Automatic Transmissions

4L80e “Bad Boy” Description 

“Bad Boy” is a designation  High Impact adds to a custom built automatic transmission to differentiate it from a stock replacement transmission. We feel that GM engineers were directed by marketing types to make  the trans shift more like a luxury car and less like a truck.  Apparently, the larger segment of truck owners wanted a soft ride to a real truck that shifts like a truck, etc. The bean counters then got in there and saved a penny here, a nickel there, cutting corners to make a price /profit point. These "niceties" involve compromises that make a pretty good basic trans design unable to hold up under real truck use. 

The 4L80e was GM's answer to the demand for a heavy duty, Turbo 400 level automatic overdrive transmission. While these transmissions seem to survive fairly well in trucks where the truck is used for general duty transportation, when the transmission is used for heavy towing, high load, motorhome , or extreme off road use, is sometimes not up to the task. 

One answer many truck owners have resorted to in conversion to a manual trans. We have found conversion to an NV4500 to be a popular solution. Another is a "High Impact "Bad Boy" Automatic trans.

These 4L80e transmissions are built for aftermarket conversions and applications where the demands placed upon the transmission far exceed anything GM ever built the 4L80e for.

There a number of standard upgrades used in Bad boy units, such as an upgraded HD torque converter with furnace brazed turbine elements and HD lock up clutches, oversize sprags, upgraded pressure regulator and reverse boost valve, and internal modifications for improved oiling and shifting. Units are specifically engineered to match the exact vehicle application they are to be used in, on a one at a time basis 

A Bad Boy is typically engineered and built for a specific application. Diesel applications require further pump upgrades. Racing applications require ability to handle hard shifts high RPMs as a matter of course. 4WD applications must operate reliably at crazy angles, and not slip, even at very low crawling RPMs. Towing applications must be able to withstand sustained high torque. 4WD and Towing both tend to exaggerate the heat loads. Shift firmness and shift points are calibrated to the application.

4L80e Transmission Specifications:

This transmission has a main case length of 26”.

Gear Ratios:

1^st:= 2.48         2^nd  =1.48        3^rd =1.0          4^th = 0.75

Power Capacity: 700 ft-lbs of torque, 800 HP

Electronic Control

The 4L80e requires a computer for shift control. The Factory GM computer will work with our transmission. For extreme applications, however, we feel the OEM controller  programming, is one of the primary culprits preventing the 4L80e reach its full potential. 4L80e "Bad Boy" systems can incorporate an external, fully user programmable stand-alone computer. This computer allows the transmission programming to be optimized for durability and to shift as the application requires. It can provide full manual shift control, then swap back to full auto operation at the flip of a switch. Many custom features can be programmed into it. It can be used in conjunction with the GM computer, in computer controlled engine applications, or it may be used entirely stand-alone, in vehicles the do not have any engine computer controls.

Full data on the controller we use: Powertrain Control Solutions TCM

Misc technical and application notes:

Connectors on Trans

There is a large connector: This is the connector to the valve body, connections for shift solenoids, system pressure control and TC lockup go through here. There is also a small connector on the side of the bellhousing: This is the input speed sensor. Also, SOME 4L80e trannies are equipped with an output speed sensor. This connector is just like the input speed sensor connector, but is located up from the large main connector.