Ford’s AOD evolved into a highly successful mechanically modulated transmission from its 1980 introduction until production ended in 1991. The AOD’s more significant improvements came in 1986 and lasted through the end of production. Ford developed the AODE and 4R70W to achieve cohesive engine and transmission function in 1991.
This Tech Tip is From the Full Book, FORD AOD TRANSMISSIONS: REBUILDING AND MODIFYING THE AOD, AODE AND 4R70W. For a comprehensive guide on this entire subject you can visit this link:
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Differences from AOD
There was a need for engine and transmission performance to be linked through the system’s PCM, which makes the AODE and 4R70W different transmissions from the AOD. Although these transmissions have a great deal in common, they are also very different, with limits in interchangeability. The only inter-changeable components are geartrain related.
The AODE/4R70W is a 4-speed, rear-drive automatic overdrive with electronic control, hence the AODE designation. Ford went to electronic control not only for engine/transmission cohesion, but also improved shift quality by removing the short-comings of mechanical control. Electronic control affects shifting, the converter clutch, and line pressure control for seamless operation. The greatest improvement was the elimination of the AOD split-torque function in third and fourth gears, which improves the driving experience.
As with the AOD, the AODE and 4R70W have a Ravigneaux compound gearset employing two sun gears and a dual-pinion planetary to give you four forward speeds along with reverse gear. There are two bands, two one-way clutches, and four friction clutches used to lock and drive the gearsets. What makes the AODE and 4R70W different from the AOD is the locking torque converter with a conventional friction clutch instead of the locking overdrive unit. The AODE/4R70W rotating mass is similar to that of the AOD. The AODE/4R70W front pump is high-efficiency aluminum rather than iron.
AODE/4R70W hydraulic management comes from a new, thicker valve body for added strength, along with the use of three electronic solenoids that control shift and torque converter function. Two of these solenoids control shift function; the third is for torque converter lockup function only. Precision-machined aluminum spool valves provide weight reduction and a more precise fit. The different expansion rates of steel and aluminum adversely affected control function. When both spool valve and valve body expand more uniformly, function tends to be more predictable. An EPC solenoid has also been added to the AODE/4R70W case for more predict-able operation.
To better tie the engine, vehicle, and transmission functions together, Ford went to an output shaft speed sensor and manual shift lever sensor, along with a multiplex electrical connector to simplify service. As the 4R70W evolved to the 4R75W, an input shaft sensor was added.
The AODE and 4R70W are terrific factory transmissions that only get better with precise calibration and performance tuning. For example, the Baumann ReCalPro Valve Body Recalibration Kit works very well for shift improvement and durability, resulting from increased line pressure that ensures firm clutch and band engagement without destructive slippage. Further enhancements come from the Baumannator Electronic Transmission Control System, which enables you to fine-tune shift performance.
Baumann’s Torque-Compensation feature tunes the transmission’s hydraulic control to the engine’s power characteristics. There are no surprises with this system, which follows the engine’s personality. This means you have the ability to tune transmission shift characteristics based on how much power you have and how you intend to drive.
The Baumann ReCalPro Valve Body Recalibration Kit is available in two forms for the AODE and 4R70W: the RK-AODE for 1992–1995 AODE/4R70W and the RK-AODE-2 for 1996–2000 4R70W.
AODE units through 1995 are standard ratio with 2.40:1/1.47:1 gearsets, except those installed behind the 4.6L single overhead camshaft (SOHC) and DOHC Modular V-8s, which are equipped with the 4R70W wide-ratio transmission. A good rule to remember is that AODEs are standard ratio with 2.40:1/1.47:1 gearsets, while the AOD and 4R70W are wide ratio with 2.84:1/1.55:1 gearsets. The 4.6L V-8 needs the 2.84:1 and 1.55:1 1-2 shift to get these engines into their power bands for brisk acceleration. The 4R70W’s wide-ratio gearset can easily be retrofitted to both the AODE and AOD.
Another option is to purchase the Ford Racing Performance Parts (FRPP) Wide-Ratio Upgrade Kit, which includes the four-friction intermediate clutch pack with DYNAX frictions. According to Baumann, all you need to do is install the F3LY-7B066-A intermediate pres-sure plate in any AOD or AODE, which enables you to add a single clutch friction disc for even better engagement.
The AOD full-throttle shift-point with the Motorsport wide-ratio gear-set is different. Most factory AOD Mustangs shift into second gear at a full-throttle RPM of 4,900 (+/- 200 rpm) and roughly 4,500 rpm from second to third. A switch to the wide-ratio gearset increases the 1-2 shift-point by 18.3 percent (multiply 4,800 rpm by 1.183 to obtain a new shift-point of about 5,680 rpm). The 2-3 shift-point is also raised by a factor of 5.4 percent to produce a full-throttle 2-3 shift at about 4,750 rpm.
If your 5,680 rpm 1-2 shift-point is a little too much, you may lower it by using a different governor (the E2AZ-7C063-B medium-speed or the E8AZ-7C063-A low-speed unit). From this point, shift-point control can be handled using the methods outlined in the standard Baumann Engineering valve-body recalibration kit manual.
Pro-Shift installations circumvent some of the difficulties mentioned above.
Structure and Function
Before getting into the workings of the AODE and 4R70W, it is important to understand their structure. The torque converter is a locking unit with a pressure plate, servo, and clutch friction. With the locking converter comes a wider bellhousing than the AOD has. Converter function segues into a redesigned gerotor front pump with the same capacity, yet higher ﬂuid ﬂow in a lightweight aluminum design. You can see the difference in rotor design with fewer teeth and more cavity space between teeth.
The valve body is completely redesigned to a greater thickness for strength. Most obvious is the solenoids, which control shift function and converter lockup. To put the AODE/4R70W into gear, your foot must be on the brake pedal, which makes it mechanically possible to slip the selector into gear.
