Isuzu N-Series. Manual - part 835

MANUAL TRANSMISSION 7B-1

MANUAL TRANSMISSION AND CLUTCH 

MYY SERIES

SECTION 7B

MANUAL TRANSMISSION

Contents

MANUAL TRANSMISSION MECHANISM............ 7B-2

Function and Operation ..................................... 7B-2
Inspection .......................................................... 7B-3

ON-VEHICLE SERVICE ....................................... 7B-7

Change Lever .................................................... 7B-7
Gear Control Cable............................................ 7B-8
Vehicle Speed Sensor ..................................... 7B-15
Reverse and Neutral Switch ............................ 7B-15
Rear Oil Seal (5MT)......................................... 7B-17
Rear Oil Seal (6MT)......................................... 7B-20
Transmission Assembly................................... 7B-22

UNIT REPAIR ..................................................... 7B-27

Transmission (5MT)......................................... 7B-27
Transmission (6MT)......................................... 7B-44
Top Gear Shaft ................................................ 7B-63
Main Shaft (5MT)............................................. 7B-64
Main Shaft (6MT)............................................. 7B-75
Counter Shaft (5MT)........................................ 7B-85
Counter Shaft (6MT)........................................ 7B-89
Control Box...................................................... 7B-93
Transfer System (MYY Rigid Type)................. 7B-98
Transfer Assembly (MYY Rigid Type) ............. 7B-99
Transfer (MYY Rigid Type)............................7B-101

7B-2 MANUAL TRANSMISSION

MANUAL TRANSMISSION MECHANISM

Function and Operation

• 5MT

N7A0275E

MANUAL TRANSMISSION 7B-3

• 6MT

MYY transmission is designed to enable weight saving
and to adapt larger available torque input 392 N

⋅m (40

kg

⋅m/289.3 lb⋅ft). New technology is adopted such as

aluminum-tube type case (3 piece) structure, tapered
roller bearing (main shaft front and rear, counter shaft
front and rear) and twin-rod type shift control layout.

Inspection

Diagnostic chart for troubleshooting

N7A0276E

Trouble

Cause

Treatment

Noise

Wear of flywheel pilot bearing

Replace

Wear or damage of bearing (main shaft, counter 
shaft)

Replace

Wear, crack and damage of gear (main shaft, 
counter shaft, reverse idle gear)

Replace

Wear of spline (main shaft, synchronizer clutch hub)

Replace

Seizure of gear or bearing thrust surface

Replace

Backlash shortage of mesh gear

Replace

Shift difficulty

Clutch pedal play inaccuracy

Adjust

Wear of change lever sliding portion

Repair or replace, lubricate 
grease

Wear of shift block, shift rod or control box sliding 
portion

Replace

Wear of shift arm or synchronizer sleeve groove

Replace the worn parts

Wear of thrust washer, collar or gear thrust surface 
(main shaft and counter shaft thrust play)

Replace the worn parts

Wear of synchronizer parts

Replace

7B-4 MANUAL TRANSMISSION

Oil Inspection

1. Remove the filler plug.
2. Check the oil level by inserting a finger to the filler

plug hole.

3. Refill oil when the oil level is out of the specified

amount.

• Applicable oil = Besco gear oil transaxle (5W-

30)

4. Fix the filler plug to the specified torque.

Tighten:
Filler plug to 39 N

⋅m (4.0 kg⋅m / 29 lb⋅ft)

• 5MT

• 6MT

Oil Replacement

1. Start the engine and idle the transmission suffi-

ciently.

2. Stop the engine, remove the drain plug, and then

drain oil.

3. Fix the drain plug.

Tighten:
Drain plug to 39 N

⋅m (4.0 kg⋅m / 29 lb⋅ft)

4. Remove the filler plug.
5. Fill oil through the filler plug hole to the lower edge

of the hole.

• Applicable oil = Besco gear oil transaxle (5W-

30)

Out of gear

Wear of detent ball

Replace

Wear of shift rod or control box sliding portion

Replace

Wear of shift arm or synchronizer sleeve groove

Replace the worn parts

Wear of thrust washer, collar or gear thrust surface 
(main shaft and counter shaft thrust play)

Replace the worn parts

Wear or damage of bearing

Replace

Wear of spline (main shaft, synchronizer hub)

Replace

Fatigue or damage of synchronizer spring

Replace

Oil leakage

Looseness of drain plug or filler plug

Tighten the plug or refill oil

Damaged gasket

Replace

Wear or damage of oil seal

Replace

Trouble

Cause

Treatment

N7A1005E

Legend

1. Filler plug
2. Drain plug

N7A1006E