front JEEP CHEROKEE 1994 Service Repair Manual

(11) Adjust transfer case shift linkage.
(12) Lower vehicle.
TRANSFER CASE DISASSEMBLY AND OVERHAUL
Two versions of the NP231 are used in current
models. One version retains the synchronizer
components used in previous years. A newly intro-
duced version does not have synchro components.
The non-synchro version does not have a synchro
gear, struts, spring and stop ring. During over-
haul, note which version is being serviced and or-
der needed parts accordingly.
(1) Remove fill and drain plugs.
(2) Remove front yoke. Discard yoke seal washer
and nut. They should not be reused.
(3) Move transfer case range lever rearward to 4L
position.
(4) Remove extension housing attaching bolts.
(5) Tap extension housing in clockwise direction to
break sealer bead and remove housing (Fig. 1).
CAUTION: To avoid damaging the sealing surfaces
of the extension housing and rear retainer, do not
pry or wedge the housing off the retainer.
(6) Remove rear bearing snap ring (Fig. 2).
(7) Remove rear retainer attaching bolts.
(8) Remove rear retainer. Position screwdriver un-
der each tab on retainer housing (Fig. 3). Then care-
fully pry retainer upward and off rear case.
CAUTION: Do not pry against the sealing surfaces of
the retainer or rear case. The surfaces could be dam-
aged.
(9) Remove bolts attaching rear case to front case.
Retain bolts and washers.
(10) Separate rear case from front case (Fig. 4) Insert
screwdrivers into slots cast in case ends. Then gently
pry upward to break sealer bead and loosen rear case.
CAUTION: Do not pry against the sealing surfaces
of the retainer or rear case. The surfaces could be
damaged.
Fig. 1 Extension Housing Removal
Fig. 2 Rear Bearing Snap Ring Removal
Fig. 3 Rear Retainer Removal
Fig. 4 Loosening Rear Case
JNP231 TRANSFER CASE 21 - 277

(11) Remove oil pump and rear case as an assem-
bly (Fig. 5).
(12) Slide oil screen out of case pocket. Disconnect
screen from pickup tube and remove screen (Fig. 6).
(13) Remove pickup tube from oil pump (Fig. 6).
(14) Remove oil pump from rear case.
(15) Remove pickup tube O-ring from oil pump
(Fig. 7).
(16)The oil pump can be disassembled for
cleaning and inspection as described in steps(17) and (18). However, the pump parts are NOT
serviceable separately. If any pump component
is worn, or damaged, the pump must be re-
placed as an assembly.
(17) If oil pump will be disassembled for inspec-
tion, mark position of oil pump housings for reference
(Fig. 8). Remove screws that attach two halves of the
pump. Then remove feed housing from gear housing
(Fig. 8).
(18) Mark position of pump gears and remove
them from housing (Fig. 8).
(19) Remove mode spring (Fig. 9).
(20) Tap front output shaft upward with a rawhide
mallet to free it from shaft bearing.
(21) Remove front output shaft and drive chain as
assembly (Fig. 10).
Fig. 5 Rear Case And Oil Pump Removal
Fig. 6 Removing Oil Screen And Pickup Tube 16
Fig. 7 Pickup Tube O-Ring Location
Fig. 8 Oil Pump Components
21 - 278 NP231 TRANSFER CASEJ

(22) Remove mainshaft, mode fork and shift rail as
assembly (Fig. 11).(23) Remove mode fork and shift rail from synchro
sleeve (Fig. 12).
(24) Remove synchro hub snap ring (Fig. 13).
Fig. 9 Mode Spring Removal
Fig. 10 Front Output Shaft And Drive Chain
Removal
Fig. 11 Removing Mainshaft, Mode Fork And Shift
Rail
Fig. 12 Removing Mode Fork From Sleeve
Fig. 13 Synchro Hub Snap Ring Removal/Installation
JNP231 TRANSFER CASE 21 - 279

