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Guide To Automatic Overdrive Transmissions

Get Good Performance And Gas Mileage With Our Guide To Automatic Overdrive Transmissions


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.


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

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

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