2. AUTOMATIC TRANSMISSION
SECTION AT
CONTENTS
SERVICE DATA AND SPECIFICATIONS
(SDS) ................................................................... MA-2
General Specification...................................... MA-2
Adjustment Value............................................ MA-3
Tightening Torque........................................... MA-4
TROUBLE DIAGNOSES AND CORRECTIONS. MA-5
OIL CIRCUITOIL CIRCUIT.................................. MA-8
Oil Passages from Oil Strainer to Control Valve
Body................................................................ MA-8
Oil Passages from Control Valve Body to
Main Shaft..................................................... MA-10
OIL PRESSURE CIRCUIT DIAGRAM .............. MA-11
AUTOMATIC TRANSMISSION......................... MA-15
Construction.................................................. MA-15
Test............................................................... MA-20
Adjustment of Brake Pedal ........................... MA-22
Adjustment of Inching Pedal......................... MA-22
Adjustment of Inching Valve ......................... MA-23
Removal and Installation .............................. MA-24
Disassembly ................................................. MA-24
Torque Converter Housing ........................... MA-25
Torque Converter ......................................... MA-25
Oil Pump....................................................... MA-26
Main transmission Case ............................... MA-26
Disassembly of Clutch Drum Assembly........ MA-28
Control Valve ................................................ MA-32
Oil Pump....................................................... MA-33
Reduction Gear ............................................ MA-33
Torque Converter ......................................... MA-35
Oil Pump....................................................... MA-36
Clutch Drum.................................................. MA-37
Tightening Torque ........................................ MA-38
SPECIAL SERVICE TOOLS............................. MA-39
3. AT-2
SERVICE DATA AND SPECIFICATIONS (SDS)
General Specification
1D1/1D2 SERIES: ATM AND FINAL DRIVE (F/D)
Out Line
1. Basically ATM and Final Drive (F/D) follow current model.
2. New ATM established for K21 engine in P1 series: New combination of gear ratio: ATM and Final Drive (F/D).
(New type)
Torque converter
1-speed A/T
Symmetrica, 3-element, 1-stage, 2-phase torque converter
Type
Transmission
Type 1-speed forward and 1-speed reverse, constant-mesh
Clutch Multi-disc clutch
Number of drive plate
Forward 6
Reverse 6
Number of drive plate
Forward 6
Reverse 6
Oil pump
Type
Internally intermeshing involute gear pump
Automatic transmission fluid DEXRONTM
or M2C-33E or F
Lubrication system Forced lubrication by oil pump
Cooling system Water-cooled by oil cooler
Vehicle P1 P2 P3
Engine QD32 K21 QD32 K25 QD32 K25
STD
ATM
T/C stall torq ratio 2.8 2.8 2.8 2.8 2.8 2.8
Gear ratio 3.105 2.762 2.762 3.105 2.762 3.105
Shift change
control
Electric Electric Electric Electric Electric Electric
F/D
Model H263 (2P) H263 (2P) H296 (4P) H296 (4P) H310 (4P) H310 (4P)
Gear ratio 5.286 5.857 5.857 5.857 6.166 6.166
Low
noise
(OPT)
ATM
T/C stall torq ratio 2.8 2.8 2.8 2.8 2.8 2.8
Gear ratio 2.762 2.762 2.762 3.105 2.762 3.105
Shift change
control
Electric Electric Electric Electric Electric Electric
F/D
Model H263 (2P) H263 (2P) H296 (4P) H296 (4P) H310 (4P) H310 (4P)
Gear ratio 5.286 5.857 5.857 5.857 6.166 6.166
SERVICE DATA AND SPECIFICATIONS (SDS)
4. AT-3
Adjustment Value
Unit: mm (in)
HYDRAULIC PRESSURE VALUE
Unit: kPa (bar, kg/cm2
, psi)
ENGINE STALL REVOLUTION
Unit: rpm
OIL CAPACITY
Unit : l (lmp qt)
Item Service standard Repair limit
Torque converter External diameter of the oil slide of the oil pump
sleeve
41.915 - 41.965
(1.6502 - 1.6522)
—
Lateral runout of driven plate 0.2 (0.008) 0.5 (0.020)
