transfer DODGE RAM 1500 1998 2.G Workshop Manual

TRANSFER CASE - NV273
TABLE OF CONTENTS
page page
TRANSFER CASE - NV273
DESCRIPTION........................542
OPERATION..........................543
DIAGNOSIS AND TESTING - TRANSFER
CASE - NV273.......................543
REMOVAL............................544
DISASSEMBLY........................544
CLEANING...........................554
INSPECTION.........................554
ASSEMBLY...........................556
INSTALLATION........................568
SPECIFICATIONS
TRANSFER CASE - NV273.............568
SPECIAL TOOLS
TRANSFER CASE NV271/NV273.........569
EXTENSION HOUSING SEAL AND DUST BOOT
REMOVAL............................571
INSTALLATION........................571FLUID
STANDARD PROCEDURE - FLUID DRAIN AND
REFILL............................571
FRONT OUTPUT SHAFT SEAL
REMOVAL............................572
INSTALLATION........................572
MODE SENSOR
DESCRIPTION........................573
OPERATION..........................573
SELECTOR SWITCH
DESCRIPTION........................574
OPERATION..........................574
SHIFT MOTOR
DESCRIPTION........................575
OPERATION..........................575
REMOVAL............................575
INSTALLATION........................575
TRANSFER CASE - NV273
DESCRIPTION
The NV273 is an electronically controlled part-time
transfer case with a low range gear reduction system.
The NV273 has three operating ranges plus a NEU-
TRAL position. The low range system provides a gear
reduction ratio for increased low speed torque capa-
bility.
The geartrain is mounted in two aluminum case
halves attached with bolts. The mainshaft front and
rear bearings are mounted in aluminum case halves.
OPERATING RANGES
Transfer case operating ranges are:
²2WD (2-wheel drive)
²4HI (4-wheel drive)
²4LO (4-wheel drive low range)
²NEUTRAL
The 2WD range is for use on any road surface at
any time.The 4HI and 4LO ranges are for off road use only.
They are not for use on hard surface roads. The only
exception being when the road surface is wet or slip-
pery or covered by ice and snow.
The low range reduction gear system is operative
in 4LO range only. This range is for extra pulling
power in off road situations. Low range reduction
ratio is 2.72:1.
SHIFT MECHANISM
Operating ranges are selected with a dash
mounted shift selector switch. The shift selector
switch provides a input to the Transfer Case Control
Module (TCCM) to indicate the driver's desire to
change operating ranges. The TCCM uses this input,
along with input from the transfer case mounted
mode sensor and information from the vehicle's bus,
to determine if a shift is permitted. If the TCCM
decides the shift is permitted, the TCCM controls the
shift motor, mounted to the exterior of the transfer
case, to perform the shift.
21 - 542 TRANSFER CASE - NV273DR

IDENTIFICATION
A circular ID tag is attached to the rear case of
each transfer case (Fig. 1). 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.
OPERATION
The input gear is splined to the transmission out-
put shaft. The input gear drives the mainshaft
through the planetary assembly and range sleeve.
The front output shaft is operated by a drive chain
that connects the shaft to a drive sprocket on the
mainshaft. The drive sprocket is engaged/disengaged
by the mode fork, which operates the mode sleeve
and hub. The sleeve and hub are not equipped with a
synchronizer mechanism for shifting.
DIAGNOSIS AND TESTING - TRANSFER CASE - NV273
DIAGNOSIS CHART
Condition Possible Cause Correction
Transfer case difficult to shift or will
not shift into desired range.1) Transfer case electronically
controlled shift system malfunction.1) Verify proper operation per the
appropriate diagnostic manual.
2) If vehicle was operated for an
extended period in 4HI mode on
dry surface, driveline torque load
may cause difficulty.2) Drive the vehicle in a straight line
and momentarily release the
accelerator. The transfer case can
then be shifted to the desired mode.
3) Insufficient or incorrect lubricant. 3) Drain and refill transfer case with
the correct quantity of MoparTAT F
+4, Automatic Transmission Fluid.
4) Internal transfer case
components binding, worn, or
damaged.4) Repair or replace components as
necessary.
Transfer case noisy in all drive
modes.1) Insufficient or incorrect lubricant. 1) Drain and refill transfer case with
the correct quantity of MoparTAT F
+4, type 9602, Automatic
Transmission Fluid.
2) Internal transfer case
components binding, worn, or
damaged.2) Repair or replace components as
necessary.
Fig. 1 Transfer Case - Rear View
1 - TRANSFER CASE
2 - IDENTIFICATION TAG
DRTRANSFER CASE - NV273 21 - 543
TRANSFER CASE - NV273 (Continued)

