The 8DT is available for front-longitudinal configuration in four variants (standard, all-wheel drive, hybrid, all-wheel hybrid) in three torque classes up to 1,000 Nm.
ZF
With an all-new 8-speed dual-clutch transmission (8DT), ZF and Porsche have collaborated to develop a modular hybrid transmission kit. One major goal was to make electric power an option. Thanks to a new gear set design, a 100 kW hybrid module could be integrated without increasing the length of the transmission, as compared to the current 7DT sports transmission. This also applies to the integrated all-wheel-drive distribution option that drives the front axle in the most fuel-efficient manner possible using the hang-on principle. The new transmission is manufactured at ZF’s Brandenburg plant. Volume production featuring the 8DT began with the new Porsche Panamera.
“In the new 8DT sports transmission, we combine blazing-fast shifts, a great level of efficiency and all-electric driving with the flexibility to integrate different variants within a tight installation space – without compromise”, says Dr. Jürgen Greiner, Head of Development for passenger car transmissions at ZF Friedrichshafen AG. Both the torque resistance and the efficiency of the new 8-speed dual clutch transmission surpass the current 7DT. Power loss could be reduced by up to 28 percent and the incredibly quick shift times were perfected even further according to ZF.
Four transmission variants
The new 8-speed dual clutch transmission is available in four variants (standard, all-wheel drive, hybrid, all-wheel hybrid) for front-longitudinal configuration in three torque classes of up to a maximum of 1,000 Nm. To make the 8DT basic transmission as short and compact as possible, a new gear set concept with two countershafts and one summation shaft was constructed according to the manufacturer. The fixed gears, which are all located on the transmission input shafts, can be used several times, resulting in fewer gear levels, making the basic transmission significantly shorter. This was the only way to integrate the hybrid module without increasing the length. This gear set architecture offers another advantage. Its modular concept will make it not only suitable for front-longitudinal applications but it will also be able to cater for other powertrain configurations.
ZF has customised a compact hybrid module for the optional variant of the new 8-speed dual clutch transmission. It includes a torsional damper, a separating clutch with actuators, as well as the electric motor, and it can be integrated directly into the clutch bell housing. This does not alter the dimensions of the overall transmission but has considerable impact on its properties according to ZF. With 100 kW peak output, 55 kW continuous power and 400 Nm torque, a vehicle can accelerate up to 140 km/h on electric power alone. With this technology, all other hybrid functions are also possible, from recuperation to boost mode.