(32) Remove sector shaft bushing and O-ring (Fig.
20).
(33) Remove shift detent plunger, spring and plug
(Fig. 21). Remove O-ring from plug after removal.
(34) Turn front case over and remove front bearing
retainer bolts (Fig. 22).
(35) Remove front bearing retainer. Position screw-
drivers in retainer slots and lift upward to loosen
and remove retainer (Fig. 23).
(36) Remove input gear snap ring (Fig. 24).
(37) Press input and low range gear assembly out
of input gear bearing with shop press (Fig. 25).
(38) Remove low range gear snap ring (Fig. 26).
(39) Remove retainer, thrust washers and input
gear from low range gear (Fig. 27).
(40) Remove oil seals from rear retainer, rear ex-
tension housing, oil pump feed housing and case
halves.
(41) Remove magnet from front case.(42) Remove the speedometer driven gear, seals
and adapter.
Fig. 20 Removing/Installing Sector Shaft Bushing
And O-Ring
Fig. 21 Detent Component Removal
Fig. 22 Front Bearing Retainer Bolt Locations
Fig. 23 Removing Front Bearing Retainer
Fig. 24 Removing Input Gear Snap Ring
JNP231 TRANSFER CASE 21 - 281

CLEANING AND INSPECTION
Clean the transfer case components thoroughly
with solvent. Remove all traces of sealer from the
case and retainer seal surfaces.Clean the oil pickup screen with solvent and dry it
with compressed air. Also use compressed air to re-
move solvent residue from all oil feed passages and
channels.
Inspect the low range annulus gear (Fig. 28).If
the gear is damaged, replace the gear and front
case as an assembly. Do not attempt to remove
the gear.
Inspect the case halves, extension housing and re-
tainers for cracks, porosity, or damaged sealing sur-
faces. Inspect the shafts, gears, chain and shift
components for wear or damage. Replace the oil
pump as an assembly if any pump part is worn or
damaged.
Inspect all of the transfer case bearings for wear,
roughness, pitting, or galling. Replace worn or dam-
aged bearings as outlined in the assembly section.
TRANSFER CASE ASSEMBLY
CAUTION: The bearing bores in various transfer
case components contain oil feed holes. Be sure re-
placement bearings do not block these feed holes.
(1) Lubricate components with automatic transmis-
sion fluid (or petroleum jelly where indicated) during
assembly.
(2) Remove front output shaft seal from front case.
(3) Remove front output shaft bearing snap ring
(Fig. 29).
(4) Tap old front output shaft bearing out of front
case with plastic mallet. Install new bearing with
Tool Handle C-4171 and Installer Tool 5064 (Fig. 30).
(5) Secure front output shaft bearing in front case
with new snap ring (Fig. 29).
(6) Install new front output shaft seal in front
case.
(7) Press input gear bearing from the front case
with Tool Handle C-4171 and Installer Tool C-4210
(Fig. 31). Then turn front case over.
Fig. 25 Removing Input And Low Range Gear
Assembly
Fig. 26 Removing Low Range Gear Snap Ring
Fig. 27 Input And Low Range Gear Components
Fig. 28 Low Range Annulus Gear Location
21 - 282 NP231 TRANSFER CASEJ

(8) Install snap ring on new input gear bearing
and start bearing in case.
(9) Carefully press input gear bearing into case un-
til bearing snap ring seats against case (Fig. 32).
(10) Remove mainshaft pilot bearing from input
gear with Tool MD-998346 and two suitable size open
end wrenches (Fig. 33).(11) Install new pilot bearing in input gear with
shop press, Tool Handle C-4171 and Installer 5065
(Fig. 34).
Fig. 29 Removing/Installing Front Output Shaft
Bearing Snap Ring
Fig. 30 Installing Output Shaft Front Bearing
Fig. 31 Removing Input Gear Bearing
Fig. 32 Input Gear Bearing Installation
Fig. 33 Removing Mainshaft Pilot Bearing From
Input Gear
Fig. 34 Installing Mainshaft Pilot Bearing In Input
Gear
JNP231 TRANSFER CASE 21 - 283

