2002 JEEP GRAND CHEROKEE Front differential

TRANSFER CASE - NV242
TABLE OF CONTENTS
page page
TRANSFER CASE - NV242
DESCRIPTION........................280
OPERATION..........................281
DIAGNOSIS AND TESTING - TRANSFER
CASE - NV242.......................281
REMOVAL............................282
DISASSEMBLY........................282
CLEANING...........................292
INSPECTION.........................293
ASSEMBLY...........................295
INSTALLATION........................307
SPECIFICATIONS
TRANSFER CASE - NV242.............308
SPECIAL TOOLS
TRANSFER CASE - NV242.............308
FLUID
STANDARD PROCEDURE - FLUID DRAIN/
REFILL............................310FRONT OUTPUT SHAFT SEAL
REMOVAL............................310
INSTALLATION........................310
POSITION SENSOR
DESCRIPTION........................311
OPERATION..........................311
REMOVAL............................312
INSTALLATION........................312
REAR RETAINER BUSHING AND SEAL -
NV242HD
REMOVAL............................312
INSTALLATION........................312
SHIFT CABLE
REMOVAL............................313
INSTALLATION........................313
TRANSFER CASE - NV242
DESCRIPTION
The NV242 is a full transfer case (Fig. 1). It pro-
vides full time 2-wheel, or 4-wheel drive operation.
A differential in the transfer case is used to control
torque transfer to the front and rear axles. A low
range gear provides increased low speed torque capa-
bility for off road operation. The low range provides a
2.72:1 reduction ratio.
The geartrain is mounted in two aluminum case
halves attached with bolts. The mainshaft front and
rear bearings are mounted in aluminum retainer
housings bolted to the case halves.
TRANSFER CASE IDENTIFICATION
Two versions of the NV242 are used in the WJ
vehicles, NV242LD and NV242HD. The two transfer
cases can be distinguished from one another by the
rear output shaft retainer. The NV242LD uses a rub-
ber boot to cover the rear output shaft, while the
NV242HD uses a cast aluminum housing. Other than
this difference, the two transfer cases are serviced
the same.
A circular ID tag is attached to the rear case of
each transfer case (Fig. 2). The ID tag provides the
transfer case model number, assembly number, serial
number, and low range ratio.The transfer case serial number also represents
the date of build.
SHIFT MECHANISM
Operating ranges are selected with a lever in the
floor mounted shifter assembly. The shift lever is con-
nected to the transfer case range lever by an adjust-
able cable. A straight line shift pattern is used.
Range positions are marked on the shifter bezel.
Fig. 1 NV242 Transfer Case
21 - 280 TRANSFER CASE - NV242WJ

REMOVAL
(1) Shift transfer case into NEUTRAL.
(2) Raise vehicle.
(3) Remove transfer case drain plug and drain
transfer case lubricant.
(4) Mark front and rear propeller shaft yokes for
alignment reference.
(5) Support transmission with jack stand.
(6) Remove rear crossmember and skid plate, if
equipped (Fig. 3).
(7) Disconnect front/rear propeller shafts at trans-
fer case. (Refer to 3 - DIFFERENTIAL & DRIV-
ELINE/PROPELLER SHAFT/PROPELLER SHAFT -
REMOVAL)
(8) Disconnect transfer case cable from range
lever.
(9) Disconnect transfer case vent hose (Fig. 4) and
transfer case position sensor.
(10) Support transfer case with transmission jack.
(11) Secure transfer case to jack with chains.
(12) Remove nuts attaching transfer case to trans-
mission.(13) Pull transfer case and jack rearward to disen-
gage transfer case.
(14) Remove transfer case from under vehicle.
DISASSEMBLY
REAR RETAINER - NV242LD
(1) Remove output shaft boot. Spread band clamp
that secures boot on slinger with a suitable awl.
Then slide boot off shaft (Fig. 5).
Fig. 3 Crossmember Removal
1 - CROSSMEMBER
2 - REAR TRANSMISSION MOUNT
Fig. 4 Transfer Case Mounting
1 - NV242 TRANSFER CASE
Fig. 5 Output Boot - Typical
1 - SLINGER
2 - BOOT
3-AWL
4 - TRANSFER CASE
21 - 282 TRANSFER CASE - NV242WJ
TRANSFER CASE - NV242 (Continued)

(13) Slide low range fork pin out of shift sector
slot.
(14) Remove low range fork and sleeve (Fig. 35).
(15) Remove shift sector.(16) Remove the shift sector shaft bushing and
o-ring (Fig. 36).
INPUT GEAR/LOW RANGE ASSEMBLY
(1) Remove front bearing retainer bolts.
(2) Remove front bearing retainer. Carefully pry
retainer loose with screwdriver (Fig. 37). Position
screwdriver in slots cast into retainer.
(3) Remove input gear snap-ring (Fig. 38).
Fig. 34 Differential Removal
1 - DIFFERENTIAL
2 - MAINSHAFT
Fig. 35 Low Range Fork And Hub Removal
1 - LOW RANGE FORK
2 - FORK HUB
Fig. 36 Remove the Shift Sector O-Ring
1 - TRANSFER CASE FRONT HOUSING
2 - SHIFT SECTOR O-RING
Fig. 37 Front Bearing Retainer Removal
1 - FRONT BEARING RETAINER
2 - RETAINER SLOT
21 - 290 TRANSFER CASE - NV242WJ
TRANSFER CASE - NV242 (Continued)

