preload JEEP GRAND CHEROKEE 2002 WJ / 2.G User Guide

(11) Apply a bead 6.35mm (1/4 inch) of red Mopar
Silicone Rubber Sealant or equivalent to the housing
cover (Fig. 48).
CAUTION: If cover is not installed within 3 to 5 min-
utes, the cover must be cleaned and new RTV
applied or adhesion quality will be compromised.
(12) Install differential cover and tighten cover
bolts in a criss-cross pattern to 41 N´m (30 ft. lbs.).
(13) Fill differential with gear lubricant to bottom
of the fill plug hole.
(14) Tighten fill plug to 34 N´m (25 ft. lbs.).
(15) Remove support and lower the vehicle.
DIFFERENTIAL CASE
BEARINGS
REMOVAL
(1) Remove differential case from housing.
(2) Remove bearings from the differential case
with Puller C-293-PA, Adapters 8352 and Plug
SP-3289 (Fig. 49).
INSTALLATION
NOTE: If replacement differential side bearings or
differential case are being installed, differential side
bearing shim requirements may change. Refer to
Adjustments (Differential Bearing Preload and Gear
Backlash) to determine the proper shim selection.
CAUTION: Vari-lokTplenum must be fully seated
against the differential case prior to installing the
ring gear side differential bearing.
(1) Install differential side bearings with Handle
C-4171 and Installer C-3726-A (Fig. 50).
(2) Install differential in housing.
Fig. 48 DIFFERENTIAL COVER
1 - COVER
2 - SEALANT
3 - SEALANT BEADFig. 49 DIFFERENTIAL CASE BEARING
1 - ADAPTERS
2 - BEARING
3 - DIFFERENTIAL
4 - PLUG
5 - PULLER
3 - 44 FRONT AXLE - 186FBIWJ
DIFFERENTIAL (Continued)

(10) Remove pinion gear and collapsible spacer
from housing (Fig. 53).
(11) Remove front pinion bearing cup, bearing, oil
slinger and pinion seal with Remover D-158 and
Handle C-4171 (Fig. 54).(12) Remove rear pinion bearing cup (Fig. 55) with
Remover C-4307 and Handle C-4171.
(13) Remove collapsible preload spacer from pinion
gear (Fig. 56).
(14) Remove rear pinion bearing from the pinion
with Puller/Press C-293-PA and Adapters C-293-42
(Fig. 57). Remove oil slinger/pinion depth shim from
the pinion shaft and record thickness.
INSTALLATION
NOTE: Pinion depth shims are placed between the
rear pinion bearing cone and the pinion head to
achieve proper ring and pinion gear mesh. If ring
and pinion gears are reused, the pinion oil slinger/
depth shim should not require replacement. Refer
to Adujstments (Pinion Gear Depth) to select the
proper thickness shim before installing pinion gear.
(1) Apply Mopar Door Ease or equivalent lubricant
to outside surface of pinion bearing cups.
(2) Install rear bearing cup with Installer C-4308
and Handle C-4171 and verify cup is seated (Fig. 58).
(3) Install bearing cup with Installer D-144 and
Handle C-4171 (Fig. 59) and verify cup is seated.
(4) Install front pinion bearing, and oil slinger if
equipped.
Fig. 53 REMOVE PINION GEAR
1 - RAWHIDE HAMMER
Fig. 54 FRONT PINION BEARING CUP
1 - REMOVER
2 - HANDLE
Fig. 55 REAR PINION BEARING CUP
1 - REMOVER
2 - HANDLE
3 - 46 FRONT AXLE - 186FBIWJ
PINION GEAR/RING GEAR (Continued)

(5) Apply a light coating of gear lubricant on the
lip of pinion seal and install seal with an appropriate
installer (Fig. 60).
(6) Install rear pinion bearing and oil slinger/depth
shim onto the pinion shaft with Installer 6448 and a
press (Fig. 61).
(7) Install anewcollapsible spacer on pinion shaft
and install the pinion into the housing (Fig. 62).
(8) Install pinion companion flange, with Installer
W-162-B, Cup 8109 and Spanner Wrench 6958.(9) Install pinion washer and anewnut onto the
pinion gear and tighten the nut to 298 N´m (220 ft.
lbs.).Do not over-tighten.
CAUTION: Never loosen pinion gear nut to decrease
pinion rotating torque and never exceed specified
preload torque. If preload torque is exceeded a new
collapsible spacer must be installed.
(10) Use Flange Wrench 6958, a length of 1 in.
pipe and a torque wrench set at 500 N´m (368 ft. lbs.)
and crush collapsible spacer until bearing end play is
taken up (Fig. 63).
(11) Slowly tighten the nut in 6.8 N´m (5 ft. lb.)
increments until the required rotating torque is
achieved. Measure the rotating torque frequently to
avoid over crushing the collapsible spacer (Fig. 64).
(12) Rotate the pinion a minimum of ten times.
Verify pinion rotates smoothly and check rotating
torque with an inch pound torque wrench (Fig. 64).
Pinion gear rotating torque is:
²Original Bearings: 1 to 2.25 N´m (10 to 20 in.
lbs.).
²New Bearings: 1.7 to 3.4 N´m (15 to 30 in. lbs.).
(13) Invert the differential case and start two ring
gear bolts. This will provide case-to-ring gear bolt
hole alignment.
Fig. 60 PINION SEAL
1 - HANDLE
2 - INSTALLER
Fig. 61 REAR PINION BEARING
1 - INSTALLER
2 - OIL SLINGER
3 - PINION GEAR
4 - REAR PINION BEARING
5 - PRESS
Fig. 62 COLLAPSIBLE PRELOAD SPACER
1 - COLLAPSIBLE SPACER
2 - SHOULDER
3 - PINION GEAR
4 - DEPTH SHIM
5 - REAR BEARING
3 - 48 FRONT AXLE - 186FBIWJ
PINION GEAR/RING GEAR (Continued)

