Tom Wilson
February 4, 2010

Horse Sense:
The AOD was not a clean-sheet-of-paper design from Ford-it was based off the venerable three-speed C4 automatic.

Now that Ford's automatic overdrive transmission has been around for so long, we sometimes forget it was really the first widely used overdrive automatic gearbox in the United States. But it was, making its debut in 1980 on passenger cars, then showing up in Mustangs from 1984 to 1993. Even then, the AOD was replaced by itself, dolled up with electronic shifting controls as the AODE in 1994.

While not thought so at first, the AOD has proven a fairly stout gearbox-stout, that is, if given the proper upgrades. And considering the numerous methods of arriving at major 5.0 horsepower, it's a good thing for auto-shift fans that the AOD can be readily modified to near-bulletproof status.

This is especially true for Ricky Best. Well known in the Mustang world as racing coordinator at Vortech Engineering, Ricky recently acquired a '93 coupe as a street/strip project vehicle for himself. And, while cumshawing a V-1 T-Trim blower onto it was reasonably easy (do you think?), he knew his little coupe's stock AOD would never make it without upgrading.

Recalling that one of the original AOD pioneers was reknowned automatic-transmission specialist Art Carr, Ricky headed off to California Performance Transmission, where Art does business these days. That's where we tagged along to review what an AOD should get when being prepped for modern performance use.

At California Performance Trans-mission, we reviewed what makes an AOD fail to tick when belted with more torque than it was designed to handle. A four-speed automatic with an overdrive top gear, the AOD has several weak points in high-power applica-tions. For starters, the Third gear (sometimes called "direct") clutch pack has only five "clutches and steels." This is a minimal number, and the arrangement has difficulty transmitting torque without slipping.

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