
TRANSAXLE AND POWER TRANSFER UNIT
CONTENTS
page page
31TH AUTOMATIC TRANSAXLE.............. 1
41TE AUTOMATIC TRANSAXLE............. 71POWER TRANSFER UNIT................. 165
31TH AUTOMATIC TRANSAXLE
INDEX
page page
GENERAL INFORMATION
31TH TRANSAXLE........................ 2
FLUID LEVEL AND CONDITION.............. 2
SELECTION OF LUBRICANT................ 3
SPECIAL ADDITIVES...................... 3
DESCRIPTION AND OPERATION
CLUTCHES, BAND SERVOS, AND
ACCUMULATOR
...................... 3
FLOW CONTROL VALVES.................. 3
GEARSHIFT AND PARKING LOCK CONTROLS . . 4
GOVERNOR............................. 4
HYDRAULIC CONTROL SYSTEM............. 3
PRESSURE REGULATING VALVES........... 3
PRESSURE SUPPLY SYSTEM............... 3
TORQUE CONVERTER CLUTCH SOLENOID
WIRING CONNECTOR................... 4
TORQUE CONVERTER CLUTCH............. 3
DIAGNOSIS AND TESTING
CLUTCH AND SERVO AIR PRESSURE TESTS . 15
FLUID LEAKAGE-TRANSAXLE TORQUE
CONVERTER HOUSING AREA............ 15
HYDRAULIC PRESSURE TESTS............ 13
ROAD TEST............................. 4
THREE SPEED TRANSAXLE DIAGNOSIS AND
TESTS............................... 4
SERVICE PROCEDURES
ALUMINUM THREAD REPAIR.............. 18
FLUID AND FILTER CHANGE............... 16
FLUID DRAIN AND REFILL................. 18
FLUSHING COOLERS AND TUBES.......... 18
OIL PUMP VOLUME CHECK............... 19
REMOVAL AND INSTALLATION
FRONT PUMP OIL SEAL.................. 21
PARK/NEUTRAL STARTING AND BACK-UP
LAMP SWITCH........................ 19
TRANSAXLE AND TORQUE CONVERTER
REMOVAL............................ 20
VEHICLE SPEED SENSOR PINION GEAR..... 19DISASSEMBLY AND ASSEMBLY
ACCUMULATOR-RECONDITION............ 36
DIFFERENTIAL REPAIR................... 46
FRONT CLUTCH-RECONDITION............ 32
FRONT PLANETARY & ANNULUS GEAR-
RECONDITION........................ 35
KICKDOWN SERVO (CONTROLLED LOAD)-
RECONDITION........................ 37
LOW/REVERSE (REAR)
SERVO-RECONDITION.................. 36
OIL PUMP-RECONDITION................. 31
OUTPUT SHAFT REPAIR.................. 43
PARKING PAWL......................... 42
REAR CLUTCH-RECONDITION............. 33
TRANSAXLE........................... 21
TRANSFER SHAFT REPAIR................ 38
VALVE BODY RECONDITION............... 27
CLEANING AND INSPECTION
VALVE BODY........................... 50
ADJUSTMENTS
BAND ADJUSTMENT..................... 51
BEARING ADJUSTMENT PROCEDURES...... 52
DIFFERENTIAL BEARING................. 53
GEARSHIFT CABLE ADJUSTMENT.......... 51
HYDRAULIC CONTROL PRESSURE
ADJUSTMENTS....................... 52
OUTPUT SHAFT BEARING................ 52
THROTTLE PRESSURE LINKAGE
ADJUSTMENT......................... 51
TRANSFER SHAFT BEARING.............. 54
SCHEMATICS AND DIAGRAMS
31TH TRANSAXLE HYDRAULIC SCHEMATIC . . 56
SPECIFICATIONS
31TH AUTOMATIC TRANSAXLE............. 64
31TH TORQUE SPECIFICATIONS........... 65
SPECIAL TOOLS
31TH AUTOMATIC TRANSAXLE............. 66
NSTRANSAXLE AND POWER TRANSFER UNIT 21 - 1

GEARSHIFT AND PARKING LOCK CONTROLS
The transaxle is controlled by a lever type gear-
shift incorporated within the steering column. The
control has six selector lever positions: P (park), R
(reverse), N (neutral), and D (drive), 2 (second), and
1 (first). The parking lock is applied by moving the
selector lever past a gate to the P position.Do not
apply the parking lock until the vehicle has
stopped; otherwise, a severe ratchet noise will
occur.