Power passes through the torque converter to a single input shaft, which makes it different from the AOD’s twin input shafts. In final drive, however, power passes through the unit differently. Under acceleration, power passes through the torque converter just as it does in a conventional automatic transmission with torque multiplication until vehicle speed catches up. Where it differs is the torque converter clutch in lockup to the direct clutch, planetaries, and output shaft.
The torque converter shell, which is connected to the engine’s crankshaft via a ﬂexplate, drives the transmission’s front pump to provide hydraulic pressure and lubrication. The torque converter’s turbine drives the input shaft. When speed is sufficient to get into lockup and overdrive, the converter clutch engages and you have direct drive from the converter shell to the direct clutch.
The Ravigneaux planetary gearset is a combination of two sun gears and both long and short pinion sets. One planetary member is driven while the other is held. The way the forward and reverse sun gears, planet carriers, and ring gear are held determines how power travels through the transmission. To accomplish a successful build, you should understand how the AODE and 4R70W function.
Direct Clutch Assembly
Step 1: Install Direct Clutch Piston Seals
When removing the old direct clutch piston seals, observe the seal installation and lip direction. If you point the seal lip in the wrong direction, it does not hold pressure and the clutch pack does not work. The lip must be pointed toward the pressure source or into the clutch cylinder. Be very careful not to scratch the clutch piston.
Step 2: Install Direct Clutch Piston (Special Tool)
Carefully install the direct clutch piston using a seal installation tool to protect the seal lip. Slowly walk the tool around, protecting the seal lip. Use an abundance of transmission assembly lube.
Step 3: Install Direct Clutch Piston Return Springs
You can use C-clamps or a spring compressor to compress the springs and install a C-clip. Protect your eyes and face for this step.
Step 4: Install Torrington Needle Bearing
Install the number-7 thrust needle bearing, also known as a Torrington bearing, along with the number-7 bearing support, which is a washer and not a bearing.
Step 5: Install Number-7 C-Clip
Generously lube the thrust bearings and supports with transmission assembly lube. Install the number-7 C-clip.
Step 6: Assemble Direct Clutch Pack
This is the direct clutch, steels, and thrust/needle bearings. All that is needed now are clutch discs between the clutch plates. Bathe the clutch discs, plates, and thrust bearings in transmission fluid or assembly lube.
Step 7: Install Direct Clutch Hub
The direct clutch hub goes up against the number-7 thrust bearing. Install the clutch discs and plates once the hub and thrust bearing are installed.
Step 8: Install Direct Clutch Discs and Plates
Install the direct clutch discs and plates alternately. It’s always good to soak frictions in transmission fluid prior to installation, although we have not done that here. Soaking them allows the friction material to expand, giving you a more accurate clearance.
Step 9: Install Direct Clutch Snap Ring
With all clutches and steels installed and clearances checked (.060–.091 inch), install the snap ring. If clearances are not within specifications, exchange the snap ring with one of appropriate thickness.
Step 10: Install Direct Clutch Needle Bearing
This is the number-8 needle bearing at the direct clutch, which shoulders the thrust load at the output shaft ring gear. It is recommended that you lube the thrust bearing with transmission assembly lube for a good wet start-up.
Step 11: Install Output Shaft Sealing Rings
Four iron sealing rings install on the output shaft. There are four grooves but just three sealing rings. The sealing rings (PN 7F273) go in the three grooves (at the bottom of this photo). A lone sealing ring (PN 87054-S96) goes in the top groove. Give these rings and grooves abundant lubrication.
Step 12: Install Direct Clutch Sealing Rings
The two direct clutch scarf-cut sealing rings must properly lap or they will not seal. The lap joint must meet head-on and be perfectly aligned. If these seal ends overlap, you get internal leakage.
Reverse Clutch Assembly
Step 1: Install Number-9 Needle Bearing
Install the number-9 needle bearing in the case, using transmission assembly lube. Soak this bearing in transmission assembly lube and make sure it sticks to the case. Make sure it remains centered during installation.
Step 2: Prepare to Assemble Reverse Clutch
This is the reverse clutch drum assembly, including the piston and seals. Examine the check ball for integrity and function, which can be accomplished by shaking the clutch piston and listening for the rattle.
Step 3: Install Reverse Clutch Piston
Install the reverse clutch piston seals using generous amounts of transmission assembly lube. Pay close attention to the seal status. The seal grooves and seals must be hospital clean. Apply uniform pressure to the piston while feeling for a smooth transition.
Step 4: Install Reverse Clutch Piston Snap Ring
The reverse clutch piston snap ring pops into the clutch hub and retains the piston. Check this ring carefully for proper seating. It can pop out if it is not completely seated.
Step 5: Install Belleville Spring and Snap Ring (Critical Inspection)
Inspect the reverse clutch Belleville return spring for cracks and distortion prior to installation. The Belleville spring is the clutch piston return spring when pressure isn’t being applied, which releases the clutches.
Step 6: Install Reverse Clutch Pressure Plate
Install the reverse clutch pressure plate against the Belleville spring. Check the pressure plate for freedom of movement in the clutch drum.
Step 7: Install Reverse Clutch Plates
Lay the clutch discs and plates into the reverse clutch drum. Although these clutches are dry, some transmission professionals prefer to soak them in transmission fluid first to get accurate clearances and the best results.
Step 8: Install Reverse Clutches
The reverse clutch discs alternate with plates. The plates should have been resurfaced or replaced. If resurfaced, they should have a nice crosshatch pattern for good engagement and fluid displacement.
Step 9: Install Reverse Clutch Rear Pressure Plate
Install the reverse clutch pressure plate (rear or outer) while checking all clutches and plates for freedom of movement. Clutch clearances should be .040 to .059 inch. If this cannot be achieved, go with the appropriate retaining ring: .060 to .064, .074 to .078, .088 to .092, or .102 to .106 inch.
Step 10: Install Retaining Ring
The reverse clutch retaining ring is your adjustment for clutch clearances. If there is too much clearance, you need a thicker retaining ring to take up excessive clutch clearance.
