The Automatic Transmissions Put in Ford Mustangs

The Ford Mustang’s legacy is rich with tales of pavement-pounding performance and rampant on-track success. Behind these triumphs are numerous factors, many of which center around the proactive engineering employed in the design of each particular Mustang. In fact, during its 60-plus year tenure, the Mustang has come equipped with a number of highly desirable drivetrain packages.

Of these individual drivetrains packages, few components are as highly valuable, yet as often overlooked as the automatic transmission. The following is a brief guide to Mustang automatic transmission usage, as listed in chronological order.

1965-1986: C4/C5 Transmission

The C4 automatic was one of the first transmissions to be offered upon the Mustang’s release in 1964/1965. At the time, the C4 was often referred to as the Dual-Range Cruise-O-Matic. The C4 served as the eventual replacement of Ford’s primitive Ford-O-Matic Transmission. In general, the C4 was a longitudinal three-speed transmission, featuring a Simpson planetary gear set.

Ford’s C4 automatic transmission underwent a number of design changes throughout the years. This most notably included the change from a 24-spline to 26-spline input shaft, thereby significantly increasing durability. Eventually, the C4 was phased out in favor of a new C5 Automatic, which was essentially little more than a C4 transmission with a locking torque converter.

By the mid-1980s, even the C5 was discontinued in favor of Ford’s AOD/AOD-E automatic.

1984-1995: AOD/AOD-E Transmission

As of the mid-1980s, the Mustang came equipped with Ford’s all-new AOD transmission. This served as the latest in a long line of auto transmission development, ultimately enhancing the Mustang’s reliability as a whole. The AOD automatic transmission was of a four-gear configuration, the last of which served as overdrive, providing greater top-end performance.

While Ford’s AOD 4-speed automatic underwent a number of design changes throughout the years, none were as significant as the implementation of electronic control. The use of such controls allowed the AOD’s shift points to be varied under a wide range of operating conditions. Transmissions utilizing such technology received the AOD-E designation during the early to mid-1990s.

The AOD-E 4-speed was ultimately dropped from production in 1996, making way for the use of Ford’s 4R70W/4R75W class automatics.

1996-2004: 4R70W/4R75W Transmission

Initially released in 1996, the 4R70W automatic served as a redesigned version of the prior AOD-E, complete with a wide ratio gear set. Like the AOD-E before it, the 4R70W was also of a 4-speed configuration, with the fourth of these providing overdrive. In 1998, the 4R70W’s one-way clutch was replaced with a mechanical diode for enhanced reliability.

Then, in 2003, Ford introduced the 4R75W, which provided vast updates over the prior 4R70W. Some of the most notable of these updates included the installation of a revised planetary gear ring, a new front pump, and an upgraded intermediate clutch. The 4R75W also came equipped with a vehicle speed sensor and output shaft speed sensor.

The 4R75W would remain in production until 2005, at which time Ford’s 5R55S would be introduced.

2005-10: 5R55S Transmission

The 2005 Mustang came equipped with Ford’s newly introduced 5R55S automatic, which utilized 5 forward gears, as well as reverse. In fact, the 5R55S was directly derived from the 5R55SE, the first domestically-offer 5-speed automatic. Additionally, the 5R55S utilized an aluminum case, in a bid to reduce its overall service weight.

While the 5R55S proved outwardly reliable, it did possess a couple of known failure points, the most common of which was overdrive servo bore wear. Torque converter clutch modulator bore wear was also a point of concern. Those intending to hit the track often outfitted their 5R55S automatics with higher stall torque converters.

The 5T55S automatic’s production run was relatively short-lived, lasting only until 2010, at which time the 6R80 was placed into production.

2011-17: 6R80 Transmission

The 6R80 is often regarded as one of the most reliable and bullet-proof transmissions ever produced by the Ford Motor Company. In fact, many drag racers still rely heavily upon Coyote V8-equipped Mustangs, backed by the 6R80. The 6R80 itself was of a 6-speed configuration and featured a lightweight aluminum case.

Of additional note, the 6R80, like the 5R55S before it, did not have a traditional dipstick like prior Mustang transmissions. However, some consumers opted for the addition of an aftermarket transmission pan that included a distinct port. Additionally, those interested in high-performance applications often prioritized the purchase and installation of an aftermarket transmission oil cooler.

Finally, in 2018, the 6R80 was discontinued in favor of the 10R80, which is still in production today.

2018-Present: 10R80 Transmission

The 10R80 serves as proof positive that even in heated competition, the auto industry’s top manufacturers can come together for a good cause. This remarkable automatic transmission was pioneered during a joint venture between Ford and Chevrolet in 2013. Utilizing 10 forward gears, the 10R80 is capable of lightning-quick, yet extremely smooth shifts.

Quite ironically, the Mustang was found to be even quicker when equipped with the 10R80 automatic, rather than the make’s standard 6-speed manual. The 10R80 is also known for its compact and lightweight design, especially when considering its 10-speed layout.

This reduction in size and weight was accomplished by a number of means, including the installation of two hydraulic pumps for internal clutch operation, which proves rather conservative in the consumption of space.

Ford’s 10R80 automatic is still in use today and is widely utilized in a number of vehicles outside of the Mustang line.