1998 DODGE RAM 1500 tow

MANUAL TRANSMISSION - NV4500
TABLE OF CONTENTS
page page
MANUAL TRANSMISSION - NV4500
DESCRIPTION.........................43
OPERATION...........................43
DIAGNOSIS AND TESTING................44
REMOVAL.............................44
DISASSEMBLY.........................46
CLEANING............................62
INSPECTION..........................62
ASSEMBLY............................63
INSTALLATION.........................80
SPECIFICATIONS.......................81
SPECIAL TOOLS.......................81ADAPTER HOUSING SEAL
REMOVAL.............................85
INSTALLATION.........................85
EXTENSION HOUSING SEAL
REMOVAL.............................85
INSTALLATION.........................85
SHIFT MECHANISM
REMOVAL.............................86
INSTALLATION.........................87
SHIFT COVER
REMOVAL.............................87
INSTALLATION.........................87
MANUAL TRANSMISSION -
NV4500
DESCRIPTION
The NV4500 is a five speed constant mesh manual
transmission. All gear ranges including reverse are
synchronized. Fifth gear is an overdrive range. The
transmission has a cast iron gear case and aluminum
shift cover.
Two versions are used, a standard duty for 5.7L
applications and a heavy duty for V10 and Cummins
diesel applications. Main difference is a larger diam-
eter input shaft, for the heavy duty model.
Tapered roller bearings support the drive gear,
mainshaft and countershaft in the gear case. Roller
bearings in the drive gear support the forward end of
the mainshaft. The mainshaft gears are all supported
on caged type roller bearings. Drive gear thrust reac-
tion is controlled by a needle type thrust bearing.
The bearing is located at the forward end of the
mainshaft.
The transmission is a top loader style. The shift
lever is located in a shifter tower which is bolted to
the shift cover and operates the shift forks and rails
directly. The shift forks and rails are all located
within the aluminum cover which is bolted to the top
of the gear case.
IDENTIFICATION
The transmission identification tag is attached to
the driver side PTO cover (Fig. 1).
The tag provides the transmission model number,
build date and part number. Be sure to reinstall the
I.D. tag if removed during service. The information
on the tag is essential to correct parts ordering.
OPERATION
The manual transmission receives power through
the clutch assembly from the engine. The clutch disc
is splined to the transmission input shaft and is
turned at engine speed at all times that the clutch is
engaged. The input shaft is connected to the trans-
mission countershaft through the mesh of fourth
speed gear on the input shaft and the fourth counter-
shaft gear. At this point all the transmission gears
are spinning.
Fig. 1 IDENTIFICATION TAG LOCATION
1 - PTO COVER
2 - I.D. TAG
DRMANUAL TRANSMISSION - NV4500 21 - 43

