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

In the dual clutch transmission this becomes possible by connecting two separate transmissions to the engine via two parallel powershift clutches. The even gears are located on one transmission, the uneven ones on the other. This basic principle of the transmission has the advantage that one gear in one of these transmissions ensures propulsion, whereas in the other transmission the next gear is already preselected by the electrohydraulic control unit. When shifting, one clutch is closed while the other opens. During the shifting process, traction is not interrupted. This means that, during acceleration, engine torque is continuously transformed and propels the vehicle – making an essential difference from the manual transmissions which were usually 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 also suited for higher speeds of up to 8,000 revolutions.

All gear changes – also downshifts – are processed just as evenly and quickly with the 7DT 50 (that is the ZF-internal product designation); so the ZF dual clutch transmission sets a new benchmark for sportiness. A new speed governing concept, which is used for the first time in volume production with the 7DT, also contributes to these extremely short shifting times.

The drivers can choose from fully automatic shifting or manual gear selection via shift paddles or a shift lever. Also in the fully automatic mode, ZF offers several shifting programs: Apart from the comfort mode, there is also a sports and a supersports mode, the latter with considerably increased shifting dynamics (fastest shifting times and race-start function).

The 7DT sports transmission by Porsche and ZF 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 according to special, ZF-specific delivery instructions. 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 very good efficiency, also achieves consumption values which are below those of a manual transmission.

Especially with sports cars, there is a demand for transaxle transmissions – that is, transmissions with an integrated differential and axle drive – the 7DT sports transmission can also be supplied in this variant, which is suited for mid-engined vehicles with rear axle 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.