Derek Bell on Porsche's New PDK Dual-Clutch Transmission
We sat down with former Porsche factory driver Derek Bell to discuss the Porsche's new dual-clutch transmission. PDK (which stands for Porsche Doppelkupplungsgetriebe, or "Porsche double-clutch gearbox" in English) is being offered for the first time in a road car on the 2009 911.
Porsche is finally building a road-version of the PDK transmission. What are your memories of the system in racing?
Porsche was always developing something new so you had to be prepared for that. That was part of the excitement of driving for Porsche. Generally, when they introduced something it was always an advantage. For me, it started when we went to electronic instead of mechanical fuel systems. It was difficult to drive at first but then they of course perfected it and it was a heck of an advantage. When it came to PDK, it was a similar situation. I believe I first ran it at a test at Paul Ricard and the principle was brilliant; just keep pulling the lever back and it will drop into the next gear. We picked up time, without a doubt. The big help was that you didn't have to depress the clutch; you could keep your foot on the footrest, supporting your body. Helpful in a car that can pull such g's in a corner. But it didn't often happen the way it was supposed to. It added a lot of extra weight. I have to say, it felt like you had a trailer on the back. We tried to persevere with it but the system just wouldn't last a 1000-km race. I'd use it with [Hans] Stuck in the shorter races. Also, it [PDK] nearly cost me the World Championship in 1986 [see below]. But Porsche would stick to something because that's what they had to do. They would just make us develop this darn stuff, in spite of the fact that you weren't going to win races or championships. Stucky and I did win the 1986 race at Monza with it [PDK].
How did the system function in the car?
At first, we had a lever that moved forward and back and then they moved it up onto the steering wheel and we used buttons. You just used the foot clutch when coming to a rest or pulling away. It worked basically like a modern sequential box. The biggest thing to us [the drivers] wasn't the time it saved but it took away the worry of grinding gears. Thirty to forty percent of the worry of winning long races was if you were going to destroy the gearbox [with bad shifts].
Talk about your experiences with PDK in Group C racing.
At the last race of 1986, the 1000 kms at Fuji, the cars had both PDK and ABS brakes. I didn't even know we were developing ABS. So now, all this kit made the car even heavier! I threw a wobbly [a fit], something I only did once before, during the development of electronic fuel systems. I remember saying to Peter Falk [director of racing] this is ridiculous. The public can't understand that we're sitting behind other cars just because we're developing something. They come here to be entertained. So Peter called up Professor Bott [Peter Bott, board member for research and development] to tell him that I was throwing a wobbly. He said that I have to run one of the systems, PDK or ABS brakes. It was frustrating as I kept walking past the truck that had the standard five-speed gearbox inside knowing that I could be world champion with that box but I can't with PDK. I said fine, I won't go with ABS but I'll go with PDK. Of course, it rained the whole time [ABS would have been nice] and the driveshaft [halfshaft] broke on the gearbox. They had gotten very good at changing driveshafts by this point! I did end up winning the championship for the second year in a row due to a finishing position I got earlier in the year at the Norisring.
Given all of this, are you surprised to see PDK on a road car today?
Nothing is a surprise with Porsche. They have such a good group of engineers who do things for such good reasons. It's a wonderful system and I'm sure it doesn't add a ton of weight. I'm sure no one is going to complain about it and people will win races with it. Sure, it's twenty-some years down the road but they haven't been sitting on their thumbs.