2002 JEEP GRAND CHEROKEE lock

Condition Possible Causes Correction
Axle Noise 1. Insufficient lubricant. 1. Fill differential with the correct
fluid type and quantity.
2. Improper ring gear and pinion
adjustment.2. Check ring gear and pinion
contact pattern.
3. Unmatched ring gear and pinion. 3. Replace gears with a matched
ring gear and pinion.
4. Worn teeth on ring gear and/or
pinion.4. Replace ring gear and pinion.
5. Loose pinion bearings. 5. Adjust pinion bearing pre-load.
6. Loose differential bearings. 6. Adjust differential bearing
pre-load.
7. Mis-aligned or sprung ring gear. 7. Measure ring gear run-out.
Replace components as necessary.
8. Loose differential bearing cap
bolts.8. Inspect differential components
and replace as necessary. Ensure
that the bearing caps are torqued
tot he proper specification.
9. Housing not machined properly. 9. Replace housing.
VARI-LOKT
(1) Park the vehicle on a level surface or raise
vehicle on hoist so that the vehicle is level.
(2) Remove the axle fill plug.
(3) Verify that the axle fluid level is correct. The
fluid level is correct if the fluid is level with the bot-
tom of the fill hole.
(4) Shift the transfer case into the 4WD full-time
position.
(5) Drive the vehicle in a tight circle for 2 minutes
at 5mph to fully prime the pump.
(6) Block the tires opposite the axle to be tested to
prevent the vehicle from moving.
(7) Shift the transfer case into the 4WD Low posi-
tion and the transmission into the Park position.
(8) Raise both the wheels of the axle to be tested
off of the ground.
(9) Rotate the left wheel by hand at a minimum of
one revolution per second while an assistant rotates
the right wheel in the opposite direction.
(10) The left wheel should spin freely at first and
then increase in resistance within 5 revolutions until
the wheels cannot be continuously rotated in opposite
directions.
(11) The Vari-loktdifferential has engaged prop-
erly if the wheels cannot be rotated in opposite direc-tions for a moment. After the wheels stop rotating for
a moment, the fluid pressure will drop in the differ-
ential and the wheels begin to rotate once again.
(12) If the system does not operate properly,
replace the Vari-loktdifferential.
REMOVAL
(1) Raise and support the vehicle.
(2) Position a lifting device under the axle and
secure axle.
(3) Remove the wheels and tires.
(4) Remove brake calipers and rotors.
(5) Disconnect parking brake cables from brackets
and lever.
(6) Remove wheel speed sensors.
(7) Remove brake hose at the axle junction block.
Do not disconnect the brake hydraulic lines at the
calipers.
(8) Disconnect the vent hose from the axle shaft
tube.
(9) Mark propeller shaft and yokes for installation
reference.
(10) Remove propeller shaft.
(11) Disconnect stabilizer bar links.
(12) Remove upper suspension arm rear axle ball
joint nut.
WJREAR AXLE - 198RBI 3 - 55
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)

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)

(5) Remove axle bearing from the shaft with, a
press and Splitter 1130 placed between the seal and
bearing (Fig. 27).
(6) Remove seal from axle.
(7) Remove retaining plate from axle shaft.
INSTALLATION
(1) Verify axle shaft retaining plate is flat with a
straight edge.
NOTE: If the plate is warped or the studs are loose
in the plate replace the retaining plate.
(2) Install retaining plate on the axle shaft (Fig.
28).
(3) Apply a coat of multi-purpose grease on sealing
surface of axle seal.
(4) Install seal on the axle shaft with cavity away
from retaining plate (Fig. 28).
(5) Lubricate bearing with Mopar Wheel Bearing
Grease or equivalent. Wipe excess grease from the
bearing.
(6) Install bearing on the axle shaft with Installer
7913 and a press (Fig. 29).
Fig. 27 AXLE BEARING AND SEAL
1 - SPLITTER
2 - AXLE
3 - BLOCKS
4 - PRESS PLATES
Fig. 28 AXLE BEARING AND SEAL COMPONENTS
1 - RETAINING RING
2 - SEAL
3 - AXLE
4 - RETAINING PLATE
5 - AXLE BEARING
Fig. 29 PRESS BEARING ON AXLE
1 - PRESS RAM
2 - INSTALLER
3 - AXLE BEARING
4 - SEAL
5 - RETAINING PLATE
6 - AXLE
3 - 70 REAR AXLE - 198RBIWJ
AXLE BEARINGS/SEALS (Continued)

DISASSEMBLY
(1) Remove pinion shaft lock screw (Fig. 50).
(2) Remove pinion shaft.
(3) Rotate differential side gears and remove dif-
ferential pinions and thrust washers (Fig. 51).
(4) Remove differential side gears and thrust
washers.
ASSEMBLY
(1) Install differential side gears and thrust wash-
ers.
(2) Install differential pinion gears and thrust
washers.
(3) Install the pinion mate shaft.
(4) Align hole in the pinion mate shaft with the
hole in the differential case and install the pinion
mate shaft lock screw.
(5) Lubricate all differential components with
hypoid gear lubricant.
INSTALLATION
NOTE: If replacement differential bearings or differ-
ential case are being installed, differential side
bearing shim requirements may change. Refer
Adjustments (Differential Bearing Preload and Gear
Backlash) to determine the proper shim selection.
(1) Position Spreader W-129-B with Adapter set
6987 on differential housing locating holes. Install
the holddown clamps and tighten the tool turnbuckle
finger-tight.
(2) Install a Pilot Stud C-3288-B at the left side of
the differential housing. Attach Dial Indicator C-3339
to pilot stud. Load the indicator plunger against the
opposite side of the housing and zero the indicator.
CAUTION: Never spread the housing over 0.38 mm
(0.015 in). If housing is over-spread, it could be dis-
torted or damaged.
(3) Spread housing enough to install the case in
the housing.
(4) Remove the dial indicator.
(5) Install differential case in housing (Fig. 52).
Verify differential bearing cups remain in position on
the bearings and preload shims are between the face
of the bearing cup and the housing. Tap the differen-
tial case to ensure bearings cups and shims are
seated in the housing.
CAUTION: On a Vari-lokTdifferential the oil feed
tube must be pointed at the bottom of the housing
(Fig. 53). If differential is installed with the oil feed
tube pointed at the top, the anti-rotation tabs will be
damaged.
(6) Install bearing caps in their original locations
(Fig. 54).
(7) Loosely install differential bearing cap bolts.
(8) Remove axle housing spreader.
(9) Tighten bearing cap bolts in a criss-cross pat-
tern to 77 N´m (57 ft. lbs.).
(10) Install the axle shafts.
Fig. 50 SHAFT LOCK SCREW
1 - LOCK SCREW
2 - PINION SHAFT
Fig. 51 DIFFERENTIAL GEARS
1 - THRUST WASHER
2 - SIDE GEAR
3 - DIFFERENTIAL PINION
WJREAR AXLE - 198RBI 3 - 77
DIFFERENTIAL (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)