Product Overview
The BMW ZF6HP21/28/34 and AUDI 6HP28 (2006 &up) transmission is based on the ZF6HP26 that has been in existence since 2002. These transmissions are often referred to as the “2nd Generation” and are used in low and high torque capacity vehicle applications. This Transmission features a Torque Converter with Lock-up Clutch, 3 driving clutches referred to as clutch A, B and E, 2 brake clutches referred to as clutch C and D, a Lepelletier Planetary Gear Train, and internal Transmission Control module referred to as a Mechatronic Module. Mechanically, the six forward speeds and reverse are accomplished through the use of what is known as a Lepelletier planetary gear train, 3 driving clutches and 2 holding brakes as seen in the application chart displayed in Figure 1. Electrically and Hydraulically, this gear box is controlled by what is known as "The Mechatronic Module." This is a combination of a transmission control module and valve body configured as one unit. In other words, the computer for the transmission is mounted onto the valve body and is submerged in transmission fluid. As a result of this Mechatronic Module technology, the pass through case connector from the module to the vehicle harness will basically contain power, ground and CAN Bus network wiring, as well as inputs from the “Tiptronic” Shifter. The Mechatronic Module controls shift timing and shift feel based on inputs from the Engine Control Module, ABS, and the Driver Information Module via the CAN. Shift strategy is controlled by the Mechatronic Module based on shifter input and engine load information received through the CAN bus. The following pages provide information on the valve body breakdown including check ball function and valve function for this family of transmissions. Note: the following information is based on an AUDI 6HP28 valve body that has a manual valve. Some BMW have “E” shift which does not incorporate a manual valve, which changes the valve body configuration.
