2003 JEEP GRAND CHEROKEE spec

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 suitable lifting device under the
axle.
(3) Secure axle to lift.
(4) Remove the wheels and tires.
(5) Remove the brake calipers and rotors (Refer to
5 - BRAKES/HYDRAULIC/MECHANICAL/ROTORS
- REMOVAL) from the axle.
(6) Disconnect the wheel sensor wiring harness
from the vehicle wiring harness.
(7) Disconnect the vent hose from the axle shaft
tube.
(8) Mark propeller shaft and yoke/pinion flange for
installation alignment reference.
(9) Remove propeller shaft.
(10) Disconnect stabilizer bar links at the axle.
(11) Disconnect shock absorbers from axle brack-
ets.
(12) Disconnect track bar.
(13) Disconnect the tie rod and drag link from the
steering knuckle.
(14) Disconnect the steering damper from the axle
bracket.
(15) Disconnect the upper and lower suspension
arms from the axle brackets.
(16) Lower the lifting device enough to remove the
axle. The coil springs will drop with the axle.
(17) Remove the coil springs from the axle.
3 - 20 FRONT AXLE - 186FBIWJ
FRONT AXLE - 186FBI (Continued)

DIFFERENTIAL
Differential side bearing preload and gear backlash
is achieved by selective shims positioned behind the
differential side bearing cones. The proper shim
thickness can be determined using slip-fit Dummy
Bearings D-348 in place of the differential side bear-
ings and a Dial Indicator C-3339. Before proceeding
with the differential bearing preload and gear back-
lash measurements, measure the pinion gear depth
and prepare the pinion for installation. Establishing
proper 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. 9). Differential shim measurements
are performed with spreader W-129-B removed.
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 side bearings D-348 on differen-
tial case.
(4) Install differential case in the housing.
CAUTION: When installing a Vari-LokTdifferential,
the oil feed tube must point to the bottom of the
housing. If differential is forced in with the oil feed
towards the top, the anti-rotation tabs will be dam-
aged.
(5) Record the thickness of Dummy Shims 8107.
Insert the shims between the dummy bearings and
the differential housing (Fig. 10).
Fig. 9 ADJUSTMENT SHIM LOCATIONS
1 - PINION DEPTH SHIM/OIL SLINGER
2 - DIFFERENTIAL BEARING SHIM
3 - RING GEAR
4 - DIFFERENTIAL BEARING SHIM
5 - COLLAPSIBLE SPACER
Fig. 10 DUMMY SHIM LOCATION
1 - DUMMY SHIM
2 - DIFFERENTIAL HOUSING
3 - DIFFERENTIAL CASE
4 - DUMMY BEARINGS
3 - 24 FRONT AXLE - 186FBIWJ
FRONT AXLE - 186FBI (Continued)

(33) Push and hold ring gear upward while not
allowing the pinion gear to rotate.
(34) Zero dial indicator face to pointer.
(35) Push and hold ring gear downward while not
allowing the pinion gear to rotate. Dial indicator
reading should be between 0.12 mm (0.005 in.) and
0.20 mm (0.008 in.). If backlash is not within specifi-
cations transfer the necessary amount of shim thick-
ness from one side of the housing to the other (Fig.
20).
(36) 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.
GEAR CONTACT PATTERN
The ring gear and pinion teeth contact patterns
will show if the pinion depth is correct in the hous-
ing. It will also show if the ring gear backlash has
been adjusted correctly. The backlash can be adjusted
within specifications to achieve desired tooth contact
patterns.
(1) Apply a thin coat of hydrated ferric oxide or
equivalent to the drive and coast side of the ring gear
teeth.
(2) Wrap, twist and hold a shop towel around the
pinion yoke to increase the turning resistance of the
pinion. This will provide a more distinct contact pat-
tern.
(3) With a boxed end wrench on a ring gear bolt,
rotate the differential case one complete revolution inboth directions while a load is being applied from
shop towel.
The areas on the ring gear teeth with the greatest
degree of contact against the pinion teeth will squee-
gee the compound to the areas with the least amount
of contact. Note and compare patterns on the ring
gear teeth to Gear Tooth Contact Patterns chart (Fig.
21)and adjust pinion depth and gear backlash as nec-
essary.
Fig. 20 BACKLASH SHIM ADJUSTMENT
3 - 28 FRONT AXLE - 186FBIWJ
FRONT AXLE - 186FBI (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 3.31, 3.55, 3.73, 3.91
Differential Side Gear Clearance 0.13-0.20 mm (0.005-0.008 in.)
Differential Bearing Preload 0.152 mm (0.006 in.)
Ring Gear Diameter 186 mm (7.33 in.)
Ring Gear Backlash 0.13-0.20 mm (0.005-0.008 in.)
Pinion Gear Std. Depth 92.08 mm (3.625 in.)
Pinion Bearing Preload - Original Bearings 1-2 N´m (10-20 in. lbs.)
Pinion Bearing Preload - New Bearings 1.7-3.4 N´m (15-30 in. lbs.)
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Fill Hole Plug 34 25 -
Differential Cover Bolts 41 30 -
Bearing Cap Bolts 61 45 -
Ring Gear Bolts 108 80 -
Axle Nut 237 175 -
Hub Bearing Bolts 102 75 -
3 - 30 FRONT AXLE - 186FBIWJ
FRONT AXLE - 186FBI (Continued)