TORQUE CONVERTER CLUTCH SOLENOID WIRING
CONNECTOR
If wiring connector is unplugged, the torque con-
verter will not engage (Fig. 1) .
GOVERNOR
The governor may be serviced by removing the
transaxle oil pan and valve body assembly. The gov-
ernor may be unbolted from the governor support
and removed from the transaxle for reconditioning or
replacement.
When cleaning or assembling the governor, make
sure the governor valves move freely in the bores of
the governor body.
DIAGNOSIS AND TESTING
THREE SPEED TRANSAXLE DIAGNOSIS AND
TESTS
Automatic transaxle malfunctions may be caused
by four general conditions:
(1) Poor engine performance
(2) Improper adjustments
(3) Hydraulic malfunctions
(4) Mechanical malfunctionsDiagnosis of these problems should always begin
by checking the easily accessible variables; fluid level
and condition, gearshift cable adjustment, and throt-
tle pressure cable adjustment. Then perform a road
test to determine if the problem has been corrected
or that more diagnosis is necessary. If the problem
exists after the preliminary tests and corrections are
completed, hydraulic pressure tests should be per-
formed
31TH HYDRAULIC TROUBLE CODE CHARTS
The following charts should be used to help diag-
nose hydraulic or mechanical faults in the transaxle .
ROAD TEST
Prior to performing a road test, check the fluid
level, and control cable adjustments.
During the road test, the transaxle should be oper-
ated in each position to check for slipping and any
variation in shifting.
If vehicle operates at high speeds, but has poor
acceleration, the converter's overrunning clutch may
be slipping. If acceleration is normal, but high throt-
tle opening is needed for high speeds, the stator
clutch may have seized.
Observe closely for slipping or engine speed flare-
up. Slipping or flare-up in any gear usually indicates
clutch, band, or overrunning clutch problems. If the
condition is far advanced, an overhaul will probably
be necessary to restore normal operation.
In most cases, the clutch or band that is slipping
can be determined by noting the transaxle operation
in all selector positions. Then comparing which inter-
nal units are applied in those positions. The Ele-
ments in Use Chart provides a basis for road test
analysis .
The rear clutch is applied in both the D first gear
and 1 first gear positions. Also the overrunning
clutch is applied in D first gear and the low/reverse
band is applied in 1 first gear position. If the tran-
saxle slips in D range first gear, but does not slip in
1 first gear, the overrunning clutch is slipping. Simi-
larly, if the transaxle slips in any two forward gears,
the rear clutch is slipping.
Using the same procedure, the rear clutch and
front clutch are applied in D third gear. If the tran-
saxle slips in third gear, either the front clutch or the
rear clutch is slipping. By selecting another gear
which does not use one of those units, the unit which
is slipping can be determined. If the transaxle also
slips in reverse, the front clutch is slipping. If the
transaxle does not slip in reverse, the rear clutch is
slipping.
The process of eliminating can be used to detect
any unit which slips and to confirm proper operation
of good units. Road testing can usually diagnose slip-
ping units. Although the actual cause of the problem
Fig. 1 Torque Converter Clutch Solenoid Wiring
Connector
21 - 4 TRANSAXLE AND POWER TRANSFER UNITNS
DESCRIPTION AND OPERATION (Continued)

may not be detected. Practically any condition can be
caused by leaking hydraulic circuits or sticking
valves.
Therefore, unless the condition is obvious, the tran-
saxle should never be disassembled until hydraulic
pressure tests have been performed.
HYDRAULIC PRESSURE TESTS
Pressure testing is a very important step in the
diagnostic procedure. These tests usually reveal the
cause of most transaxle problems.
Before performing pressure tests, be certain that
fluid level and condition, and control cable adjust-
ments have been checked and approved. Fluid must
be at operating temperature (150 to 200 degrees F.).
