mesh, fully synchronized manual transmission. Fifth
gear is an overdrive range with a ratio of 0.80:1. The
Transmission is available in 4-cyl. equipped 2WD
models.

The transmission gear case consists of two alumi-

num gear housings and a detachable clutch housing.

The mainshaft is supported by two sealed ball

bearings, and the countershaft is supported by two
tapered roller bearings. The transmission gears all
rotate on caged type needle bearings. A roller bearing
is used between the input and output shaft.

The Transmission has a single shaft shift mecha-

nism with three shift forks all mounted on the shaft.
The shaft is supported in the front and rear housings
by bushings. Internal shift components consist of the
forks, shaft, shift lever socket, and detent compo-
nents.

NV1500 GEAR RATIOS

RANGE

RATIO

FIRST

3.85 :1

SECOND

2.25 :1

THIRD

1.48 :1

FOURTH

1.00 :1

FIFTH

0.80 :1

REVERSE

3.52 :1

Identification bar code tags (Fig. 1) are located on

each side of the transmission, below the shift tower.
The tag located on the right side has the part num-
ber and the tag located on the left side has the build
sequence and date information.

TRANSMISSION AND TRANSFER CASE

21 - 1

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.

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 we are
up-shifting or down-shifting). The synchronizer 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 friction 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 synchronizer
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 - NV1500 MANUAL
TRANSMISSION

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.

Leaks can occur at the mating surfaces of the gear

case, intermediate plate and adaptor or extension

Fig. 1 NV1500 IDENTIFICATION

21 - 2

MANUAL - NV1500

MANUAL - NV1500 (Continued)

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 hous-

ing will be from the housing oil seals. Leaks at com-
ponent 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 dripping from the clutch
housing after extended operation. If the leak is
severe, it may also contaminate the clutch disc caus-
ing the disc to slip, grab, and/or chatter.

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 rec-
ommendations 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.

HARD SHIFTING

Hard shifting is usually caused by a low lubricant

level, improper, or contaminated lubricants. The con-
sequence of using non–recommended lubricants is
noise, 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 a damaged clutch pressure plate or disc are addi-
tional probable causes of increased shift effort. Incor-
rect adjustment or a worn/damaged pressure plate or
disc can cause incorrect release. If the 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 gener-

ally 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) Disconnect battery negative cable.
(2) Shift transmission into Neutral.
(3) Remove floor console. Refer to 23 Body for pro-

cedures.

(4) Remove screws attaching shift boot to floorpan.

Then slide boot upward on lever extension.

(5) Remove shift lever extension from the shift

tower and lever assembly.

(6) Raise and support vehicle.
(7) Mark

propeller

shaft

and

axle

companion

flange for alignment reference. Use paint, scriber, or
chalk to mark flange.

(8) Remove propeller shaft.
(9) Disconnect and remove exhaust system Y-pipe.
(10) Disconnect wires at backup light switch.
(11) Support engine with adjustable safety stand

and wood block.

(12) If transmission is to be disassembled for

repair, remove drain plug and drain lubricant from
transmission.

(13) Remove bolts/nuts attaching transmission to

rear mount.

(14) Support transmission with a transmission

jack. Secure transmission to jack with safety chains.

(15) Remove rear crossmember.
(16) Remove bolts attaching clutch slave cylinder

to clutch housing. Then move cylinder aside for work-
ing clearance.

(17) Remove starter.
(18) Remove transmission dust shield.
(19) Remove transmission harness wires from clips

on transmission shift cover.

(20) Lower transmission slightly.
(21) Remove the bolts attaching the shift tower

and lever assembly to the transmission housing.
Then remove the shift tower and lever assembly.

(22) Remove

bolts

attaching

transmission

engine.

(23) Slide transmission and jack rearward until

input shaft clears clutch disc.

(24) Lower transmission jack and remove trans-

mission from under vehicle.

DISASSEMBLY

FRONT HOUSING

(1) Shift transmission into Neutral.
(2) Remove drain plug and drain lubricant into a

container.

(3) Inspect drain plug magnet for debris.
(4) Remove backup light switch (Fig. 2).
(5) Remove shift tower bolts and remove tower and

lever assembly (Fig. 3).

MANUAL - NV1500

21 - 3

MANUAL - NV1500 (Continued)

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