My recent post on the AOD transmission brought out some unfavorable comments on that particular transmission. The AOD was designed during the time period not known for great transmissions. American manufacturers were concerned with meeting CAFE requirements but at the same time were also trying to minimizes costs. These circumstances were not ideal for the development of all new transmissions and lead to some pretty poor designs.
Many of the transmissions designed in this era, like Ford’s AOD and GMs TH700-R4, helped increase fuel efficiency but were compromised designs that suffered from under engineered components, poor reliability and poor operation. Fortunately, as time went transmission design was improved, especially with the adoption of electronic control. Some older designs, like the aforementioned AOD and TH700-R4, were modernized in the 1990s and become good transmissions.
With that said, the era previous to this from the mid-1960s to the late 1970s produced some of the America’s best transmissions. The majority were 3-speed automatics based on the Simpson gearset that resulted in some basic, but great transmissions that not only operated very well, but were generally very durable. They were so good, that even some European manufactures used them, such as GM TH400 in Ferrari’s, Rolls’ Royce and Jaguar.
Going further back to the late 1940s to the early 1960s was an era that produced the earliest mainstream automatic transmissions. There was little standardization in design during this time, which lead to a wide variety of designs. There was the game changing Hydramatic, which had four-speeds, but used a fluid coupler instead of the torque converter. Chevrolet had its venerable Powerglide, but also produced the short-lived trouble prone Turboglide. Even Packard and Studebaker got into the game with Packard Ultramatic and the Studebaker (Brog-Warner) Automatic Drive. It was also during this time that the more conventional Chrysler’s Torqueflite A-488 was first released for the 1956 model year. It proved to be winning forward going into the 1960s.
Today, much like the early 1980s, fuel economy has become a prevailing factor in transmission design, resulting in much more complex multi-speed transmissions and CVTs. Unlike the early 1980s, the engines today are stronger than ever and the transmissions are correspondingly stronger than ever before. Case in point, Ford and GM’s joint venture on the 10-speed automatic transmission for RWD applications is rated to handle over 600 lbs-ft of torque in its strongest variations. Of course, these new generation transmissions have their own complaints. The large number of speeds has led to shift confusion, erratic shifts and expensive repairs. CVTs seem to be either loved or hated and also have had spotty reliability records.
That leads us to the question of the day. What is your favorite and least favorite automatic transmission? Tell us your choice and share your experiences good or bad.