1990 Ford Aerostar

1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

1985-92 AUTOMATIC TRANSMISSIONS

Ford A4LD Overhaul

APPLICATION
A4LD APPLICATION
Model Axle/Engine Equipment Type
1985
Bronco II 4WD/2.9L Optional
Ranger 2WD/2.3L Optional
2WD & 4WD/2.8L Optional
1986
Aerostar 2WD/2.3L Optional
2WD/2.8L Optional
2WD/3.0L Optional
Bronco II 2WD & 4WD/2.9L Optional
Ranger 2WD/2.3L Optional
2WD & 4WD/2.9L Optional
1987
Aerostar 2WD/2.3L Optional
2WD/3.0L Optional
Bronco II AWD & 4WD/2.9L Optional
Mustang 2WD/2.3L Optional
Ranger 2WD/2.3L Optional
2WD & 4WD/2.9L Optional
Thunderbird 2WD/2.3L Optional
Merkur Scorpio 2WD/2.9L Standard
1988
Aerostar 2WD/3.0L Optional
Bronco II AWD & 4WD/2.9L Optional
Mustang 2WD/2.3L Optional
Ranger 2WD/2.3L Optional
2WD & 4WD/2.9L Optional
Thunderbird 2WD/2.3L Optional
Merkur Scorpio 2WD/2.9L Standard
1989-90
Aerostar 2WD/3.0L Optional
2WD/4.0L (1) Optional
AWD/4.0L Standard
Bronco II 2WD & 4WD/2.9L Optional
Mustang 2WD/2.3L Optional

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Ranger 2WD/2.3L Optional

2WD & 4WD/2.9L Optional
2WD & 4WD/4.0L Optional
Merkur Scorpio 2WD/2.9L (2) Standard
1991-92
Aerostar 2WD/3.0L Optional
2WD/4.0L (1) Optional
AWD/4.0L Standard
Explorer 2WD & 4WD/4.0L Optional
Mustang 2WD/2.3L Optional
Ranger 2WD/2.3L Optional
4WD/2.9L Optional
2WD/3.0L Optional
2WD & 4WD/4.0L Optional
(1) Extended length model only.

(2) 1989 Only

IDENTIFICATION
The A4LD 4-speed automatic transmission can be identified by the Safety Standard Certification label. Label is
located on driver's door lock pillar. Transmission code on label is under TRANS designation. The code for
automatic 4-speed transmission is "T".

NOTE: Ford Motor Co. uses the code "T" in certification label for both AOD and A4LD
transmissions.

Automatic transmissions are also equipped with service identification tags. See Fig. 1. Tag is attached to lower
left side extension housing bolt. Top line of tag shows transmission model number and line shift code. Bottom
line on tag shows build date code.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 1: Service Identification Tag

Courtesy of FORD MOTOR CO.

DESCRIPTION
The A4LD is a 4-speed automatic overdrive transmission with lock-up type torque converter. Transmission
consists of torque converter, planetary gear train, 3 multiple disc clutch packs, 3 bands, 2 one-way clutches and
a hydraulic control system.

The on-board EEC-IV system controls operation of a converter clutch solenoid to engage or disengage a
piston/plate clutch located in the torque converter. Piston/plate clutch locks and unlocks torque converter to
provide "solid drive" function when appropriate.

The EEC-IV system also controls operation of a shift solenoid for 3rd-4th gear upshift and downshifts with 4th
gear acting as overdrive. Overdrive (4th gear) is engaged or disengaged as necessary to provide for fuel
economy, and torque or acceleration conditions.

Manual selection of gears is also provided. Park, Neutral and Reverse function is the same as all other Ford
automatic transmissions. If 1st gear is manually selected at speeds above 30 MPH (48 km/h), transmission will
downshift to 2nd gear, followed by downshift to 1st gear when speed decreases to 30 MPH (48 km/h). If 2nd
gear is manually selected, transmission will remain in 2nd gear regardless of vehicle speed. This is useful for
start-up on slippery surfaces or for engine braking on downgrades.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

LUBRICATION & ADJUSTMENTS

See appropriate TRANSMISSION SERVICING - A/T article in TRANSMISSION SERVICING.

ON-VEHICLE SERVICE
VALVE BODY

NOTE: Note length and position of valve body bolts for reassembly reference. See Fig.
2.

Removal

1. Raise and support vehicle. Loosen oil pan bolts and drain fluid. Remove oil pan, filter screen and "O"
rings. Remove low-reverse servo cover, piston, spring and gasket. See LOW-REVERSE SERVO under
ON-VEHICLE SERVICE. Disconnect 2 wires at converter clutch solenoid and 2 wires at 3-4 shift
solenoid. See Fig. 2.

NOTE: Note location of 3-4 shift solenoid inner and outer retainers for reassembly
reference.

2. Hold valve body in position and remove control valve body bolts. Remove detent spring from location
"A". See Fig. 2. Carefully ease valve body from case while unlocking and detaching selector lever
connecting rod ("Z" link). Clean and inspect valve body thoroughly. See CLEANING & INSPECTION.

Installation

1. Attach and lock selector lever connecting rod ("Z" link) to manual valve. Using care not to deform "Z"
link, ease valve body into case.
2. Install "A" and "B" bolts finger tight, to locate valve body into case. See Fig. 2. Install remaining bolts
finger tight, except filter screen bolt and 3-4 shift solenoid bolts. Ensure proper bolts are installed in their
correct location.
3. Tighten valve body bolts, starting from center bolts and working to outer edges. See TORQUE
SPECIFICATIONS. Remove bolt "A" and install detent spring to bolt. Reinstall bolt "A"and tighten to
specification.
4. Install low reverse servo cover, piston, spring and gasket. Connect solenoid wires.
5. Clean filter screen with solvent and install filter screen and "O" rings. Using a new gasket, install gasket
and oil pan. Tighten oil pan bolts to specifications.
6. Add 3 Qts. (2.8L) of transmission fluid and start engine. Add fluid as necessary.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 2: Locating Control Valve Body Bolts

Courtesy of FORD MOTOR CO.

LOW-REVERSE SERVO

Removal & Installation

Remove transmission oil pan and filter screen with "O" rings. Remove low-reverse servo bolts. Remove servo
cover, gasket, piston and spring. See Fig. 3. To install, reverse removal procedure.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 3: Removing & Installing Low-Reverse Servo Assembly

Courtesy of FORD MOTOR CO.

EXTENSION HOUSING

Removal

1. Raise and support vehicle. Mark drive shaft rear yoke and pinion flange for reassembly reference.
Remove drive shaft. Disconnect speedometer cable from extension housing.
2. Support transmission with transmission jack. Remove rear support bolts. Raise transmission slightly and
remove rear support from extension housing. Loosen extension housing bolts and allow transmission fluid
to drain.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

3. Remove bolts and slide extension housing off output shaft. See appropriate component under
CLEANING & INSPECTION.

Installation

1. Ensure parking pawl and spring are installed in housing correctly and are preloaded. Install new housing
gasket and position extension housing on case.
2. Ensure parking pawl actuating rod is seated in extension housing guide cup bore. Install and tighten bolts.
See TORQUE SPECIFICATIONS. To complete installation, reverse removal procedure.

EXTENSION HOUSING SEAL & BUSHING

Removal

1. Raise and support vehicle. Mark drive shaft rear yoke and pinion flange for reassembly reference.
Remove drive shaft.
2. Using Seal Remover (T71P-7657-A), remove extension housing oil seal. Using Bushing Remover (T77L-
7697-E), remove extension housing bushing. See appropriate component under CLEANING &
INSPECTION.

Installation

1. Using Bushing Installer (T77L-7697-F), install bushing. Using Seal Installer (T74P-77052A), install seal.
2. Apply multipurpose long-life lubricant to seal lip and drive shaft yoke. Align index marks and install
drive shaft. Add fluid as necessary

GOVERNOR

Removal

1. Raise and support vehicle. Remove extension housing. See EXTENSION HOUSING under ON-
VEHICLE SERVICE. Remove governor body-to-oil collector body bolts. See Fig. 4.

NOTE: Components are not retained once governor body bolts have been
removed. It is necessary to hold body and components together while
removing and installing governor.

