Key Facts you Need to Know about the Porsche PDK Transmission

If you've ever considered Porsche models as an option when buying a car, you must have come across an unusual abbreviation PDK, when examining Porsche’s specifications. This advanced transmission solution, built in-house, ensures extremely fast gear shifting and found application in numerous Porsche models for a good reason. But what exactly is PDK and how does it work?

What Is a PDK Transmission?

PDK is an abbreviation for Porsche-Doppelkupplungsgetriebe, which can be rendered in English as Porsche double-clutch transmission. As you might have guessed, it’s Porsche’s version of a dual-clutch transmission (DCT) and actually its operational concept is mainly identical to other DCTs available on the market today.

Porsche representative tells about PDK transmission

In fact, PDK is a 7-speed solution developed by Porsche in collaboration with the German company ZF. This sophisticated solution operates in both manual and automatic modes and ensures very smooth gear shifting and lack of power losses.

Historical Background of PDK

The first developments of this transmission date back to the sixties, when the carmaker tried to unlock the potential of its promising technical solutions in motorsports. It took about two decades for Porsche engineers to develop the early PDK version, which debuted in the 956/962 racing program. This solution received many mixed reviews: despite its fast shifting performance, some drivers complained about issues with overcomplicated electronics and hydraulic units of the transmission. Moreover, the first PDK versions were significantly heavier than other transmission solutions used at that time, and the maximum weight reduction of car components has always been a priority in the world of auto racing. These challenges provided Porsche engineers with food for thought and they spent the following years on modification of this promising transmission technology and its adjustment for passenger cars, and subsequently their efforts paid off when in the 2000-s the company finally installed the long-expected transmission on its 997 and 911 models. The PDK was not the first dual-clutch solution on the market, but it gained popularity thanks to its durability and reliability in comparison with DSG solutions.

Design peculiarities and principle of operation.

Released in 2009, the PDK solution challenges the limits of operational characteristics and acceleration parameters by ensuring more rapid gear shifting than traditional transmissions. Moreover, this sophisticated mechanism doesn’t need clutch replacements and ensures more accurate starts from a standstill.

Porsche PDK transmission

So what is the secret of this transmission and why did it find application in numerous Porsche models?

In fact, the PDK transmission consists of two gearboxes combined in one housing. It is logical to assume that the presence of two gearboxes requires two clutches, thus Porsche engineers installed integrated two separate wet clutches operating in the oil bath. They ensure necessary lubrication of transmission components. This dual clutch alternately connects two gearboxes with the engine via two separate drive shafts. Shafts are based on the two-in-one principle. One shaft is hollow and the second shaft is located inside the first one.

In terms of design, one gearbox with its wet clutch is responsible for even gears (2, 4, 6) and an R gear, while the second gearbox controls the engagement of odd gears (1,3,5,7). The gear shifting process is based on the overlap principle, i.e. when the odd gear is engaged, the following even gear gets pre-selected. That is why dual clutch transmissions are also called preselective.

Learn more about PDK transmission operation

Thus, the engine power flow is constantly transmitted via one gearbox and one wet clutch, while another gearbox pre-selects the next gear. As a result, to shift to the following gear the PDK transmission has to lock one clutch and simultaneously unlock the other one. Therefore, the process of shifting from one gear to the next gear occurs within milliseconds.

The total number of gear in the PDK transmission is 7. Top speed is achieved on the 6-th gear, while the 7-th gear with a high gear range helps to reduce fuel consumption. The gear shifting can be implemented automatically or manually with the help of special paddle shifters.

Manual vs. PDK

Due to its complex design, the PDK transmission is 30 kg heavier than its manual 7-speed analog.

State-of-the-art technical solutions implemented in this transmission allowed achieving the following:

• Unmatched gear shifting speed;
• Improved fuel efficiency in comparison with classic automatics;
• High smoothness of gear shifting.

When it comes to drawbacks of this transmission, it should be noted that this transmission is quite expensive and it is considered almost irreparable due to its structural complexity. If the PDK transmission gets out of order on a non-warranty car, then the owner will have to pay up to 1/3 of the cost of a new car for the new transmission unit and its installation. Similar to a conventional automatic transmission, the PDK unit has a traditional economy running mode(D) and a sport mode (S). When the sport mode gets engaged, the engine RPM aims to achieve high limit values, and the 7-th gear gets blocked. In the Sport Chrono Plus package, the PDK is completed with additional features “Launch Control” and “Performance Start”. To use the Launch Control function, it is necessary to depress the brake pedal, and press on the gas pedal. When the engine RPM reaches more than 3000 RPM, it is necessary to release the brake pedal and the car will accelerate abruptly from stop.

8-speed PDK for hybrids

8-speed hybrid PDK transmission

Nowadays, due to constant toughening of environmental restrictions, major automakers gradually shift to environment-friendly technologies investing significant financial resources to development of hybrid and electrical drivetrain components, and Porsche is not an exception. After a huge success of the 7-speed PDK model, Porsche engineers designed an 8-speed version for its Panamera model, which has hybrid as well as non-hybrid application. The new product incorporates the original system's swift gear shifting capacity with more compact design, a higher torque limit (737 ft-lbs) and an extra gear for the next-gen of cars and fuel economy.

The hybrid unit is embedded straight into the dual-clutch casing. The 8-speed solution affords 3 overdrive ratios for enhanced efficiency, and the Panamera reaches its maximum speed in 6-th gear. Both the 7-th and 8-th gears have a longer ratio for the purpose of keeping the RPM rate low at high speeds. This solution makes the Panamera both faster and more efficient than ever before.

PDK vs. Manual

In contrast to a manuals, the PDK solution ensures more rapid speed ups as well as greater operational flexibility. A driver can shift gears manually with the help of paddle-shifters and fully automatically when it is required to focus on the road. Owners of Porsche models equipped with the PDK gearbox also can enjoy the following benefits:

• Swift gear shifting
• Improved fuel economy
• Better driving experience
• High durability of the unit

Reliability

The PDK transmission is quite reliable in comparison with other dual-clutch transmissions, but the service life of this unit directly depends on regular maintenance servicing and compliance with operation rules specified by the automaker. Regular ATF changes are a must, if you want to avoid premature wear-out of costly transmission components. The best way to guarantee that the PDK transmission will not fail before its time is to monitor the ATF condition and never forget about regular maintenance services.

PDK Repair

The PDK is a sophisticated piece of machinery, but quite a pricy one. Therefore, to minimize potential financial losses related to the repair and maintenance of this gearbox, it is necessary to know when it’s a high time to visit the nearest repair shop. In most cases, Porsche drivers start having issues with the PDK unit because of insufficient fluid level. Thus, it is required to check the ATF condition timely and to change it when you notice any signs of fluid contamination. If you notice a puddle of fluid under your car, it’s probably leaking. Other common signs of malfunction you have to keep in mind are the following:

• Illuminated warning lights
• Unusual smells
• Delays in gear shifting
• Uncommon grinding noises

All in all, this advanced transmission has no significant weaknesses, except its high price and issues with repair. This transmission allows owners of Porsches to realize the full potential of the car’s performance capacity and to enjoy the process of driving.