If you've ever considered Porsche models as anoption when buying a car, you must have come across an unusual abbreviationPDK, when examining Porsche’s specifications. This advanced transmissionsolution, built in-house, ensures extremely fast gear shifting and foundapplication in numerous Porsche models for a good reason. But what exactly isPDK and how does it work?
What Is a PDK Transmission?
PDK is an abbreviation forPorsche-Doppelkupplungsgetriebe, which can be rendered in English as Porschedouble-clutch transmission. As you might have guessed, it’s Porsche’s versionof a dual-clutch transmission (DCT) and actually its operational concept ismainly identical to other DCTs available on the market today.
Porsche representative tells about PDK transmission
In fact, PDK is a 7-speed solution developed byPorsche in collaboration with the German company ZF. This sophisticatedsolution operates in both manual and automatic modes and ensures very smooth gearshifting and lack of power losses.
Historical Background of PDK
The first developments of this transmissiondate back to the sixties, when the carmaker tried to unlock the potential ofits promising technical solutions in motorsports. It took about two decades forPorsche engineers to develop the early PDK version, which debuted in the956/962 racing program. This solution received many mixed reviews: despite itsfast shifting performance, some drivers complained about issues with overcomplicatedelectronics and hydraulic units of the transmission. Moreover, the first PDKversions were significantly heavier than other transmission solutions used atthat time, and the maximum weight reduction of car components has always been apriority in the world of auto racing. These challenges provided Porscheengineers with food for thought and they spent the following years onmodification of this promising transmission technology and its adjustment forpassenger cars, and subsequently their efforts paid off when in the 2000-s thecompany finally installed the long-expected transmission on its 997 and 911models. The PDK was not the first dual-clutch solution on the market, but itgained popularity thanks to its durability and reliability in comparison withDSG solutions.
Design peculiarities and principle ofoperation.
Released in 2009, the PDK solution challengesthe limits of operational characteristics and acceleration parameters by ensuringmore rapid gear shifting than traditional transmissions. Moreover, this sophisticatedmechanism doesn’t need clutch replacements and ensures more accurate startsfrom a standstill.
Porsche PDKtransmission
So what isthe secret of this transmission and why did it find application in numerousPorsche models?
In fact,the PDK transmission consists of two gearboxes combined in one housing. It islogical to assume that the presence of two gearboxes requires two clutches,thus Porsche engineers installed integrated two separate wet clutches operatingin the oil bath. They ensure necessary lubrication of transmission components. Thisdual clutch alternately connects two gearboxes with the engine via two separatedrive shafts. Shafts are based on the two-in-one principle. One shaft is hollowand the second shaft is located inside the first one.
In terms of design, one gearbox with its wetclutch is responsible for even gears (2, 4, 6) and an R gear, while the secondgearbox controls the engagement of odd gears (1,3,5,7). The gear shifting processis based on the overlap principle, i.e. when the odd gear is engaged, thefollowing even gear gets pre-selected. That is why dual clutch transmissionsare also called preselective.
Learn more about PDK transmission operation
Thus, the engine power flow is constantly transmittedvia one gearbox and one wet clutch, while another gearbox pre-selects the nextgear. As a result, to shift to the following gear the PDK transmission has tolock one clutch and simultaneously unlock the other one. Therefore, the processof shifting from one gear to the next gear occurs within milliseconds.
The total number of gear in the PDK transmissionis 7. Top speed is achieved on the 6-th gear, while the 7-th gear with a highgear range helps to reduce fuel consumption. The gear shifting can be implementedautomatically or manually with the help of special paddle shifters.
Manual vs. PDK
Due to its complexdesign, the PDK transmission is 30 kg heavier than its manual 7-speed analog.
State-of-the-arttechnical solutions implemented in this transmission allowed achieving thefollowing:
- Unmatchedgear shifting speed;
- Improvedfuel efficiency in comparison with classic automatics;
- Highsmoothness of gear shifting.
When it comes to drawbacks of thistransmission, it should be noted that this transmission is quite expensive andit is considered almost irreparable due to its structural complexity. If thePDK transmission gets out of order on a non-warranty car, then the owner willhave to pay up to 1/3 of the cost of a new car for the new transmission unitand its installation. Similar to a conventional automatic transmission, the PDKunit has a traditional economy running mode(D) and a sport mode (S). When the sportmode gets engaged, the engine RPM aims to achieve high limit values, and the7-th gear gets blocked. In the Sport Chrono Plus package, the PDK is completedwith additional features “Launch Control” and “Performance Start”. To use theLaunch Control function, it is necessary to depress the brake pedal, and presson the gas pedal. When the engine RPM reaches more than 3000 RPM, it isnecessary to release the brake pedal and the car will accelerate abruptly fromstop.
8-speed PDK forhybrids
8-speed hybrid PDK transmission
Nowadays, due to constant toughening of environmentalrestrictions, major automakers gradually shift to environment-friendlytechnologies investing significant financial resources to development of hybridand electrical drivetrain components, and Porsche is not an exception. After ahuge success of the 7-speed PDK model, Porsche engineers designed an 8-speedversion for its Panamera model, which has hybrid as well as non-hybridapplication. The new product incorporates the original system's swift gearshifting 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 isembedded straight into the dual-clutch casing. The 8-speed solution affords 3overdrive ratios for enhanced efficiency, and the Panamera reaches its maximumspeed in 6-th gear. Both the 7-th and 8-th gears have a longer ratio for thepurpose of keeping the RPM rate low at high speeds. This solution makes thePanamera both faster and more efficient than ever before.
PDK vs. Manual
In contrast to a manuals, the PDK solutionensures more rapid speed ups as well as greater operational flexibility. Adriver can shift gears manually with the help of paddle-shifters and fullyautomatically when it is required to focus on the road. Owners of Porschemodels equipped with the PDK gearbox also can enjoy the following benefits:
- Swift gear shifting
- Improved fuel economy
- Better driving experience
- Highdurability of the unit
Reliability
The PDK transmission is quite reliable incomparison with other dual-clutch transmissions, but the service life of thisunit directly depends on regular maintenance servicing and compliance with operationrules specified by the automaker. Regular ATF changes are a must, if you wantto avoid premature wear-out of costly transmission components. The best way toguarantee that the PDK transmission will not fail before its time is to monitorthe 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 lossesrelated to the repair and maintenance of this gearbox, it is necessary to knowwhen it’s a high time to visit the nearest repair shop. In most cases, Porsche drivers start havingissues with the PDK unit because of insufficient fluid level. Thus, it isrequired to check the ATF condition timely and to change it when you notice anysigns 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 inmind are the following:
- Illuminatedwarning lights
- Unusualsmells
- Delays ingear shifting
- Uncommon grinding noises
All in all, this advanced transmissionhas no significant weaknesses, except its high price and issues with repair. Thistransmission allows owners of Porsches to realize the full potential of the car’sperformance capacity and to enjoy the process of driving.