Step 11: Install Number-2 Needle Bearing
Lay the number-2 needle bearing in place, using plenty of transmission assembly lube for lubrication and adhesion. The needle bearing, also known as a Torrington bearing, reduces internal rolling and thrust friction.
First Gear in Drive
In first gear, the forward clutch is applied, which ties the primary input shaft to the forward sun gear. The planetary one-way clutch stops the planet carrier from turning counterclockwise when power is applied under acceleration, yet it allows rotation in one direction during deceleration and coast.
First Gear in Manual 1
As in drive range, the forward clutch is applied, tying the input shaft to the forward sun gear. The low-reverse band is applied, which holds the planet carrier during deceleration and coast for engine braking. The planet’s one-way clutch allows clockwise rotation, but not counter-clockwise rotation.
Second Gear in Drive
When the AODE/4R70W shifts into second gear in drive, the for-ward clutch is applied, connecting the input shaft to the forward sun gear. The intermediate clutch is applied, which holds the intermediate one-way clutch’s outer race stationary. The intermediate one-way clutch keeps the reverse clutch drum, shell, and reverse sun gear from rotating counterclockwise when power is being applied (acceleration). The planetary one-way clutch overruns.
Second Gear in Manual
The forward clutch is applied, connecting the input shaft (outer) to the forward sun gear. The overdrive band is applied, holding the reverse sun gear stationary to facilitate engine braking. Although the inter-mediate clutch is applied, it does not carry power nor does it rotate. The planetary one-way clutch overruns.
Third Gear in Drive
In third gear in the drive range, the forward clutch is applied, connecting the input shaft to the forward sun gear. The direct clutch is applied, tying the input shaft to the planet carrier to the smaller inside input shaft (stub shaft). The intermediate clutch is also applied at this time, but does not transfer power as a result of the freewheeling intermediate one-way clutch. The planet’s one-way clutch overruns.
Fourth Gear in Drive (Overdrive)
The direct clutch is now applied, which connects the input shaft to the planet carrier. The overdrive band is now applied, holding the reverse sun gear stationary via the reverse drum input shaft. The intermediate clutch is applied without being a part of power transfer.
Reverse Gear and Neutral
The reverse clutch is applied, connecting the input shaft to the reverse sun gear. The low-reverse band is applied, which holds the planet carrier. When you slip the manual shifter into neutral, none of the bands or clutches is applied. Park gives the same result but also engages the parking pawl.
Internal Components Installation
Step 1: Install Low-Reverse Band
The output shaft and ring gear assembly have been installed along with the planet carrier. The planet carrier splines inside the ring gear with gentle back-and-forth twisting to achieve proper engagement.
Step 2: Assemble and Install Intermediate One-Way Clutch (Documentation Required)
This is the intermediate one-way clutch, which is mounted on the reverse clutch drum, allowing rotation one way but not the other. Take note of how the rollers fit into the cage. Do not get this backward.
Step 3: Install Intermediate One-Way Clutch
This is the intermediate one-way clutch installed. Note the proper installation and how the rollers are located (arrows). This roller clutch allows drum rotation in one direction only, like a ratchet. Be sure to lubricate the rollers generously.
Step 4: Install Planetary Support Assembly
The planetary support assembly fits into the main case. This center support carries the planet carrier. Use plenty of lubrication on the center support bushing.
Step 5: Install Anti-Clunk Spring
The anti-clunk spring (arrow), which prevents the center support from moving and clunking, acts as a shock absorber for the center support. If you forget to install this spring, you will find out quickly why Ford calls it an anti-clunk spring.
Step 6: Install Center Support Retaining Ring
Install the center support retaining ring and check the security of the center support. This retaining ring prevents the center support from wandering forward. Once this ring is seated, check its security.
Step 7: Install Forward Sun Gear
This is the forward sun gear stub shaft, which fits into the heart of the planet carrier. The number-5 needle bearing is already installed here. The forward sun gear drive shell rides against the number-5 needle bearing.
Step 8: Install Forward Sun Gear Drive Shell Stub Shaft
This is the forward sun gear stub shaft splined into the planet carrier with the number-5 needle bearing installed. All bearing surfaces should have been lubricated.
Step 9: Install Forward Sun Gear Drive Shell
The forward sun gear drive shell splines into the planet carrier and stub shaft. Work the sun gear drive shell back and forth to seat.
Step 10: Install Forward Sun Gear Drive Shell (CONTINUED)
This is the for-ward sun gear drive shell installed prior to the number-4 needle bearing placement. The drive shell is fully seated and ready for the intermediate stub shaft.
Step 11: Install Intermediate Stub Shaft
The intermediate stub shaft splines into the planet carrier. This shaft operates inside the outer stub shaft. Twist and wiggle the stub shaft and feel for proper seating.
Step 12: Install Number-4 Thrust Needle Bearing
The number-4 thrust needle bearing installs inside the forward sun gear drive shell. Use plenty of lubrication as a pre-lube and for adhesion.
Step 13: Install Forward Clutch Hub
The forward clutch hub splines onto the outer forward sun shell stub shaft. Apply transmission assembly lube on all contact surfaces.
Step 14: Install Number-3 Thrust Needle Bearing
The number-3 thrust needle bearing installs inside the forward clutch hub. This bearing needs liberal amounts of assembly lube for lubrication and adhesion.
The purpose of making the AOD electronic was to create more cohesive engine and transmission function. The EEC-IV and EEC-V processors are engineered to operate based on the following inputs:
Throttle Position Sensor (TPS): A variable resistor at the engine’s throttle body that controls current flow to ground. It controls spark, fuel, and transmission shift curves based on throttle position and current ﬂ ow.
Mass Airflow (MAF) Sensor: Contributes to engine and transmission control via air ﬂow and variable resistance.
Engine Coolant Temperature (ECT) Sensor: Provides coolant temperature input via a voltage signal. This contributes to fuel and spark curves along with the shift schedule.
Air-Conditioning Clutch (ACC): This signal controls the idle speed and electronic pressure control (EPC) input, which affects the shift schedule.
Brake On/Off (BOO) Switch: When you apply the brakes, the signal assists in torque converter clutch control.