Install an engine tachometer, raise vehicle on hoist
which allows front wheels to turn, and position
tachometer so it can be read.
Disconnect throttle cable and shift cable from tran-
saxle levers so they can be controlled from outside
the vehicle.
Attach 150 psi gauges to ports required for test
being conducted. A 300 psi gauge (C-3293) is required
for reverse pressure test at rear servo.
Test port locations are shown in (Fig. 2) .
TEST ONE (SELECTOR IN 1)
(1) Attach gauges to line and low-reverse ports.
(2) Operate engine at 1000 rpm for test.
(3) Move selector lever on transaxle all the way
rearward (1 position).
(4) Read pressures on both gauges as throttle lever
on transaxle is moved from full clockwise position to
full counterclockwise position.
(5) Line pressure should read 52 to 58 psi with
throttle lever clockwise. Pressure should gradually
increase, as lever is moved counterclockwise, to 80 to
88 psi.(6) Low-reverse pressure should read the same as
line pressure within 3 psi.
(7) This tests pump output, pressure regulation,
and condition of rear clutch and rear servo hydraulic
circuits.
TEST TWO (SELECTOR IN 2)
(1) Attach one gauge to line pressure port and tee
another gauge into lower cooler line fitting. This will
allow lubrication pressure readings to be taken..
(2) Operate engine at 1000 rpm for test.
(3) Move selector lever on transaxle one detent for-
ward from full rearward position. This is selector 2
position.
(4) Read pressures on both gauges as throttle lever
on transaxle is moved from full clockwise position to
full counterclockwise position.
(5) Line pressure should read 52 to 58 psi with
throttle lever clockwise. Pressure should gradually
increase, as lever is moved counterclockwise, to 80 to
88 psi.
(6) Lubrication pressure should be 10 to 25 psi
with lever clockwise and 10 to 35 psi with lever full
counterclockwise.
(7) This tests pump output, pressure regulation,
and condition of rear clutch and lubrication hydraulic
circuits.
TEST THREE (SELECTOR IN D)
(1) Attach gauges to line and kickdown release
ports.
(2) Operate engine at 1600 rpm for test.
(3) Move selector lever on transaxle two detents
forward from full rearward position. This is selector
D position.
(4) Read pressures on both gauges as throttle lever
on transaxle is moved from full clockwise position to
full counterclockwise position.
(5) Line pressure should read 52 to 58 psi with
throttle lever clockwise. Pressure should gradually
ELEMENTS IN USE AT EACH POSITION OF THE SELECTOR LEVER
NSTRANSAXLE AND POWER TRANSFER UNIT 21 - 13
DIAGNOSIS AND TESTING (Continued)

increase, as lever is moved counterclockwise to 80 to
88 psi.
(6) Kickdown release is pressurized only in direct
drive and should be same as line pressure within 3
psi, up to kickdown point.
(7) This tests pump output, pressure regulation,
and condition of rear clutch, front clutch, and
hydraulic circuits.
TEST FOUR (SELECTOR IN REVERSE)
(1) Attach 300 psi gauge to low-reverse port.
(2) Operate engine at 1600 rpm for test.
(3) Move selector lever on transaxle four detents
forward from full rearward position. This is selector
R position.
(4) Low-reverse pressure should read 180 to 220
psi with throttle lever clockwise. Pressure should
gradually increase, as lever is moved counterclock-
wise to 260 to 300 psi.
(5) This tests pump output, pressure regulation,
and condition of front clutch and rear servo hydraulic
circuits.
(6) Move selector lever on transaxle to D position
to check that low-reverse pressure drops to zero.
(7) This tests for leakage into rear servo, due to
case porosity, which can cause reverse band burn out.
TEST RESULT INDICATIONS
(1) If proper line pressure, minimum to maximum,
is found in any one test, the pump and pressure reg-
ulator are working properly.
(2) Low pressure in D, 1, and 2 but correct pres-
sure in R indicates rear clutch circuit leakage.
(3) Low pressure in D and R but correct pressure
in 1 indicates front clutch circuit leakage.