2. Remove governor body from collector body. Remove governor valve, spring and weight from governor
body.

Installation

Reassemble governor body and components. Ensure correct spring is used for model application. Position
governor body over oil feed holes of oil collector body. Install bolts and tighten to specifications. See
TORQUE SPECIFICATIONS. To complete installation, reverse removal.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 4: Removing & Installing Governor Assembly

Courtesy of FORD MOTOR CO.

NEUTRAL SWITCH

WARNING: When battery is disconnected, vehicle computer and memory systems

may lose memory data. Driveability problems may exist until computer
systems have completed a relearn cycle. See COMPUTER RELEARN
PROCEDURES article in APPLICATIONS & IDENTIFICATION before
disconnecting battery.

Removal & Installation

Disconnect negative battery cable. Disconnect neutral switch wires from switch. Using Neutral Switch Socket

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

(T74P-77247-A), remove switch and "O" ring from transmission. To install, reverse removal procedure. Tighten
neutral switch to specification. See TORQUE SPECIFICATIONS.

VACUUM DIAPHRAGM

Removal & Installation

Remove heat shield (if equipped). Disconnect vacuum hose. Remove bolt and clamp. Remove vacuum
diaphragm and control rod from case. To install, reverse removal procedure. Tighten bolt to specification. See
TORQUE SPECIFICATIONS.

TROUBLE SHOOTING
PRELIMINARY CHECKS

NOTE: When TROUBLE SHOOTING symptom indicates computer/computer controlled

device failure, refer to appropriate AUTO TRANS DIAGNOSIS - FORD A4LD
article.

Accelerator Linkage

Ensure accelerator linkage is free from interference and returns to idle when released. Adjust accelerator linkage
or dashpot as necessary.

Computer Controls

Ensure all computer control systems are operating properly before diagnosing transmission shifting problems.
Refer to appropriate AUTO TRANS DIAGNOSIS - FORD A4LD article.

Downshift Linkage

1. Downshift linkage is self-adjusting. With ignition off, press accelerator pedal firmly to the floor, then
release.
2. If kickdown function is difficult or not possible, check for interference to throttle cable and/or kickdown
cable by floormat or pads.
3. Check for interference in engine compartment by hoses, wiring harnesses, etc. Adjust trim or engine
components as required.

Fluid Level

1. Vehicle must be on level surface. Bring vehicle to normal operating temperature. Move shift selector
through all positions, allowing enough time for each position to engage.
2. Securely engage shift lever in Park position. Vehicles with 4WD must have 4WD selector in any position
other than Neutral. Apply parking brake.
3. Check fluid with dipstick and add as necessary. If fluid is low, leakage is indicated. Locate and repair
source of leak.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Manual Shift Cable

When column or console position is selected, ensure transmission detent position corresponds exactly. Adjust
cable or indicator as necessary.

Vacuum Diaphragm

Remove hose from vacuum diaphragm. If transmission fluid is present on vacuum side of diaphragm unit,
replace diaphragm unit. For further tests of vacuum diaphragm and engine vacuum supply, see VACUUM
DIAPHRAGM UNIT TEST and ENGINE VACUUM SUPPLY TEST under TESTING.

Clutch & Band Application Chart

The clutch and band application chart can be used with or without Rotunda Automatic Transmission Tester
(014-00737) to assist the technician with trouble shooting. See Fig. 5.

Fig. 5: Cross Section of A4LD Transmission with Clutch & Band Application Chart
Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

SYMPTOM CHARTS

NOTE: Many symptoms can be caused by improper fluid level or linkage adjustment or
damage. ALWAYS do preliminary checks before trouble shooting by symptom.
See Fig. 6-Fig. 16 for TROUBLE SHOOTING SYMPTOM CHARTS.

Fig. 6: A4LD Trouble Shooting Symptom Charts (1 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 7: A4LD Trouble Shooting Symptom Charts (2 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 8: A4LD Trouble Shooting Symptom Charts (3 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 9: A4LD Trouble Shooting Symptom Charts (4 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 10: A4LD Trouble Shooting Symptom Charts (5 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 11: A4LD Trouble Shooting Symptom Charts (6 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 12: A4LD Trouble Shooting Symptom Charts (7 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 13: A4LD Trouble Shooting Symptom Charts (8 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 14: A4LD Trouble Shooting Symptom Charts (9 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 15: A4LD Trouble Shooting Symptom Charts (10 of 11)

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 16: A4LD Trouble Shooting Symptom Charts (11 of 11)

Courtesy of FORD MOTOR CO.

TESTING
After completing PRELIMINARY CHECKS, use initial road test to verify malfunction of transmission.
Ensure engine is operating properly.

SHIFT SPEED TEST

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Road Test

This test will determine if electronics, governor and shift control valves are functioning properly. Converter
lock-up is difficult to detect. A vacuum gauge and tachometer should be used to determine lock-up speeds.

1. Check light throttle upshift with transmission in Overdrive (with approximately 10 in. Hg). Transmission
should start in 1st gear and shift automatically into and through each gear, then lock converter at
predetermined speeds. See appropriate SHIFT SPEEDS table.
2. Converter clutch lock-up only occurs after Overdrive gear is obtained. With transmission in "D", all
upshifts are automatic (except for overdrive). With transmission selector in 2nd gear, transmission will
only operate in 2nd gear.
3. When travelling over 45 MPH with transmission in 3rd gear, transmission should downshift into 2nd gear
when selector lever is manually shifted from "D" to 1st gear. This will determine if governor pressure and
shift control valves are functioning properly.
4. When traveling at approximately 45 MPH in Overdrive or "D" and transmission is manually shifted into
1st gear, transmission should shift into 2nd gear. When speed drops below 30 MPH, transmission will
downshift into 1st gear.
5. During coastdown from approximately 45 MPH with transmission in Overdrive and throttle closed, as
vehicle speed drops, downshift sequence is:

Converter Electronically Unlocks (When Accelerator Pedal Is Released)

Downshift From Overdrive-To-3rd
Downshift From 3rd-To-2nd
Downshift From 2nd-To-1st

In-Shop Test

The shift speed test can be performed in-shop to check shift valve operation, governor circuits, shift delay
pressures, throttle boost and downshift valve action.

CAUTION: DO NOT exceed 60 MPH speedometer reading.

1. Raise and support vehicle so that rear wheels are clear of floor. Disconnect and plug line to vacuum
diaphragm. Connect an adjustable vacuum source to vacuum diaphragm unit.
2. Start vehicle. Apply 18 in. Hg vacuum to vacuum diaphragm unit. Shift transmission into Overdrive
position. At minimum throttle position, allow transmission to shift through gears and into converter lock-
up.
3. Note shift speeds and compare against appropriate SHIFT SPEEDS table. If shift speeds are not within
specifications, proceed to GOVERNOR PRESSURE TEST to isolate problem.
4. If shift speeds are within specifications, the 1-2, 2-3, 3-4 and converter clutch shift valves and governor
are okay. Shift to Neutral position. Run engine at 1000 RPM for 15 seconds to cool transmission. Proceed
to next step.
5. Apply 1-2 in. Hg vacuum to vacuum diaphragm unit. Shift transmission into Overdrive position. Allow

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

transmission to shift from 1-2.

6. If shift speed is within specification, throttle boost and shift delay systems are functioning properly. Shift
to Neutral position. Run engine at 1000 RPM for 15 seconds to cool transmission. Proceed to next step.
7. Apply 1-2 in. Hg vacuum to vacuum diaphragm unit. Shift transmission into Overdrive position. Move
the kickdown linkage through detent into wide open throttle position. Allow transmission to shift from 1-
2. Shift speed should be higher than normal specification.

Shift Speed Vacuum Gauge Readings (Except Mustang)

All minimum throttle shift speeds should occur with 10-15 in. Hg reading. Part throttle 1-2 and 2-3 shift speeds
should occur with 1.5-2.0 in. Hg reading. All wide open throttle shift speeds and part throttle 3-2 shift speeds
should occur with 1 in. Hg reading. Overdrive 3-4 and 4-3 shifts at minimum throttle or part throttle are
electronically controlled.

