Jeep Cherokee 2000 Service Manual - Nv3550 Manual Transmission
NV3550 MANUAL TRANSMISSION
TABLE OF CONTENTS
page
page
GENERAL INFORMATION
NV3550 MANUAL TRANSMISSION. . . . . . . . . . . . 42
LUBRICANT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
DIAGNOSIS AND TESTING
LOW LUBRICANT LEVEL . . . . . . . . . . . . . . . . . . . 44
HARD SHIFTING . . . . . . . . . . . . . . . . . . . . . . . . . 44
TRANSMISSION NOISE . . . . . . . . . . . . . . . . . . . . 44
REMOVAL AND INSTALLATION
TRANSMISSION. . . . . . . . . . . . . . . . . . . . . . . . . . 44
SHIFT TOWER . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
YOKE SEAL—2WD . . . . . . . . . . . . . . . . . . . . . . . 47
REAR HOUSING YOKE BUSHING . . . . . . . . . . . . 48
DISASSEMBLY AND ASSEMBLY
TRANSMISSION. . . . . . . . . . . . . . . . . . . . . . . . . . 48
CLEANING AND INSPECTION
TRANSMISSION COMPONENTS . . . . . . . . . . . . . 83
SPECIFICATIONS
TORQUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
SPECIAL TOOLS
NV3550 MANUAL TRANSMISSION. . . . . . . . . . . . 85
GENERAL INFORMATION
NV3550 MANUAL TRANSMISSION
DESCRIPTION
The NV3550 is a medium-duty, 5-speed, constant
mesh, fully synchronized manual transmission. Fifth
gear is an overdrive range with a ratio of 0.78:1. The
NV3550 is available in two and four–wheel drive con-
figurations.
The transmission gear case consists of two alumi-
num housings. The clutch housing is a removable
component. It is not an integral part of the transmis-
sion front housing.
A combination of roller and ball bearings are used
to support the transmission shafts in the two hous-
ings. The transmission gears all rotate on caged type
needle bearings. A roller bearing is used between the
input and output shaft.
The NV3550 has a single shaft shift mechanism
with three shift forks all mounted on the shaft. The
shaft is supported in the front and rear housings by
bushings and one linear ball bearing. Internal shift
components consist of the forks, shaft, shift lever
socket, and detent components (Fig. 1).
GEAR RATIOS
Gear ratios for the NV3550 are as follows:
RANGE
RATIO
FIRST
4.01:1
SECOND
2.32:1
THIRD =
1.40:1
FOURTH =
1:1
FIFTH =
0.78:1
REVERSE =
3.55:1
IDENTIFICATION
The NV3550 identification and part number bar
code tags (Fig. 2) are located on the top of the trans-
mission, forward of the shift tower.
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.
21 - 42
NV3550 MANUAL TRANSMISSION
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