Fig. 2 Test Port Locations
Fig. 3 Governor Pressure Tap
21 - 14 TRANSAXLE AND POWER TRANSFER UNITNS
DIAGNOSIS AND TESTING (Continued)

(5) Continuity should exist only with transaxle in
Reverse position.
(6) No continuity should exist from either pin to
the case.
TRANSAXLE AND TORQUE CONVERTER REMOVAL
NOTE: Transaxle removal does NOT require engine
removal.
The transaxle and torque converter must be
removed as an assembly; otherwise, the torque con-
verter drive plate, pump bushing, or oil seal may be
damaged. The drive plate will not support a load;
therefore, none of the weight of the transaxle should
be allowed to rest on the plate during removal.
REMOVAL
(1) Disconnect negative battery cable.
(2) Remove air cleaner and hoses.
(3) Disconnect throttle linkage and shift linkage
from transaxle.
(4) Unplug torque converter clutch connector,
located near the dipstick. Unplug the gear position
switch.
(5) Remove transaxle dipstick tube.
(6) Remove the transaxle cooler lines and plug.
(7) Install engine support fixture (Fig. 5) .
(8) Remove bell housing upper bolts.
(9) Raise vehicle. Remove front wheels. Refer to
Group 2, Suspension to remove or install wheel hub
nut and both drive shafts.
CAUTION: The exhaust flex joint must be discon-
nected from the exhaust manifold anytime the
engine is lowered. If the engine is lowered while the
flex pipe is attached, damage will occur.(10) Remove bolts securing exhaust flex joint to
exhaust manifold. Disconnect exhaust pipe from
manifold.
(11) Remove torque converter dust cover. Mark
torque converter and drive plate with chalk, for reas-
sembly. Rotate engine clockwise and remove torque
converter mounting bolts.
(12) Remove engine mount bracket from front
crossmember.
(13) Remove front mount insulator through-bolt
and bellhousing bolts.
(14) Position transaxle jack (Fig. 6) .
(15) Remove rear engine mount shield.
(16) Remove rear engine mount bracket bolts and
bracket.
(17) Remove left engine mount thru-bolt.
(18) Remove left engine mount from transaxle.
(19) Remove starter. Remove lower bell housing
bolts.
(20) Carefully work transaxle and torque converter
assembly rearward off engine block dowels and dis-
engage converter hub from end of crankshaft.Attach
a small C clamp to edge of bell housing. This
will hold torque converter in place during tran-
saxle removal.Lower transaxle and remove assem-
bly from under the vehicle.
(21) To remove torque converter assembly, remove
C±clamp from edge of bellhousing and slide converter
out of transaxle.
INSTALLATION
(1) When installing transaxle, reverse the above
procedure.
(2) If torque converter was removed from transaxle
be sure to align pump inner gear pilot flats with
torque converter impeller hub flats.
(3) Adjust gearshift and throttle cables.
(4) Refill transaxle with Mopar ATF PLUS 3
(Automatic Transmission Fluid) Type 7176.
Fig. 5 Engine Support Fixture
Fig. 6 Transaxle Jack
21 - 20 TRANSAXLE AND POWER TRANSFER UNITNS
REMOVAL AND INSTALLATION (Continued)

Attach a dial indicator to transaxle bell housing
with its plunger seated against end of input shaft
(Fig. 17).
Move input shaft in and out to obtain end play
reading. End play specifications are 0.19 to 1.50 mm
(0.008 to 0.060 inch).
Record indicator reading for reference when reas-
sembling the transaxle.
Remove Number 6 thrust washer from sun
gear driving shell.
Fig. 17 Measure Input Shaft End Play
Fig. 18 Loosen Lock Nut and Tighten Kickdown
Band Adjusting Screw
Fig. 19 Pump Attaching Bolts
Fig. 20 Install Tool C-3752 with Adapters L-4437
Fig. 21 Oil Pump with No. 1 Thrust Washer
NSTRANSAXLE AND POWER TRANSFER UNIT 21 - 23
DISASSEMBLY AND ASSEMBLY (Continued)

Inspect all valve springs for distortion and col-
lapsed coils. Inspect all valves and plugs for burrs,
nicks, and scores. Small nicks and scores may be
removed with crocus cloth, providing extreme care is
taken not to round off sharp edges. The sharpness of
these edges is vitally important. It prevents foreign
matter from lodging between valve and valve body.
