeller shaft and pinion yoke refer-
ence marks. Install U-joint straps and nuts tighten to
19 N´m (14 ft. lbs.).
(14) Install the wheels and tires.
(15) Add gear lubricant, if necessary.
(16) Remove support and lower the vehicle.
(17) Tighten lower suspension arm bolts to 177
N´m (130 ft. lbs.).
(18) Tighten track bar bolts to 100 N´m (74 ft.
lbs.).
ADJUSTMENTS
Ring and pinion gears are supplied as matched
sets only. The identifying numbers for the ring and
pinion gear are etched into the face of each gear (Fig.
6). A plus (+) number, minus (±) number or zero (0) is
etched into the face of the pinion gear. This number
is the amount (in thousandths of an inch) the depth
varies from the standard depth setting of a pinion
etched with a (0). The standard setting from the cen-
ter line of the ring gear to the back face of the pinion
is 96.850 mm (3.813 in.). The standard depth pro-
vides the best gear tooth contact pattern. Refer to
Backlash and Contact Pattern Analysis paragraph in
this section for additional information.
Fig. 4 REAR BALL JOINT
1 - REMOVER
2 - UPPER SUSPENSION ARM
3 - BALL JOINT STUD
Fig. 5 REAR BALL JOINT NUT
1 - UPPER SUSPENSION ARM
2 - REAR AXLE BALL JOINT
3 - REAR AXLE
3 - 56 REAR AXLE - 198RBIWJ
REAR AXLE - 198RBI (Continued)

Compensation for pinion depth variance is
achieved with a select shim. The shims are placed
between the rear pinion bearing and the pinion gear
head (Fig. 7).
If a new gear set is being installed, note the depth
variance etched into both the original and replace-
ment pinion. Add or subtract this number from the
thickness of the original depth shim/oil slinger to
compensate for the difference in the depth variances.
Refer to the Pinion Gear Depth Variance chart.
Note where Old and New Pinion Marking columns
intersect. Intersecting figure represents plus or
minus the amount needed.Note the etched number on the face of the pinion
gear head (±1, ±2, 0, +1, +2, etc.). The numbers rep-
resent thousands of an inch deviation from the stan-
dard. If the number is negative, add that value to the
required thickness of the depth shims. If the number
is positive, subtract that value from the thickness of
the depth shim. If the number is 0 no change is nec-
essary.
PINION GEAR DEPTH VARIANCE
Original Pinion
Gear Depth
VarianceReplacement Pinion Gear Depth Variance
24232221 0 +1 +2 +3 +4
+4+0.008 +0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0
+3+0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 020.001
+2+0.006 +0.005 +0.004 +0.003 +0.002 +0.001 020.00120.002
+1+0.005 +0.004 +0.003 +0.002 +0.001 020.00120.00220.003
0+0.004 +0.003 +0.002 +0.001 020.00120.00220.00320.004
21+0.003 +0.002 +0.001 020.00120.00220.00320.00420.005
22+0.002 +0.001 020.00120.00220.00320.00420.00520.006
23+0.001 020.00120.00220.00320.00420.00520.00620.007
24020.00120.00220.00320.00420.00520.00620.00720.008
Fig. 6 PINION GEAR ID NUMBERS
1 - PRODUCTION NUMBERS
2 - PINION GEAR DEPTH VARIANCE
3 - GEAR MATCHING NUMBER
Fig. 7 SHIM LOCATIONS
1 - PINION GEAR DEPTH SHIM
2 - DIFFERENTIAL BEARING SHIM
3 - RING GEAR
4 - DIFFERENTIAL BEARING SHIM
5 - COLLAPSIBLE SPACER
WJREAR AXLE - 198RBI 3 - 57
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)

(8) Slide the dial indicator probe across the gap
between the pinion height block and the arbor bar
with the scooter block against the pinion height block
(Fig. 11). When the dial probe contacts the arbor bar,
the dial pointer will turn clockwise. Bring dial
pointer back to zero against the arbor bar, do not
turn dial face. Continue moving the dial probe to the
crest of the arbor bar and record the highest reading.
If the dial indicator can not achieve the zero reading,
the rear bearing cup or the pinion depth gauge set is
not installed correctly.
(9) Select a shim equal to the dial indicator read-
ing plus the pinion depth variance number etched in
the face of the pinion (Fig. 6). For example, if the
depth variance is ±2, add +0.002 in. to the dial indi-
cator reading.
DIFFERENTIAL
Differential side bearing preload and gear backlash
is achieved by selective shims positioned behind the
differential cas bearing cups. The proper shim thick-
ness can be determined using slip-fit Dummy Bear-
ings D-348 in place of the differential side bearings
and a Dial Indicator C-3339. Before proceeding with
the differential bearing preload and gear backlash
measurements, measure the pinion gear depth and
prepare the pinion for installation. Establishingproper pinion gear depth is essential to establishing
gear backlash and tooth contact patterns. After the
overall shim thickness to take up differential side
play is measured, the pinion is installed, and the
gear backlash shim thickness is measured. The over-
all shim thickness is the total of the dial indicator
reading and the preload specification added together.
The gear backlash measurement determines the
thickness of the shim used on the ring gear side of
the differential case. Subtract the gear backlash shim
thickness from the total overall shim thickness and
select that amount for the pinion gear side of the dif-
ferential (Fig. 12). Differential shim measurements
are performed with the spreader W-129-B removed.
PRELOAD SHIM SELECTION
NOTE: It is difficult to salvage the differential side
bearings during the removal procedure. Install
replacement bearings if necessary.
(1) Remove differential side bearings from differ-
ential case.
(2) Install ring gear on differential case and
tighten bolts to specification.
(3) Install Dummy Bearings D-348 on differential
case.
(4) Install differential case in the housing.
Fig. 11 PINION GEAR DEPTH MEASUREMENT
1 - ARBOR
2 - SCOOTER BLOCK
3 - DIAL INDICATOR
Fig. 12 SHIM LOCATIONS
1 - PINION GEAR DEPTH SHIM
2 - DIFFERENTIAL BEARING SHIM
3 - RING GEAR
4 - DIFFERENTIAL BEARING SHIM
5 - COLLAPSIBLE SPACER
WJREAR AXLE - 198RBI 3 - 59
REAR AXLE - 198RBI (Continued)