Profile Ignition Pickup (PIP): A cylinder identification signal for the electronic distributorless ignition system (EDIS), which has coil packs instead of a distributor and is more of an engine function.
Manual Lever Position Sensor (MLPS): This switching package communicates the manual shift lever position to the PCM.
Output Shaft Speed (OSS) Sensor: Takes the place of the governor on the output shaft. It does what the governor did hydraulically. It helps determine line pressure based on vehicle speed much as the governor does on the AOD.
Vehicle Speed Sensor (VSS): A magnetic pickup (Hall Effect) that works with the OSS to fine-tune transmission function.
Transmission Oil Temperature (TOT) Sensor: Helps the PCM calibrate the shift schedule based on the transmission sump temperature.
Electronically triggered solenoids are simple electromagnets. They’re either on or off or on/off in a duty-cycle (pulse) pattern.
Electronic Pressure Control (EPC) Solenoid: Your AODE/4R70W’s pace-maker. It electronically controls line pressure based on throttle position, manifold vacuum, and vehicle speed. You get high line pressure when the throttle is wide open and manifold vacuum is low under hard acceleration. At WOT, you want high line pressure for firm clutch and band engagement.
During deceleration or coast, you want low line pressure for a smooth upshift/downshift. You don’t want to feel downshift. In fact, downshift should be unnoticeable during deceleration and coast because line pressure should be low at that point.
Your Ford’s PCM allows a given amount of current ﬂow to and from the EPC solenoid based on driving conditions. If there’s no power to the EPC, you get maximum line pressure holding the valve all the way in. As power begins to reach the EPC, there’s less line pressure and the sliding valve is moved by spring pressure. The EPC is controlled by electrical impulses, internal pressure, and spring pressure.
Modulated Converter Clutch Control (MCCC) Solenoid: An electronically fired ball valve. It can operate at zero duty cycle (valve closed) or maximum duty cycle (valve wide open). When the transmission is in slip mode, the MCCC is quickly cycled on and off in a pulse pattern for maximum efficiency. The MCCC engages and disengages the torque converter clutch.
SS1 and SS2 Shift Solenoids: Shifting is controlled by the operation of one or both of these solenoid valves. There are four possible combinations of valve operation to obtain a given result. The shift solenoids open the shift valves when they receive power. When there is no power, the shift valves are closed. When the solenoids are energized, the valves are open.
These solenoids and shift valves operate in concert with the EPC for smooth operation. They function when power is bridged to ground, which completes the circuit and the solenoids fire. Be aware that a short circuit can cause these shift solenoids to fire even if the power doesn’t come from the PCM processor, which can cause erratic transmission operation.
Internal Components Installation (CONTINUED)
Step 1: Inspect Forward Clutch Assembly
This is the forward clutch with input shaft. Examine the check ball valves for freedom of movement. They should rattle when you shake the clutch and shaft assembly.
Step 2: Assemble Forward
Install the forward clutch piston seals. Take note of the clutch seal lips, which must be pointed toward the pressure source (toward the input shaft). Pressure causes the lip to seal. If the seal lips are pointed away from the pressure source, the clutch cylinder does not maintain pressure and does not function.
Step 3: Lubricate Seals (Important!)
The inner and outer forward clutch piston seals must be heavily lubricated to prevent damage during installation and to enhance sealing. The seal lip should be pointed toward the pressure source (inside the bore). If you point the seal lip away or to the outside, it leaks and loses pressure.
Step 4: Install Forward Clutch Piston (Special Tool)
The forward clutch piston installs using a Lip Wizard. It allows the seals to transition smoothly without binding. Any seal bind is a guaranteed leak. Do a leak check with compressed air.
Step 5: Install Clutch Piston Return Spring
The forward clutch piston return spring is a single spring that returns the piston to rest when pressure isn’t being applied. The spring is compressed to make way for the C-clip retainer.
Step 6: Install C-Clip
Using a spring compressor or C-clamps, compress the forward clutch piston return spring and install the retaining C-clip. Make sure the C-clip is secure before moving on.
Step 7: Install Forward Clutch Steels
Alternate the forward clutch plates with clutch friction discs. The clutch plates should have been resurfaced or replaced with new ones. The plates should have a good crosshatch pattern.
Step 8: Install Forward Clutch Discs
Install the forward clutch frictions alternately between the steels. Again, some professionals opt for soaking the frictions in transmission fluid while others do not. It does affect clearances.
Step 9: Install Pressure Plate and Retaining Ring
The forward clutch friction and steel clearances should be .050 to .089 inch. Ring thicknesses are .060 to .064, .074 to .078, .086 to .092, and .102 to .106 inch.
Step 10: Mate Forward and Reverse Clutches
The forward clutch hub splines into the reverse clutch drum’s clutch frictions. Rock these assemblies back and forth until the forward clutch is completely seated in the reverse clutch drum.
From Electric to Hydraulic
Your Ford’s EEC-IV and EEC-V processor conducts the orchestra that is your AODE/4R70W’s hydraulics. Transmission problems are often perceived as mechanical or hydraulic when they are actually electrical issues that adversely affect the hydromechanical parts. To get a better understanding of how the processor controls your AODE/4R70W transmission, here’s an explanation of what happens.
First Gear in Drive
In first gear in the drive range, the SS1 is on and the SS2 is off. The MCCC is off (on the torque converter, no lockup). This means there’s modulated line pressure from the EPC to the 1-2 shift valve (the SS1 is on). It also means there’s no pressure to the intermediate clutch pack. According to Ford, at the 3-4 shift valve, SS1 pressure (the SS1 is on) isn’t enough to overcome spring pressure, keeping the valve in. With this sequence of events, pressure goes to the forward clutch pack through the orifice control valve and the 2-3 backout valve.
First Gear in Manual 1
In first gear in manual 1, you get much the same scenario with the SS1 on and the SS2 off; the MLPS indicates the driver has chosen manual 1, which prevents the SS1 from being disabled. This keeps the transmission in first gear. The MCCC is off.