Oil pump Gap between inner gear and oil pump cover 0.02 - 0.04
(0.0008 - 0.0016)
0.08 (0.0031)
Gap between outer gear and oil pump cover 0.02 - 0.04
(0.0008 - 0.0016)
0.08 (0.0031)
Gap between the outer gear tooth tips and the
crescent
0.20 - 0.34
(0.0079 - 0.0134)
0.38 (0.0150)
Gap between the external circumference of the
outer gear and the oil pump housing
0.09 - 0.18
(0.0035 - 0.0071)
0.25 (0.0098)
Internal diameter of the oil pump sleeve bushing 42.00 - 42.039
(1.6535 - 1.6551)
42.139 (1.6590)
Clutch drum Wear of drive plate 2.5 - 2.65
(0.0984 - 0.1043)
2.2 (0.087)
Wear of driven plate 1.53 - 1.67
(0.0602 - 0.0657)
1.4 (0.055)
Seal ring groove width 2.26 - 2.29
(0.0890 - 0.0902)
2.4 (0.094)
Seal ring width 2.05 - 2.15
(0.0807 - 0.0846)
2.01 (0.0791)
Clearance between retaining plate and snap ring 1.8-2.4(0.071-0.094) 6.5 (0.256)
Engine speed
Hydraulic pressure
700 rpm 2,000 rpm
Main pressure
883 - 1,078
(8.8 - 10.8, 9 - 11, 128 - 156)
980 - 1,274
(9.8 - 12.7, 10 - 13, 142 - 185)
Clutch pressure
883 - 1,078
(8.8 - 10.8, 9 - 11, 128 - 156)
980 - 1,274
(9.8 - 12.7, 10 - 13, 142 - 185)
T/C inlet pressure
49 - 294
(0.49 - 2.94, 0.5 - 3.0, 7.1 - 42.6)
196 - 539
(1.96 - 5.39, 2.0 - 5.5, 28.4 - 42.6)
K21 + K25 QD32
1850 - 2150 rpm 1850 - 2150 rpm
Oil capacity in transmission case 5.5 (4 7/8).
Oil capacity in torque converter 2.5 (2-1/4)
SERVICE DATA AND SPECIFICATIONS (SDS)
6. AT-5
TROUBLE DIAGNOSES AND CORRECTIONS
Condition Probable cause Corrective action
Low output Torque converter
Low oil pressure
(1) Insufficient oil quantity
(2) Air sucked from suction side
(3) Clogged oilfilter
(4) Worn oil pump (low discharge)
(5) Fatigue of regulator valvecoil spring
(6) Malfunction of regulator valve spool
(7) Worn piston ringor O-ring
Brake in stator freewheel cam
Seize stator freewheel
Broken blades or interference of blade
Add oil.
Retighten or change packing.
Clean or replace.
Replace.
Replace.
Repair or replace.
Replace.
Replace torque converter assembly.
Replace torque converter assembly.
Replace torque converter assembly.
Transmission
Use of improper oil or air bubbles
(1) Air sucked from suction side
(2) Air bubbles due to too low torque
converter pressure
(3) Water in oil
Improper position of brake shift spool and
link lever
Slippery clutch
(1) Low main pressure
(2) Wear on piston ring or O-ring
(3) Break in clutch piston
(4) Seizure or drag of clutch plate
Solenoid valve
Broken solenoid valve, foreign objects ordirt,
or poor electrical power
Replace.
Retighten or change packing.
Adjust.
Change oil.
Adjust.
Replace oil pump, control valve.
Replace.
Replace.
Replace.
Replace solenoid valve assembly.
Unusual rise of oil temperature Torque converter
Improper oil quantity
Clogged oil filter (insufficient circulating
quantity)
Interference of wheel vane
Faulty stat or freewheel
Air sucked into system.
Wateroil tank or transmission case
To large resistance in piping (insufficient
circulating quantity)
Worn or seize bearing
Faulty instrument
Add or reduce oil.
Clean or replace.
Replace torque converter assembly.
Replace torque converter assembly.
Retighten or change gasket.
Change oil.
Repair or replace.
Repair or replace.
Replace.
Transmission
Dragging of clutch
Faulty instrument
Worn or seized bearing
Replace clutch plate or solenoid valve
assembly.
Replace.
Replace.
TROUBLE DIAGNOSES AND CORRECTIONS
7. AT-6
Noisy operation Torque converter
Break in drive plate
Worn or faulty bearing
Interference of vane wheel.
Loose bolt
Worn spline
Noise in gear pump
Replace drive plate.
Replace torque converter assembly.
Replace torque converter assembly.
Retighten or replace.
Replace torque converter assembly.
Repair or replace.
Transmission
Dragging of clutch due to seizure
Worn or seized bearing
Break in gear
Loose bolt
Worn spline
Cavitation caused by clogged strainer
Replace clutch plate.