SPECIAL TOOLS
PULLER C-293-PA
PLUG SP-3289
ADAPTER C-293-42
PULLER C-452
FLANGE WRENCH C-3281
DIAL INDICATOR C-3339
INSTALLER C-3716-A
HANDLE C-4171
INSTALLER C-4308
REMOVER C-4307
WJFRONT AXLE - 186FBI 3 - 31
FRONT AXLE - 186FBI (Continued)

AXLE SHAFT SEALS
REMOVAL
(1) Raise and support vehicle.
(2) Remove axle shafts.
(3) Remove differential assembly.
(4) Remove inner axle shaft seals with a pry bay.
INSTALLATION
(1) Remove any sealer remaining from original
seals.
(2) Install oil seals with Discs 8110 and Turn-
buckle 6797 (Fig. 24). Tighten tool until disc bottoms
in housing.
(3) Install differential and axle shafts.
(4) Fill differential with lubricant.
(5) Remove support and lower vehicle.
AXLE - C/V JOINT
REMOVAL
NOTE: The only service procedure to be performed
on the axle C/V joint, is the replacement of the joint
seal boot. If any failure of internal axle shaft com-
ponents is diagnosed during a vehicle road test, the
axle shaft must be replaced as an assembly.
(1) Remove axle shaft.
(2) Remove large and small C/V boot clamps (Fig.
25) and discard.
(3) Slid boot off the C/V joint housing and slide it
down the axle shaft.
(4) Remove C/V joint from axle then slid boot off
the axle.
(5) Thoroughly clean and inspect axle C/V joint
assembly and axle shaft for any signs of excessive
wear.
INSTALLATION
(1) Slidenewboot over axle shaft.
(2) Install C/V joint onto the axle shaft.
(3) Distribute 1/2 the amount of grease provided in
seal boot service package(DO NOT USE ANY
OTHER TYPE OF GREASE)into axle C/V joint
assembly housing. Put the remaining amount into
the sealing boot.
(4) Position boot on the axle locating grove and on
the C/V joint.
Fig. 24 AXLE SEAL TOOLS
1 - TURNBUCKLE
2 - DISCS
Fig. 25 OUTER C/V BOOT CLAMPS
1 - C/V JOINT HOUSING
2 - LARGE CLAMP
3 - AXLE SHAFT
4 - SMALL CLAMP
5 - SEALING BOOT
WJFRONT AXLE - 186FBI 3 - 35