(7) Inspect low range annulus gear (Fig. 42).Gear
is not a serviceable component. If damaged,
replace gear and front case as assembly.
(8) Remove oil seals from following components:
²front bearing retainer.
²rear retainer.
²oil pump.
²case halves.
DIFFERENTIAL
(1) Mark differential case halves for reference.
(2) Remove differential case bolts.
(3) Invert differential on workbench.
(4) Separate top case from bottom case. Use slots
in case halves to pry them apart (Fig. 43).
(5) Remove thrust washers and planet gears from
case pins (Fig. 44).
(6) Remove mainshaft and sprocket gears from
bottom case (Fig. 45). Note gear position for reference
before separating them.
CLEANING
Clean the transfer case parts with a standard
parts cleaning solvent. Remove all traces of sealer
from the cases and retainers with a scraper and all
purpose cleaner. Use compressed air to remove sol-
vent residue from oil feed passages in the case
halves, retainers, gears, and shafts.
The oil pickup screen can be cleaned with solvent.
Shake excess solvent from the screen after cleaning
and allow it to air dry. Do not use compressed air.
Fig. 42 Inspecting Low Range Annulus Gear
1 - LOW RANGE ANNULUS GEAR
Fig. 43 Separating Differential Case Halves
1 - TOP CASE
2 - CASE BOLTS
3 - CASE BOLTS
4 - CASE SLOTS
5 - CASE BOLTS
Fig. 44 Planet Gears And Thrust Washer Removal
1 - MAINSHAFT GEAR
2 - THRUST WASHERS (12)
3 - PLANET GEARS (6)
21 - 292 TRANSFER CASE - NV242WJ
TRANSFER CASE - NV242 (Continued)

(5) Align and position differential top case on bot-
tom case (Fig. 67). Align using scribe marks made at
disassembly.
(6) While holding differential case halves together,
invert the differential and start the differential case
bolts.
(7) Tighten differential case bolts to specified
torque.
INPUT GEAR/LOW RANGE ASSEMBLY
(1) Assemble low range gear, input gear thrust
washers, input gear and input gear retainer (Fig. 68).
(2) Install low range gear snap ring (Fig. 69).
(3) Lubricate input gear and low range gears with
automatic transmission fluid.
(4) Start input gear shaft into front case bearing.
(5) Press input gear shaft into front bearing.
(6) Install new input gear snap ring (Fig. 70).
(7) Apply 3 mm (1/8 in.) wide bead of Mopartgas-
ket maker or silicone adhesive sealer to seal surface
of front bearing retainer.
(8) Install front bearing retainer (Fig. 71). Tighten
retainer bolts to 16 ft. lbs. (21 N´m) torque.
SHIFT FORKS, SECTOR, AND MAINSHAFT
(1) Install the shift sector shaft o-ring and bush-
ing.
(2) Install shift sector.(3) Install new pads on low range fork, if neces-
sary.
(4) Assemble low range fork and sleeve.
Fig. 67 Differential Case Assembly
1 - TOP CASE
2 - BOTTOM CASE
3 - CASE ALIGNMENT MARKS
Fig. 68 Low Range And Input Gear Assembly
1 - THRUST WASHERS
2 - LOW RANGE GEAR
3 - INPUT GEAR
4 - RETAINER
Fig. 69 Install Low Range Gear Snap-Ring
1 - LOW RANGE GEAR SNAP-RING
21 - 300 TRANSFER CASE - NV242WJ
TRANSFER CASE - NV242 (Continued)

(5)Position low range fork and sleeve in case. Be
sure low range fork pin is engaged in shift sector slot.
(6) Install first mainshaft bearing spacer on main-
shaft (Fig. 72).
(7) Install bearing rollers on mainshaft (Fig. 72).
Coat bearing rollers with generous quantity of petro-
leum jelly to hold them in place.
(8) Install remaining bearing spacer on mainshaft
(Fig. 72). Do not displace any bearings while install-
ing spacer.(9) Install differential (Fig. 73). Do not displace
mainshaft bearings when installing differential.
Fig. 70 Input Gear Snap-Ring Installation
1 - INPUT GEAR
2 - SNAP-RING
Fig. 71 Installing Front Bearing Retainer
1 - FRONT BEARING RETAINER
Fig. 72 Installing Mainshaft Bearing Rollers and
Spacers
1 - MAINSHAFT BEARING ROLLERS
2 - BEARING SPACERS
Fig. 73 Differential Installation
1 - DIFFERENTIAL
2 - MAINSHAFT
WJTRANSFER CASE - NV242 21 - 301
TRANSFER CASE - NV242 (Continued)