Replace.
Replace.
Retighten or replace.
Replace.
Clean or replace.
Unusual main pressure/torque
converter oil pressure
Too high pressure
Clogged oil filter (outlet side)
Malfunction of regulator valve
Too large resistance in piping
Cold weather (when high viscosity oil is
used)
Faulty instrument
Use of improper oil
Clean.
Repair or replace valve.
Clean or repair.
Repair.
Repair.
Replace.
Change oil.
Too low pressure
Faulty gear pump(wear)
Excessive oil leak
(1) Faulty regulator valve coil spring
(2) Faulty regulator valve spool
(3) Faulty modulator valve coil spring
Air is sucked into system.
Insufficient oil
Clogged oil filter
Replace.
Replace.
Repair or replace valve.
Replace.
Retighten or change packing.
Add.
Clean or replace.
Transmission
Excessive oil leak
Faulty instrument
Solenoid valve
Broken solenoid valve, foreign objects or
dirt, or poor electrical power
Replace.
Replace.
Replace solenoid valveassembly.
Oil leak from torque converter/
transmission/Solenoid valve
Oil leak from oil seal
Oil leak from jointing surfaces of case
Oil leak from joint or pipe
Oil leak from drain plug
Cracks or blow holes
Flowing out of oil from transmission case
and tank
Leakage from the solenoid valve seal
Leakage from the solenoid valve
Excessive oil
Replace oil seal. Replace pump boss,
coupling, etc.
Retighten bolts or change packing.
Repair or replace pipe gasket.
Retighten or replace gasket.
Repair or replace.
Change oil.
Retighten or replace packing.
Replace O-ring and gasket.
Replace solenoid valve assembly if
necessary.
Reduce oil.
TROUBLE DIAGNOSES AND CORRECTIONS
8. AT-7
No transmission of power Torque converter
Break in drive plate
Insufficient oil
Faulty oil pump driving system
Broken shaft
No oilpressure
Replace.
Add oil.
Replace.
Replace.
Replace.
Transmission
Insufficient oil
Improper location of inching spool and link
lever
Improper location of forward/reverse spool
and link lever
Clutch acting in both directions
(1) Faulty piston ring of servo case
(2) Clutch seizure/deformation
(3) Broken conical plate
Seized clutch
Broken shaft
Break in clutch drum (snap ring groove)
Broken snap ring for clutch drum
Foreign matter caught in oil passage to
clutch
Worn shaft spline
Add oil.
Adjust.
Adjust.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Clean or replace.
Replace.
Solenoid valve
Broken solenoid valve, foreign objectsor
dirt, or poor electrical power
Replace solenoid valve assembly.
TROUBLE DIAGNOSES AND CORRECTIONS
18. AT-17
Construction (Cont’d)
OIL PUMP AND TORQUE CONVERTER
CONTROL VALVE
1 Inching valve
2 Regulator valve
3 Regulator spring
4 Side plate
5 Relief valve
6 Modulator spring
7 Modulator piston
8 Check valve
9 Check spring
10 Modulator plug
ATM0114
ATM0115
AUTOMATIC TRANSMISSION
19. AT-18
Construction (Cont’d)
SOLENOID VALVE
Specifications
1 Body
2 Spool
3 Plug
4 Pin
5 Spring
6 Retainer A
7 Retainer B
8 Pin
9 Solenoid coil
10 Bolt
11 O-ring
12 O-ring
13 O-ring
14 Stopper
15 Plug
16 Tube
17 Plunger
18 O-ring
19 Snap ring
Applied voltage V 10 - 15
Oil temperature °C (°F) -30 to 130 (-22 to 266)
Coil resistance Ω/°C (°F) 5.4/20 (68)
ATM0116
ATT0132
AUTOMATIC TRANSMISSION
20. AT-19
Construction (Cont’d)
Forward solenoid (SOL.a) and reverse solenoid (SOL.b) are as
figure.
The SOL.a lead-wire is white and the SOL.b lead-wire is black.
Inspection
Troubleshooting
Inspection item Factory-set value Service limits Out-of-limits countermeasure
Coil resistance
5.4Ω±5%
[20°C(68°F)]
5.4Ω±10% [20°C
(68°F)]
Coil wire is cut or shorted.
Replace the solenoid valve
assembly.
Coil insulation resistance More than 100 MΩ 10 MΩ
Coil insulation is bad. Replace
the solenoid valve assembly.