CAUTION: Never loosen pinion nut to decrease pin-
ion rotating torque and never exceed specified pre-
load torque. If preload torque or rotating torque is
exceeded a new collapsible spacer must be
installed.
(4) Rotate pinion a minimum of ten time and ver-
ify pinion rotates smoothly. Rotate the pinion shaft
with an inch pound torque wrench. Rotating torque
should be equal to the reading recorded during
removal plus 0.56 N´m (5 in. lbs.) (Fig. 33).
(5) If the rotating torque is low, use Spanner
Wrench 6958 to hold the pinion companion flange
(Fig. 34), and tighten the pinion shaft nut in 6.8 N´m
(5 ft. lbs.) increments until proper rotating torque is
achieved.
CAUTION: If maximum tightening torque is reached
prior to reaching the required rotating torque, thecollapsible spacer may have been damaged.
Replace the collapsible spacer.
Fig. 31 PINION SEAL
1 - REMOVER
2 - SLIDE HAMMER
3 - PINION SEAL
Fig. 32 PINION SEAL
1 - HANDLE
2 - INSTALLER
Fig. 33 PINION ROTATION TORQUE
1 - PINION YOKE/COMPANION FLANGE
2 - INCH POUND TORQUE WRENCH
Fig. 34 PINION SHAFT NUT
1 - PINION FLANGE
2 - FRONT AXLE
3 - SPANNER WRENCH
3 - 38 FRONT AXLE - 186FBIWJ
PINION SEAL (Continued)

(6) Install propeller shaft with installation refer-
ence marks aligned.
(7) Fill differential with gear lubricant.
(8) Install brake rotors and calipers.
(9) Install wheel and tire assemblies.
(10) Lower the vehicle.
COLLAPSIBLE SPACER
REMOVAL
(1) Raise and support the vehicle.
(2) Remove wheel and tire assemblies.
(3) Remove brake rotors and calipers. Refer to 5
Brakes for procedures.
(4) Mark the propeller shaft and pinion companion
flange for installation reference.
(5) Remove propeller shaft from the pinion com-
panion flange.
(6) Rotate pinion gear a minimum of ten times and
verify pinion rotates smoothly.
(7) Record pinion gear rotating torque with a
torque wrench for installation reference.
(8) Remove pinion nut and washer. Using a short
piece of pipe and Spanner Wrench 6958 to hold the
pinion companion flange.
(9) Remove pinion companion flange with Remover
C-452 and Flange Wrench C-3281.
(10) Remove pinion shaft seal with Remover
7794-A and slide hammer (Fig. 35).
(11) Remove front pinion bearing using a pair of
pick tools to pull the bearing straight off pinion
shaft.NOTE: If bearing becomes bound on the pinion
shaft, lightly tap the end of the pinion gear with a
rawhide/rubber mallet.
(12) Remove the collapsible spacer.
INSTALLATION
(1) Install anewcollapsible preload spacer on pin-
ion shaft.
(2) Install pinion front bearing.
(3) Apply a light coating of gear lubricant on the
lip of pinion seal. Install seal with an appropriate
installer (Fig. 36).
(4) Install pinion companion flange with Installer
W-162-D, Cup 8109 and Flange Holder 6958.
(5) Install pinion washer and anewnut on the
pinion gear. Tighten the nut to 298 N´m (220 ft. lbs.)
minimum.Do not overtighten.Maximum torque is
500 N´m (368 ft. lbs.).
CAUTION: Never loosen pinion nut to decrease pin-
ion rotating torque and never exceed specified pre-
load torque. If preload torque is exceeded a new
collapsible spacer must be installed.
(6) Using Spanner Wrench 6958, a length of 1 in.
pipe and a torque wrench set at 500 N´m (368 ft. lbs.)
crush collapsible spacer until bearing end play is
taken up (Fig. 37).
(7) Slowly tighten the nut in 6.8 N´m (5 ft. lbs.)
increments until the required rotating torque is
achieved. Measure the rotating torque frequently to
avoid over crushing the collapsible spacer.
(8) Rotate pinion gear a minimum of ten times and
verify pinion rotates smoothly. Check rotating torque
with an inch pound torque wrench. The rotating
torque should be the amount recorded during
removal plus:
²Original Bearings: 0.56 N´m (5 in. lbs.).
Fig. 35 PINION SEAL PULLER
1 - REMOVER
2 - SLIDE HAMMER
3 - PINION SEAL
Fig. 36 PINION SEAL INSTALLER
1 - HANDLE
2 - INSTALLER
WJFRONT AXLE - 186FBI 3 - 39
PINION SEAL (Continued)