NV242HD REAR RETAINER
(1) Apply bead of MopartSealer, or LoctiteŸ
Ultra Gray, to mating surface of rear retainer. Sealer
bead should be a maximum of 3/16 in.
(2) Install rear retainer on rear case. Tighten
retainer bolts to 20-27 N´m (15-20 ft. lbs.) torque.
(3) Install new output shaft bearing snap-ring
(Fig. 91). Lift mainshaft slightly to seat snap-ring in
shaft groove, if necessary.
(4) Apply 3 mm (1/8 in.) wide bead of Mopartgas-
ket maker or silicone adhesive sealer to mounting
surface of extension housing. Allow sealer to set-up
slightly before proceeding.(5) Install extension housing on rear retainer.
(6) Install extension housing bolts and tighten to
35-46 N´m (26-34 ft. lbs.).
COMPANION FLANGE
(1) Lubricate companion flange hub with transmis-
sion fluid and install flange on front shaft.
(2) Install new seal washer on front shaft.
(3) Install flange on front shaft and tighten nut to
122-176 N´m (90-130 ft. lbs.).
INSTALLATION
(1) Mount transfer case on a transmission jack.
(2) Secure transfer case to jack with chains.
(3) Position transfer case under vehicle.
(4) Align transfer case and transmission shafts
and install transfer case on transmission.
(5) Install and tighten transfer case attaching nuts
to 35 N´m (26 ft. lbs.) torque (Fig. 4).
(6) Align and connect propeller shafts. (Refer to 3 -
DIFFERENTIAL & DRIVELINE/PROPELLER
SHAFT/PROPELLER SHAFT - INSTALLATION)
(7) Fill transfer case with correct fluid. Check
transmission fluid level. Correct as necessary.
(8) Install rear crossmember and skid plate, if
equipped. Tighten crossmember bolts to 41 N´m (30
ft. lbs.) torque.
(9) Remove transmission jack and support stand.
(10) Connect shift rod to transfer case range lever.
(11) Connect transfer case vent hose and transfer
case position sensor.
(12) Adjust transfer case shift cable.
(13) Lower vehicle and verify transfer case shift
operation.
Fig. 91 Install Output Bearing Snap-ring
1 - REAR RETAINER
2 - SNAP-RING
3 - REAR BEARING
WJTRANSFER CASE - NV242 21 - 307
TRANSFER CASE - NV242 (Continued)

OPERATION
Under normal driving conditions, the system oper-
ates conventionally, and the majority of available
torque is applied to the rear wheels. However, when
front-to-rear wheel speed variations exist, the pro-
gressive differential transfers torque to the axle with
the better traction, thus minimizing wheel spin and
maximizing control.
The key to this design is a progressive coupling
(Fig. 3), which is supplied with pressurized oil by a
gerotor style pump. The pump rotor and case are
driven by the front and rear driveshafts respectively,
and deliver pressurized oil flow to the coupling in
proportion to their speed difference. The progressive
coupling contains a multi-disc clutch pack that is
alternately splined to the front and rear driveshafts,
and controls torque variation between the front and
rear driveshafts as dictated by the pump.
A set of orifices and valves control the speed-differ-
ential starting point and rate of torque transfer rise
in the clutch. This allows the system to disregard the
normal speed differences between axles that result
from variations in front-to-rear loading and typical
cornering.
Transfer case operating ranges are selected with a
floor mounted shift lever. The shift lever is connectedto the transfer case range lever by an adjustable
cable. Range positions are marked on the shifter
bezel plate.
DIAGNOSIS AND TESTING - TRANSFER CASE - NV247
CONDITION POSSIBLE CAUSE CORRECTION
TRANSFER CASE DIFFICULT TO
SHIFT OR WILL NOT SHIFT INTO
DESIRED RANGE1. Vehicle speed too great to permit
shifting1. Reduce speed to 3-4 km/h (2-3
mph) before attempting to shift
2. Transfer case external shift cable
binding2. Lubricate, repair or replace cable,
or thighten loose components as
necessary
3. Insufficient or incorrect lubricant 3. Drain and refill to edge of fill hole
with correct lubricant
4. Internal components binding,
worn, or damaged4. Disassemble unit and replace
worn or damaged components as
necessary
TRANSFER CASE NOISY IN ALL
MODES1. Insufficient or incorrect lubricant 1. Drain and refill to edge of fill hole
with correct lubricant.If unit is still
noisy after drain and refill,
disassembly and inspection may
be required to locate source of
noise
Fig. 3 Progressive Coupling
21 - 316 TRANSFER CASE - NV247WJ
TRANSFER CASE - NV247 (Continued)