The RC4A-EL transmission, also known as the JR405E, is used in the States in the Mazda RX8 vehicle. It has a much broader use overseas. Since this is not a transmission that shows up on the bench regularly here, when a shop gets one we usually receive a call for help on placing the three tension springs shown in Figure 1.
There is very little information written about this transmission concerning the valve body and its associated hydraulic operations. For this reason ATSG has produced a Technician Guide that provides extensive information including valve-body mapping and a complete set of hydraulics. In the process of developing this guide, we discovered a unique way in which this unit controls clutch application. The high-clutch amplifier valve in the upper valve body (Figure 2) serves as a perfect example.