ZF Debuts 8P45R Motorsport Transmission

The 8HP ZF automatic transmission has made a name for itself after showcasing its unparalleled performance and qualities in the BMW M235i Racing Cup since last year’s season. And now, ZF presents the next evolution—the powerful 8P45R motorsport transmission. The new transmission, which is lighter, more dynamic and perfectly suitable for motorsports, had its first-ever successful track appearance at the VLN race at the renowned Nürburgring.

Not long ago, an automatic transmission was regarded as somewhat rare construction in motorsport. However, ZF introduced this fresh solution during the 2014 season. The 8HP transmission significantly eases the workload for BMW M235i Racing Cup competitors, and enables the racing drivers to stay focused both on their environment and on the track.

ZF now views the previous automatic transmission, which was based on a standard production line design and modified software, as good potential for a pure motorsport planetary transmission. The redesign aims to ensure that ratios, shift points and shift speed will fulfill the greater demands in motorsport without compromise. Putting high value on low weight, ZF also omitted the converter and other reduction measures, thus saving designers approximately 15 percent on weight. Plus, the internal power loss was reduced.

The designers kept the assembly scheme and fundamental design—consisting four planetary gear sets and five shift elements—from the old 8HP transmission. With the converter omitted in the transmission, the pulling away or drive-off process is executed by internal shift elements. There is also a vibration damper upstream from the transmission input that inhibits damage through engine oscillations.

The gear ratio has been made closer and the revolution drops between gears have been reduced. Only the first six gears of the former 8HP transmission were used when racing. In the all-new transmission, the eight gears are spaced sensibly in the operating range.

Commenting on the new transmission, Dirk Adorf, chief instructor of the BMW Motorsport junior program, said that he never thought it was possible to develop an automatic transmission without a torque converter that offers fast changing of the gears as well as effortless and comfortable starting. “The clutch elements are extremely fine-tuned. I am sure that this system will be an example for other racing gearboxes and even for the development of series transmissions.”

Reports say that ZF will roll out the 8P45R transmission in the second quarter of next year. Initially, the powerful transmission is solely offered for the BMW M235i Racing, but is envisioned for use in the sportscars of other manufacturers in the future.