The driver selects a particular gear by moving the
shift lever to the desired gear position. This move-
ment moves the internal transmission shift compo-
nents to begin the shift sequence. As the shift lever
moves the selected shift rail, the shift fork attached
to that rail begins to move. The fork is positioned in
a groove in the outer circumference of the synchro-
nizer sleeve. As the shift fork moves the synchronizer
sleeve, the synchronizer begins to speed-up or slow
down the selected gear (depending on whether the
driver is up-shifting or down-shifting). The synchro-
nizer does this by having the synchronizer hub
splined to the mainshaft, or the countershaft in some
cases, and moving the blocker ring into contact with
the gear's friction cone. As the blocker ring and fric-
tion cone come together, the gear speed is brought up
or down to the speed of the synchronizer. As the two
speeds match, the splines on the inside of the syn-
chronizer sleeve become aligned with the teeth on
the blocker ring and the friction cone and eventually
will slide over the teeth, locking the gear to the
mainshaft, or countershaft, through the synchronizer.
DIAGNOSIS AND TESTING
LOW LUBRICANT LEVEL
A low transmission lubricant level is generally the
result of a leak, inadequate lubricant fill or an incor-
rect lubricant level check. A correct lubricant level
check can only be made when the vehicle is level.
Also allow the lubricant to settle for a minute or so
before checking. These recommendations will ensure
an accurate check and avoid an underfill or overfill
condition. Always check the lubricant level after any
addition of fluid to avoid an incorrect lubricant level
condition.
Leaks can occur at the mating surfaces of the gear
case, adaptor or extension housing, or from the front/
rear seals. A suspected leak could also be the result
of an overfill condition. Leaks at the rear of the
extension or adapter housing will be from the hous-
ing oil seals. Leaks at component mating surfaces
will probably be the result of inadequate sealer, gaps
in the sealer, incorrect bolt tightening or use of a
non-recommended sealer. A leak at the front of the
transmission will be from either the front bearing
retainer or retainer seal. Lubricant may be seen drip-
ping from the clutch housing after extended opera-
tion. If the leak is severe, it may also contaminate
the clutch disc causing the disc to slip, grab and or
chatter.
HARD SHIFTING
Hard shifting is usually caused by a low lubricant
level, improper or contaminated lubricants. The con-
sequence of using non-recommended lubricants isnoise, excessive wear, internal bind and hard shift-
ing. Substantial lubricant leaks can result in gear,
shift rail, synchro, and bearing damage. If a leak
goes undetected for an extended period, the first indi-
cations of component damage are usually hard shift-
ing and noise.
Component damage, incorrect clutch adjustment or
damaged clutch pressure plate or disc are additional
probable causes of increased shift effort. Incorrect
adjustment or a worn/damaged pressure plate or disc
can cause incorrect release. If clutch problem is
advanced, gear clash during shifts can result. Worn
or damaged synchro rings can cause gear clash when
shifting into any forward gear. In some new or
rebuilt transmissions, new synchro rings may tend to
stick slightly causing hard or noisy shifts. In most
cases this condition will decline as the rings wear-in.
TRANSMISSION NOISE
Most manual transmissions make some noise dur-
ing normal operation. Rotating gears generate a mild
whine that is audible, but generally only at extreme
speeds. Severe highly audible transmission noise is
generally the initial indicator of a lubricant problem.
Insufficient, improper or contaminated lubricant
will promote rapid wear of gears, synchros, shift
rails, forks and bearings. The overheating caused by
a lubricant problem, can also lead to gear breakage.
REMOVAL
(1) Shift transmission into Neutral.
(2) Remove shift boot screws from floorpan and
slide boot upward on the shift lever.
(3) Remove shift lever extension from shift tower
and lever assembly.
(4) Remove shift tower bolts (Fig. 2).
Fig. 2 SHIFT TOWER
1 - SHIFT TOWER
2 - SHIFTER
3 - BOLTS
21 - 44 MANUAL TRANSMISSION - NV4500DR
MANUAL TRANSMISSION - NV4500 (Continued)

(5) Remove shift tower and isolator plate from
transmission shift cover.
(6) Raise and support vehicle.
(7) Remove skid plate, if equipped.
(8) Mark propeller shaft and axle yokes for instal-
lation reference and remove shaft/shafts.
(9) Remove exhaust system Y-pipe.
(10) Disconnect speed sensor and backup light
switch connectors.
(11) Support engine with safety stand and a wood
block.
(12) If transmission is to be disassembled, remove
drain bolt at bottom of PTO cover and drain lubri-
cant (Fig. 3).
TWO WHEEL DRIVE
(1) Remove bolts attaching transmission to rear
crossmember mount.
(2) Support and secure transmission with safety
chains to a transmission jack.
(3) Remove rear crossmember bolts and pry out
crossmenber.
(4) Remove clutch slave cylinder bolts and move
cylinder aside for clearance.
NOTE: The hydraulic linkage has a quick connect at
the slave cylinder. This fitting should not be discon-
nected.
(5) Remove transmission harness wires from clips
on transmission shift cover.
(6) Remove transmission to clutch housing bolts.
(7) Slide transmission and jack rearward until
input shaft clears clutch housing.
(8) Lower transmission jack and remove transmis-
sion from under vehicle.
FOUR WHEEL DRIVE
(1) Disconnect transfer case shift linkage at trans-
fer case range lever. Then remove transfer case shift
mechanism from transmission (Fig. 4).
(2) Support and secure transfer case to transmis-
sion jack with safety chains.
(3) Remove transfer case mounting nuts.
(4) Move transfer case rearward until input gear
clears transmission mainshaft.
(5) Lower transfer case assembly and move it from
under vehicle.
(6) Support and secure transmission with safety
chains to a transmission jack.
(7) Remove transmission harness from retaining
clips on transmission shift cover.
(8) Remove bolts/nuts attaching transmission
mount to rear crossmember.
(9) Remove rear crossmember bolts and pry out
crossmenber.
(10) Remove clutch slave cylinder splash shield, if
equipped.
(11) Remove clutch slave cylinder bolts and move
cylinder aside for clearance.
NOTE: The hydraulic linkage has a quick connect at
the slave cylinder. This fitting should not be discon-
nected.
(12) Remove transmission to clutch housing bolts.
(13) Slide transmission and jack rearward until
input shaft clears clutch housing.
(14) Lower transmission jack and remove trans-
mission from under vehicle.
Fig. 3 FILL AND DRAIN PLUGS
1 - PTO COVER
2 - DRAIN BOLT
3 - FILL PLUG
Fig. 4 TRANSFER CASE SHIFTER-TYPICAL
1 - TRANSMISSION
2 - TRANSFER CASE SHIFT MECHANISM
DRMANUAL TRANSMISSION - NV4500 21 - 45
MANUAL TRANSMISSION - NV4500 (Continued)