(12) Assemble low range gear, input gear thrust
washers, input gear and input gear retainer (Fig. 35).
(13) Install input gear snap ring (Fig. 36).
(14) Lubricate input gear with automatic transmis-
sion fluid.
(15) Start input gear in front bearing.
(16) Press input gear into front bearing (Fig. 36).
CAUTION: Use a proper size tool to press the input
gear into the front bearing. An incorrect tool could
push the input gear pilot bearing too far into the
gear bore (Fig. 45). Also, do not press against the
end surfaces of the low range gear. The gear case
and thrust washers could be damaged.
(17) Install input gear snap ring (Fig. 37).
(18) Install new oil seal in front bearing retainer.
(19) Apply 3 mm (1/8 in.) wide bead of Mopar Gas-
ket Maker, silicone adhesive/sealer, or Loctite 518 to
front bearing retainer seal surface (Fig. 38).
(20) Install front bearing retainer on front case (Fig.
22). Tighten retainer bolts to 21 Nzm (16 ft. lbs.) torque.
(21) Install new sector shaft O-ring and bushing
(Fig. 39).
Fig. 37 Installing Input Gear Snap Ring
Fig. 38 Applying Sealer To Front Bearing Retainer
Fig. 39 Installing Sector O-Ring And Bushing
Fig. 35 Input And Low Range Gear Assembly
Fig. 36 Input And Low Range Gear Installation
21 - 284 NP231 TRANSFER CASEJ

(22) Install shift sector in the case (Fig. 40).
(23) Install range lever and lever attaching nut on
shift sector. Tighten attaching nut to 30 Nzm (22 ft.
lbs.) torque.
(24) Install detent plunger, spring and plug (Fig.
41). Tighten plug to 20 Nzm (15 ft. lbs.) torque.
(25) Inspect range fork pads (Fig. 42). Be sure
pads are secure and in position.
(26) Assemble range fork and shift hub (Fig. 43).
(27) Engage range fork pin in sector slot (Fig. 44).
(28) If drive sprocket bearings are to be replaced,
remove and install them as follows:
(a) Press both bearings out of sprocket simulta-
neously with Remover Tool C-4667, or 5066 and
Tool Handle C-4171 (Fig. 45).
(b) Before installing new bearings, refer to Fig-
ure 46 and note correct bearing position in
sprocket. Bearings must be also be installed in
proper sequence. Install front bearing first and
rear bearing last.CAUTION: Do not press the bearings any farther
into the sprocket than indicated in Figure 46. The
bearings could block the mainshaft oil feed hole if
pressed too deeply into the sprocket.
Fig. 42 Range Fork Pads
Fig. 43 Assembling Range Fork And Shift Hub
Fig. 44 Seating Range Fork In Sector
Fig. 40 Installing Shift Sector
Fig. 41 Installing Detent Plunger, Spring And Plug
JNP231 TRANSFER CASE 21 - 285

(c) Install newfrontbearing first. Press bearing
flush with edge of sprocket bore (Fig. 47).
(d) Install newrearbearing (Fig. 48). Press
bearing in until 4.6 mm (3/16 in.) below edge of
bore as shown in Figure 46.
(29) Install spring and three struts in synchro hub
(Fig. 49).(30) Lubricate drive sprocket bearings, stop ring
and synchro hub with automatic transmission fluid.
(31) Install sprocket, stop ring and synchro hub on
mainshaft (Fig. 50).Be sure to seat hub struts on
stop ring lugs.
Fig. 45 Removing Drive Sprocket Bearings
Fig. 46 Correct Position Of Bearings In Sprocket
Fig. 47 Installing Drive Sprocket Front Bearing
Fig. 48 Installing Drive Sprocket Rear Bearing
Fig. 49 Installing Synchro Hub Spring And Struts
21 - 286 NP231 TRANSFER CASEJ

(32) Install new synchro hub snap ring (Fig. 51).
(33) Install sleeve on synchro hub. Be sure sleeve
is installed with beveled spline ends facing stop ring.
(34) Install new pads on mode fork and install
shift rail in fork.
(35) Engage mode fork in synchro sleeve (Fig. 52).
(36) Install mode fork-mainshaft assembly in case
(Fig. 52). Be sure the mode fork rail is seated in both
range fork bushings.
(37) Assemble and install output shaft and drive
chain (Fig. 53). Lift mainshaft slightly to ease chain
and shaft installation.
(38) Install mode spring on shift rail (Fig. 54).
(39) If front output shaft rear bearing is to be re-
placed, install new bearing as follows:(a) Remove bearing from rear case with Bearing
Remover MD-998346 and two suitable size
wrenches (Fig. 55).
Fig. 51 Installing Synchro Hub Snap Ring
Fig. 50 Drive Sprocket, Stop Ring And Synchro Hub
Installation
Fig. 52 Installing Mainshaft And Mode Fork
Assembly
Fig. 53 Drive Chain And Front Output Shaft
Installation
Fig. 54 Installing Mode Spring
JNP231 TRANSFER CASE 21 - 287