If you’ve read about, shopped for or driven a Porsche in the past decade, you’ve probably heard of the brand’s PDK dual-clutch transmission. PDK shifts faster than other types of transmissions, includes a launch control feature and, even better, doesn’t need clutch replacements — ever. But what exactly is PDK and how does it work?
The 2009 Porsche 911 was the first to offer a PDK transmission option.
PDK is an acronym for Porsche Doppel Kupplungs getriebe (strictly, Porsche-Doppelkupplungsgetriebe), which translates to Porsche double-clutch transmission. As the name suggests, it’s Porsche’s version of a dual-clutch transmission (DCT) and fundamentally operates in the same way as other DCTs on the market today.
A DCT is more similar to a manual transmission than a traditional automatic, but instead of one clutch engaging with a flywheel, two separate clutches work together. A PDK gearbox uses hydraulically actuated wet-clutch packs, one enveloped around the other. One clutch connects reverse, first, third, fifth and seventh gears, the other handles second, fourth and sixth. As opposed to a clutch pedal on the floor, an electronically controlled valve body actuates the correct clutch when it’s needed. The PDK only engages one clutch at a time. However, because gear sets alternate between clutches, as one disengages the other can engage in one fluid motion.
The internal gears and clutch pack of a PDK transmission. Blue highlights which gears the clutch operates.
The internal gears and clutch pack of a PDK transmission. Green highlights which gears the clutch operates.
Think of a PDK like a seven-person Olympic relay race team. By the time one runner nears the end of his stint, another gets up to speed separately and is ready to begin, so the baton is effectively handed off instantly, with no loss in speed. And just like perfectly nourished and hydrated athletes, the oil-soaked wet-clutches don’t overheat or wear out under pressure. That’s how Porsche avoids damaging parts with launch control. Rev the engine to a high-power point and slip the clutches to get maximum torque to the wheels without spinning them. It’s stunningly effective.
As do so many automotive innovations, PDK got its start in racing because its faster shifts meant quicker lap times. Fuel efficiency gains were coincidental, but also consequential because over time the design started replacing traditional automatic and manual transmissions in Porsche cars, even the driver-focused GT3.
Objectively, you can’t argue with PDKs. But enthusiasts want more than the objective. So we fought the trend and, in the case of the GT3 at least, won. Why? As Lingeman said in his 911 GT3 review, “… even with my penchant for lap times, I’d still pick the zero-dollar 6MT option. It. Just. Feels. Right.”
Robin Warner – Robin Warner is Editorial Manager at Autoweek. He once tried and failed to become a professional race car driver, but succeeded in learning about debt management and having a story to tell. A former engineer, Warner loves cars for their technology and capability.
See more by this author»