This reduces the possibility of sticking. Inspect all
valves and plugs for freedom of operation in valve
body bores.
When bores, valves, and plugs are clean and dry,
the valves and plugs should fall freely in the bores.
The valve body bores do not change its dimensions
with use. Therefore, a valve body that was function-
ing properly when vehicle was new, will operate cor-
rectly if it is properly and thoroughly cleaned. There
is no need to replace valve body unless it is damaged
in handling.
ADJUSTMENTS
GEARSHIFT CABLE ADJUSTMENT
Lift and rotate the gearshift hand lever into the
park (P) gate position and remove the ignition key.
This confirms the shift lever is in the gated park (P)
position.
After confirming the park gate position, turn the
ignition switch. If the starter will operate, the park
gate position is correct. Move the shift lever into the
neutral (N) position. If the starter will operate in this
position, the linkage is properly adjusted. If the
starter fails to operate in either position, linkage
adjustment is required.
(1) Park the vehicle on level ground and set the
parking brake.
(2) Place the gearshift lever in park (P) gate posi-
tion and remove key.
(3) Loosen the cable adjustment screw at the tran-
saxle operating lever (Fig. 160).
(4) Pull the transaxle operating lever fully forward
to the park detent position.
(5) Release the park brake, then rock the vehicle
to assure it is in park lock. Reset the park brake.
(6) Tighten the cable adjustment screw to 8 N´m
(70 in. lbs.). Gearshift cable should now be properly
adjusted.
(7) Verify PRNDL indicator still displays the corre-
sponding gear completely. If not, readjustment of
PRNDL may be required.
(8) Check adjustment by using the preceding pro-
cedure.
THROTTLE PRESSURE LINKAGE ADJUSTMENT
The throttle pressure rod adjustment is very
important to proper transaxle operation. This adjust-
ment positions a valve which controls shift speed,shift quality, and part throttle downshift sensitivity.
If the setting is too short, early shifts and slippage
between shifts may occur. If the setting is too long,
shifts may be delayed and part throttle downshifts
may be very sensitive.
With engine at operating temperature, adjust idle
speed of engine using a tachometer. Refer to Group
14, Fuel System for idle speed Specifications and
adjustment.
ROD ADJUSTMENT PROCEDURE
(1) Perform transaxle throttle pressure adjustment
while engine is at normal operating temperature.
(2) Loosen adjustment swivel lock screw.
(3) To insure proper adjustment, swivel must be
free to slide along flat end of throttle rod. Disassem-
ble and clean or repair parts to assure free action, if
necessary.
(4) Hold transaxle throttle lever firmly toward
engine, against its internal stop. Tighten swivel lock
screw to 11 N´m (100 in. lbs.)
(5) The adjustment is finished and linkage back-
lash was automatically removed by the preload
spring.
(6) I
f lubrication is required see Group 0, Lubrica-
tion.
BAND ADJUSTMENT
KICKDOWN BAND (FRONT)
The kickdown band adjusting screw is located on
left side (top front) of the transaxle case.
(1) Loosen locknut and back off nut approximately
five turns. Test adjusting screw for free turning in
the transaxle case.
(2) Using wrench, tighten adjusting screw to 8
N´m (72 in. lbs.).
Fig. 160 Gearshift Cable Adjustment
NSTRANSAXLE AND POWER TRANSFER UNIT 21 - 51
CLEANING AND INSPECTION (Continued)

(3) Back off adjusting screw the number of turns
listed in Specifications. Hold adjusting screw in this
position and tighten locknut to 47 N´m (35ft. lbs.)
LOW/REVERSE BAND (REAR)
To adjust low-reverse band, proceed as follows:
(1) Loosen and back off locknut approximately 5
turns.
(2) Using an inch-pound torque wrench, tighten
adjusting screw to 5 N´m (41 in. lbs.) true torque.
(3) Back off adjusting screw the number of turns
listed under Specifications. This chart is located at
the rear of this section.