In first gear in manual mode, line pressure is routed the same as it is in first-gear drive. The difference is the SS1 function. The SS1 stays on, keeping the transmission in first gear. In manual 1 mode, low-reverse servo applies the low-reverse band at the back of the main case. Servo apply pressure is controlled by the low servo modulator valve.
If you have a malfunction in manual 1, check for power to the SS1 solenoid. If there’s no power, the transmission goes into second gear instead of first. If you have no engine braking in manual 1, the problem isn’t electronic. Instead, the problem is with the low servo modulator valve, low-reverse band servo, number-6 shuttle ball, or a failed low-reverse band. Begin your troubleshooting with electronics, then mechanicals.
Second Gear in Drive
In second gear in drive range, both the SS1 and SS2 are off. The MCCC is controlled by the PCM. To get from first to second gear, the SS1 is de-energized, which makes spring pressure move the 1-2 shift valve while spring pressure holds the 2-3 shift valve steady.
Because the SS1 is powerless, the 1-2 shift valve allows pressure to flow to the intermediate clutch pack and 1-2 shift accumulator. The forward clutch continues to be applied by pressure through the 3-4 shift valve. Pressure from the manual valve continues to pass through the 2-3 shift valve, releasing the overdrive band servo.
Second Gear in Manual
In second gear in manual range, both the SS1 and SS2 are off. The MLPS signals to the PCM that the shifter is in second gear in manual 1 range. The converter clutch control solenoid is then controlled by the PCM.
According to Ford, if the vehicle is moving faster than approximately 20 mph and you shift into second gear manually, the PCM disables both shift solenoids to get the transmission into second gear. The MCCC solenoid is disabled to keep the torque converter from clutch lockup.
The ﬂuid pressure is the same as second gear in drive range. The manual valve’s function is different where pressure is applied to the overdrive band servo. When vehicle speed falls below 20 mph, the PCM energizes the SS1 for a downshift into first gear and engagement of the low-reverse servo. If the SS1 solenoid remains energized or the 1-2 shift valve sticks, you don’t get a 1-2 upshift.
Ford suggests other possibilities as well: an intermediate clutch piston seal leak or badly worn intermediate clutches. Another possibility is a leaking 1-2 accumulator cover or piston seal. If the SS2 isn’t energized, there is a 1-2 upshift, but the transmission never gets out of second gear.
Third Gear in Drive (Overdrive)
In third gear in overdrive range, the SS1 is off and the SS2 is on. The MCCC gets pulsing signals from the PCM. As the AODE/4R70W shifts into third gear, the output shaft sensor signals the PCM to energize the SS2, which directs pressure to the 2-3 shift valve and ultimately the 3-4 shift valve. The 2-3 shift valve moves under pressure against spring pressure. The 1-2 shift valve remains as is. Pressure ﬂows to the direct clutch and the 2-3 accumulator through the 2-3 backout valve. Pressure all by itself doesn’t move the 3-4 upshift valve. As a result, Ford engineers added a spring to give the 3-4 shift valve a helping hand. The 2-3 back-out valve, as the name implies, regulates the feel of a 2-3 upshift. With light throttle pressure, the 2-3 back-out valve applies ﬂuid under pressure via an orifice. Put the pedal to the metal and ﬂuid under pressure ﬂows through a different orifice to apply greater pressure.
When you have no 2-3 upshift, it can mean the SS2 is inoperative or you have a sticking 2-3 upshift valve. Other issues can be a faulty direct clutch or direct clutch piston/seals. If you get a harsh 2-3 upshift, the problem is likely the 2-3 accumulator or excessive line pressure.
Internal Components Installation (CONTINUED)
Step 1: Install Forward and Reverse Clutch Assembly
The forward and reverse clutch assembly installs in the main case. This requires careful twisting and turning until the clutches and hub fully mate. Also install the input shaft sealing rings at this time.
Step 2: Install Overdrive Band
Install a new overdrive band and anchor it to the pin. Line it up for the overdrive band servo piston. Double-check the security of the band at the servo and anchor pins.
Step 3: Prep Overdrive Band Servo Piston
Prepare a new overdrive band servo piston for installation with generous amounts of transmission assembly lube. Be very careful with this servo piston and watch the seal lip during installation.
Step 4: Install Overdrive Band Servo Piston (Special Tool)
This home garage servo piston installation tool consists of a 7/8-inch box-end wrench and shallow socket, large flat washer, and an appropriate-size bolt. Use a little leverage to install the snap ring. You may also use the Ford tool (PN T92P-70023-A).
Step 5: Check Band Anchor and Servo Pin Alignment
Look through the front of the case and observe the over-drive band anchor and servo piston pin alignment. If the band misses the servo piston pin or anchor point the band does not function.
Step 6: Stack Intermediate Clutch Steels and Frictions
The intermediate clutch discs and plates stack up like this. Begin with a plate and alternately stack clutch discs and plates. Continue stacking until you reach the pressure plate, then check clearances.
Step 7: Install Top Clutch Plate
Once you have established the intermediate clutch clearances, which are 1.634 to 1.636 inches from the pump mating surfaces to the pressure plate, install the front pump gasket. Adjust clearance via the clutch plates, which are .071 to .067, .081 to .077, .091 to .087, or .101 to .097 inch, using a depth micrometer. The top clutch plate should be your plate.
Step 8: Install Front Pump Gasket
The front pump gasket has been located and all passages and bolt holes checked for proper alignment. Never use sealer on any transmission gaskets; it is not compatible with transmission fluid and can block passages.
Fourth Gear in Overdrive
Fourth gear in overdrive range has both the SS1 and SS2 on. The MCCC again gets pulses from the PCM tied to driving conditions. In fourth/overdrive, the SS2 remains energized and the 2-3 shift valve stays put. This allows for a pressure path to the direct clutch (engaged). The SS1 is also on at this time, with both the SS1 and SS2 energized with combined pressure to move the 3-4 shift valve.
