2002 JEEP GRAND CHEROKEE Rear differential

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)

CONDITION POSSIBLE CAUSE CORRECTION
NOISY INÐOR JUMPS OUT OF
4WD LOW RANGE1. Transfer case not completely
engaged in 4WD LOW (possibly
from shift to 4L while rolling)1. Stop vehicle, shift transfer case
to neutral, then shift back to 4WD
LOW
2. Shift linkage loose, binding, or is
misadjusted2. Tighten, lubricate, or repair
linkage as necessary. Adjust linkage
if necessary
3. Range fork cracked, inserts
worn, or fork is binding on shift rail3. Disassemble unit and repair as
necessary
4. Annulus gear or lockplate worn
or damaged4. Disassemble unit and repair as
necessary
LUBRICANT LEAKING FROM
OUTPUT SHAFT SEALS OR FROM
VENT1. Transfer case over filled 1. Drain to correct level
2. Vent closed or restricted 2. Clear or replace vent if necessary
3. Output shaft seals damaged or
installed correctly3. Replace seals. Be sure seal lip
faces interior of case when installed.
Also be sure yoke seal surfaces are
not scored or nicked. Remove
scores and nicks with fine
sandpaper or replace yoke(s) if
necessary.
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. 4).
(7) Disconnect front propeller shaft from transfer
case at companion flange. Remove rear propeller
shaft from vehicle. (Refer to 3 - DIFFERENTIAL &
DRIVELINE/PROPELLER SHAFT/PROPELLER
SHAFT - REMOVAL)
CAUTION: Do not allow propshafts to hang at
attached end. Damage to joint can result.
(8) Disconnect transfer case cable from range
lever.
(9) Disconnect transfer case vent hose (Fig. 5).
(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 (Fig. 5).
(14) Remove transfer case from under vehicle.
DISASSEMBLY
Position transfer case on shallow drain pan.
Remove drain plug and drain lubricant remaining in
case.
Fig. 4 Crossmember Removal
1 - CROSSMEMBER
2 - REAR TRANSMISSION MOUNT
WJTRANSFER CASE - NV247 21 - 317
TRANSFER CASE - NV247 (Continued)

(6) Connect front propeller shaft and install rear
propeller shaft. (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 (Fig. 71) and skid
plate, if equipped. Tighten crossmember bolts to 41
N´m (30 ft. lbs.) torque.
(9) Remove transmission jack and support stand.
(10) Verify transfer case is in NEUTRAL. Connect
shift cable to transfer case range lever.
(11) Lower vehicle and verify transfer case shift
operation.
(12) Adjust the transfer case shift cable, if neces-
sary.
SPECIFICATIONS
TRANSFER CASE - NV247
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Bolt, crossmember 41-47 30.2-34.7 -
Plug, Detent 16-24 11.8-17.7 -
Plugs, drain/fill 20-34 15-25 -
Bolts, front brg. retainer 16-24 11.8-17.7 -
Bolts, case half 27-34 19.9-25 -
Nut, companion flange 122-176 90-130 -
Bolts, rear extension 27-34 19.9-25 -
Lock-nut, shift 27-34 19.9-25 -
Nuts, T-case mount stud 33-41 24.3-30.2 -
Fig. 71 Crossmember Installation
1 - CROSSMEMBER
2 - REAR TRANSMISSION MOUNT
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TRANSFER CASE - NV247 (Continued)