(4) Tighten locknut to 14 N´m (10 ft. lbs.).
HYDRAULIC CONTROL PRESSURE ADJUSTMENTS
LINE PRESSURE
An incorrect throttle pressure setting will cause
incorrect line pressure readings even though line
pressure adjustment is correct. Always inspect and
correct throttle pressure adjustment before adjusting
the line pressure.
The approximate adjustment for line pressure is
1-5/16 inches, measured from valve body to inner
edge of adjusting nut. However, due to manufactur-
ing tolerances, the adjustment can be varied to
obtain specified line pressure.
The adjusting screw may be turned with an Allen
wrench. One complete turn of adjusting screw
changes closed throttle line pressure approximately
1-2/3 psi. Turning adjusting screw counterclockwise
increases pressure, and clockwise decreases pressure.
THROTTLE PRESSURE
Throttle pressures cannot be tested accurately;
therefore, the adjustment should be measured if a
malfunction is evident.
(1) Insert gauge pin of Tool C-3763 between the
throttle lever cam and kickdown valve.
(2) By pushing in on tool, compress kickdown
valve against its spring so throttle valve is com-
pletely bottomed inside the valve body.
(3) While compressing spring, turn throttle lever
stop screw with adapter C-4553. Turn until head of
screw touches throttle lever tang, with throttle lever
cam touching tool and throttle valve bottomed. Be
sure adjustment is made with spring fully com-
pressed and valve bottomed in the valve body.
BEARING ADJUSTMENT PROCEDURES
(1) Take extreme care when removing and install-
ing bearing cups and cones.Use only an arbor
press for installation, as a hammer may not
properly align the bearing cup or cone.Burrs or
nicks on the bearing seat will give a false end play
reading, while gauging for proper shims. Improperlyseated bearing cup and cones are subject to low-mile-
age failure.
(2) Bearing cups and cones should be replaced if
they show signs of pitting or heat distress.
(3) If distress is seen on either the cup or bearing
rollers, both cup and cone must be replaced.
NOTE: Bearing end play and drag torque specifica-
tions must be maintained to avoid premature bear-
ing failures.
(4) Used (original) bearing may lose up to 50 per-
cent of the original drag torque after break-in.
NOTE: All bearing adjustments must be made with
no other component interference or gear inter-
mesh, except the transfer gear bearing.
(5) Refer to the conversion chart in specifications
to convert inches to millimeter measurements. Refer
to bearing shim chart for proper shim thicknesses.
OUTPUT SHAFT BEARING
(1) With output shaft gear removed, install a 13.65
mm (.537 inch) and a 1.34 mm (.053 inch) gauging
shims on the planetary rear annulus gear hub using
grease to hold the shims in place. The 13.65 mm
shim has a larger inside diameter and must be
installed over the output shaft first. The 1.34 mm
shim pilots on the output shaft.
(2) Install output shaft gear and bearing assembly,
torque to 271 N´m (200 ft. lbs.).
(3) To measure bearing end play:
(4) Attach Tool L-4432 to the output shaft gear.
(5) Mount a steel ball with grease into the end of
the output shaft.
(6) Push and pull the gear while rotating back and
forth to insure seating of the bearing rollers.
(7) Using a dial indicator, mounted to the tran-
saxle case, measure output shaft end play.
(8) Once bearing end play has been determined,
refer to the output shaft bearing shim chart.
(9) The 12.65 mm (.498 inch), 13.15 mm (.518
inch) or 13.65 mm (.537 inch) shims are always
installed first.These shims have lubrication slots
which are necessary for proper bearing lubrica-
tion.
(10) Shims thinner than 12.65 mm listed in the
chart are common to both the transfer shaft and out-
put shaft bearings.
(11) Use Tool L-4434 to remove the retaining nut
and washer. To remove the output shaft gear use Tool
L-4407.
(12) Remove the two gauging shims and install the
proper shim combination, making sure to install the
12.65, 13.15, or 13.65 mm shim first. Use grease to
21 - 52 TRANSAXLE AND POWER TRANSFER UNITNS
ADJUSTMENTS (Continued)