Because the 3-4 shift valve has moved, there is no ﬂuid pressure to the forward clutch. Pressure is instead directed to the overdrive servo regulator valve. This allows full pressure to the overdrive servo and band. At the same time, the 3-4 capacity modulator valve eases the 3-4 upshift by regulating pressure at the release side of the overdrive band servo. The forward clutch release pressure unseats the valve body’s number-2 check ball (WOT) or through to the FC34 ﬂuid circuit (light or no throttle), which depends on 2-3 backout valve position.
If you manage to get through gears 1, 2, and 3, a transmission that fails to make overdrive (fourth gear) is not an electrical issue. If your AODE/4R70W experiences no 3-4 upshift, it is a sticking 3-4 shift valve, overdrive servo issue, or a failed overdrive band. Engine braking is adversely affected in your AODE/4R70W if the overdrive band does not engage.
In reverse, the SS1 is on and the SS2 is off. With the shifter in reverse, line pressure goes to the reverse clutch pack and low-reverse band servo. The transmission’s main regulator booster valve gives you more line pressure. Because the reverse clutch pack is engaged only in reverse, you’re looking at only the reverse clutch or the reverse ﬂuid circuit in the valve body when there’s a malfunction.
Torque Converter Clutch
And finally, torque converter clutch function can be full on, full off, or a smooth engagement, which is controlled by the MCCC. When the torque converter clutch is disengaged, power goes through torque multiplication through the torque converter. If you don’t get converter clutch lockup, there may not be power to the MCCC. Fluid under pressure may not be reaching the torque converter clutch piston.
Internal Components Installation (CONTINUED)
Step 1: Replace Front Pump Bushing
Replace the front pump bushing by pressing out the old bushing and installing the new one. Use a bushing driver of the correct size and a press. If you don’t have a press, just about any machine shop has one.
Step 2: Install Front Pump Seal
Using a press and a seal driver, install the new front pump seal using a thin film of Permatex’ The Right Stuff around the seal’s outside perimeter and gently press into place. Generously lubricate the seal lip with assembly lube.
Step 3: Install Intermediate Clutch Piston Seals
As you install the new intermediate clutch piston seals, keep in mind the seal lips must point toward the pressure source or inside the pump housing bore. Pressure against the seal lip is self-sealing and fail-safe. If you point the seal lip toward the intermediate clutches, you will have an internal hydraulic leak and no intermediate clutch function.
Step 4: Install Front Pump Perimeter Seal
The AODE/4R70W has two forms of front pump sealing: a gasket and a seal to prevent leakage. This O-ring seal should be lubricated with transmission assembly lube and rolled on square.
Step 5: Install Intermediate Clutch Piston
The thing that makes the AOD family different from most Ford automatics is a clutch servo piston and bore in the front pump. Install the intermediate clutch servo piston in the front pump. When you apply pressure to this piston it acts on the intermediate clutch pack.
Step 6: Install Clutch Piston (Special Tool)
Use a seal protection tool to install the intermediate clutch piston installation. Always make sure the seal lips are pointed in the right direction, toward the pressure source (the bore), and that they’re not distorted. If the seal lip is pointed away from the bore, it does not hold pressure and the servo piston does not function.
Step 7: Examine Intermediate Clutch Pressure Plate
Inspect the intermediate clutch pressure plate for spring integrity and inventory. There should be nine springs in serviceable condition free of distortion. Because these springs are attached to the pressure plate, they should all be present and in serviceable condition.
Step 8: Install Intermediate Clutch Pressure Plate
Check for proper spring alignment and positioning. Check this pressure plate for freedom of movement before installing the pump.
Step 9: Check Pump Rotor Side Clearances
The AODE/4R70W transmission has a high-efficiency front pump for improved volume. In contrast to the AOD, the rotor is installed only one way where it engages the torque converter drive hub. Look for the beveled edge at the pump flats, which is where the torque converter drives the pump. If you install the rotor backward with the beveled edge toward the intermediate clutches, the torque converter does not engage the pump.
Step 10: Pack Pump Rotor Cavity with Assembly Lube (Professional Mechanic Tip)
Because you want immediate fluid flow when the engine is fired, pack the pump with assembly lube and transmission fluid for a good prime. You also want to service the torque converter (not shown) with 2 quarts of transmission fluid, which helps prime the pump.
Step 11: Install Front Pump Sealing Rings
These are the front pump stator support iron sealing rings, which are like piston rings in an engine. Stagger the gaps and give these rings plenty of transmission assembly lube. Staggering the gaps helps the sealing rings hold pressure.
Step 12: Assemble Pump Halves
Make sure all holes line up, then mate and secure the pump halves. Before mating them, make sure all contact surfaces are clean. Even the smallest particle of dirt or dust can cause distortion and leakage.
Step 13: Install Bolts and Torque to Spec (Torque Fasteners)
Install the bolts with lubricated threads and torque the bolts to 15 to 19 ft-lbs in a crisscross fashion for uniform tightening. Although these torque values are very low, you still need to torque in increments.
Step 14: Inspect Pump Stator Support Sealing Ring Gaps
Examine the pump stator support ring end gaps and position them at 45-degree increments. Staggering these gaps helps contain line pressure at the source. These sealing rings must be well lubricated for pump installation.
Step 15: Install Thrust Washer
Use assembly lube as an adhesive to install the thrust washer. This is the natural color version (.085 to .089 inch). The other four thickness options are green (.050 to .054 inch), yellow (.068 to .072 inch), red (.102 to .106 inch), and blue (.119 to .123 inch).
Step 16: Compare Main Case and Pump Passages
There is only one way to install the front pump. Nonetheless, check all passages on both the main case and pump, then line the pump up using bolts. Lubricate the bolt threads and check the bolt travel. If you encounter any binding, chase the threads and remove the debris.
Step 17: Install Front Pump Assembly
Fit the front pump, then slowly run the bolts down and pull the pump tight. Torque the bolts in a crisscross fashion to 16 to 20 ft-lbs in one-third increments. This allows for proper seating and prevents warping.
