If you know about automatic transmissions then you know about the legendary GM 4L80E transmission. The 4L80E debuted in 1991. Features included an overdrive and a lock-up torque converter. It was also computer-controlled, which was a first for GM. Used mostly in Chevrolet and GMC trucks, it lasted almost 20 years in one GM product or another. Though long out of production, they are still in demand for projects that require a stout automatic right out of the box.
Was GM’s 4L80E automatic a completely new design?
The 4L80E was a stouter 700R4. It, in turn, was a TH400 three-speed Turbohydramatic transmission but with overdrive, which was launched in 1964. Being almost bulletproof, it lasted until the advent of the 700R4.
The 400 Turbo worked so well that even Ferrari and Rolls-Royce used versions of it for certain production vehicles. This was the last transmission produced without a lockup torque convertor or overdrive by GM. With the success of the 700R4, GM wanted a stouter version for heavy-duty applications.
Thus, it could handle 8,000 lbs GVWR, and power up to 440 lb-ft of torque. One notch up from the 4L80E is the 4L85E for vehicles with 16,500 GVWR and 460 lb-ft of torque. These can handle a towing capacity of 22,000 lbs.
What did the 4L80E transmission come in?
The 4L80E uses many of the 400 Turbo’s internals. But the added fourth gear adds an additional 1 ½-inches of length. It can accommodate two-wheel and four-wheel drive applications. GM used it in it full-size pickups, Suburbans, Escalades, and the Hummer H1.
Both big-block V8 engines and Duramax diesel engines were backed by the 4L80E. However, when GM began offering the Allison automatics, many buyers opted for it due to its higher towing capacity rating. That, and the introduction of the 6L80 six-speed automatic in 2006 cut into 4L80 demand. At least the 4L80 never experienced the dreaded Chevy Shake.
On the technical side, the 4L80 eas controlled by PCM transmitting input to the ECM. A PWM solenoid controls the torque converter lockup. Its Transmission Control Module or TCM communicates with the ECM CAN bus system. Many 4L80 automatics are used in DIY projects which are not computer controlled. For those applications, GM makes an aftermarket control module that takes care of controlling the transmission.
Will the 4L80E transmission work in a non-computer-controlled vehicle?
Speed sensors need monitoring to control all of the electronic applications, with three different generations each paired to specific controllers. These are the 1991 to 1999 TBI and Gen II, 1999 to 2007 Gen III, and 2007 on up Gen IV engines. According to NovakAdapt, Gen IV 4L80 transmissions feature an integrated TCM. So they require additional inputs beyond aftermarket ECMs.
Though not without some glitches throughout its lifetime, the 4L80E has proven to be a stout, reliable, and versatile four-speed automatic transmission, whether found in original or aftermarket applications.