4L80E Transmission Controllers and the GM 4L80E Transmission
Introduction
A GM 4L80E transmission controller can control this versatile automatic transmission made by General Motors. It has been used in heavy duty vehicles like trucks, SUVs and utility vans. Its robust design and ability to handle heavy loads makes it a popular choice today in a wide variety of vehicles and custom builds.History of the GM 4L80E
The transmission is based on the GM TurboHydramatic TH400 automatic transmission. A major difference with the TH400 transmission and the 4L80E is that the latter contains an extra overdrive gear and has electronic shift controls.The 4L80E was first released in 1991 in General Motors C/K trucks, and was still produced for use in new vehicles all the way up until 2013.
The 4L80E design has remained relatively consistent over the years but has had two major variations. The early models built from 1991-96 have a different kind of connector that goes through the case, and also a different lubrication system. The late models built from 1997-onwards have an updated and improved lubrication system and a newer case plug for the electronic shift controls.
Specifications of the 4L80E
-Maximum Engine Input Torque: 440 ft. lbs.-Maximum Output Torque: 885 ft. lbs.
-Maximum Gross Vehicle Weight Rating: 8000 lbs.
-Longitudinally Positioned Transmission
-Build Material: Die-cast aluminum.
Gear Ratios of the 4L80E
The gear ratios are quite closely spaced in the 4L80E to ensure the rpm drop between shifts isn’t too high. This helps keep the rpm in the power band so that the torque output doesn’t drop too drastically between shifts. The COMPUSHIFT 4L80E transmission controller allows you to customize a shift strategy that works best for your vehicle.
Strengths of the 4L80E transmission
As the 4L80E is an electronically controlled transmission, it can be linked up to a 4L80E transmission controller like the COMPUSHIFT for instance.The shifts can be programmed for optimal shift timing and so can the torque converter clutch (TCC) lockup be controlled. The sensors used by the transmission controller provides information about the status of the transmission.
The torque converter clutch can be applied using pulse width modulation (PWM) for a smooth clutch application. The TCC when engaged provides a direct drive from the engine output shaft to the transmission, without any rotational speed losses.
The addition of the extra overdrive gear ratio also helps lower engine revs on the highway, bringing about fuel savings, less noise and less engine wear while cruising.
It improves on General Motors 4L60E transmission, as it can handle more horsepower and torque. Therefore, while the 4L60E is rated for vehicles weighing a maximum of 6000 lbs., the 4L80E is rated for vehicles weighing up to 8000 lbs.
Potential Problems with 4L80E transmission
Cooling issues
On the early models of the 4L80E produced from 1991-96, the transmission coolant line fittings were attached just behind the bellhousing.This design didn’t always let the rear planetary get enough lubrication and be cooled sufficiently, which caused problems as the planetary could get too hot and get damaged during operation.
Therefore from 1997 onwards the later models of the transmission design were modified, so that the oil feed cooler was run to the back of the case to improve cooling and lubrication.
Going into “limp mode”
If there is a problem with the electronics such as a short circuit, the transmission may not engage the solenoids in the valve body. Therefore, when the 4L80E goes into limp mode and both the solenoids are disengaged, only 2nd gear will be available due to the design of the valve body.Electrical problems with sensors like the speed sensors or throttle position sensor can also affect the transmission operation.
Poor lubrication
If the forward drums don’t get enough oil for lubrication and cooling, the clutches can slip and cut grooves in the drum. When the drum tries to apply the clutch pack, it will apply only part of it and not engage gears properlyTorque Converter Clutch failures
If the torque converter clutch doesn’t lockup, the engine will be spinning faster at cruising speeds and consume more fuel than it needs to. Some of the 4L80E transmissions built prior to 2006 are known to have problems with the clutch piston cracking.Another potential issue if the Torque Converter Clutch (TCC) malfunctions and stays locked, is that when you come to a stop, the engine will stall as the torque converter won’t disconnect the flow of power from the engine to the wheels.
Popular custom vehicles that use the 4L80E transmission
The 4L80E is mainly found in trucks and SUVs, especially in vehicles produced by the GM group, which include the Chevrolet marque. GM vehicles which came with the 4L80E include the:- GM Sierra
- Chevrolet C/K
- Chevrolet Silverado (Truck)
- Chevrolet Suburban (SUV)
The 4L80E was also featured on a number of other vehicles like the Hummer H1 SUV and the Workhorse range of trucks such as the Workhorse P30. It even saw its way into premium English cars like the Bentley Continental, Jaguar XJR and Rolls Royce Spur.
In custom vehicle builds, the 4L80E is a common transmission to upgrade to from the 4L60E. Both these transmissions share the same bellhousing bolt patterns and can be attached to the same engines.
If an engine swap or performance enhancements is done on a vehicle which uses the 4L60E, like the Chevrolet Camaro for example. Then upgrading that vehicle’s transmission to a 4L80E with a quality 4L80E transmission controller might be a good idea, because the 4L60E could get damaged with too much horsepower.
The 4L80E is overall very versatile as it can be used in many different types of vehicles, including in drag racing applications where the horsepower produced can easily be in excess of 700 horsepower.
Controlling the 4L80E transmission with the COMPUSHIFT
As the transmission is electronically controlled, the shift points, torque converter lockup, and overdrive can all be controlled by the user, offering endless possibilities and full control.The 4L80E needs to have an electronically controlled speed sensor, for the 4L80E transmission controller to work properly.
Mechanical speedometer tail-shaft conversions can be used in older vehicles. In rear wheel drive applications, the transmission needs to have 2 speed sensors – Front and rear of the transmission on a 2-wheel drive.
In 4-wheel drive vehicles, the transmission output speed sensor (TOSS) needs to be in the transfer cases. The early cases don’t have a 4-wheel drive speed sensor but you can put a tone ring, also known as a speed sensor ring. This is mounted on the rear planetary gearset. It provides an electric signal from the changing voltage produced in the coil due to the rotations.
The early models of the transmission, mainly those which were produced from 1991-1993 are not serviceable, as the main body plug used on those models are no longer available.
The main harness included with the COMPUSHIFT 4L80E transmission controller doesn’t have a bolt in it, so it can’t be plugged into the early models. Therefore, the early models of the 4L80E will have to be fitted with the internal wiring harness and the case plug from a late model. The early models also don’t use the temperature sensor included with the COMPUSHIFT and neither do they have mounting holes for the neutral safety switch.
For a custom build, it would be highly recommended to use a later model 4L80E transmission along with the COMPUSHIFT transmission controller. To get the right accessories and connectors for your vehicle fill out our quick questionnaire on our website to get a customized 4L80E controller kit list for your vehicle.
