Isuzu N-Series. Manual - part 869

THIS MANUAL INCLUDES THE FOLLOWING SECTIONS:

SECTION No.

CONTENTS

7B1

MANUAL TRANSMISSION (MZZ)

7C

CLUTCH (FOR MZZ TRANSMISSION)

MANUAL TRANSMISSION (MZZ) 7B1-1

MANUAL TRANSMISSION AND CLUTCH 

MZZ SERIES

SECTION 7B1

MANUAL TRANSMISSION (MZZ)

Contents

DESCRIPTION.................................................... 7B1-2

6-speed Transmission ..................................... 7B1-2

ON-VEHICLE SERVICE ..................................... 7B1-4

Transmission Oil Level Check ......................... 7B1-4
Changing Transmission Oil ............................. 7B1-4
Gearshift Lever ................................................ 7B1-4
Gearshift Cable................................................ 7B1-5
Vehicle Speed Sensor ..................................... 7B1-9
Reverse, Neutral and Selector Switches ......... 7B1-9
Rear Oil Seal .................................................7B1-11
Transmission .................................................7B1-13
Top Gear Shaft .............................................. 7B1-29
Main Shaft .....................................................7B1-31
Countershaft ..................................................7B1-41
Control Box.................................................... 7B1-43

SPECIFICATIONS ............................................7B1-46

Specifications ................................................7B1-46
Fixing Torque.................................................7B1-46

SPECIAL TOOLS.............................................. 7B1-48

Special Tools .................................................7B1-48

7B1-2 MANUAL TRANSMISSION (MZZ)

DESCRIPTION

6-speed Transmission

Notice:
When fasteners are removed, always reinstall them at the same location from which they were removed. If a fastener
needs to be replaced, use the correct part number fastener for that application. If the correct part number fastener is
not available, a fastener of equal size and strength (or stronger) may be used. Fasteners that are not reused, and
those requiring thread locking compound will be called out. The correct torque value must be used when installing
fasteners that require it. If the above conditions are not followed, parts or system damage could result.

The newly designed MZZ transmission has a 3-piece
aluminum case to greatly reduce weight.
Taper roller bearings are used for both ends of the coun-
tershaft (front and rear). 
The transmission features a twin-rod shift control.

N7A0516E

MANUAL TRANSMISSION (MZZ) 7B1-3

PROBLEM

POSSIBLE CAUSE

CORRECTION

Abnormal noise

1. Flywheel pilot bearing wear

1. Replace the bearing.

2. Main shaft or countershaft bearing 

wear or other damage

2. Replace the bearing(s).

3. Main shaft gear, countershaft gear, 

and/or reverse idle gear wear or 
other damage

3. Replace the gear(s).

4. Main shaft spline and/or synchro-

nizer hub spline wear

4. Replace the spline(s).

5. Gear or bearing thrust surface scor-

ing

5. Replace the gear(s) and/or bearing(s).

6. Insufficient backlash between mat-

ing gears

6. Replace the gears.

Difficult shifting

1. Insufficient clutch pedal play

1. Adjust the play.

2. Change lever contact surface wear

2. Repair or replace the change lever and 

apply grease.

3. Shift block, shift rod, and/or control 

box contact surface wear

3. Replace the worn components.

4. Shift arm and/or synchronizer 

sleeve wear

4. Replace the worn parts.

5. Thrust washer and collar and/or 

gear thrust surface wear (Main shaft 
and countershaft thrust play)

5. Replace the worn parts.

6. Synchronizer wear

6. Replace the synchronizer.

Gear slippage

1. Detent ball wear

1. Replace the detent ball.

2. Shift rod and/or control box contact 

surface wear

2. Replace the worn components.

3. Shift arm and/or synchronizer 

sleeve wear

3. Replace the worn parts.

4. Thrust washer and collar and/or 

gear thrust surface wear (Main shaft 
and countershaft thrust play)

4. Replace the worn parts.

5. Bearing wear or other damage

5. Replace the worn or damaged bearings.

6. Main shaft spline and synchronizer 

hub spline wear

6. Replace the worn parts.

7. Synchronizer spring weak or broken

7. Replace the spring.

Oil leakage

1. Drain plug and/or filler plug loose

1. Tighten the plug(s).

2. Broken gasket

2. Replace the gasket.

3. il seal wear or damage

3. Replace the oil seal.