SCHWEINFURT – The 8HP ZF automatic transmission has proven its qualities in the BMW M235i Racing Cup since the 2014 season. Now, ZF introduces the next evolution – the 8P45R motorsport transmission. It is even more dynamic, lighter and consequently perfectly suited for use in motorsport. The 8P45R had its first successful track appearance at the VLN race end of October at the legendary Nürburgring.
Previously, an automatic transmission was considered a somewhat unusual construction in motorsport; however, ZF paved the way for this new solution during the 2014 season. The automatic 8HP transmission eases the workload considerably for BMW M235i Racing Cup competitors, and allows the racing drivers to stay almost completely focused on their environment and on the track. Mechanical damage as a result of shift mistakes is also excluded as are fatal blockages and dynamically unbalancing shocks on the driven axle.
Whereas the previous automatic transmission was based on a standard production line design and modified software, ZF now sees good potential for a pure motorsport planetary transmission. The aims of the redesign: ratios, shift points and shift speed should fulfill the greater demands in motorsport without compromise. ZF also attached value to low weight. By omitting the converter and other reduction measures, the designers saved about 15 per cent on weight. The internal power loss was also reduced.
The designers retained the fundamental design and assembly scheme – comprised of four planetary gear sets and five shift elements – from the previous 8HP transmission. One of several new features is the omission of a converter in the transmission. The pulling away or drive-off process is implemented by internal shift elements. A vibration damper upstream from the transmission input prevents damage through engine oscillations.
The gear ratio spacing is closer and the rev drops between gears have been reduced. Normally only the first six gears of the former 8HP transmission were used when racing. In the new transmission all eight gears are spaced sensibly in the operating range.
Throughout the 2015 season, the new gearbox underwent a test and dyno testing program. End of October it withstood its baptism of fire on the legendary Nordschleife of the Nürburgring in a specially equipped BMW M235i Racing. Dirk Adorf, chief instructor of the BMW Motorsport junior program, is convinced by the new development: „I am truly fascinated by the performance of ZF´s engineers after my first laps with the new gearbox. Being an automotive technician myself, I wouldn´t have thought it possible to build an automatic transmission without a torque converter, that provides such a fast changing of the gears as well as easy 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."
ZF plans the transmission’s market launch in the second quarter of 2016. Initially, the 8P45R transmission is exclusively available for the BMW M235i Racing. In the future, it is also envisaged for use in other manufacturers’ sportscars.