(14) Invert the differential case in the vise.
(15) Install new ring gear bolts and alternately
tighten to 108 N´m (80 ft. lbs.) (Fig. 65).
CAUTION: Never reuse the ring gear bolts. The
bolts can fracture causing extensive damage.
NOTE: If equipped with Veri-LokTdifferential install
oil feed plenum and side bearing.
(16) Install differential in housing and verify dif-
ferential bearing preload, gear mesh and contact pat-
tern. Refer to Adjustment for procedure.
(17) Install differential cover and fill with gear
lubricant.
(18) Install propeller shaft with reference marks
aligned.
(19) Remove supports and lower vehicle.
Fig. 63 Pinion Nut
1 - PINION FLANGE
2 - FRONT AXLE
3 - SPANNER WRENCH
Fig. 64 PINION ROTATING TORQUE
1 - TORQUE WRENCH
2 - PINION YOKE/FLANGE
Fig. 65 RING GEAR BOLTS
1 - TORQUE WRENCH
2 - RING GEAR BOLTS
3 - RING GEAR
4 - DIFFERENTIAL CASE
WJFRONT AXLE - 186FBI 3 - 49
PINION GEAR/RING GEAR (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

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)

(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)

(8) Thread Pilot Stud C-3288-B into rear cover bolt
hole below ring gear (Fig. 17).
(9) Attach a Dial Indicator C-3339 to pilot stud.
Position the dial indicator plunger on a flat surface
between the ring gear bolt heads (Fig. 17).
(10) Push and hold differential case to pinion gear
side of the housing and zero dial indicator (Fig. 18).
(11) Push and hold differential case to ring gear
side of the housing and record dial indicator reading
(Fig. 19).
(12) Add 0.152 mm (0.006 in.) to the zero end play
total. This new total represents the thickness of
shims to compress, or preload the new bearings when
the differential is installed.
(13) Rotate dial indicator out of the way on the
pilot stud.
(14) Remove differential case and dummy bearings
from the housing.
(15) Install the pinion gear in axle housing. Install
the pinion yoke and establish the correct pinion
rotating torque.
(16) Install differential case and Dummy Bearings
D-348 in the housing.
(17) Install a single dummy shim in the ring gear
side. Install bearing caps and tighten bolts snug.
(18) Seat ring gear side dummy bearing (Fig. 16).
(19) Position the dial indicator plunger on a flat
surface between the ring gear bolt heads. (Fig. 17).(20) Push and hold differential case toward pinion
gear and zero dial indicator (Fig. 20).
(21) Push and hold differential case to ring gear
side of the housing and record dial indicator reading
(Fig. 21). Add dummy shim thickness to this reading.
This will be the total shim thickness to achieve zero
backlash.
(22) Subtract 0.076 mm (0.003 in.) from the dial
indicator reading to compensate for backlash between
ring and pinion gears. This total is the thickness
shim required to achieve proper backlash.
(23) Subtract the backlash shim thickness from
the total preload shim thickness. The remainder is
Fig. 17 DIFFERENTIAL SIDE PLAY
1 - DIFFERENTIAL CASE
2 - DIFFERENTIAL HOUSING
3 - PILOT STUD
4 - DIAL INDICATOR
Fig. 18 ZERO DIAL INDICATOR
1 - FORCE DIFFERENTIAL CASE TO PINION GEAR SIDE
2 - PILOT STUD
3 - DIAL INDICATOR
4 - ZERO DIAL INDICATOR FACE
Fig. 19 DIFFERENTIAL TO RING GEAR SIDE
1 - DIAL INDICATOR
2 - FORCE DIFFERENTIAL CASE TO RING GEAR SIDE
3 - DIFFERENTIAL HOUSING
WJREAR AXLE - 198RBI 3 - 61
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)

DIFFERENTIAL BEARING PRELOAD CHECK
The final check on the differential assembly before
installing the axles is torque to rotate pinion and dif-
ferential combined. This will verify the correct differ-
ential bearing preload.Torque to rotate the differential and pinion should
be the torque to rotate the pinion plus 0.79-1.24 N´m
(7-11 in. lbs.).
SPECIFICATIONS
AXLE SPECIFICATIONS
DESCRIPTION SPECIFICATION
Axle Ratio 3.07, 3.31, 3.55, 3.73, 4.11
Differential Bearing Preload 0.1 mm (0.004 in.)
Ring Gear Diameter 198 mm (7.795 in.)
Ring Gear Backlash 0.12-0.20 mm (0.005-0.008 in.)
Pinion Gear Std. Depth 96.85 mm (3.813 in.)
Pinion Bearing Preload - Original Bearings 1-2 N´m (10-20 in. lbs.)
Pinion Bearing Preload - New Bearings 1.7-3.9 N´m (15-35 in. lbs.)
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Differential Cover Bolts 41 30 -
Bearing Cap Bolts 77 57 -
Ring Gear Bolts 129-142 95-105 -
Pinion Nut Minimum 272 200 -
Pinion Mate Shaft Screw 16.25 12 -
Axle Bearing Retainer Plate
Nuts61 45 -
WJREAR AXLE - 198RBI 3 - 65
REAR AXLE - 198RBI (Continued)