Page 4653 of 6020
MANUAL TRANSMISSION 7B1-47
Main Data and Specifications
General Specifications
MUA 5G MUA 5H MUA 5S
Transmission type Fully synchronized forward and reverse gears
Control method Remote control with the gear shift lever on the floor.
Gear ratio: Transmission 1st 4.008 4.008 4.357
2nd 2.301 2.301 2.502
3rd 1.427 1.427 1.501
4th 1.000 1.000 1.000
5th 0.828 0.744 0.809
Rev. 3.651 3.651 3.970
Transmission oil capacity 2.95 lit. (3.12 US qt)
Type of lubricant Engine oil: Refer to the chart in "SECTION 0"
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Page 4657 of 6020
MANUAL TRANSMISSION 7B1-51
TROUBLESHOOTING
1. ABNORMAL NOISE
1) NOISY IN NEUTRAL
Checkpoint Trouble Cause Countermeasure
Replenish or replace the gear
oilInsufficient or improper gear
oil
NG
Mainshaft splines
Synchronizer clutch hub
splinesReplace the main shaft and
the synchronizer clutch hub
Replace the gear(s)
Replace the flywheel pilot
W orn splines
W orn or scuffed gear tooth
contact surfaces
Flywheel pilot bearingW orn flywheel pilot bearing
Bearings (Mainshaft,
countershaft, and transfer
shaft)
Gears (Mainshaft,
countershaft, reverse idler
gear and transfer gears)
Replace the bearing(s)W orn or broken bearing(s)
OK NG
NG
NG
NG
OK
OK
OK
Gear oil
TransmissionRealign the transmissionTransmission misalignment
OK
NG
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ISUZU KB P190 2007
Page 4658 of 6020
7B1-52 MANUAL TRANSMISSION
2) NOISY OPERATION
Checkpoint Trouble Cause Countermeasure
Replenish or replace the gear
oilInsufficient or improper engine
oil
NG
Replace the gear(s)
Replace the gear(s)
Replace the bearing(s)
Gears (Gear whining)Lack of backlash between
meshing gears
Free running gears seizing on
the thrust face or the inner
face
Bearings (Hissing, thumping
or bumping)W orn or broken bearing(s)
Gears (Squealing at high
speeds)
Replace the gear(s)Gears (Growling, humming, or
grinding)W orn, chipped, or cracked
gear(s)
NG
NG
NG
NG
OK
OK
OK
OK
Gear oil (Metallic rattling)
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ISUZU KB P190 2007
Page 4659 of 6020
MANUAL TRANSMISSION 7B1-53
2. HARD SHIFTING
Checkpoint Trouble Cause Countermeasure
Change lever play
Clutch pedal free play
Repair or replace the
applicable parts and regrease
Readjust the clutch pedal free
play
W orn change lever sliding
portions
Improper clutch pedal free
play
Change lever operationRepair or regrease the change
lever assembly
Replenish or replace the
engine oil
Hard operating change lever
caused insufficient grease
Insufficient or improper gear
oil
OK
OK NG
NG
NG
NG
OK
OKGear oil
Continued on the next page
Shift rod and quadrant box
sliding faces, and other partsReplace the shidt rod and/or
the quadrant boxW orn shift rod and/or sliding
faces
Repair or replace the sleeveSleeve movement failure
NG
NG
OKShift block sleeve movement
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ISUZU KB P190 2007
Page 4663 of 6020
MANUAL TRANSMISSION 7B1-57
4. OIL LEAKAGE
Checkpoint Trouble Cause Countermeasure
Gear oilReplace the gear oilImproper gear oil
Drain plug and/or filler plugTighten the plug(s) and
replenish the oil
Drain the oil to the correct
level
Loose plug(s)
Oil level too high
OK NG
NG
NG
OK
OKOil level
Rear cover oil seal
Air breather
Replace the oil seal
Install the air breather
Replace the air breather
W orn or scratched oil seal
Air breather not installed
Air breather clogged
Front cover oil sealReplace the oil seal
Replace the gasket(s)
W orn or scratched oil seal
Defective or improperly
installed gasket(s)
OK NG
NG
NG
NG
OK
OKGaskets
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ISUZU KB P190 2007
Page 4664 of 6020
7B1-58 MANUAL TRANSMISSION
Special Tools (4×
××
×
2)
ILLUSTRATION TOOL NO.