Condition Possible Cause Correction
Transfer case noisy while in, or
jumps out of, 4LO mode.1) Transfer case not completely
engaged in 4LO position.1) While rolling 2-3 MPH and the
transmission in NEUTRAL, or clutch
depressed on vehicles equipped
with a manual transmission, shift
transfer case to the 2WD or 4HI
position, and then back into the 4LO
position.
2) Range fork damaged, inserts
worn, or fork is binding on the shift
rail.2) Repair or replace components as
necessary.
3) Low range gear worn or
damaged.3) Repair or replace components as
necessary.
Lubricant leaking from transfer case
seals or vent.1) Transfer case overfilled. 1) Drain lubricant to the correct
level.
2) Transfer case vent closed or
restricted.2) Clean or replace vent as
necessary.
3) Transfer case seals damaged or
installed incorrectly.3) Replace suspect seal.
Abnormal tire wear. 1) Extended operation in 4HI mode
on dry surfaces,1) Operate vehicle in 2WD mode on
dry surfaces.
REMOVAL
(1) Shift transfer case into 2WD.
(2) Raise vehicle.
(3) Drain transfer case lubricant.
(4) Mark front and rear propeller shafts for align-
ment reference.
(5) Support transmission with jack stand.
(6) Remove the transfer case skid plate, if
equipped.
(7) Disconnect front and rear propeller shafts at
transfer case.
(8) Disconnect transfer case shift motor and mode
sensor wire connectors.
(9) Disconnect transfer case vent hose.
(10) Support transfer case with transmission jack.
(11) Secure transfer case to jack with chains.
(12) Remove nuts attaching transfer case to trans-
mission (Fig. 2).
(13) Pull transfer case and jack rearward to disen-
gage transfer case.
(14) Remove transfer case from under vehicle.
DISASSEMBLY
Position transfer case in a shallow drain pan.
Remove drain plug and drain any remaining lubri-
cant remaining in case.
Fig. 2 Remove Transfer Case - Typical
1 - TRANSMISSION
2 - TRANSFER CASE
3 - MODE SENSOR CONNECTOR
21 - 544 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

COMPANION FLANGE AND EXTENSION HOUSING
(1) Install two bolts 180É apart into the front out-
put shaft companion flange.
(2) Place holder over the bolts and against the
companion flange (Fig. 3).
(3) Remove and discard the front companion flange
nut.
(4) Remove the companion flange from the front
output shaft. It may be necessary to use Flange
puller 8992 to remove the companion flange.
(5) Use a suitable chisel or pry tool to remove the
rear extension housing dust boot (Fig. 4).
(6) Use a suitable chisel or pry tool to remove the
rear extension housing seal.
(7) Remove rear extension bolts (Fig. 5).
Fig. 3 Remove Companion Flange Nut - Typical
1 - HOLDER 6719
2 - BOLTS
Fig. 4 Remove Extension Housing Dust Boot
1 - EXTENSION HOUSING
2 - DUST BOOT
Fig. 5 Remove Extension Housing Bolts
1 - EXTENSION HOUSING
2 - BOLTS
DRTRANSFER CASE - NV273 21 - 545
TRANSFER CASE - NV273 (Continued)

(8) Remove rear extension housing (Fig. 6). Tap
extension once or twice with a plastic mallet to break
sealer bead and loosen it.
OIL PUMP AND REAR CASE
(1) Disengage the oil pump pick-up tube (Fig. 7)
from the oil pump.
NOTE: The oil pump pick-up tube seals to the oil
pump with an o-ring. Verify that the o-ring was
removed with the tube and is in good condition.
Replace the o-ring if necessary.(2) Remove the oil pump (Fig. 8).
(3) Remove rear case-to-front case bolts (Fig. 9).
Fig. 7 Disengage The Oil Pick-up From Oil Pump
1 - OIL PUMP
2 - OIL PICK-UP TUBE
Fig. 6 Remove Extension Housing
1 - REAR CASE HALF
2 - EXTENSION HOUSING
Fig. 8 Remove Oil Pump
1 - REAR CASE HALF
2 - REAR OUTPUT SHAFT
3 - OIL PUMP
Fig. 9 Remove Case Half Bolts
1 - FRONT CASE HALF
2 - REAR CASE HALF
3 - BOLTS
21 - 546 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

(4) Remove the rear output shaft bearing inner
snap-ring (Fig. 10) from the output shaft using suit-
able snap-ring pliers.
(5) Remove the rear output shaft bearing inner
snap-ring (Fig. 11) from the output shaft.
(6) Loosen rear case with pry tool to break sealer
bead. Insert tool at each end of case (Fig. 12).
(7) Unseat rear case from alignment dowels.
(8) Remove the rear case from the front case (Fig.
13).
Fig. 10 Remove Rear Bearing Inner Snap-Ring
1 - OUTPUT SHAFT
2 - REAR CASE HALF
3 - SNAP-RING
Fig. 11 Remove Rear Bearing Inner Snap-Ring
1 - OUTPUT SHAFT
2 - REAR CASE HALF
3 - SNAP-RING
Fig. 12 Separate Front and Rear Case Halves
1 - FRONT CASE HALF
2 - REAR CASE HALF
Fig. 13 Remove Rear Case Half
1 - FRONT CASE HALF
2 - REAR CASE HALF
DRTRANSFER CASE - NV273 21 - 547
TRANSFER CASE - NV273 (Continued)

