History of the Ford AODE
The Ford Motor Company developed and manufactured the Automatic Overdrive (AOD) transmission in 1980. Based on Ford X transmission the Ford AOD contained 3 forward gears with an additional overdrive gear.
Due to the recession in the late 70’s and the sharp rise of oil prices around that time, car buyers were looking for more fuel-efficient vehicles. Hence, the AOD transmission was a key part to making Ford’s vehicles more fuel efficient. As you’ll see, it came with a lot of new features and design improvements to save fuel, yet deliver impressive performance.
At the beginning of the 1980’s, the AOD was widely implemented in Ford sedans like the Mustang, Fairmont and LTD due its lighter weight and ability to handle copious amounts of torque and horsepower.
In 1990, Ford introduced the AODE with electronic controls. The electronic control unit
solved many issues with the older AOD and this made its entire operation more efficient as well.
In 1993, Ford upgraded the AODE and gave it a new name: the 4R70W. It was very similar to the AODE with improvements such as the use of lighter materials, as well as a new-and-improved valve body with computer-controlled solenoid packages.
The 4R75W models introduced from 2005 onwards, contained improved internals to handle more torque. It had a different torque converter to improve launch as well as a quicker and more precise electronic control system.
The original AOD design made a big impact when it was first released, and its success kept it evolving and being manufactured in a range of variations and models for over 25 years. The entire AODE, 4R70W and 4R75W range is one of the most popular transmissions ever made by Ford.
Specifications of the AODE, 4R70W/E and 4R75W/E
The AODE, 4R70W, 4R75W are very popular for muscle cars but also suitable for many other types of sedans, due to its size and ability to handle lots of horsepower and torque.
The maximum recommended horsepower the AODE can handle is about 450hp. A well-built 4R70W or 4R75W, could handle over 575hp but that would be on the borderline. Anything more is possible, however that would require the internals to be significantly upgraded.
The AODEs and 4R70Ws come in two case sizes. 3.8L, 4.2L and 5.0L engines use one case size, whilst the 4.6L and 5.4L engines use a different size.
The 4R70W and 4R75W names tells us a bit about the transmission. 4 refers to 4 forward gear ratios, R refers to rear wheel drive and the number at the end refers to the max input torque it can handle.
For instance, 70 in the 4R70W corresponds to 70X10 = 700Nm (516 ft-lb)
of max input torque. The W at the end signifies wide-ratio transmission, whilst the E on some models of the 4R70W and 4R75W refers to the upgraded electronic controls. The E models have a turbine speed sensor for detecting the torque converter slip, which helps fine-tune shift speed and feel.
Until 2001, the AOD and 4R70W had only one output speed sensor. Then in 2001, the design for the speed sensor was changed. Also added was an input speed sensor along with a different valve body. Once the 4R75W was introduced in 2003, it had even stronger parts, allowing it to handle more torque and horsepower..
Gear Ratios of AODE, 4R70W and 4R75W
4R70W and 4R75W
Strengths of the AODE, 4R70 and 4R75
The biggest strengths with the AODE range of transmissions are its ability to handle lots of power, while being lightweight and efficient. The 4R70W and 4R75W in particular are much better for higher speeds and high torque applications due to its stronger gear set and output shaft. Their lower gear ratio also provides better acceleration.
The lock up torque converter clutch gets activated in 3 rd or 4th gear, and this transmits more power to the rear wheels at higher speeds and full throttle. As it provides a direct drive from the engine to the drivetrain, it eliminates rotational losses of the torque converter, allowing lower engine revs to be used at cruising speeds, helping improve fuel efficiency.
Common Problems / Weaknesses with the AODE, 4R70W, 4R75W
The AODE, 4R70W and 4R75W while similar in design and concept, have various differences. Each newer model usually improved upon and addressed the most common problems of its predecessor.
The transmission mostly suffers from problems due to worn internals. A lot of these issues can be solved by doing an inexpensive rebuild with specific upgrades and modifications, as well as by precisely calibrating the shift strategy.
Here are some common problems seen throughout the years in the various versions of the transmissions:
The AODE is known to have a weak inner input shaft which can fail when subject to higher torque. Other than the input shaft, the internal components are weaker and aren’t able to handle as much horsepower and torque as the 4R70W or 4R75W.
Shift problems between 1 st and 2nd gear:
These two gears usually tend to have more issues than the other gears. The problem could be a shudder, no shift or a very late up-shift. This is often caused by the accumulator rubber O-ring wearing out and causing a leak.
Torque Converter Shudders:
This can happen with all the transmissions from the AODE to 4R75W. This often happens due to transmission fluid breakdown. When used over a long period or when the temperatures get too hot, the transmission fluid can thicken up and cause poor lubrication. This problem will start to become more obvious in 3 rd and 4th (OD) gear. Adding a transmission cooler or changing to a different type of transmission fluid might solve the issue.
Popular Custom Vehicles that use the AODE, 4R70W and 4R75W
Being designed and built by Ford, it’s no surprise the AODE series is mostly fitted into Ford vehicles such as the Ford Mustang and Thunderbird. The Lincoln Motor Company (owned by Ford) also uses the AODE series in the Lincoln Town Car and Lincoln Mark VIII.
As the AOD was first built to replace the C4 and FMX transmissions older and classic Fords like the Fairlane and Mustangs from the 60s onwards can work well with the AODE.
Because the gear ratio and power capability of the 4R70/75W is similar to the C6 transmission, vehicles that came with the C6 transmission like the older Ford Bronco SUV and Ford F-150 truck could be upgraded to a 4R70/75W transmission.
A 2004 Ford F-150
A 1964 Ford Fairlane
Controlling the Ford AODE, 4R70W and 4R75W with the COMPUSHIFT Transmission Controller
Being able to control a transmission, especially if you’re an enthusiast is a great feeling and in certain applications like racing, it’s essential that you can control the shifts and lockup torque converter when you want to. For any custom build, it’s almost mandatory that you have a transmission controller with a well-turned shift strategy.
As the AODE has been through a lot of changes over 25 years, you’ll have to consider the various differences between transmissions.
Most importantly, when purchasing the wiring loom, you need to make sure the connector is compatible with your transmission. The early/older connector is a little oval shaped with rounded edges, whilst the late connector is rectangular. They are not interchangeable. See the website for pictures.
After setting up the wiring loom, the sensors, paddle shifters (optional) and display (optional) you can calibrate the shift strategy of the COMPUSHIFT via the free to download app which links to the controller via Bluetooth.