The Turbo 350 and 400, along with the C4, 6, and Chrysler's 727 are mainstays of high-performance street and strip transmissions. They have been around for decades, are well supported by the aftermarket, and can be built to handle big horsepower numbers.
But what if your tastes, budget, or eardrums dictate a different course of action? Say you want one more ratio than direct drive's 1.00:1? Yes, overdrives are a viable option, too. As they advance in age, more high-performance parts become available for them as well. A modern overdrive transmission can be built to handle as much power as all but the most radical street car can dish out, plus give you relaxed highway cruising to and from the racetrack.
This is our guide to the popular automatic overdrive transmissions available today and what their performance potential is. Some, like the 200-4R and 700-R4, have also been covered in great detail, but others, such as Ford's 4R70W, don't get much press. We consulted the industry's best to compile this list: Art Carr of California Performance Transmissions, Mark Bowler of Bowler Performance Transmissions, Greg Ducato of Phoenix Transmission Products, the tech guys at Performance Automotive and Transmission Center, and AOD specialist Karl Baumann of Baumann Electronic Controls. There's no time like the present to meet the overdrives.
| Transmission Dimensions |
| | Overall | Face-To-Mount |
| TH200-4R | 27 3/4 | 26 3/4 |
| TH700-R4 | 30 3/4 | 22 1/4 or 27 5/8 |
| 4L80E | 32 3/16 | 30 5/16 |
| AOD/E | 30 3/4 | 22 3/8 |
| A-500 | 37 3/4 | 24 1/4 |
| A-518 | 38 1/4 | 25 1/4 |
| Gear Ratios |
| TH200-4R | 2.74 | 1.57 | 1.00 | 0.67 |
| 4L80E | 2.48 | 1.48 | 1.00 | 0.75 |
| TH700-R4 | 3.06 | 1.62 | 1.00 | 0.70 |
| AOD | 2.40 | 1.47 | 1.00 | 0.67 |
| 4R70W | 2.84 | 1.55 | 1.00 | 0.70 |
| E4OD | 2.71 | 1.53 | 1.00 | 0.71 |
| A-500 | 2.74 | 1.54 | 1.00 | 0.69 |
| A-518 | 2.45 | 1.45 | 1.00 | 0.69 |
General Motors TH200-4R
This transmission first appeared in midsize GM sedans starting in 1981. Its dual-bolt-pattern bellhousing allows it to fit behind a Grand National's Buick V-6 as well as a Monte Carlo SS small-block V-8. Carr loves these transmissions. They can be built to handle big-block power: big Buick, Cadillac, Olds, and Pontiac power-as well as a big-block Chevy.
Manufactured: 1981 to 1988
OE rating: 300 hp
Strengths: Dual bolt pattern allows it to fit behind any rear-drive GM V-8 or V-6; same overall length as a TH350; no computer required; can be built to handle massive amounts of horsepower.
Weaknesses: You need to replace most of the internals to handle massive power; short production run means fewer are available now.
Build it with: A Torrington bearing kit; a wide intermediate band; a hardened sun shell; a Bowler's Tru-Shift throttle correction kit and lock-up module.
Can be built to handle: Carr builds one rated at 1,000 hp.