7-Speed Dual-Clutch Transmission by Porsche and ZF Enters Volume Production

Business Wire, June 23, 2008

* Faster shifting without traction interruption

* Improved fuel economy and driving performance

* Volume production launch in the Porsche 911 Carrera

NORTHVILLE, Mich. -- The new 7-speed dual-clutch transmission developed by Porsche and ZF is now in volume production. Its first application is the Porsche 911 Carrera. With quick transfer of power and smooth shifting, the ZF 7-speed dual-clutch transmission combines the sporty agility of a manual transmission and the shifting comfort of an automatic transmission - ideal for high-performance sports cars with powerful engines.

The transmission was developed in Germany and is being produced at the Brandenburg, Germany site of ZF's Car Driveline Technology division.

In the dual clutch transmission this performance is possible by connecting two separate transmission shafts to the engine via two parallel powershift clutches. The even gears are located on one shaft, the odd on the other. This basic principle allows one gear to be engaged, while the next gear is preselected by the electrohydraulic control unit. When shifting, one clutch is closed while the other opens, ensuring uninterrupted traction. This means that, during acceleration, engine torque is continuously transferred - a key difference from manual transmissions which are commonly installed in powerful sports cars. In contrast to torque converters, the dual-clutch module by ZF Sachs, the Powertrain and Suspension Components division of ZF, is suited for higher speeds of up to 8,000 rpm.

All gear changes - including downshifts - are processed evenly and quickly with the 7DT 45. A new speed governing concept - used for the first time in volume production with the 7DT 45 - also contributes to these extremely short shifting times.

Drivers can choose from fully automatic shifting or manual gear selection via shift paddles or a shift lever. Within the fully automatic mode, ZF offers several shifting programs: a comfort mode, sports mode, and a supersports mode, with considerably increased shifting dynamics (fastest shifting times and race-start function).

The new transmission excels thanks to its high power-to-weight ratio: The gears and shafts of the dual clutch transmission, which weighs approximately 120 kg, are produced from case-hardened steel. ZF engineers have introduced several measures - for example, controlling the cooling fluid flow as required - to keep drag losses low. The 7-speed dual clutch transmission not only allows for particularly sporty driving performance but, thanks to its efficiency, achieves better fuel economy than a manual transmission.

Within the sports car market, there is a demand for transaxle transmissions - those with an integrated differential and drive axle. The 7DT sports transmission can be supplied in this variant, which is suited for mid-engine vehicles with rear or all-wheel drive. This transaxle version of ZF's 7-speed dual clutch transmission is starting volume production in the torque range up to 450 Newton meters.

ZF is a leading worldwide supplier of driveline and chassis technology. Headquartered in Friedrichshafen, Germany, ZF is among the 15 largest automotive suppliers in the world. The company employs approximately 58,000 at 119 locations in 25 countries, and totaled sales of $17.3 billion in 2007.

ZF operates an extensive manufacturing network in North America, combined with global research and development capabilities, to provide advanced technology to the NAFTA region. The ZF Group North American Operations Headquarters and Technical Center is located in Northville, Mich., USA.