SHIFT SPEEDS (3.0L AEROSTAR & RANGER W/3.73 AXLE RATIO)

Throttle Position & Drive Range Shift MPH
Idle (Closed Throttle)
OD, D 3-2 8-14
OD, D 2-1 6-11
Minimum Throttle
OD, D 1-2 9-15
OD, D 2-3 17-25
OD 3-4 35-43
Part Throttle
OD, D 1-2 26-32
OD, D 2-3 35-41
OD 3-2 26-32
Wide Open Throttle
OD, D 1-2 40-46
OD, D 2-3 65-71
OD, D 3-2 60-66
OD, D 3-1, 2-1 35-41
Manual Pull-Down (1st) 2-1 32-42

SHIFT SPEEDS (4.0L AEROSTAR W/3.73 AXLE RATIO)

Throttle Position & Drive Range Shift MPH
Idle (Closed Throttle)
OD, D 3-2 11-16
OD, D 2-1 6-11
Minimum Throttle
OD, D 1-2 11-15
OD, D 2-3 16-22
OD 3-4 37-44

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Part Throttle
OD, D 1-2 23-28
OD, D 2-3 36-41
OD 3-2 29-34
Wide Open Throttle
OD, D 1-2 35-39
OD, D 2-3 59-64
OD, D 3-2 55-60
OD, D 3-1, 2-1 27-33
Manual Pull-Down (1st) 2-1 24-33

SHIFT SPEEDS (EXPLORER W/3.08 AXLE RATIO)

Throttle Position & Drive Range Shift MPH
Idle (Closed Throttle)
OD, D 3-2 14-18
OD, D 2-1 8-12
Minimum Throttle
OD, D 1-2 13-15
OD, D 2-3 19-24
OD 3-4 34-49
Part Throttle
OD, D 1-2 33-37
OD, D 2-3 48-52
OD 3-2 41-45
Wide Open Throttle
OD, D 1-2 40-44
OD, D 2-3 70-75
OD, D 3-2 65-70
OD, D 3-1, 2-1 32-38
Manual Pull-Down (1st) 2-1 30-38

SHIFT SPEEDS (2.3L RANGER W/3.73 AXLE RATIO)

Throttle Position & Drive Range Shift MPH
Idle (Closed Throttle)
OD, D 4-3 16-22
OD, D 3-2 9-15
OD, D 2-1 5-11
Minimum Throttle
OD, D 1-2 10-15
OD, D 2-3 15-24
OD 3-4 37-45

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Part Throttle
OD, D 1-2 28-34
OD, D 2-3 39-45
OD 3-4 60-66
OD 4-3 51-57
OD 3-2 32-38
Wide Open Throttle
OD, D 1-2 33-39
OD, D 2-3 57-63
OD, D 3-2 53-59
OD, D 3-1, 2-1 27-33
Manual Pull-Down (1st) 2-1 26-32

SHIFT SPEEDS (2.9L RANGER W/3.45 AXLE RATIO)

Throttle Position & Drive Range Shift MPH
Idle (Closed Throttle)
OD, D 3-2 10-17
OD, D 2-1 9-13
Minimum Throttle
OD, D 1-2 11-17
OD, D 2-3 20-26
OD 3-4 37-47
Part Throttle
OD, D 1-2 32-38
OD, D 2-3 43-49
OD 3-4 82-90
OD 4-3 87-95
OD 3-2 36-42
Wide Open Throttle
OD, D 1-2 41-47
OD, D 2-3 67-73
OD, D 3-2 63-69
OD, D 3-1, 2-1 36-42
Manual Pull-Down (1st) 2-1 32-42

SHIFT SPEEDS (4.0L RANGER W/3.08 AXLE RATIO)

Throttle Position & Drive Range Shift MPH
Idle (Closed Throttle)
OD, D 3-2 13-19
OD, D 2-1 7-13
Minimum Throttle

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

OD, D 1-2 13-18

OD, D 2-3 19-27
OD 3-4 45-53
Part Throttle
OD, D 1-2 28-34
OD, D 2-3 43-49
OD 3-2 35-41
Wide Open Throttle
OD, D 1-2 42-47
OD, D 2-3 71-77
OD, D 3-2 66-72
OD, D 3-1, 2-1 33-39
Manual Pull-Down (1st) 2-1 29-39

Shift Speed Vacuum Gauge Readings (Mustang)

All closed throttle and minimum throttle shift speeds should occur with 10-15 in. Hg reading. Part throttle 4-3
and 3-2 shift speeds should occur with 1.0 in. Hg reading. Converter lock and unlock is hydraulically scheduled
but can be electronically overridden.

SHIFT SPEEDS (MUSTANG W/3.73 AXLE RATIO)

Throttle Position & Drive Range Shift MPH
Closed Throttle
OD, D 3-2 9-15
OD, D 2-1 6-12
Minimum Throttle
OD, D 1-2 10-15
OD, D 2-3 14-21
OD 3-4 30-38
Part Throttle
OD, D 1-2 25-31
OD, D 2-3 36-42
OD 3-4 59-65
OD 4-3 47-53
OD, D 3-2 29-35
Wide Open Throttle
OD, D 1-2 32-38
OD, D 2-3 56-62
OD, D 3-2 51-57
OD, D 3-1, 2-1 27-33
Manual Pull-Down (1st) 2-1 25-31

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

CONVERTER CLUTCH TEST

NOTE: Ensure engine coolant temperature is above 128°F (53°C) and below 240°F (116°
C). Due to the difficulty of feeling converter clutch shift, a tachometer and/or
vacuum gauge must be connected to engine.

1. To check converter for engagement and disengagement, drive vehicle at approximately 50 MPH. While
maintaining this speed, lightly tap brake pedal. Engine RPM and vacuum should increase when clutch
disengages, with light brake pedal application.
2. Engine RPM will decrease when pedal is released and clutch engages. If converter clutch does not engage
or is engaged continuously, see AUTO TRANS DIAGNOSIS - FORD A4LD article.

VACUUM DIAPHRAGM UNIT TEST

1. Remove hose from vacuum diaphragm. If transmission fluid is present on vacuum side of diaphragm unit,
replace unit. Fluid indicates diaphragm in unit is defective.

NOTE: If replacing vacuum diaphragm unit, ensure correct replacement is used.

Diaphragm units may appear identical, but cannot be interchanged.

2. Attach a vacuum pump to diaphragm unit. Apply 18 in. Hg of vacuum. If gauge reading holds steady,
diaphragm unit is good. If gauge reading drops, diaphragm unit is defective and must be replaced.
3. Remove diaphragm unit from transmission. Apply 18 in. Hg of vacuum. Hold finger over end of unit
control rod. When hose is removed, diaphragm unit should push control rod out. Replace as necessary.

ENGINE VACUUM SUPPLY TEST

1. Disconnect vacuum line at diaphragm unit. Connect vacuum line to gauge. At idle, engine vacuum must
hold steady at an acceptable level for the altitude at which the vehicle is tested.
2. If vacuum reading is low, check for vacuum leaks in vacuum hoses and engine vacuum related
components (power brake booster, etc.).
3. If vacuum reading is okay, press the accelerator pedal quickly, then release. Vacuum reading should drop
rapidly then recover immediately when pedal is released.
4. If vacuum reading does not change or recover quickly, check supply line for restriction or incorrect
connection.

CONTROL PRESSURE TEST

Using Engine Vacuum

1. If vacuum diaphragm unit is working properly and linkage is adjusted correctly, all shifts should occur
within specified road speed limits. See appropriate SHIFT SPEEDS table. If not within specifications or
slipping occurs, check engine vacuum supply and vacuum operated units for possible defect.
2. Connect tachometer to engine. Connect vacuum gauge to manifold vacuum line, using "T" fitting at
diaphragm unit. Attach pressure gauge to control pressure take-off located on left side of transmission

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case. See Fig. 17.

3. Apply parking brake firmly. Start engine and ensure idle RPM is correct. If engine idle cannot be brought
within limits, check throttle and downshift linkages for binding. Check for vacuum leaks in hoses, tubes
and all vacuum components such as power brake booster.
4. With engine at idle, read and record control pressures in all selector positions. Read and record control
pressures with vacuum gauge reading at 10 in. Hg and at one in. Hg (wide open throttle). See appropriate
CONTROL PRESSURE SPECIFICATIONS and CONTROL PRESSURE TEST RESULTS.

Fig. 17: Gauge Hookup for Control Pressure Testing

Courtesy of FORD MOTOR CO.

NOTE: Governor can be checked at same time and in the same manner as control
pressure test.

Using Vacuum Pump

1. Disconnect vacuum line from diaphragm unit and attach vacuum pump. See Fig. 17. Apply parking and
service brakes. Start engine and apply 15 in. Hg of vacuum to diaphragm unit. Read and record control
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 1990 Ford Aerostar
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pressures in all selector positions.

