The 4L60E was first seen in 1993 model cars and trucks. The predecessor to the 700R4 was now an electronically shifted transmission. Not only does it have shift solenoids, and torque converter clutch control, but it also has electronic pressure control. It has gone through many changes and updates since it first began 25 years ago.
This unit has a number of issues that are common failure points. The 3-4 clutch is definitely at the top of the list. The engineers at GM new this clutch was going to be a problem from day one. They were right. This clutch pack has gone through many updates in order to withstand the loads that it has to hold up under. Another weak point is the band. The band is used in 2nd and 4th gear. The reaction shell was a high failure item early on, but went through a number of engineering changes and the final version of this part became a reliable part. These three are definitely the top failure areas, but there are many other smaller factors that would cause the unit to fail. The valve body has a few high wear items that need attention during rebuilds. Some of these are commonly the root cause of clutch failure.
The rebuild process begins with a complete tear down and cleaning of the transmission and all sub-assemblies. All 'soft parts' are removed and discarded. Soft parts are what is included in a common rebuild kit. Typically, this includes gaskets, seals, clutches, bands, sealing rings, bushings, and the filter. In addition to the rebuild kit, additional parts are replaced as necessary to address worn areas in the transmission. Some parts are updated to eliminate known weak points in the transmission. All the hard parts, which are mainly the steel or aluminum components, are inspected to verify they meet proper standards. Any parts that are worn or damaged are discarded and replaced. All sub-assemblies, such as the valve body, pump, and clutch drums are all reassembled and tested to ensure they meet strict standards and function properly. All work is performed by an experienced, expert rebuilder to ensure nothing is overlooked.
Maine Transmission Rebuilding offers a heavy duty version of the 4L60E which is built to withstand towing and plowing that would put an average unit to the test. We address the common weak points of the unit and beef these up to help eliminate failure. First, the 3-4 clutch is expanded to increase torque capacity and the clutch components are upgraded to handle the heat much better. Second, the 2-4 band is upgraded to handle the heat generated while shifting. The servos for the band are also upgraded to add more holding capacity on the band, once it is applied. We also upgrade the reaction shell to a heavy duty aftermarket version. The pump and valve body both are upgraded to better control pressure and clutch application. The result is a smooth shifting transmission for comfortable daily driving while providing strong, reliable use for years to come.