DISASSEMBLY
SHIFT MECHANISM
(1) Remove bolts holding shift tower to shift mech-
anism cover and remove tower.
(2) Remove bolts holding shift mechanism cover to
transmission.
(3) Pry up shift mechanism cover at slot (Fig. 5) in
cover.
(4) Raise mechanism up enough to disengage it
from the dowl pins (Fig. 6).
(5) Raise front of the mechanism and lift up and
off the transmission.EXTENSION/ADAPTER HOUSING
(1) Remove bolts attaching extension/adapter hous-
ing to gear case (Fig. 7).
(2) Remove extension/adapter housing (Fig. 8).
There is one alignment dowel in the gear case and
one in the extension/adapter housing.
Fig. 5 LOOSEN SHIFT MECHANISM
1 - SHIFT MECHANISM COVER SLOT
2-PRYTOOL
Fig. 6 SHIFT MECHANISM COVER
1 - SHIFT MECHANISM COVER
2 - ALIGNMENT DOWELS
Fig. 7 EXTENSION/ADAPTER HOUSING BOLTS
1 - EXTENSION HOUSING
2 - BOLTS (8)
Fig. 8 EXTENSION/ADAPTER HOUSING
1 - GEAR CASE
2 - EXTENSION HOUSING
21 - 46 MANUAL TRANSMISSION - NV4500DR
MANUAL TRANSMISSION - NV4500 (Continued)

(3) Remove reverse idler shaft (Fig. 33).
(4) Rotate countershaft outward and push reverse
idler gear away from countershaft and toward front
of case (Fig. 34).(5) Remove idler gear (Fig. 35).
(6) Keep reverse idler gear bearings and spacer
together (Fig. 36). Insert idler shaft through gear and
bearings to keep them in place.
(7) Remove idler gear thrust washers from gear
case. Install washers on idler shaft to keep them
together for cleaning and inspection.
Fig. 33 REVERSE IDLER SHAFT
1 - REVERSE IDLER SHAFT
Fig. 34 IDLER GEAR AND COUNTERSHAFT
1 - REVERSE IDLER GEAR
2 - COUNTERSHAFT
Fig. 35 REVERSE IDLER GEAR
1 - REVERSE IDLER GEAR
2 - DRIVE GEAR BORE
Fig. 36 IDLER GEAR COMPONENTS
1 - BEARINGS
2 - REVERSE IDLER GEAR
DRMANUAL TRANSMISSION - NV4500 21 - 53
MANUAL TRANSMISSION - NV4500 (Continued)

(10) Remove second gear clutch cone snap ring
from mainshaft synchro hub groove (Fig. 50).
(11) Remove second gear clutch cone, synchro
clutch ring and synchro stop ring (Fig. 51).(12) Remove 1-2 synchro hub snap ring (Fig. 52).
(13) Remove 1-2 synchro sleeve, hub, struts and
springs as an assembly (Fig. 53).
NOTE: Tapered side of sleeve also goes toward
front. Do not disassemble synchro components
unless worn or damaged.
Fig. 50 SECOND GEAR CLUTCH CONE SNAP RING
1 - 1-2 SLEEVE
2 - SNAP RING
3 - SECOND GEAR CLUTCH CONE
Fig. 51 SECOND GEAR CLUTCH CONE AND RING
1 - 1-2 SLEEVE AND HUB
2 - SYNCHRO STOP RING
3 - CLUTCH RING
4 - SECOND GEAR CLUTCH CONE
Fig. 52 1-2 SLEEVE AND HUB SNAP RING
1 - 1-2 HUB SNAP RING
2 - 1-2 SLEEVE AND HUB
Fig. 53 1-2 SYNCHRO SLEEVE AND HUB
1 - 1-2 SLEEVE AND HUB
21 - 58 MANUAL TRANSMISSION - NV4500DR
MANUAL TRANSMISSION - NV4500 (Continued)

