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, overdrive transmissions are a viable option, too. As they advance in age, more high-performance parts become available for them as well. Modern overdrive transmissions 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 overdrive transmissions.
TRANSMISSION DIMENSIONS OVERALL FACE-TO-MOUNT TH200-4R 273/4 263/4 TH700-R4 303/4 221/4 or 275/8 4L80E 323/16 305/16 AOD/E 303/4 223/8 A-500 373/4 241/4 A-518 381/4 251/4
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.
TH700-R4/4L60E
Based on the internals of a TH350, the 700-R4 and its updated version-the 4L60E-was Chevrolet's bread-and-butter four-speed automatic for the last 20 years and came in everything from passenger cars to light trucks.
Manufactured: 1982 to 2005 OE rating: 350 hp (approximate) Strengths: Strong aftermarket support; there were millions made; 700-R4s don't need computer control; can be rebuilt to 4L65E specs. Weaknesses: Chevrolet bolt pattern only (BOP adapter kits are available); big rpm drop between First and Second gears; sun-reaction shell tends to break at input shaft splines. Build it with: Five-pinion planetary gearset; The Beast sun shell; hardened oil pump rings and new vanes; steel sleeve support on input shaft; Bowler's Tru-Shift throttle correction kit and lock-up module. Can be built to handle: 700 to 1,000 hp depending whom you ask Notes: The '87-and-later 700s are stronger transmissions with an improved pump design and an auxiliary valvebody for better line pressure control. The 700 was renamed 4L60 in 1992. Electronic control appeared in 1993. Bolt-on bellhousing case design debuted in 1998. PATC sells a new planetary gearset that changes the gear ratios to 2.84, 1.55, 1.00, and 0.64:1.
The Beast sun shell (left) is made by SPX, a transmission parts manufacturer. It is considerably stronger than the stock piece, which tends to break where the sun gear attaches to the drum.
4L80E
This is a heavy-duty transmission based on TH400 internals. It was standard equipment on 3/4- and 1-ton pickups.
Manufactured: 1993 to 2005 OE rating: 450 hp Strengths: Proven strong internals; gaining popularity with the aftermarket; can handle huge amounts of power. Weaknesses: Input shaft can break; heavy; needs computer control. Build it with: Updated reverse band; molded steel direct clutch piston; 300M hardened input shaft; five-pinion rear planetary gearset; 44-element sprag (stock is 34 element); wide kickdown band with new apply piston. Can be built to handle: 1,000 hp
We like that the 300M billet input shaft Bowler installs in its 800-lb-ft 4L80E.
Ford AOD
The AOD was the first production four-speed overdrive automatic transmission by a domestic manufacturer. It was loosely based on the FMX three-speed.
Manufactured: 1980 to 1993 OE rating: 250 to 300 hp Strengths: Millions were made; strong aftermarket support; simple, lightweight, and compact design. Weaknesses: Reputation for lazy, soft shifts; concentric input shaft torque converter lock-up design. Build it with: Alto's Direct Clutch Power Pack that allows up to eight friction plates; recalibrate valvebody for better shift feel; Torrington bearing kit; hardened intermediate shaft; Kolene steels in forward and direct drum. Can be built to handle: 600 hp
AOD-E/4R70W
Ford updated the AOD in the early '90s, strengthening it substantially and adding electronic shift control. It was soon equipped with a new, wide-ratio gearset and renamed 4R70W-and is one of the best transmissions Ford has ever made. "They can handle a lot of abuse," Baumann says.
Manufactured: 1992 to 2005 OE rating: 350 hp Strengths: 2-inch-wide overdrive band for better holding power; stronger input shaft; torque converter is locked up by a clutch that can be pulse-width-modulated by the ECM; the 4R70W has a wide-ratio gearset that better matches shifts to engine powerband. Weaknesses: Needs computer to operate. Build it with: Heavy-duty direct clutch pack; 4R70W gears in an AOD-E; Baumann's ReCal-Pro valvebody calibration kit; Baumannator TCS transmission controller. Can be built to handle: 700 lb-ft Notes: The best transmissions to get are from '98-and-later cars; 4R70Ws from '96 to '01 Explorers and 3.8L or 4.2L V-6 Mustangs have a Windsor engine bellhousing bolt pattern, making them ideal swap candidates.
Chrysler
A500
Chrysler added a Fourth gear to the 904, and the A-500 was born. Fourth gear and torque converter lockup are activated electronically via computer control.
Manufactured: 1989 to 2007 OE rating: 275 hp Strength: Can be built with heavy-duty 904 parts. Weaknesses: Light-duty transmission; small clutches and bands; oiling problems cause overheating, especially of the output shaft; need to wire a switch to engage Fourth gear and lockup converter. Build it with: Five-clutch direct clutch pack; wide front and rear bands; four-pinion planetary gears; Phoenix Transmission's wiring for Fourth gear engagement and torque converter lockup. Can be built to handle: 400 hp
Left to right: Chrysler's A518, 727, A500, and 904.
A518
Operating with a similar plan, Chrysler engineers, needing a heavy-duty overdrive trans, added a Fourth gear to the 727 TorqueFlite three-speed, creating the A518. It was original equipment in Dodge trucks. Manufactured: 1990 to 2007 OE rating: 350 hp Strengths: Heavy-duty design based on the 727; can be built with strong 727 parts. Weaknesses: Oiling problems can burn up the output shaft; need to wire a switch to engage Fourth gear and lockup converter; giant size makes it difficult to fit in older body styles; they may not clear the torsion bar mounts on some body styles. Build it with: Four-pinion front planetary gear; heavy-duty intermediate band strut; high-capacity direct clutch drum; Phoenix Transmission's wiring for Fourth gear engagement and torque converter. Can be built to handle: 500 hp Notes: The A518 can be built to fit behind B- and RB-series engines.