2. Bring engine RPM to 1000. Reduce vacuum to 10 in. Hg. Read and record control pressures in "OD",
"D", "2" and "1" selector positions.
3. Reduce vacuum to one in. Hg. Read and record control pressures in "OD", "D", "2", "1" and "R" selector
positions. See appropriate CONTROL PRESSURE SPECIFICATIONS table and CONTROL
PRESSURE TEST RESULTS.

CONTROL PRESSURE SPECIFICATIONS (PSI @ SEA LEVEL)

Drive Range 15 in. Hg & Above 10 in. Hg WOT Stall Thru Detent
OD, D,2,1 57-78 114-134 205-235
R 67-105 157-177 282-316
P, N 57-78 - -

CONTROL PRESSURE SPECIFICATIONS (PSI @ 5000 FT.)

Drive Range 15 in. Hg & Above 10 in. Hg WOT Stall Thru Detent
OD, D,2,1 57-67 90-110 180-210
R 67-77 124-144 247-280
P, N 57-67 - -

CONTROL PRESSURE TEST RESULTS

Compare recorded control pressures to control pressures listed in table. See appropriate CONTROL
PRESSURE SPECIFICATIONS table. If control pressures are outside of specified ranges, use flow chart to
determine cause of trouble. See Fig. 18.

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 1990 Ford Aerostar
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Fig. 18: Control Pressure Test Result Flow Chart

Courtesy of FORD MOTOR CO.

GOVERNOR PRESSURE TEST

1. Raise vehicle until drive wheels clear ground. Disconnect and plug vacuum line to vacuum diaphragm
unit. Connect a vacuum pump to vacuum diaphragm unit.

CAUTION: DO NOT exceed 60 MPH speedometer reading. After each test, move
selector lever to Neutral position and run engine at 1000 RPM for 15
seconds to cool transmission.

2. Place transmission in "D" position. Apply 10 in. Hg to vacuum diaphragm with no load on engine.
Increase speed slowly and watch speedometer. Note speed at which control pressure cut-back occurs.

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 1990 Ford Aerostar
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3. Pressure cut-back should occur between 5-15 MPH. Decrease vacuum to 0-2 in. Hg and repeat test.
Control pressure cut-back should occur at 7-20 MPH. Governor is okay if cut-back occurs as specified.
4. If cut-back does not occur as specified, check shift speeds to verify problem is in governor and not due to
stuck cut-back valve. See SHIFT SPEED TEST. Repair or replace governor as necessary.

STALL SPEED TEST

Testing Precautions

1. Engine coolant and transmission fluid must be at proper levels and operating temperatures. Linkages must
be set properly. Hold accelerator down just long enough to get a stable tachometer reading. DO NOT
floor accelerator for more than 5 seconds.
2. DO NOT exceed maximum specified RPM for vehicle. Before shifting into each selector position, run
engine in Neutral at 1000 RPM for 15 to 20 seconds to cool transmission. If engine speed exceeds
specification, release accelerator immediately, as this is an indication of clutch or band slippage.

Testing Procedure

Connect tachometer to engine. Apply parking and service brakes firmly. Place selector lever in each gear. Press
accelerator completely to floor and record tachometer reading in each gear. DO NOT exceed 5 second limit.
Engine speed should be within specifications. See STALL SPEED SPECIFICATIONS.

STALL SPEED SPECIFICATIONS

Application Engine Min.-Max. RPM
Mustang 2.3L 2495-2885
Ranger (2WD) 2.3L 2437-2833
Aerostar (2WD) 3.0L (V6) 2720-3165
Ranger (2WD, 4WD) 2.9L (V6) 2781-3288
Aerostar (2WD, AWD) 4.0L (V6) 2550-2950
Explorer (2WD, 4WD) 4.0L (V6) 2550-2950
Ranger (2WD, 4WD) 4.0L (V6) 2550-2950

STALL TEST RESULTS

Low In All Ranges

Poor engine performance. Faulty torque converter stator one-way clutch.

High In All Ranges

General transmission problems are indicated. Perform control pressure tests.

High In "O/D" Only

Forward clutch faulty.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

High In "O/D", "D" & "1"

Overdrive one-way clutch or rear one-way clutch faulty.

High In "D", "2" & "1"

Forward clutch or overdrive clutch faulty.

High In "2" Only

Overdrive one-way clutch, intermediate band or servo faulty.

High In "1" Only

Low-reverse band or servo faulty.

High In "R" Only

Overdrive clutch, overdrive one-way clutch. reverse and high clutch, low-reverse band or servo faulty.

AIR PRESSURE TESTS

A "No Drive" condition can exist, even with correct transmission fluid pressure, due to inoperative clutches or
bands. Inoperative units can be located through a series of checks by substituting air pressure for fluid pressure
to determine location of malfunction.

To check unit, drain transmission fluid. Remove oil pan, gasket and control valve body. See VALVE BODY
removal procedure under ON-VEHICLE SERVICE. Using shop air, apply air to indicated points. See Fig. 19.
Check unit operation as follows.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 19: Air Pressure Testing Points

Courtesy of FORD MOTOR CO.

Forward Clutch

Apply air pressure into forward clutch passage. A dull thud can be heard when clutch piston is applied. If no
thud is heard, movement of piston can be felt by placing fingertips on input shell.

Governor

Apply air pressure into the forward clutch control pressure-to-governor passage. Listen for sharp clicking or
whistling noise indicating governor valve movement.

Overdrive Servo

1. Apply air pressure to overdrive servo apply passage. Operation of servo is indicated by a tightening of

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

overdrive band around overdrive drum.

2. While continuing to apply air pressure to servo apply passage, apply air pressure to overdrive servo
release passage. The overdrive servo should release overdrive band.

Overdrive Clutch

Apply air pressure to overdrive clutch feed passage. A dull thud indicates the overdrive clutch piston has moved
to the applied position.

NOTE: If air pressure applied to either clutch passage fails to operate clutch or
operates both clutches at once, check fluid passages in case and oil pump. Use
air pressure to detect obstructions.

Reverse-High Clutch

Apply air pressure into reverse-high clutch passage. A dull thud can be heard when clutch piston is applied. If
no thud is heard, movement of piston can be felt by placing fingertips on clutch drum.

Intermediate Servo

1. Hold air nozzle in intermediate servo apply passage. Operation of servo is indicated by tightening of
intermediate band around drum.
2. While continuing to apply air pressure at servo apply passage, apply air pressure to intermediate servo
release passage. Intermediate servo should release band against pressure in apply passage.

Low-Reverse Servo

Apply air pressure to low-reverse servo apply passage. Low-reverse band should tighten around drum if servo is
operating properly.

TRANSMISSION FLUID COOLER FLOW CHECK

NOTE: Before performing TRANSMISSION FLUID COOLER FLOW CHECK, ensure shift
cables and linkages are properly adjusted. Ensure fluid level is correct and
control pressures are within specifications. See CONTROL PRESSURE TEST.

1. Remove transmission dipstick from filler tube. Install a funnel into filler tube. Raise and support vehicle.
Disconnect transmission cooler return line (upper line) from transmission case fitting.
2. Connect one end of a hose to transmission cooler return line. Install other end of hose into filler tube
funnel. With transmission in Neutral position, set idle speed to 1000 RPM.
3. Note fluid flow at funnel. Wait until flow is constant. This indicates air bleeding has been completed.
Fluid flow should be free and heavy. If flow is intermittent or light, check flow from transmission fluid
output line to determine source of restriction.
4. If transmission output line flow is good, restriction is in cooler. Repair as necessary. If output line flow is
poor, check for main oil circuit leakage, oil pump defect or a stuck converter charge relief valve.

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 1990 Ford Aerostar
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TORQUE CONVERTER
TORQUE CONVERTER FLUSHING

Whenever transmission has been disassembled to replace worn or damaged parts or because valve body sticks
due to foreign material, converter must be cleaned using a mechanically agitated cleaner, such as Rotunda (014-
00028). Under no conditions should converter be cleaned by hand agitation using solvent.

After removing torque converter from cleaning equipment, thoroughly drain remaining solvent from converter
hub. Add 2 Qts. (1.9L) of clean transmission fluid to converter and agitate by hand. Thoroughly drain converter
hub.

NOTE: Torque converter is a sealed unit and cannot be disassembled for service.
Replace if found to be defective. Perform the following tests to ensure converter
is defective before replacing unit.