Oil leaking from Solenoid valve -- Oozing out
Replace the O-ring on the
Solenoid valve.
Trouble symtoms Possible cause Corrective action
Solenoid valve dose not
operate properly.
a. When the solenoid valve is
energized, the spool is not
changed over and so the
power is not transmitted to
the vehicle.
b. When the current to the
solenoid valve is cut off,
the spool is not changed
over and so the power to
the vehicle is not turned off.
Foreig object is caught in
the spool.
1. Checkcontinuity.
The solenoid valve should be installed to the
transmission assembly.
2. When it does not operate properly, push the pin 5
several times with your fingers, then check the
continuity again.
When it operates properly, go to step 8.
3. When it does not operate properly, remove
thesolenoid valve body from the transmission
assembly; then perform steps 4 to 8 below.
4. Blow air from the port hole to the spool 4.
5. Push the pin 5 several times, then check the
continuity.
At this time, visually check the spool 4 can move
from the port hole.
6. When it operates properly, install it to the
transmission assembly, then check the continuity.
7. When it does not operate properly, replace the
solenoid valve as an assembly.
8. By changing over the solenoid valve sevaral times,
check that the Solenoid valve operates properly.
Pushing pressure of pin 5 = approx. 10 - 29 N
(1 - 3 kg, 2 - 7lb)
Before performing the steps shown above, be sure
to take safety measures such as jacking up the front
wheels, etc.
ATM0123
AUTOMATIC TRANSMISSION
21. AT-20
Test
LINE PRESSURE TEST
Tools and equipment
Oil pressure gauge assembly
(with adapters)
ST0221S000
Engine tachometer
Wrench
Sealing tape
Chock
Test procedures
1. Before testing, check coolant, engine oil and torque converteroil;
warm up torque converter oil to operating temperature.
2. Secure front and rear wheels with chocks and apply hand brake.
3. Remove blind plug and connect oil pressure gauge to its opening.
4. Mount engine tachometer.
5. Measure clutch oil pressure while engine is running more than
1,000 rpm with gears shifted into Forward or Reverse position.
6. Measure torque converter oil pressure while engine is
runningmore than 1,000 rpm.
If oil pressure builds up in the FORWARD (or the REVERSE)
position, shift gears to the REVERSE (or the FORWARD)
position.
Oil pressure should drop to zero upon gearshifting.
Hydraulic Pressure Value
Unit: kPa (bar, kg/cm2, psi)
Engine speed
Hydraulic pressure
700 rpm 2,000 rpm
Main pressure
883 - 1,078
(8.8 - 10.8, 9 - 11, 128 - 156)
980 - 1,274
(9.8 - 12.7, 10 - 13, 142 - 185)
Clutch pressure
883 - 1,078
(8.8 - 10.8, 9 - 11, 128 - 156)
980 - 1,274
(9.8 - 12.7, 10 - 13, 142 - 185)
T/C inlet pressure
49 - 294
(0.49 - 2.94, 0.5 - 3.0, 7.1 - 42.6)
196 - 539
(1.96 - 5.39, 2.0 - 5.5, 28.4 - 42.6)
ATM0117
AUTOMATIC TRANSMISSION
22. AT-21
Test (Cont’d)
STALL TEST
The purpose of this test is to check for transmission and engine
malfunction by measuring the maximum engine rpm while truck is in
a stalled condition. Compere measured values with standard values.
Tools and equipment
Engine tachometer
Chock
Test procedures
1. Before testing, check coolant, engine oil and torque converteroil;
warm up torque converter oil to operating temperature.
2. Mount engine tachometer in a location visible from operator's
seat.
3. Secure front and rear wheels with chocks and apply hand brake.
Besure to depress brake pedal firmly with the left foot before
depressing accelerator pedal.
Do not depress inching brake pedal.
4. Turn selector lever into position "F"
5. Slowly depress accelerator pedal fully.
Quickly read and record engine rpm when engine begins to rotate
steadily and then release accelerat or pedal.
Engine stall speed:
K21 1850 - 2150
K25 1850 - 2150
QD32 1850 - 2150
6. Shift selector lever to neutral and run engine at approximately
1,500 rpm for more than one minute to cool down torque
converter oil and coolant.
7. Make similar stall test in position "R".
8. After the stall test "F" and "R" cool down the motor and
transmission, keeping the motor running at idle for at least 1
minute.
CAUTION:
The stall test operation specified in item (5) should be made
within 30 seconds.
If it takes too long, oil deteriorates and clutches are adversely
affected.
