Dual-clutch transmission: What is it and how does it work?

What is dual-clutch transmission?

In the not too distant past there were two types of transmissions for a car - manual or automatic. 

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These types of transmissions are known by many names, including dual-clutch automatic, twin-clutch transmission, DCT, PDK, DSG, EcoShift, Powershift and many other acronyms and branded names, but they all work the same way.

In this story we’ll explain what a dual-clutch transmission actually is, tell you how does a dual-clutch transmission work and answer the question ‘is dual-clutch transmission good?’

What does dual-clutch mean?

It means the transmission has two clutches instead of one. In a manual transmission, there is a clutch that must be disengaged so the next gear can be selected. The dual-clutch, as the name says, uses one clutch to work with the odd gears and a second clutch to use the even gears.

How does dual-clutch transmission work?

The two clutches work independently of each other. So, a dual-clutch transmission that starts in first gear will already have second gear selected by the second clutch, and when the time comes to change from one gear to the next, the first clutch simply disengages and the second one engages.

This allows for faster, smoother gear changes than a conventional automatic gearbox while also making it more efficient, which helps to save fuel.

What is the history of dual-clutch transmission?

While the manual and automatic were the dominant transmission until the early 2000s, the dual-clutch transmission actually dates back to the 1930s.

French engineer Adolphe Kegresse is credited with working on the concept in 1939 for a Citroen. In 1961 the Hillman Minx used the first production version of a DCT but it quickly disappeared.

Porsche then began working on the concept again in the 1980s, specifically for its Le Mans racing cars, the idea being that a dual-clutch transmission could help reduce both turbo lag and fuel economy. 

However, the dual-clutch transmission as we know it today really began in 2003 when the Volkswagen Golf R32 used it and helped popularise the technology.

How does it differ from other types of transmission?

A dual-clutch transmission vs a manual is actually closer than you might think, or at least is the closest you can get in terms of how it works.

Obviously, a manual only has a single clutch and the driver changes gears themself, but it works using a clutch rather than a torque converter (like an automatic).

A DCT has two clutches and can change automatically, but can be operated manually by the driver, too, in most cars. 

A dual-clutch transmission vs automatic may seem similar but the torque converter is a very different method of changing gears. It isn’t as fast or as efficient as a DCT.

Finally, a dual-clutch transmission vs CVT is complex to explain, as a CVT is a dramatically different type of transmission which uses a belt and pulley system rather than gear cogs.

Theoretically a CVT provides better fuel efficiency but a DCT offers fuel economy benefits while also offering faster, smoother gear changes.

Are there any dangers or things to look out for?

Common dual-clutch transmission problems include jerkiness and hesitation at low speeds if they aren’t calibrated properly. This was a particular problem with earlier examples of the technology.

It is also a more complex technology. Two clutches create potential for twice as many problems, with some earlier examples having major reliability issues.

Few were more high-profile than Ford and its 'Powershift DCT' that suffered problems between 2011 and 2018 and resulted in a class action lawsuit that went to the High Court in 2024.

What kinds of cars use dual-clutch transmissions?

Originally cars with dual-clutch transmission were sporty models, like the Ferrari 458, Nissan GT-R and VW Golf R32. But over time, as the technology has been refined it has spread across dozens of models in a wide variety of shapes and sizes. You can find a DCT in everything from supercars to hatchbacks and even trucks.