FRONT OUTPUT SHAFT AND DRIVE CHAIN
(1) Remove the oil pick-up tube (Fig. 14) and
screen from the front case half.
(2) Remove the front output shaft drive sprocket
retaining ring (Fig. 15).
(3) Remove the rear output shaft drive sprocket
retaining ring (Fig. 16).(4) Pull front sprocket (Fig. 17), rear sprocket, and
chain upward until clear of the front and rear output
shaft sprocket splines.
(5) Remove chain and sprockets as an assembly.
Fig. 14 Remove Oil Pick-Up Tube and Screen
1 - FRONT CASE HALF
2 - OIL SCREEN
3 - PICK-UP TUBE
Fig. 15 Remove Front Output Shaft Sprocket
Retaining Ring
1 - FRONT OUTPUT SHAFT
2 - DRIVE SPROCKET
3 - RETAINING RING
Fig. 16 Remove Rear Output Shaft Sprocket
Retaining Ring
1 - REAR OUTPUT SHAFT
2 - DRIVE SPROCKET
3 - RETAINING RING
Fig. 17 Remove Drive Chain and Sprockets
1 - FRONT CASE HALF
2 - CHAIN
3 - DRIVE SPROCKETS
21 - 548 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

SHIFT FORKS AND MAINSHAFT
(1) Remove the bolts (Fig. 18) that hold the shift
motor assembly to the transfer case.
(2) Remove the shift motor assembly (Fig. 19) from
the transfer case.(3) Remove the sector support with Socket 9033.
(4) Loosen detent plug (Fig. 20).
(5) Remove detent plug, spring, and plunger (Fig.
21). Note that the plug has an O-ring seal. Remove
and discard this seal.
Fig. 18 Remove Shift Motor Assembly Bolts
1 - TRANSFER CASE
2 - SHIFT MOTOR ASSEMBLY
3 - BOLTS
Fig. 19 Remove Shift Motor Assembly From
Transfer Case
1 - TRANSFER CASE
2 - SHIFT MOTOR ASSEMBLY
Fig. 20 Loosen the Detent Plug
1 - FRONT CASE HALF
2 - DETENT PLUG
Fig. 21 Remove Detent plug, Spring, and Plunger
1 - FRONT CASE HALF
2 - DETENT PLUG
3 - SPRING
4 - PLUNGER
DRTRANSFER CASE - NV273 21 - 549
TRANSFER CASE - NV273 (Continued)

(6) Using a screw mounted in a slide hammer,
remove the front output shaft seal.
(7) Remove the front output shaft snap-ring (Fig.
22).
(8) Remove front output shaft from bearing in case
(Fig. 23).(9) Pull mainshaft assembly out of input gear,
mode sleeve, and case (Fig. 24).
(10) Remove mode fork, mode sleeve, and shift rail
as assembly (Fig. 25). Note which way the sleeve fits
in the fork (long side of sleeve goes to front or the
points on the sleeve teeth go to the rear of case).
Fig. 22 Remove Front Output Shaft Bearing Inner
Snap-Ring
1 - FRONT CASE HALF
2 - SNAP-RING
Fig. 23 Remove Front Output Shaft
1 - FRONT CASE
2 - FRONT OUTPUT SHAFT
Fig. 24 Remove Mainshaft Assembly
1 - FRONT CASE HALF
2 - MAINSHAFT ASSEMBLY
Fig. 25 Mode Fork And Sleeve Removal
1 - MODE SLEEVE
2 - MODE FORK AND RAIL
21 - 550 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

(11) Remove range fork and hub as an assembly
(Fig. 26). Note fork position for installation reference.
(12) Remove the shift sector (Fig. 27).MAINSHAFT
(1) Remove the clutch gear (Fig. 28) from the out-
put shaft.
(2) Remove the mode hub retaining ring (Fig. 29)
from the mainshaft.
Fig. 29 Remove Mode Hub Retaining Ring
1 - MAINSHAFT
2 - MODE HUB
3 - RETAINING RING
Fig. 26 Range Fork And Hub Removal
1 - RANGE HUB
2 - RANGE FORK
Fig. 27 Remove Shift Sector
1 - SHIFT SECTOR
Fig. 28 Remove Clutch Gear
1 - OUTPUT SHAFT
2 - CLUTCH GEAR
3 - MODE HUB
DRTRANSFER CASE - NV273 21 - 551
TRANSFER CASE - NV273 (Continued)