LEAK TEST

If torque converter welds indicate leakage, attach Torque Converter Leak Detector (Rotunda 021-00054) to
converter and follow detector kit instructions.

TURBINE & STATOR END PLAY CHECK

1. Insert Torque Converter End Play Tester (T80L-7902-A) into converter pump drive hub until it bottoms.
Expand sleeve in turbine spline by tightening threaded inner post of tester until it is securely locked into
spline. See Fig. 20.
2. Attach dial indicator to tester with dial indicator tip on converter housing. Zero dial face. Lift tester
upward as far as it will go and note dial indicator reading.
3. Reading is total end play of turbine and stator. If end play exceeds .023" (.58 mm) on new or rebuilt
converter, or .050" (1.27 mm) on used converter, replace torque converter assembly.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 20: Installing Torque Converter End Play Tester

Courtesy of FORD MOTOR CO.

CONVERTER ONE-WAY CLUTCH CHECK

1. Insert one-way Clutch Holder (D84L-7902-A) into one of the grooves in the stator thrust washer. Insert
Torque Adapter (T77L-7902-B) into converter impeller hub so as to engage one-way clutch inner race.
2. Attach a torque wrench to torque adapter. With clutch holder held stationary, turn torque wrench
counterclockwise. See Fig. 21. Converter one-way clutch should lock-up and hold at 10 Ft. Lbs. (14
N.m). One-way clutch should rotate freely in a clockwise direction.
3. Repeat lock-up test in at least 5 different locations around torque converter. If clutch fails to lock-up and
hold, replace torque converter.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 21: Checking Converter One-Way Clutch

Courtesy of FORD MOTOR CO.

STATOR INTERFERENCE CHECK

Stator-To-Impeller Interference Check

1. Position front pump assembly on bench with spline end of stator shaft pointing upward. Mount converter
on pump so splines of one-way clutch inner race engage splines of stator support and impeller hub
engages pump drive gear.
2. While holding pump stationary, rotate converter in both directions (clockwise and counterclockwise).
Converter should rotate freely without interference. If an interference or scraping condition exists, replace
torque converter unit.

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 1990 Ford Aerostar
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REMOVAL & INSTALLATION

See appropriate TRANSMISSION REMOVAL - A/T article in TRANSMISSION SERVICING.

TRANSMISSION DISASSEMBLY

NOTE: Disassembly procedures are listed by main components. Disassemble in order

shown. To identify components, see Fig. 22.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 22: Exploded View of A4LD Transmission

Courtesy of FORD MOTOR CO.

VALVE BODY, OIL PUMP & GOVERNOR

1. Remove torque converter and input shaft. Input shaft ends are different. Note direction of installation for
reassembly reference. Remove oil pan, filter screen and detent spring. Disconnect wires at converter
clutch solenoid and 3-4 shift solenoid.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

2. Remove valve body bolts. Unlock and remove selector connecting rod "Z" link and ease valve body and
gasket from case. Remove 5 mm Allen head bolt retaining center support. Remove extension housing.
3. Remove parking pawl and return spring. Remove governor. Remove converter housing-to-case bolts.
Remove converter housing and pump as an assembly. Use a twisting motion to keep clutches in place.
Remove gasket and No. 1 thrust washer.
4. Using Seal Remover (T74P-77428-A), remove oil pump seal from converter housing. Remove oil pump
from converter housing. Remove steel plate with "O" ring from behind oil seal. See related components
under CLEANING & INSPECTION.

NOTE: Ensure thrust washers and bearings are not mixed during reassembly. See Fig.
23.

Fig. 23: Locating Thrust Washers & Bearings (4.0L Model is Similar)
Courtesy of FORD MOTOR CO.

OVERDRIVE CLUTCH ASSEMBLY

1. Loosen overdrive band adjuster lock nut and back off adjusting screw. Discard lock nut. Remove anchor
and apply struts. Lift out overdrive clutch and band. Tag band as overdrive. Tag anchor or apply end of
band for reassembly reference.
2. Lift out overdrive one-way clutch and planetary assembly. Remove center support snap ring from case.
Remove overdrive apply lever and shaft. Remove overdrive control bracket from valve body side of case.

NOTE: Mark apply lever and shaft for reassembly to overdrive assembly.
Overdrive apply lever shaft is longer than the intermediate apply lever
shaft.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

3. Remove thrust washer from front of center support. Tag thrust washer for reassembly reference. Remove
center support by prying upward, carefully and evenly. Remove and tag thrust washer behind center
support. See related components under CLEANING & INSPECTION.

REVERSE-HIGH & FORWARD CLUTCH ASSEMBLY

Loosen intermediate band lock nut and back off adjusting screw. Discard lock nut. Remove anchor and apply
struts. Remove reverse-high and forward clutch assembly. Remove intermediate band. Tag band as
intermediate. Tag anchor or apply end of band for reassembly reference. Remove forward planet gear assembly.
Tag thrust washer (or bearing) for reassembly reference. See related components under CLEANING &
INSPECTION.

LOW-REVERSE ASSEMBLY

1. Remove sun gear shell. Remove large snap ring from reverse planet gear carrier (except 4.0L models). On
all models, remove reverse planet assembly. Remove and tag thrust washers from both sides of assembly
for reassembly reference.
2. On models with 4.0L engine, remove output shaft sleeve. On all models, remove small output shaft snap
ring and remove output shaft ring gear. Remove low-reverse drum and one-way clutch assembly. If not
previously removed, remove low-reverse servo. Remove low-reverse band.
3. Remove and tag thrust washer for reassembly reference. On 4.0L models, thrust washer is not removable.
On all models, inner race of rear one-way clutch is not removable. Remove intermediate apply lever and
shaft. Pull output shaft out from rear of transmission.
4. Remove park gear and collector body as an assembly from rear of case. Remove and tag thrust washer for
reassembly reference. Remove vacuum diaphragm retaining bolt. Remove diaphragm and actuator rod.
Ensure actuator rod moves freely in bore. Remove throttle valve.
5. Remove intermediate servo cover snap ring. Remove and mark intermediate servo cover, piston and
spring. Remove overdrive servo cover snap ring. Remove and mark overdrive cover, piston and spring.

NOTE: Servo covers are under spring pressure. Use care during snap ring
removal. If covers stick, lightly tap cover or side of case. Air pressure may
be used, but DO NOT exceed 20 psi (1.4 kg/cm2 ).

6. Remove neutral switch with Neutral Switch Socket (T74P-77247-A). Remove kickdown lever nut, lever
and "O" ring. Using care not to damage case gasket surface, remove manual linkage centering pin.
7. From inside case, remove 7/8" nut from shift lever. Remove lever, internal kickdown lever, park pawl rod
and detent plate assembly. Remove lever shaft seal from case.
8. Depress tab on solenoid wire connector on outside of case. Remove solenoid wire connector. DO NOT
remove solenoid wire connector unless replacing or degreasing case. See related components under
CLEANING & INSPECTION.

COMPONENT DISASSEMBLY & REASSEMBLY

FORWARD GEAR TRAIN ASSEMBLY

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Disassembly

1. Separate clutch hub and sun gear assembly from reverse high clutch and forward clutch assembly.
Remove and tag needle bearing washer from forward planet gear carrier. See Fig. 24.
2. Remove forward planet assembly from forward clutch. On 4.0L models, remove No. 6 needle bearing
from forward clutch. Remove forward clutch thrust washer from internal gear. Tag bearing and thrust
washers for reassembly reference.
3. On all other models, remove integral thrust washer from internal gear. Tag thrust washer for reassembly
reference. On all models, separate forward planet gear carrier and internal gear. Retain and mark No. 7
needle bearing thrust washer.
4. Separate reverse-high clutch assembly from forward clutch assembly. Remove and tag thrust washer No.
5.

NOTE: If repairing clutches, proceed to appropriate clutch DISASSEMBLY AND

REASSEMBLY procedure.

Reassembly

To reassemble, reverse disassembly procedure. Ensure needle bearings and thrust washers are installed in their
original location.

Fig. 24: Exploded View of Forward Gear Train Assembly (Standard Type Shown; 4.0L Model is Similar)
Courtesy of FORD MOTOR CO.

REVERSE-HIGH CLUTCH

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Disassembly

1. Remove pressure plate retaining ring. Remove pressure plate and clutch pack. Using Spring Compressor
(T65L-77515-A), compress clutch springs and remove retaining ring. See Fig. 25. Carefully release
pressure on springs.