TOOL NAME ILLUSTRATION
TOOL NO.
TOOL NAME
5-8840-2155-0
(J-37217)
Bearing remover 5-8840-2159-0
(J-37223)
Mainshaft end bearing installer
5-8840-2027-0
Puller 5-8840-0015-0
(J-22912-01) Bearing
remover/installer
5-8840-2160-0
(J-37224)
Holding fixture 5-8522-0050-0
(J-29769)
Rear case oil seal installer
5-8840-0003-0
(J-3289-20)
Holding fixture base 5-8840-0026-0
(J-26540)
Front cover oil seal installer
5-8840-2156-0
(J-37219)
Mainshaft nut wrench 9-8522-1165-0
(J-6133-01)
Mainshaft collar remover
5-8840-0047-0
(J-37225)
Tork bit wrench
(T– 45)
5-8840-2194-0
(J-35283)
Bearing installer
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ISUZU KB P190 2007
Page 4677 of 6020
MANUAL TRANSMISSION 7B1-71
Transmission Case
Major Component
RTW 77BLF003701
Legend
(1) Gear Control Box Assembly and Gasket (7) Counter Front Bearing Snap Ring
(2) Rear Case Assembly (8) Front Cover (with Oil Seal)
(3) Intermediate Plate with Gear Assembly (9) Top Gear Bearing Snap Ring
(4) Transmission Case (10) Release Bearing: C24SE
(5) Release Bearing (with Spring): Diesel engine (11) Shift Fork: C24SE
(6) Shift Fork and Cover: Diesel engine
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Page 4678 of 6020

7B1-72 MANUAL TRANSMISSION
Disassembly
1. Clean the exterior of the unit with solvent.
2. Remove the drain plug from the transmission case and drain the lubricant.
3. Remove the clutch release bearing with spring from the transmission case.
4. Remove the shift fork, and boot.
5. Remove the front cover and gasket from the transmission case.
6. Remove the snap ring fixing counter front bearing.
7. Use a pair of snap ring pliers to remove the snap ring fixing top gear bearing.
226RS001
8. Remove the gear control box assembly.
9. Remove the rear case assembly from the transmission case and intermediate plate.
10. Remove the intermediate plate with gear assembl
y
from the transmission case.
Rear Oil Seal Replacement
220R300025
Legend
(1) Installer 5-8840-2797-0
(2) Grip 5-8840-0007-0
1. Remove the oil seal from the rear case and discard the used oil seal.
2. Apply engine oil to the new oil seal outer surfaces.
3.
Apply recommended grease (BESCO L2) or
equivalent to the oil seal lip.
4. Use the oil seal installer 5-8840-2797-0 and grip 5- 8840-0007-0 to install the oil seal to the rear case.
Reassembly
1. Apply recommended liquid gasket (Three Bond TB1215) or its equivalent to the transmission case,
intermediate plate and rear case fitting surfaces.
2. Install the intermediate plate with gear assembly to the transmission case.
Pull out the top gear shaft until the ball bearing snap
ring groove protrudes from the transmission case
front cover fitting face.
Avoid subjecting the mainshaft to sudden shock or
stress.
3. Install the rear case with oil seal on the intermediate plate, with gear, by performing the following steps.
• Cover the shaft splines with adhesive tape.
This will prevent damage to the oil seal lip.
• Tighten the transmission rear case bolts and
nuts to the specified torque.
Torque: 37 N ⋅
⋅⋅
⋅
m (3.8 kgf ⋅
⋅⋅
⋅
m/27 lb ⋅
⋅⋅
⋅
ft)
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ISUZU KB P190 2007