Building an AODE/4R70W
Assembly should always begin with all subassemblies until you have a complete geartrain ready to install. Gather all parts on a hospital-clean work surface and organize them into groups of unassembled subassemblies that make up the various components.
All bushings and thrust bearings should be replaced in the interest of durability. Never reuse old bearings or seals. Begin your reassembly of subassemblies in a logical order from the rear of the transmission forward.
Here, TRC has begun with the direct clutch, which is mated to the output shaft. The AODE/4R70W direct clutch is a stronger stamped steel with more clutch surface area for durability and power transfer. The direct clutch should be fitted with new steels and frictions. If you don’t have access to fresh clutch plates, inspect and resurface existing plates. If they are heat cracked or bluish, do not reuse them.
Each transmission build shop has its own approach to assembly. TRC installs frictions dry. Others install them wet. Wet frictions allow for more accurate clearances during assembly. Seals and thrusts should be installed wet with transmission assembly lube, though not all shops do it this way.
Closely inspect all hard parts for scoring and cracking. Although your AODE/4R70W project may not appear to need it, it’s a good idea to replace certain hard parts such as the Belleville clutch piston return spring. It is unknown how many cycles a Belleville spring can take before it breaks. However, for the sake of longevity, replace yours.
Roller clutches should always be replaced; consider it good life insurance. Rollers become pitted, and this isn’t always visible. Cages become damaged and at times this is even harder to see. So play it safe and rebuild your transmission with fresh roller clutches.
While you’re building subassemblies, closely inspect planet gears and bushings for abnormal wear and scoring. Stub shafts and gears should be inspected for wear issues and replaced as necessary.
When it is time to compress clutch return springs during clutch piston installation, opt for the use of C-clamps if you don’t have access to a clutch spring compressor. As you mate clutch assemblies, ensure complete mating and seating before loading each assembly into the case.
Band assemblies, such as clutches, can be installed wet or dry. Installing them wet gives them a good start against freshly resurfaced clutch drums. Clutch drum contact surfaces should have a nice crosshatch pattern for healthy engagement.
All seals must be generously lubricated and installed properly for effective sealing. A seal lip pointed the wrong way is a guaranteed leaker. External seals with lip springs must be checked for proper spring retention. If the spring is missing and cannot be found, replace the seal.
Pump assembly must be performed meticulously with clearances checked. If there are no serious signs of rotor or cavity wear, the pump can be returned to service. Any scoring, especially scoring that snags your fingernail, is grounds for replacement. Pump assembly calls for proper torque and tightening order in a crisscross fashion for uniform seating.
Internal Components Installation (CONTINUED)
Step 1: Install Low-Reverse Band Servo Piston Return Spring
Install the low-reverse band servo piston return spring. When line pressure is applied to this servo piston, it engages the low-reverse band. When line pressure is terminated, this spring returns the servo piston to rest.
Step 2: Install Low-Reverse Servo Piston Cover
Install the low-reverse servo cover and snap ring. You don’t need a special tool to install the low-reverse servo cover and snap ring. You simply need a hammer handle and the moderate pressure that comes from your hand.
Step 3: Install 2-3 Accumulator Piston and Spring
The 2-3 shift accumulator assembly contains and builds pressure for a firmer 2-3 upshift. This installs exactly as you see here with a cover and C-clip.
Step 4: Install 2-3 Shift Accumulator
The 2-3 shift accumulator drops into its cavity. Make sure you have plenty of lube and smooth piston travel. Spring pressure here determines shift firmness.
Step 5: Install 1-2 Shift Accumulator
This is the 1-2 shift accumulator, which also stores pressure for a more solid upshift. Generously lube this assembly and install it, along with the cover. During installation, watch the seals and protect them from distortion.
Step 6: Install 1-2 Shift Accumulator (CONTINUED)
This cover contains line pressure at the 1-2 shift accumulator.
Step 7: Install Electronic Pressure Control Solenoid (Important!)
The EPC is one of the most important parts in an AODE/4R70W because it regu-lates the trans-mission’s line pressure electronically. Not enough line pressure and you get slippage. Too much line pressure and you can break the transmission case.
Step 8: Replace Shaft Seal and Install Manual Shift Linkage
Always replace the manual shift shaft seal while you have the transmission apart. Use plenty of lubrication, then drive the seal in. Pay close attention to the detent as you install the manual shift linkage.
Step 1: Inspect Valve Body
Examine all valve body passages, valves, and springs for obstructions or binding issues. Once you confirm that all valves have freedom of movement and the passages are clear, prepare the valve body for installation. Air pressure should be applied to serve as a valve function check.
Step 2: Install Valve Body
Position the valve body gasket and install the valve body with all 22 Metric bolts checked and in place. Torque the bolts in a strict pattern to prevent warping. The main control pilot bolts receive 140 to 160 in-lbs (not ft-lbs). Attachment bolts receive 80 to 100 in-lbs (not ft-lbs). Torque the bolts gently in one-third increments, from the inside out. Then re-torque them for a final check.
Step 3: Install Manual Shift Linkage and Manual Valve
The manual shift linkage and manual valve line up like this. Park is the last manual detent when the linkage is full forward. The MLPS is outside and is tied to the manual shift linkage. It has three alignment holes (slots). When they are lined up, torque bolts to 62 to 88 in/lbs (not ft-lbs).
Step 4: Inspect Solenoids
The standalone solenoid is for torque converter lockup via solid input or pulsing (duty cycle). The twin solenoids are shift solenoids that are on/off only with either each on or both on, depending on the shift timing.
Step 5: Install Harness
This is the solid-state wiring harness for the AODE/4R70W, which is tied to the plug-and-play external harness that leads to the two shift solenoids, the converter clutch solenoid, and the EPC solenoid. The harness protects the wiring.
Step 6: Install Filter Assembly
The transmission filter on the AODE/4R70W is a press-in type with a rubber grommet and requires no tools. Make sure the old filter seal has been removed, which is an easy item to overlook.