Fig. 25: Compressing Clutch Springs & Removing Retainer

Courtesy of FORD MOTOR CO.

2. Remove spring compressor, spring retainer and clutch springs. Turn clutch body over and carefully force
piston out with compressed air. DO NOT exceed 20 psi (1.4 kg/cm2 ). Hold finger over opposite hole.
Remove "O" rings from piston and clutch body. See related components under CLEANING &
INSPECTION.

Reassembly

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

1. Install new "O" rings on clutch piston. Apply transmission fluid to "O" rings and install clutch piston into
body. Install compression springs and spring retainer. Use Spring Compressor (T65L-77515-A) and
compress springs. See Fig. 25. Install retaining ring. Carefully remove spring compressor.
2. Install a steel plate and then a friction plate. Alternately install remaining discs in clutch pack. See Fig.
26. Install pressure plate and secure pack with retaining ring.

NOTE: The number of steel plates and friction plates varies between 4 and 6 of
each type.

3. While pushing downward on clutch pack, use a feeler gauge to check clearance between retaining ring
and pressure plate. If clearance is not between .051-.079" (1.3-2.0 mm), install a different retaining ring.
4. Retaining rings are available in thicknesses .0539", .0681", .0819" and .0961" (1.37, 1.73, 2.08 and 2.44
mm respectively). When clearance is within specification, install retaining ring.
5. Apply air pressure to hole on back side of clutch assembly. Block opposite hole with finger. Piston must
apply under pressure and release when air is removed.

Fig. 26: Exploded View of Reverse-High Clutch

Courtesy of FORD MOTOR CO.

FORWARD CLUTCH

Disassembly

Disassembly of forward clutch is the same as reverse-high clutch with the exception of clutch piston removal.
Install center support on forward clutch cylinder. Apply air pressure to left side (middle-sized) port. Piston will
be forced out. See Fig. 27. See related components under CLEANING & INSPECTION.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 27: Removing Forward Clutch Piston

Courtesy of FORD MOTOR CO.

Reassembly

1. Reassembly of forward clutch is the same as reverse-high clutch except that a rubber cushion is used over
the piston and spring assembly. Ensure cushion is installed between steel clutch plate and piston. See Fig.
28.

NOTE: The number of steel plates and friction plates varies between 5 and 6 of
each type.

2. The clearance between retaining ring and pressure plate must be .055-.083" (1.4-2.1 mm). Retaining rings
are available in thicknesses .0539", .0681", .0819" and .0961" (1.37, 1.73, 2.08 and 2.44 mm).

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 28: Exploded View of Forward Clutch Assembly

Courtesy of FORD MOTOR CO.

OVERDRIVE CLUTCH

NOTE: On all models, clutch pack consists of 3 steel plates and 3 friction plates.

Disassembly

Disassembly of overdrive clutch is the same as reverse-high clutch. See Fig. 29. See related components under
CLEANING & INSPECTION.

Reassembly

1. Reassembly of overdrive clutch is the same as reverse-high clutch, except for location of clutch springs
during assembly. Ensure clutch springs are installed in 5 groups with 3 springs in each group and a single
spring space between groups (5 spaces total).
2. Clearance between retaining ring and pressure plate must be .055-.083" (1.4-2.1 mm). Retaining rings are
available in thicknesses .0539", .0681", .0819" and .0961" (1.37, 1.73, 2.08 and 2.44 mm).

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 29: Exploded View of Overdrive Clutch Assembly

Courtesy of FORD MOTOR CO.

OVERDRIVE ONE-WAY CLUTCH

Disassembly

1. Mark and remove overdrive clutch adapter to ensure reassembly to original position. Remove sun
overdrive gear and thrust bearing rear race. Mark thrust bearing race for reassembly reference. See Fig.
31.
2. Remove planet carrier and No. 2 needle bearing. Mark No. 2 needle bearing for reassembly. Remove
retaining ring from overdrive center shaft and ring gear. Separate ring gear and center shaft.
3. Mark and remove washer. Note position of one-way clutch and remove from center shaft. One-way clutch
must be installed properly or damage can occur. See related components under CLEANING &
INSPECTION.

Reassembly

1. For reassembly, reverse disassembly procedure. Ensure part number on adapter faces sun gear. Ensure
No. 2 needle bearing is centered and lip faces toward sun gear.
2. Ensure recessed I.D. of washer faces planet carrier. Ensure one-way clutch flange side faces planet
carrier. Ensure one-way clutch rotates in proper direction. See Fig. 30.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 30: Overdrive One-Way Clutch Rotation

Courtesy of FORD MOTOR CO.

Fig. 31: Exploded View of Overdrive One-Way Clutch

Courtesy of FORD MOTOR CO.

LOW-REVERSE ONE-WAY CLUTCH

Disassembly & Reassembly

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

1. Using a screwdriver, remove snap ring. Mark and lift out one-way clutch with springs and roller bearings
as an assembly. Replace assembly if found defective. See related components under CLEANING &
INSPECTION.
2. To reassemble, insert one-way clutch with springs. Using a screwdriver, separate springs and install roller
bearings one at a time. Install snap ring. Ensure one-way clutch is installed properly as marked during
disassembly.

GOVERNOR

Disassembly

1. Remove governor body-to-oil collector body retaining bolts. When these bolts are removed, governor
components are no longer secured in position. Care must be taken not to drop governor body and
components when bolts are removed.
2. Remove outer weight, spring and primary valve from governor body. See Fig. 22. Remove 2 bolts
holding counterweight to collector body and remove counterweight. Remove seals from oil collector body
and discard. See related components under CLEANING & INSPECTION.

Reassembly

Clean and inspect all parts. Replace worn or damaged parts. Without excessive stretching, install new seals on
oil collector. Reassemble counterweight, spring and primary valve in governor body. Reassemble governor
body and counterweight to oil collector body.

CONTROL VALVE BODY

NOTE: During disassembly, place individual parts in order and in relative position for
reassembly reference. Tag all springs as they are removed for reassembly
reference.

Disassembly

1. Remove 3 Torx bolts and remove separator plate and gasket. Note location and remove check ball, shuttle
balls, check valves and relief valves with springs. See Fig. 33.
2. Ensure small filter remains with separator plate when plate is removed from valve body. Filter is located
in corner of separator plate near converter clutch solenoid connector. Remove retaining plates, dowels,
plugs and valves with springs from valve body. See Fig. 32. See related components under CLEANING
& INSPECTION.

Reassembly

Lubricate all parts with transmission fluid. Install valves, springs, plugs, and pins. See Fig. 32. Using new
gasket, apply petroleum jelly to keep gasket in place during separator plate reassembly. Install separator plate.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

Fig. 32: Exploded View of Valve Body Assembly

Courtesy of FORD MOTOR CO.

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 1990 Ford Aerostar
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Fig. 33: Locations of Check Ball, Shuttle Balls & Check Valves
Courtesy of FORD MOTOR CO.

CLEANING & INSPECTION

CLEANING

Wash all parts in cleaning solvent, except composition clutch plates, bands and synthetic seals. Use scraper or
brush for heavy deposits. Rotate bearings by hand in cleaning solvent.

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 1990 Ford Aerostar
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Dry all parts and blow out fluid passages with moisture-free compressed air. Hold bearings while drying to
prevent bearing from spinning. DO NOT spin dry bearings.

Lubricate clean bearings with transmission fluid and wrap in lint-free cloth until ready to install. Soak new
clutch plates and bands in transmission fluid for at least 15 minutes prior to installation.

INSPECTION

Case

Inspect case for cracks and stripped threads. Inspect gasket surfaces for flatness and damage. Check vent and all
fluid passages for obstruction or leakage. Inspect case bushing for scoring. Inspect parking linkage for wear or
damage.

Control Valve Body

Inspect all springs for distortion. Roll manual valve on flat surface to check for bent condition. Make a point of
cleaning and inspecting all fluid passages, especially at check balls, valves and other areas where dirt and debris
accumulate. Inspect all valve and plug bores for scores or obstructions. Inspect valves and plugs for burrs or
scoring. Polish with crocus cloth, if necessary. DO NOT round edges of plugs or valves. All valves and plugs
should move freely in bores. Valves and plugs should fall of their own weight into bores.

