Switching gears via a manual transmission is not for everyone. That is why an automatic transmission is a popular option in late model Mustangs. The automatic transmissions used in the latest model Mustangs are much more sophisticated. In many cases, they can even outperform their older siblings when compared stock to stock form.
In an age where automatic transmissions can shift just as fast as their manual transmission counterparts and often improve overall performance and reliability, it is understandable to see so many car manufacturers dropping manual transmissions in exchange for automatic transmissions.
1979 to current Mustangs have seen a wide variety of automatic transmissions in their days. Early on the Fox Body Mustang was powered by C4 & AOD automatic transmissions. These transmission were the foundation for the future AOD-E and 4R70W transmission that powered the SN95 and New Edge Mustangs. In the 2005 Mustang, we saw the first step toward more fuel-efficient and durable auto trans with the 5R55S transmission. The latest model S197 Mustang featured an automatic transmission with more gears for improved performance and fuel efficiency. The 5.0L Coyote engine Mustangs feature the 6R80 transmission that has been known to outperform the manual transmissions with some simple mods.
Below you will find some detailed information on each automatic transmission that has been seen in 1979 to current Stangs. I went ahead and threw in some useful tech tips to help you maximize the performance and maintenance of your auto trans!
Ford’s C4 transmission has been in service since 1964. The SelectShift transmission was featured on the 79 5.0L and 80-81 4.2L V8. In 1982, the 4.2L V8 was backed up by a C5. The C5 transmission is an upgraded C4 with the most notable difference being its configuration for use with a lock-up style torque converter.
The C4/C5 provides 3 forward gears, along with reverse, and has manual gear selection capability. When placed in the “D” position, upshifts and downshifts are performed automatically without driver input. These transmissions were fairly dependable and offered no unique service challenges. For performance use, an upgraded external fluid cooler is highly recommended.
The Automatic Overdrive or AOD transmission made its Mustang debut in 1984 behind the CFI equipped 5.0L Fox Body and was also available in this configuration in 1985. 1986 saw the AOD behind the SEFI 5.0L H.O.
In 1988 a rear lubrication system was integrated to extend service life. 1989 received a larger overdrive band servo, also known as the B servo. The gear selector or shifter showed 1-D-OD. For a ¼ mile run, you could select manual second by starting out in 1st, shifting to D and once the shift to second gear was completed, pull the shifter back to 1st and the transmission would hold manual 2nd until you bumped it up to D again for the 3rd gear shift. However, this gear shuffling process did cause increased wear and was linked to transmission failure. The weakest links in the transmission are the two piece input shaft used for mechanical torque converter lock-up, the direct clutch assembly and narrow overdrive band.
Transmission fluid or line pressure is controlled by a throttle valve cable also known as the TV cable. A broken TV cable bushing is the #1 cause of AOD transmission failure followed by an improperly adjusted TV cable. The AOD is NOT computer controlled. The speedometer drive gear is part of the output shaft and is not replaceable.
For performance use, an upgraded external fluid cooler is highly recommended. Companies such as Performance Automatic offer all the upgrade parts to make these transmissions very durable as well as fully built assemblies. The two most common and recommended upgrades for an AOD equipped 5.0 Fox Body Mustangs are a shift kit and 4.10 gears. A higher stall converter comes in at a close second.
The 94-95 AOD-E is essentially an electronic controlled version of the AOD. The transmission shifting and torque converter lockup are electronically controlled by the PCM via solenoids. An upgraded direct clutch assembly and a wider overdrive band are key improvements. The speedometer drive gear is part of the output shaft and is not replaceable.
The two most common and recommended upgrades for an AOD-E equipped 5.0 SN95 Mustang are a shift kit and 4.10 gears. A higher stall converter should also be at the top of your mod list. If you are thinking about racing your AOD-E Mustang, an upgraded external fluid cooler is highly recommended.
The 4R70W is an improved version of the AOD-E transmission. The 4R70W was introduced in 1996 and featured a “wide ratio” gear set. In 1998, the intermediate one-way clutch was replaced with a mechanical diode improving service life.
The 4R75W was introduced in 2003 and is simply a 4R70W with a revised planetary ring gear, revised front pump, revised intermediate clutch, and revised accumulator springs. It also features a VSS (vehicle speed sensor) as well as an OSS (output shaft speed sensor). The OSS reluctor ring has 24 teeth instead of 6 found in the 4R70W.
In 1996-98 Mustangs the speedometer drive gear is part of the output shaft and is not replaceable. 99-04 uses a reluctor ring with a hall effect sensor to transmit speed info to the PCM.
If you are thinking about drag racing or doing any performance driving, an upgraded external fluid cooler is highly recommended. The most common and recommended upgrades for Mustangs with the 4R70W transmission are shift kits, 4.10 rear end gears and a performance torque converter.
The 5R55S is a derivative of the first American used 5 speed automatic, the 5R55E. The 5R55S featured an aluminum case, 5 forward gears and reverse. The first complaint people had with this transmission was the lack of a factory installed dipstick. Luckily we offer the Performance Automatic pan and dipstick retrofit.
While these transmissions are fairly dependable, the most common failures are overdrive servo bore wear and torque converter clutch (TCC) modulator bore wear. Both can be repaired without case or valve body replacement.
A higher stall torque converter is the most common upgrade. Most aftermarket PCM tunes will greatly improve shift timing and feel. For performance use, an upgraded external fluid cooler is highly recommended.
The 6R80 transmission was first introduced on the 2011 Mustangs and became an instant hit with drag racers. These transmissions are beefy and have a very low failure rate. It is not uncommon to see the 5.0L Coyote powered automatic car outperforming their manual brothers. They feature an aluminum case, 6 forward gears and reverse.
The first complaint people had with it was the lack of a factory installed dipstick. Performance Automatic quickly stepped up by offering a pan and dipstick option. A common failure is one of the 7 control solenoids, which are easily replaceable.If you are considering any kind of performance driving we would HIGHLY recommend installing a transmission oil cooler. You can also greatly improve shift timing and feel via custom tunes with a handheld tuner such as a SCT X3 tuner.