the shim thickness required on the pinion side of the
housing.
(24) Rotate dial indicator out of the way on pilot
stud.
(25) Remove differential case and dummy bearings
from the housing.
(26) Install side bearings and cups on differential
case.(27) Install spreader W-129-B utilizing some items
from Adapter Set 6987, on the housing and spread
axle opening enough to receive differential case.
CAUTION: Never spread over 0.38 mm (0.015 in.). If
housing is over-spread, it could be distorted or
damaged.
(28) Place the bearing preload shims in the hous-
ing, against the axle tubes.
(29) Install differential case into the housing.
(30) Remove spreader from the housing.
(31) Install differential bearing caps in their origi-
nal locations.
(32) Install bearing cap bolts and tighten to 77
N´m (57 ft. lbs.).
(33) Rotate the differential case several times to
seat the side bearings.
(34) Position the indicator plunger against a ring
gear tooth (Fig. 22).
(35) Push and hold ring gear upward while not
allowing the pinion gear to rotate.
(36) Zero dial indicator face to pointer.
(37) Push and hold ring gear downward while not
allowing the pinion gear to rotate. Dial indicator
reading should be between 0.12-0.20 mm (0.005-0.008
in.). If backlash is not within specifications transfer
the necessary amount of shim thickness from one
side of the axle housing to the other (Fig. 23).
(38) Verify differential case and ring gear runout
by measuring ring to pinion gear backlash at eight
locations around the ring gear. Readings should not
vary more than 0.05 mm (0.002 in.). If readings vary
more than specified, the ring gear or the differential
case is defective.
After the proper backlash is achieved, perform
Gear Contact Pattern Analysis procedure.
Fig. 20 ZERO DIAL INDICATOR
1 - DIAL INDICATOR FACE
2 - FORCE DIFFERENTIAL CASE TO PINION GEAR SIDE
3 - PINION GEAR
4 - DIFFERENTIAL HOUSING
5 - DIFFERENTIAL CASE
Fig. 21 DIFFERENTIAL TO RING GEAR SIDE
1 - DIAL INDICATOR
2 - FORCE DIFFERENTIAL CASE TO RING GEAR SIDE
3 - PINION GEAR
4 - DIFFERENTIAL HOUSING
5 - DIFFERENTIAL CASE
Fig. 22 RING GEAR BACKLASH MEASUREMENT
1 - DIAL INDICATOR
3 - 62 REAR AXLE - 198RBIWJ
REAR AXLE - 198RBI (Continued)

(3) Apply a light coating of gear lubricant on the
lip of pinion seal and install seal with an appropriate
installer (Fig. 41).
(4) Install yoke with Screw 8112, Cup 8109 and
Spanner Wrench 6958 (Fig. 42).
(5) Install yoke washer andnewnut on the pinion
gear. Tighten the nut to 271 N´m (200 ft. lbs.).
CAUTION: Never loosen pinion gear nut to decrease
pinion rotating torque and never exceed specified
preload torque. If preload torque or rotating torque
is exceeded a new collapsible spacer must be
installed.
(6) Using yoke with Spanner Wrench 6958 and a
torque wrench set at 474 N´m (350 ft. lbs.), (Fig. 43)
slowly tighten the nut in 6.8 N´m (5 ft. lbs.) incre-
ments until the rotating torque is achieved. Measurethe rotating torque frequently to avoid over crushing
the collapsible spacer (Fig. 44).
NOTE: If more than 474 N´m (350 ft. lbs.) torque is
required to crush the collapsible spacer, the spacer
is defective and must be replaced.
Fig. 40 PINION SEAL REMOVER
1 - REMOVER
2 - SLIDE HAMMER
3 - PINION SEAL
Fig. 41 PINION SEAL INSTALLER
1 - HANDLE
2 - INSTALLER
Fig. 42 PINION YOKE INSTALLER
1 - INSTALLER
2 - PINION YOKE
3 - SPANNER WRENCH
Fig. 43 PINION NUT
1 - SPANNER WRENCH
2 - PIPE
3 - TORQUE WRENCH
3 - 74 REAR AXLE - 198RBIWJ
COLLAPSIBLE SPACER (Continued)