Extension Housing

Inspect housing for cracks or damage. Inspect bushing and seal bore for scoring and burrs. Using crocus cloth,
remove burrs. Inspect drive shaft yoke for scoring and replace it if scoring is found.

Forward Clutch Assembly

Inspect clutch cylinder thrust surfaces, piston, bore and clutch plates for scores or burrs. Minor burrs and
scoring may be polished with crocus cloth. Inspect piston check ball for proper seating. Check clutch springs for
distortion or cracks. Check clutch plates for flatness and free movement on clutch hub. Check clutch hub thrust
surfaces and splines for wear or scoring. Inspect input shaft for damaged or worn splines.

Governor

Inspect spring for distortion. Inspect fluid passages for obstruction. Inspect valve and bore for burrs or scoring.
Polish with crocus cloth, if necessary. DO NOT round edges of valve. Valves should move freely in bore.
Valve should fall of its own weight into bore.

Pinion Carrier

Inspect pins and shafts in planet assemblies for loose fit or complete disengagement. Ensure proper staking of
shaft retaining pins before installation of planet assembly. Pins should be no more than .040" (1.0 mm) below
surface of carrier. Inspect pinion gears for worn or damaged teeth. Check for free rotation of pinion gears.

Pump

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Inspect fluid passages. Inspect mating surfaces of pump body and case for burrs. Inspect gear teeth for burrs.
Inspect gear bearing surfaces and pump bushing for scoring. Minor burrs and scoring may be polished with
crocus cloth.

One-Way Clutches

Inspect outer and inner races for scoring or damage. Inspect rollers and springs for damage. Inspect roller cage
for damaged spring retainers.

Reverse-High and Overdrive Clutches

Inspect drum band surface, bushing and thrust surfaces for scoring. Minor burrs and scoring may be polished
with crocus cloth. Inspect clutch piston, bore and inner and outer bearing surfaces for scoring. Inspect clutch
plates for flatness and free movement on clutch hub. Check clutch plates for scoring or burrs. Check clutch
springs for distortion. Replace as necessary. Inspect clutch cylinder check balls for proper seating.

Servos

Inspect band lining for excessive wear and proper bonding to metal band. Inspect fluid passages for
obstructions. Inspect servo and piston bore for cracks, scoring or other damage. Inspect seals and sealing
surfaces. Repair or replace as necessary.

Stator Support

Inspect stator support splines for burrs and wear. Inspect oil ring grooves in stator support for nicks or damaged
edges. Check front pump support seal and seal rings for damage.

TRANSMISSION REASSEMBLY

NOTE: Lubricate all parts with transmission fluid during reassembly. Thrust washers
and gaskets should be held in place with petroleum jelly. See Fig. 23 for
location of thrust washers & bearings.

1. Before installing center support into case, install new high clutch seals on support hub. It is necessary to
size these seals. Apply liberal amount of petroleum jelly to center support hub and seals.

NOTE: If sizing is not done, the seals may be cut or rolled over when entering
intermediate brake drum cavity.

2. Use overdrive brake drum for sizing. Carefully rotate center support while inserting it into drum housing.
Observe seals as they enter cavity to ensure that they DO NOT roll over or get cut.
3. Ensure center support is seated fully into overdrive drum. Allow assembly to stand for several minutes for
seals to seat in grooves. Set aside until required for reassembly.

NOTE: If new output shaft is being installed, ensure correct shaft is used. The
shaft for the 4.0L model does not have a lubrication hole.

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4. Position No. 11 thrust washer in rear of case. Install collector body in rear of case. Install output shaft.
Install governor on collector body. Tighten bolts to specifications. See TORQUE SPECIFICATIONS.
5. Position No. 10 thrust washer into case from front. Using Clutch Replacement Guide (T74P-77193-A),
install low-reverse brake drum (guide not required on 4.0L models). Install output shaft ring gear and new
snap ring. On 4.0L models, install output shaft sleeve. On all models, install No. 9 thrust washer, reverse
planet assembly and No. 8 thrust washer.
6. On all models except 4.0L, install snap ring in drum to hold planet assembly. On all models, install low-
reverse band as marked at disassembly. Replace piston "O" ring and install low-reverse servo piston
assembly to hold band in position. See Fig. 3.

CAUTION: DO NOT mix any of the servo piston assemblies or covers as

transmission failure may occur.

7. Replace piston "O" ring and install intermediate servo piston assembly. Install piston cover and snap ring.
Replace piston "O" ring and install overdrive servo piston assembly. Install piston cover and snap ring.
8. Install intermediate servo apply lever and shaft into case. Install complete forward clutch and reverse-high
clutch assemblies. Turn transmission so output shaft points downward. Install intermediate band and
apply strut. Install intermediate band anchor strut. Temporarily install input shaft.
9. Check transmission rear end play to determine amount of space between thrust washer surface of
overdrive center support and intermediate brake drum. The No. 4 thrust washer is used to obtain end play
of .012-.022" (.30-.56 mm). Use steps 10) through 13) for this procedure.
10. Fabricate a depth gauge from an overdrive center support, if available. See Fig. 34. Drill a 1/8" (3 mm)
hole through thrust washer surface of center support. This will allow a measurement to be taken between
thrust surfaces of support and intermediate brake drum.
11. Place Depth Micrometer (D80P-4201-A) over drilled hole. Extend micrometer probe until it is flush with
thrust washer surface of fixture and record reading. Install fabricated depth gauge fixture into
intermediate brake drum. See Fig. 35.

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Fig. 34: Fabricated Depth Gauge Fixture

Courtesy of FORD MOTOR CO.

Fig. 35: Measuring Rear End Play

Courtesy of FORD MOTOR CO.

12. Gently wiggle input shaft to allow center support fixture to slide into intermediate brake drum. Ensure it
is fully seated. Place depth micrometer over drilled hole. Extend micrometer probe until it bottoms
against thrust washer surface. Note reading. Subtract reading obtained in step 11) from this reading.
13. Remove micrometer and measure again 180 degrees from first location. Repeat steps 11) and 12).
Average these 2 measurements to obtain final reading. Select thrust washer to obtain correct end play

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 1990 Ford Aerostar
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specification. See END PLAY SELECTIVE THRUST WASHER. End play should be .012-.022" (.30-
.56 mm).

END PLAY SELECTIVE THRUST WASHER

Thrust Washer
Average Reading Thickness In. Thrust Washer Part
In. (mm) (mm) No.
.057-.064 (1.46- .055 (1.4) 89 DT-7D014-HA
1.65)
.065-.073 (1.66- .055 (1.4) 89 DT-7D014-AA
1.85)
.074-.077 (1.87- .063 (1.6) 89 DT-7D014-BA
1.95)
.078-.081 (1.96- .067 (1.7) 89 DT-7D014-CA
2.05)
.082-.085 (2.06- .071 (1.8) 89 DT-7D014-DA
2.15)
.086-.089 (2.16- .075 (1.9) 89 DT-7D014-EA
2.25)
.090-.093 (2.26- .079 (2.0) 89 DT-7D014-FA
2.35)
.094-.096 (2.36- .083 (2.1) 89 DT-7D014-GA
2.45)
.097-.104 (2.46- .087 (2.2) 89 DT-7D014-MA
2.65)
.105-.112 (2.66- .094 (2.4) 89 DT-7D014-JA
2.84)
.113-.119 (2.86- .102 (2.6) 89 DT-7D014-KA
3.05)
.120-.124 (3.06- .110 (2.8) 89 DT-7D014-LA
3.15)

14. If average reading is outside of specifications, this indicates improper reassembly, missing parts or parts
outside of specifications. Correct before continuing reassembly. If within specifications, remove depth
gauge, fixture and input shaft. Install selected No. 4 thrust washer on center support and retain with
petroleum jelly.
15. Insert input shaft (short splines down), through intermediate brake drum and into splines of forward
clutch cylinder. Carefully place center support into case. DO NOT seat it into intermediate brake drum.
Ensure it is square with case and 5 mm Allen bolt retainer nut aligns with hole in case.
16. DO NOT apply any pressure to center support. Gently wiggle input shaft, allowing center support to slide
into intermediate brake drum of its own weight. Perform this operation until support is fully seated.
Position No. 3 thrust washer on top of center support.
17. Install snap ring to retain center support. Snap ring taper should face front of transmission. Ends of snap
ring should be positioned in wide shallow cavity located in the 5 o'clock position. Install 5 mm Allen
head bolt that retains center support to case. Two types of snap rings are used. Orient snap ring as shown.