(28) Remove reverse clutch gear (Fig. 62).
(29) Remove first gear from bearing and mainshaft
(Fig. 63).
(30) Remove first gear bearing from mainshaft
(Fig. 64).
CLEANING
Clean the gears, shafts, shift components and
transmission housings with a standard parts clean-
ing solvent. Do not use acid or corrosive base sol-
vents. Dry all parts except bearings with compressed
air.
Clean the shaft bearings with a mild solvent such
as Mopar degreasing solvent, Gunk or similar sol-
vents. Do not dry the bearings with compressed air.
Allow the bearings to either air dry or wipe them dry
with clean shop towels.
INSPECTION
NOTE: Minor corrosion, nicks, or pitting can be
smoothed with 400 grit emery and polished out with
crocus cloth.
Inspect the reverse idler gear, bearings, shaft and
thrust washers. Replace the bearings if the rollers
are worn, chipped, cracked, flat-spotted or brinnelled.
Replace the gear if the teeth are chipped, cracked or
worn thin.
Inspect the front bearing retainer and bearing cup.
Replace the bearing cup if scored, cracked, brinnelled
or rough. Check the release bearing slide surface of
the retainer carefully. Replace the retainer if worn or
damaged in any way.
Inspect mainshaft bearing surfaces, splines, snap
ring grooves and threads. Replace the shaft if any
surfaces exhibit considerable wear or damage.
Inspect the countershaft and bearings. Replace the
shaft if any surfaces exhibit considerable wear or
damage.
Inspect shift forks for wear and distortion. Check
fit of the sleeve in the fork to be sure the two parts
fit and work smoothly. Replace the fork if the roll pin
holes are worn oversize or damaged. Do not attempt
to salvage a worn fork. Replace shift fork roll pins if
necessary or if doubt exists about their condition.
The all bearings for wear, roughness, flat spots,
pitting or other damage. Replace the bearings if nec-
essary.
Inspect the blocker rings and fiction cones. replace
either part if worn or damaged in any way. Replace if
the friction material is burned, flaking off or worn.
Inspect synchro components wear or damage.
Replace parts if worn, cracked or distorted.
Inspect all of the thrust washers and locating pins.
Replace the pins if bent or worn. Replace the wash-
ers if worn or the locating pin notches are distorted.
Inspect the case and housing/adapter sealing and
mating surfaces are free of burrs and nicks. InspcetFig. 62 Reverse Clutch Gear
1 - REVERSE CLUTCH GEAR
Fig. 63 FIRST GEAR
1 - FIRST GEAR
Fig. 64 FIRST GEAR BEARING
1 - MAINSHAFT
2 - FIRST GEAR BEARING
21 - 62 MANUAL TRANSMISSION - NV4500DR
MANUAL TRANSMISSION - NV4500 (Continued)

(4) Remove countershaft rear bearing plate.
(5) Install a end play shim that will provide mini-
mum countershaft end play. Position shim on rear
bearing cup (Fig. 76).
(6) Install countershaft rear bearing plate (Fig.
73).
NOTE: Verify plate is seated in reverse idler shaft
notch and end play shims are still in position
before installing bolts.
(7) Apply 1-2 drops Mopar Loc N' Seal or equiva-
lent to threads of rear bearing plate bolts. Then
install and tighten bearing plate bolts to 23 N´m (200
in. lbs.).
SHIFT LUG AND RAIL
(1) Lubricate shift lug and rail with CastroltSyn-
torq or equivalent.
(2) Insert shift lug rail part way into case.
(3) Install shift lug on rail.
(4) Position shift rail so roll pin notches are
toward outside of case (Fig. 77).
(5) Install roll pin that secures lug to rail (Fig. 77).
MAINSHAFT AND GEARTRAIN
CAUTION: The reverse, 1-2 and 3-4 synchro compo-
nents can be assembled and installed incorrectly.
Follow assembly procedures for component identi-
fication and location.
Lubricate mainshaft bearing surfaces and all bear-
ing assemblies with CastroltSyntorq or with petro-
leum jelly.(1) Install first snap ring in rear most groove of
mainshaft hub (Fig. 78). This snap ring locates first
gear clutch gear on shaft.
NOTE: Four of these snap rings are used to secure
various components on the mainshaft 1-2 synchro
hub. The snap rings are all the same size and are
interchangeable.
Fig. 76 COUNTERSHAFT END PLAY SHIM
1 - REAR BEARING CUP
2 - END PLAY SHIM (SELECTIVE)Fig. 77 SHIFT LUG AND RAIL
1 - NOTCHES (FOR 5TH GEAR SHIFT FORK ROLL PINS)
2 - LUG RAIL
3 - ROLL PIN HOLE
4 - SHIFT LUG
Fig. 78 FIRST GEAR BEARING AND SNAP RING
1 - SNAP RING
2 - FIRST GEAR BEARING
3 - MAINSHAFT SYNCHRO HUB
21 - 66 MANUAL TRANSMISSION - NV4500DR
MANUAL TRANSMISSION - NV4500 (Continued)