Sufficient cooling time should be given between tests.
AUTOMATIC TRANSMISSION
23. AT-22
Adjustment of Brake Pedal
1. Using the stopper bolt, adjust A, the height of the pedal above the
floor (from the floor to the top of the pad). Then lock the stopper
bolt.
2. Adjust the length of the master cylinder push rod.
Adjust the clearance between the push rod and piston by rotating
the push rod. After adjusting, fasten the clevis with the nut.
3.Check the play (C) of the pedal tread.
CAUTION
• The clevis pin that joins the brake pedal and push rod must be
securely connected.
• The snap pin must be securely attached.
• When operated, the brake pedal must not catch or otherwise
work improperly.
•Unit: mm (in)
4. Securely tighten the clevis with the nut.
5. If the pedal is properly adjusted, the brake pedal play will meet the
standard: Free play (C)
Adjustment of Inching Pedal
1. Adjust and tighten the stopper bolt (inching) so that the height (A)
from the top surface of the floor plate to the center of the inching
pedal meets the standard shown below.
Standard (mm, in): 105 - 115 mm (4.13 - 4.53 in)
2. Adjust the clearance (c) of the part C bolt and linkage to the
standard indicated below. Then securely tighten with the nut.
Standard (mm, in.):
4.4 - 5.7 mm (0.173 - 0.224 in)
Items
Height of pedal A 140 (5.51)
Clearance between
push rod and piston B
1 (0.040)
Play of pedal thread C 1-3 mm (0.04 - 0.12 in)
MAT0228
AUTOMATIC TRANSMISSION
24. AT-23
Adjustment of Inching Valve
1. Preparation work
• Similar to the aforementioned oil pressure measurement, block
the steering tire and then raise the driving tire off the ground.
• Connect the oil pressure gauge to the clutch oil pressure outlet
port (position D in the figure to the left).
• Adjust the installation length of the inching cable until the
plunger is fully withdrawn.
• Securely tighten the lock nut and tighten the inching cable.
1. Adjustment procedure
• Idle the engine to raise the temperature of the transmission oil.
• Move the forward/reverse shift lever to the forward (F) position.
• Gradually press the inching pedal and force in the plunger.
Record the relationship between the stroke of the plunger and
the clutch oil pressure, Pc.
• Confirm that the aforementioned relationship is the diagram
shown in the figure. At the stroke end of the plunger, however,
the oil pressure must be completely 0 (zero).
Note: 1 kPa = 0.145 PSI; 1 mm = 0.039 in.
MAT0229L.tif
MAT0230L.tif
AUTOMATIC TRANSMISSION
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26. AT-24
Removal and Installation
Disassembly
REMOVAL AND
INSTALLATION
1. Remove differential carrier with
engine and transmission.
Refer to ER section for removal.
2. Separate engine from transmission
case.
3. Remove torque converter.
4. Remove differential carrier
mounting bolts, and remove dif-
ferential carrier from transmission
case.
2-speed A/T
FPD137
5. To install, reverse order of re-
moval.
DISASSEMBL Y
CONTROL VALVE
Control valve body assembly
Inching spool
FAT266
FAT267
AUTOMATIC TRANSMISSION
27. AT-25
Torque Converter Housing
Torque Converter
Drive plate assembly
1. Remove transmission control
valve assembly.
FAT250
2. Remove inching spool by re-
moving four bolts at control valve
assembly.
3. Remove select spool, accumulator
piston and springs by removing four
bolts at select spool housing.
Inching SPOOI~~
(ontrol valve ~bOdY J
assembly
~elect spool . :lfl
" • II'LV .t!'
~ /1 ''''',u<,~'CJ, [7/
~~ I ~V;r ,
~~~'
~~""---- Accumulator piston
FAT251
4. Thoroughly clean all parts and
check for scores, wear or damage. If
necessary, replace faulty parts.
TORQUE CONVERTER HOUSING
1. Remove two attaching bolts from
regulator valve cover.
FAT252
2. Screw bolt into thread hole
(M6 x 1.0) on head of pressure re-
gulator valve and force regulator
valve out.
3. Remove pressure regulator valve &
spring.
4. Remove inlet relief valve. check
ball and spring.
Final drive assembly
FAT253
5. Inspect all parts for damage.
TORQUE CONVERTER
I. Remove six attaching bolts (M 10)
from drive plate assembly.
2. Remove drive plate assembly and
pilot converter boss.
FAT268
3. Inspect all parts for damage.
AUTOMATIC TRANSMISSION