1994 JEEP CHEROKEE Service Repair Manual

NP231 SERVICE DIAGNOSIS
21 - 274 NP231 TRANSFER CASEJ

SHIFT LINKAGE ADJUSTMENT
LINKAGE ADJUSTMENTÐYJ
(1) Remove transfer case shift knob locknut and
remove knob (Fig. 4).
(2) Remove outer boot attaching screws and re-
move boot (Fig. 4).
(3) Remove inner boot attaching screws and re-
move boot (Fig. 4).
(4) Move shift lever into 4L position.
(5) Insert 3 mm (1/8 in.) spacer between shift lever
and forward edge of shift lever gate (Fig. 5). Secure
lever and spacer in place with tape or wire.
(6) Secure shift lever and spacer with tape or wire.
(7) Raise vehicle.
(8) Loosen lock bolt on adjusting trunnion (Fig. 6).
Linkage rod should now slide freely in trunnion.
(9) Verify that range lever is in 4L position (Fig. 6).
(10) Position linkage rod so it is a free fit in range
lever. Then tighten trunnion lock bolt (Fig. 6).
(11) Lower vehicle.
(12) Remove shift lever spacer and install inner
and outer boots and shift knob (Fig. 4).
LINKAGE ADJUSTMENTÐXJ
(1) Remove shift lever bezel.
(2) Move shift lever into 4L position.
(3) Insert 3 mm (1/8 in.) spacer between shift lever
and forward edge of shift lever gate (Fig. 7). Securelever and spacer in place with tape or wire.
(4) Raise vehicle.
(5) Loosen trunnion lock bolt (Figs. 8 and 9). Link-
age rod should now slide freely in trunnion.
(6) Verify that transfer case range lever is in 4L
position.
(7) Position linkage rod so it is a free fit in range
lever (Figs. 8 and 9). Then tighten trunnion locknut.
(8) Lower vehicle.
(9) Remove shift lever spacer and install bezel.SPEEDOMETER SERVICE
Speedometer service is covered in the automatic
transmission sections in this group. Refer to the ap-
propriate section as needed.
Fig. 4 Transfer Case Shift Lever And BootsÐYJ
Fig. 5 Installing Shift Lever SpacerÐYJ
Fig. 6 Shift Trunnion Lock Bolt PositionÐYJ
JNP231 TRANSFER CASE 21 - 275

TRANSFER CASE REMOVAL
(1) Shift transfer case into Neutral.
(2) Raise vehicle.
(3) 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, or skid plate.
(7) Disconnect front/rear propeller shafts at trans-
fer case.
(8) Disconnect vehicle speed sensor wires.(9) Disconnect transfer case linkage rod from range
lever.
(10) Disconnect transfer case vent hose.
(11) Support transfer case with transmission jack.
(12) Remove nuts attaching transfer case to trans-
mission.
(13) Secure transfer case to jack with chains.
(14) Pull transfer case and jack rearward to disen-
gage transfer case.
(15) Remove transfer case from under vehicle.
TRANSFER CASE INSTALLATION
(1) Mount transfer case on a transmission jack. Se-
cure transfer case to jack with chains.
(2) Position transfer case under vehicle.
(3) Align transfer case and transmission shafts and
install transfer case on transmission.
(4) Install and tighten transfer case attaching nuts
to 35 Nzm (26 ft. lbs.) torque.
(5) Connect vehicle speed sensor wires, and vent hose.
(6) Align and connect propeller shafts. Tighten
shaft attaching bolts to 19 Nzm (170 in. lbs.) torque.
(7) Fill transfer case with Mopar ATF Plus, or
Dexron II automatic transmission fluid.
(8) Install rear crossmember, or skid plate. Tighten
crossmember bolts to 41 Nzm (30 ft. lbs.) torque.
(9) Remove transmission jack and transmission
support stand.
(10) Connect transfer case range lever to linkage rod.
Fig. 7 Installing Shift Lever SpacerÐXJ
Fig. 8 Shift LinkageÐYJ
Fig. 9 Shift LinkageÐXJ
21 - 276 NP231 TRANSFER CASEJ

(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

(25) Remove synchro sleeve, hub and struts (Fig. 14).
(26) Remove synchro hub and stop ring (Fig. 15).
(27) Remove drive sprocket (Fig. 16).
(28) Slide range fork pin out of shift sector (Fig. 17).
(29) Remove range fork and shift hub (Fig. 18).(30) Remove range lever from sector shaft.
(31) Remove shift sector (Fig. 19).
Fig. 14 Removing Synchro Sleeve, Hub And Struts
Fig. 15 Removing Synchro Hub And Stop Ring
Fig. 16 Drive Sprocket Removal/InstallationFig. 19 Shift Sector Removal/Installation
Fig. 17 Disengaging Range Fork
Fig. 18 Range Fork And Hub Removal/Installation
21 - 280 NP231 TRANSFER CASEJ

(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