What you need to know about dual-clutch transmissions

METRO MANILA, Updated July 20, 2022 – A dual-clutch transmission (DCT) is an automated manual transmission that provides drivers the best of an automatic and a manual gearbox.

The DCT operates like an automatic, requiring no driver input to shift gears. It’s a type of multi-speed transmission system that employs two separate clutches for odd and even gearsets.

One provides the odd-numbered speeds (first, third and fifth) and the other one provides even-numbered speeds (second, fourth and sixth). The twin transmissions are joined with two clutches and worked cooperatively.

In the mechanical operation of the DCT, Autobytel presented that, “as each gear is engaged to drive the vehicle, the next higher numerical gear is pre-selected so that it can be engaged virtually instantaneously when the transmission’s automatic logic or the driver’s manual selection chooses it.”

Volkswagen, the first producer of DCT in cars, assessed that this transmission can shift gears without interrupting the torque supply to the wheels. The DCT uses clutch parts like manual transmissions rather than the torque converter in automatic.

The clutch is a mechanical part that disconnects the engine from the transmission when shifting gears, so having two of them means that the system will automatically have the next gear ready to engage when shifting up or down the gears. The result is the smoothness and easiness of an automatic transmission and a shifting speed of a manual.

According to Porsche.com, a DCT design is often similar to two separate manual transmissions with their respective clutches contained within one housing and working as one unit. The first-ever produced DCT came out in 1961 in the Hillman Minx mid-size car.

From there, other tractors and manufacturers improved the previous model to become popular and have replaced hydraulic automatic gearboxes in other car models.

How do DCTs operate?

To understand how a DCT transmission functions, it’s imperative to know how manual operates.

In a manual transmission, the driver oftentimes disengages the clutch by pressing the clutch pedal to switch gears. The clutch operates by disengaging the engine’s drive from the driveline so the gears can switch effortlessly. The DCT functions by using dual clutches instead of one that is controlled by electronics and hydraulics.

With that said, the DCT can switch gears faster than manual transmission without interrupting the power supply from the engine to the transmission. Commonly, they are computer-controlled manual transmissions without a clutch pedal but with a simplified PRNDL (park, reverse, neutral, drive, and low) gear selector. DCT transmissions can also be operated through paddle shifters that allow drivers to change gear manually if they like to.

Wet and Dry DCT clutches

Depending on the structure, there are two types of DCT: wet and dry.

A dry transmission is efficient with a simpler structure and smaller in size, but is known to easily wear out when exposed to constant traffic gridlock. It’s more useful in decreasing fuel consumption because of the lack of hydraulic structure.

Meanwhile, a wet transmission is usually more desirable since it doesn’t wear during its lifespan. It has durability for torque engines and it’s bathed in oil to provide cooling for the clutch surface.

Things to avoid while driving DCTs

Dual-clutch transmissions are a relatively newer technology in the car industry.

But just like other types of car models, DCTs also have issues to confront in terms of performance and appear constant across all makes. Below are things you shouldn’t do while driving on a dual-clutch transmission.

Put the car in N during heavy traffic

The driver should switch to D mode. When you put the car in N mode, it’s simply putting more pressure on the brake pedal.

The DCT automatically disengages both clutches if you’ve come to stop or restart and doesn’t burn fuel.

Let off the brake in an incline

By not doing this, the transmission takes the entire load to make sure the car won’t slip on an incline.

This can overheat the internal parts and can damage the transmission.

Use the accelerator on a slope

This will burden or strain the gearbox.

It will produce excessive heat and can prematurely wear the transmission. Using a brake pedal to halt the vehicle is recommended to extract power from the clutches.

Launching the car inappropriately

DCTs can shift faster than regular automatics, but these are wear and tear with improper launching.

The engine will spin the clutch while the brake will do its work and in between both will get strained or pressured.

Taking care of your DCT

The DCT has created a popular interest after top car manufacturers, such as Ferrari and Porsche, adopted it.

Aside from the don’ts discussed above, knowing to refrain from negative driving habits can increase the lifespan of your transmission. Here are some tips for caring for DCTs:

Regular maintenance

The proper way to keep the lifespan of a DCT is to give it periodic servicing from a professional car transmission specialist.

A DCT is very complex and proper care is recommended to keep it running efficiently. Follow the recommended service period as advised in the car manual and never miss the visit to the shop.

Change the fluid and filter

These must be replaced promptly.

Use the appropriate oil for the DCT from authorized dealers to ensure the correct viscosity and is up to operating temperature before further driving. The transmission oil provides not only power transfer, but also heat dissipation.

The filters should also be replaced regularly to prevent damage to the transmission.

Warm up the engine before driving

Always allow the engine and the transmission to heat up for a few minutes before you drive to prevent unnecessary stress.

When these are cold, the mechanical parts will prevent the transmission from shifting. Allowing the engine to heat up between shifts will ensure that every part gets lubricated before driving.

Drive gently

Good driving habit helps prevent premature wear and tear of the vehicle’s components while bad driving will surely strain the transmission and will stress the engine over time. Drive it with care as clutches wear out when accelerating away from a standstill. Avoid hard acceleration during stops and driving particularly when moving uphill.

Advantages and Disadvantages of DCTs

The DCT can take some getting used to.

Most owners who’ve been accustomed to DCTs find themselves comfortable driving as they give them the flexibility to operate the gear shifts manually or let the car move automatically. They’ve been around for quite a while in high-powered performance cars.

But not every new model is perfect. In terms of reliability, most DCTs are fair to good in terms of lifespan. But a common complaint is that they tend to be jerky when changing gears. There is also some slowness in the selection of the next gear, especially when trying to accelerate at lower speeds.

In addition, this type of vehicle can be expensive to buy and costly to repair. Volkswagen had fair success with DCTs, but other makes like Ford had a marked failure in such production. As of 2019, Ford failed to address DCT issues and faced a class-action lawsuit over the defective transmission.

In acknowledging past criticisms, Ford Company, for one, stressed:

(They) are continually working to refine and improve the dual-clutch transmission, so that when it changes gears the sensation won’t be any different from a traditional hydraulic step-gear transmission.

The Future of DCTs

Some auto manufacturers today use DCTs in midsize and large cars. This transmission type is also typical in high-performance vehicles and an emerging design in large-scale production.

However, DCTs are not ideal for heavy-duty pickups. They work best in all cars where fuel efficiency is the goal.

If you’re up to driving a sportier feel, but want the ease of automatic, the DCT transmission is a choice. This gearbox vehicle can be relatively more responsive than automatics or continuously variable transmissions, while delivering comparable fuel economy.

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Automart.PH Senior Content Creator VJ Bacungan contributed to this story.