Design and Development of a Magnesium Clutch Piston for an Automatic Transmission

In response to a call to reduce mass and potentially cost, a magnesium reverse clutch piston was developed for the 4T80-E transmission. The 4T80-E transmission was developed exclusively for the Cadillac Northstar engine. This paper discusses the design criteria used in the piston's design, key points with respect to material properties for the selection of magnesium and the particular alloy, validation processes and manufacturing concerns.