Step 7: Install Output Shaft Extension Housing Bushing
The extension housing received a new bushing. This drain hole must be at 6 o’clock. Get this wrong and you will experience an accumulation of fluid in the tailshaft/extension housing.
Step 8: Install Extension Housing Output Shaft Seal
After you add liberal lubrication to the output shaft seal, press it in. Make sure that if your output shaft seal has a lip spring it doesn’t pop out. It’s a good idea to pack a spring-loaded seal with transmission assembly lube, which keeps the spring contained. Lose the spring and you will have slip-yoke leakage.
Step 9: Install Housing Gasket (Performance Tip)
The extension housing gets this silicone-lined gasket on the extension housing prevents leaks. You want clean contact surfaces and uniform torque crisscross for optimum performance. Torque the gasket bolts to 107 to 132 in-lbs, not ft-lbs. Torque the extension housing bolts to 16 to 20 ft-lbs.
Troubleshooting the AODE/ 4R70W begins with ascertaining the problem. Did it come on all at once or did it arrive gradually? Does it happen in one gear range or in all? Did the problem arise after transmission service or part replacement?
Ford recommends the following steps when troubleshooting:
- Verify the problem (what is it doing?).
- Check the vehicle (visually inspect the vehicle).
- Perform a function check (test-drive).
- Review service information such as Technical Service Bulletins (TSB).
- Diagnose the problem (accurately diagnose).
- Repair and verify the repair/correction.
Ford also recommends performing your troubleshooting step-by-step so you never miss a critical step that could lead you right to the problem. Do not take shortcuts. Begin with the simplest, most commonsense issues. Ford recommends the following, which can be performed with the transmission in the vehicle:
- Check for leaks.
- Focus on any electronic add-on components.
- Are there any vehicle modifications?
- Is the shift linkage properly adjusted?
- When does the malfunction happen?
Pull the dipstick and check the ﬂuid condition and level. The ﬂuid color should be reddish-pink. If it is brown or otherwise dark in color that is a clue. Darkness indicates contamination and overheating. It means you have friction material in the ﬂuid as well as burned ﬂuid from slippage and overheating. The ﬂuid condition is your first indication of transmission health. When you check the transmission ﬂuid , it should be checked with the engine running at operating temperature (150 to 170 degrees F).
Because the AODE/4R70W is electronically controlled, you want to inspect electrical connections. Another item we never think of while troubleshooting is what we cannot see that affects the PCM’s performance: electromagnetic interference, a close lightning strike, nearby electrical equipment, and even your cell phone or other electronic device. Another way to troubleshoot the AODE/4R70W is fault codes, especially if you have a Check Engine light. Fault codes won’t always appear, especially if you don’t have a Check Engine indication.
Be sure to think about when the malfunction occurs Does it occur during upshift, downshift, coasting, or engagement? Is it a noise or vibration? Is the noise or vibration in rhythm with the engine, driveline, or wheels? Does the engine stall when the transmission selector is placed in gear? What is the engine idle speed? Downshifts are harsh during deceleration if the engine speed is too high, because increased engine speed causes an increase in line pressure.
If you place the selector into gear and there is no engagement in any gear, the first thing you need to do is check the ﬂuid level. If the ﬂuid level is normal and the ﬂuid color is good, the next item to check is the line pressure via the main pressure port. Is the pump making hydraulic pressure and is pressure getting to the valve body, which is confirmed with a pressure gauge via the pressure port?
While you’re at it, check the manual shift linkage and manual shift valve. Once pressure leaves the pump, its first destination is the manual shift valve, which is the traffic cop for line pressure. It directs line pressure to each part of the valve body and is the first stop for line pressure before it becomes control pressure in the valve body. Ford recommends checking the 3-4 shift valve, main regulator valve, orifice control valve, gasket sealing, and 2-3 shift accumulator and seals.
Can’t get reverse gear? Check the ﬂuid level and line pressure. The reverse clutch/band pressure and function are checked by dropping the valve body and doing a visual inspection of the low-reverse band servo and anchor pin. It can also mean reverse clutch piston seal problems.
Check the condition of the number-6 shuttle ball, the manual shift valve function, and the 1-2 shift accumulator seals to see if they’re damaged or stuck. Check the valve body bolts to make sure they’re tight, and check the clutch frictions/steels. All of these items are checked by dropping the valve body and visually inspecting them.
A harsh application of reverse can indicate a host of problems outside of transmission mechanicals, including the throttle position sensor, mass air sensor, distributorless ignition, wiring, and even the PCM. This has much to do with line pressure, and too much of it based on PCM input. Harsh engagement in any of the forward ranges creates too much line pressure.
Weak or soft engagement in any gear indicates insufficient line pressure from the source or leakage at clutch pistons or band servos. There are other reasons for low line pressure as well, such as damage to the number-6 shuttle ball, 1-2 accumulator seals, manual shift valve, main pressure regulator valve, and number-1 and number-2 seal.
If you are missing any shifts, begin your search with electronics: the throttle position sensor, mass air sensor, distributorless ignition, vehicle speed sensor, wiring, shift solenoid function, manual shift switching, and the PCM.
Is the torque converter doing its job? Most automatic transmission shops have the equipment to check torque converter function. The transmission must be removed to check torque converter function.
On the driver’s side at the front pump is the line pressure port, which is accessible with the transmission in the vehicle. Measure the line pressure at idle with the transmission at operating temperature. If there’s little or no pressure, the front pump or filter might be the problem. Remove the pan and inspect the filter. If the ﬂuid and filter are clean, the pump and pressure relief are the next order of business.
Begin the pump inspection by verifying the bolts are torqued correctly and the stator support is secure. In other words, are the two pump halves securely tightened?
The next items to check are the number-3 and number-4 sealing rings. The gaskets and seals are also potential leak and pressure-loss points.
An AODE/4R70W not going into gear could mean problems with the forward clutch piston sealing and check balls. Yet another issue could be the low-reverse one-way clutch.
Written by George Reid and Posted with Permission of CarTechBooks
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