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 1990 Ford Aerostar
1985-92 AUTOMATIC TRANSMISSIONS Ford A4LD Overhaul

See Fig. 36.

Fig. 36: Installing Center Support Snap Ring

Courtesy of FORD MOTOR CO.

18. Install sun gear and adapter into overdrive planet assembly and one-way clutch. Take care to center
needle bearing race inside of planetary assembly. Ensure it stays centered and is positioned with lip
upward (toward sun gear).
19. Install overdrive planet assembly and one-way clutch into case. Install overdrive drum assembly. Install
overdrive bracket, apply lever and shaft. Install overdrive band (tagged at disassembly), and apply strut.
Install anchor strut.
20. Ensure needle bearing race in overdrive planetary assembly is centered and overdrive clutch is fully
seated. Place No. 1 selective washer on top of overdrive clutch drum and temporarily install pump
assembly (without gasket) into case. Ensure pump assembly is fully seated in case and pump body is
below level of case gasket surface.

NOTE: Check for damaged or missing front pump support seal. Replace if
necessary.

21. Mount a dial indicator on oil pump with tip resting on transmission housing. See Fig. 37. Zero dial

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 1990 Ford Aerostar
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indicator and swing indicator around so plunger contacts oil pump.

Fig. 37: Checking End Play

Courtesy of FORD MOTOR CO.

22. Record dial indicator reading. Move dial indicator assembly to opposite side of pump (180 degrees). Take
another end play reading. Average the 2 readings.
23. End play range is .007-.025" (.18-.64 mm). If end play exceeds limits, replace No. 1 selective thrust
washer. See END PLAY SELECTIVE THRUST WASHER.
24. After end play check has been completed, remove oil pump and No. 1 selective thrust washer. Mark
installed position of oil pump gears in relation to one another and remove.

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 1990 Ford Aerostar
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25. Using Seal Replacer (T78L-77248-AH), install new oil pump seal. Position separator plate on converter
housing. Place pump gears into pump housing. The inside edge of small gear has a chamfer on one side.
This chamfer must face toward front of transmission.
26. The larger gear has a dimple on one side which must face toward rear of transmission. Position pump
assembly onto separator plate and converter housing. Install bolts finger tight.

NOTE: The rough appearance of pump stator casting is not a flaw. DO NOT
replace casting due to this appearance.

27. To prevent seal leakage, pump gear breakage or bushing failure, align pump in converter housing with
Pump Alignment Set (T74P-77103-X). Select smallest I.D. sleeve which will fit completely over pump
shaft. Outside diameter of sleeve will center pump in converter housing.
28. Install 5 new Allen bolts. Tighten to specification. See TORQUE SPECIFICATIONS. Remove
alignment tool. Install input shaft into pump. Install converter into pump gears. Rotate converter to check
for free movement. Remove converter and input shaft.
29. Coat converter housing gasket with petroleum jelly and position on converter housing. Install seal ring on
converter housing. Position No. 1 selected thrust washer on rear of pump. Align converter housing and
pump to transmission case. Install bolts with new "O" rings and tighten to specification.
30. Install new lock nut on OVERDRIVE band adjusting screw. Tighten adjusting screw to 120 INCH lbs.
(14 N.m). Back off exactly 2 turns (3 1/2 turns on all 1990-91 4.0L vehicles; these vehicles were
equipped with a "double wrap" type OVERDRIVE band). Hold adjusting screw and tighten lock nut to
35-45 ft. lbs. (47-61 N.m). Repeat procedure for INTERMEDIATE band. Air pressure tests may be
performed to ensure proper transmission operation. See AIR PRESSURE TESTS under TESTING.
31. Install shift lever oil seal using Shift Lever Seal Replacer (T74P-77498-A). Install internal shift linkage,
external manual control lever and centering pin. Tighten nut to 30-40 ft. lbs. (41-54 N.m). Install "O"
ring, kickdown lever and 13 mm nut. Install Neutral switch using Neutral Switch Socket (T74P-77247-
A).
32. Install converter clutch solenoid connector. Install throttle valve, rod, vacuum diaphragm, retaining clamp
and bolt. Tighten to specification. Ensure throttle valve moves freely in its bore.
33. Align valve body to separator plate and gasket using tapered punches. Use a small amount of petroleum
jelly to hold gasket in place. Install 2 bolts and tighten to 53-71 INCH lbs. (6-8 N.m). Attach and lock "Z"
link to manual valve. Carefully ease valve body into case using care not to bend "Z" link. See Fig. 38.

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Fig. 38: Connecting Internal Linkage

Courtesy of FORD MOTOR CO.

NOTE: Valve body bolts are of different lengths. Ensure each bolt is installed in
its correct location.

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 1990 Ford Aerostar
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34. Install and finger tighten bolts "A" and "B". See Fig. 2. Position solenoid retainer onto solenoid. Install
and tighten remaining bolts except filter screen bolt. Remove bolt "A" and install detent spring.
35. Connect solenoid wires. Install reverse servo piston assembly into bore along with Servo Check Spring
(D4ZZ-70031-A). Ensure piston rod is seated correctly in reverse band apply end. Install Servo Rod
Selecting Gauge (T74P-77190-A) with new servo cover gasket. See Fig. 39.

Fig. 39: Selecting Servo Piston & Rod

Courtesy of FORD MOTOR CO.

36. Tighten select guide adjusting screw to 35 INCH lbs. (4 N.m). Install dial indicator onto case. Position
indicator tip on one of 3 servo piston pads accessible through cut-out of guide. Zero dial indicator.
37. Back out adjusting screw until servo piston bottoms out on guide. Record distance servo piston moved.
Servo piston travel should be .120-.220" (3.05-5.59 mm). See Fig. 40.
38. If piston travel is greater than specification, use next longest piston and rod. If less than specification, use
next shorter piston and rod. Rods are identified by their number of grooves. Rods with 2 grooves are

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 1990 Ford Aerostar
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shortest in length; rods with no grooves are medium in length; rods with 1 groove are longest.
39. Install selected piston and rod. Recheck piston travel. If correct, remove guide and auxiliary spring.
Reinstall servo assembly, accumulator spring, gasket and cover. Install servo cover bolts and tighten to
specification.

Fig. 40: Measuring Rear Servo Piston Travel

Courtesy of FORD MOTOR CO.

40. Install new "O" rings on filter screen and lube with petroleum jelly. Install filter screen and bolt. Install
oil pan with new gasket. Tighten pan bolts to specification in 2 steps. Refer to TORQUE
SPECIFICATIONS.
41. Install parking pawl and return spring in extension housing and preload. Using new gasket, install
extension housing. Ensure operating parking rod is correctly seated in extension guide cup. Install and
tighten bolts.
42. Install input shaft and torque converter. Ensure torque converter is properly installed. When installation is
correct, measurement between torque converter pilot nose and front face of housing will be .402-
.568" (11.12-14.30 mm).

TORQUE SPECIFICATIONS

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 1990 Ford Aerostar
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TORQUE SPECIFICATIONS
Application Ft. Lbs. (N.m)
Band Adjuster Lock Nut 35-45 (47-61)
Converter Housing Cover (Except 2.3L) 12-16 (16-22)
Converter Housing-To-Case 27-39 (37-53)
Converter-To-Flywheel 20-34 (27-46)
Extension Housing-To-Case 27-39 (37-53)
Manual Lever Inner Nut 30-40 (41-54)
Oil Cooler Line-To-Connector
Nut 18-23 (24-31)
5/16" Tube Nut 12-18 (16-24)
Transmission-To-Engine
Except 3.0L Engine 28-38 (38-52)
3.0L Engine 33-44 (45-60)
INCH Lbs. (N.m)
Center Support-to-Case Bolt 89-115 (10-13)
Converter Housing Cover Bolt (2.3L) 27 (3)
Downshift Lever Outer Nut 89-133 (10-15)
Governor-To-Collector Body Bolt 89-115 (10-13)
Neutral Switch 89-115 (10-13)
Oil Pump-To-Converter Housing 89-115 (10-13)
Reverse Servo Cover Bolt 89-115 (10-13)
Separator Plate Bolt 54-71 (6-8)
Transmission Oil Pan Bolt 98-115 (11-13)
Vacuum Diaphragm Clip Bolt 89-106 (10-12)
Valve Body-to-Case Bolt 71-98 (8-11)

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