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The best of both worlds: 40 years of the Porsche dual-clutch transmissionPDK anniversary / highly efficient gearbox concept with everyday practicality
The Porsche dual-clutch transmission (PDK) combines the advantages of manual and automatic shifting, striking a great balance between performance and efficiency.
A championship-winning technological breakthrough for conquering the rigours of the racetrack, showing its performance advantages especially in rally conditions.
Introduced in 1981, first racetrack outing on the 962 at a later date, and has been featured in production cars since 2008.
Shanghai/Stuttgart.It took a long time until it was ready for series production, but with its innovative gearbox the sports car manufacturer was a technological trailblazer nevertheless. Now the Porsche dual-clutch transmission (PDK) is celebrating its 40th birthday. The search for a gearbox concept that had the advantages of a manual gearbox and avoided the disadvantages of automatic gearboxes of the time began long before its official date of birth in 1981. “Sometimes technology takes a long time to mature. Porsche was a pioneer – 20 to 30 years ahead of its time,” says Rainer Wüst, who worked first as a gearbox test engineer from 1971, and later as Head of Chassis Development at the Development Centre in Weissach until 2009. Designers and engineers at Porsche began working on a powershift dual-clutch transmission with mechanical control via cam discs way back in 1964.
“However, the powerful control electronics to implement the sensitive clutch control necessary for installation in production cars were not available at the start of the 70s,” adds Wüst. He mentions Imre Szodfridt, a Hungarian engineer who presented the idea of a dual-clutch system to Ferdinand Piëch, then Porsche Head of Development, as one of the driving forces behind the PDK back in the late 1960s. “Szodfridt was a brilliant tinkerer; he had a new idea every day,” Wüst recalls. This was also how the Type 919 gearbox came about, but it was not developed further because of its rough shifting processes. A few years later, in 1979, in response to the oil crisis of 1973, the German Federal Ministry of Research and Technology organised a competition for the automotive industry to develop a vision of a future vehicle to optimize fuel consumption, the so-called "Vehicle 2000". In this study, the PDK transmission proved to be the most forward-looking technology among all possible transmission concepts.
The head of advanced development at the time, Helmut Flegl, thought a dual-clutch transmission could be promising. “So we set up an interdisciplinary team under my leadership. For me, as a young engineer at that time, this was a particularly exciting challenge," Wüst looks back. “Luckily, we found some Szodfridt gearboxes that were still in the cellar,” Wüst recounts with a smile. Nevertheless, it was no easy task: Because at that time, there were neither powerful control electronics nor series- production electrohydraulic valves suitable for vehicles. In a Porsche 924, the team was finally able to develop the basic functions of the PDK thanks to converted prototype transmissions and successfully demonstrate them at this stage. And so the Porsche dual-clutch transmission in various versions was born – 40 years ago.
In addition to attempting to develop a standard PDK transmission, Porsche also planned to demonstrate the PDK's performance in racing with the 956. “Being able to keep your hands on the steering wheel when changing gears under full load felt very good right from the start,” says Hans-Joachim Stuck who, as a racing driver, was instrumental to the further development of the PDK. “We were able to shift and drive much faster with no interruptions to traction.” To change gears, the driver needed only to operate a switch while driving. The gears are divided between two sub- transmissions, each with its own clutch. Only one clutch is ever engaged at any one time, meaning that the new gear can already be engaged in the second sub- transmission. As with a manual gearshift, the gears are engaged via shift forks. However, the PDK uses computer-controlled electrohydraulics. To change gear, only the newly effective clutch must then be closed and the previously effective clutch opened at the same time. "This technology enables fully automatic gear changes without interrupting traction," says Wüst. “The PDK thereby combines manual and automatic shifting – and takes the best of both worlds," explains Christian Hauck, who is head of alternative drives at Porsche.
For decades, motorsport has been considered the development laboratory for technology that would later be used in series production. “The technology transfer was also exciting for me as a works driver,” says Stuck, who was allowed to test the gearbox at race speed in the Porsche 962 and other cars. “Back then, unlike my colleagues Jacky Ickx, Derek Bell and Jochen Mass, I lived just two hours away from Weissach and was able to be on site frequently and cover important test miles.” The 962 was the first racing car with PDK in the 1980s. In 1986, Stuck drove this race car to its first victory at the Monza 360 km race together with Derek Bell. In the end, both also won the 1986 world championship. In the same year, Stuck took the championship title of the prestigious and highly competitive German "ADAC Würth Supercup" with the 962. During the series for Group C sports car prototypes, which was held for the first time, he used it to test Porsche's then-new PDK dual-clutch transmission at race pace. Thus, despite the PDK's greater weight and complexity, he was able to demonstrate significant advantages in the performance of the PDK principle on the race track.
Initially, Stuck reverted to using a normal gear lever for shifting up and down; it was only later that the idea of fitting two buttons on the steering wheel came about. “Hans-Joachim Stuck was always very interested in technology, he had great fun testing a complicated gearbox. And he believed in the performance benefits of the transmission right from the start. Derek Bell was more likely to complain when he had to drive with it and said that he wanted to win races and not develop technology on the race track,” Wüst remembers. “Every time I see a Porsche with PDK driving on our roads, I’m happy that there’s a bit of ‘Wüst’ in it,” concludes Wüst.
The PDK developed by Porsche was also tested in rallying: Walter Röhrl immediately took first place in the Audi Sport-Quattro S1 with PDK in its first outing at the Semperit Rally at the end of 1985. The advantages of a powershift are particularly significant in rally conditions, as shifting is particularly frequent in a rally vehicle.
At the end of the 1980s, the attempt to transfer the PDK into series production was suspended temporarily, as the company was dependent on the support of the supplier industry. Porsche thus concentrated instead on the manually operated torque converter automatic Tiptronic for production vehicles, which was introduced in November 1989. By 2008, this version had proven itself and was constantly being further developed. The torque converter automatic Tiptronic was used in the 986 and 993 models, among others. In the early and mid-2000s, the performance of the vehicle's electronics had advanced to such an extent and the on-board electronics had also become more sophisticated that the PDK was offered as an optional extra for the 911 series in 2008. A year later, the PDK was introduced as a variant for the standard drive architecture in the Panamera: It was the first Porsche in which the PDK was fitted as standard in some models.
Today, the PDK stands for efficiency and performance in equal measure. The sportiest versions of each Porsche model series are available exclusively with the dual-clutch transmission. The most recent example is the 718 Cayman GT4 RS. Here, on the one hand, the PDK enables the fastest lap times while on the other, it ensures efficient and comfortable driving.
12/15/2021
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