Double clutch - what are the advantages and features of the repair

Slow gear shifting was once a major problem, especially for racing cars. cars. Many engineers puzzled over this question until Adolf Kegresse suggested using a pair of boxes in parallel in the 30s. But in practice, a dual clutch was first installed only in 1982 on the Porsche 956 racing car. The system was launched into mass production for passenger cars in 2003 at VW plants under the DSG brand. In 2011, Mitsubishi was the first to equip a truck with a dual-disc robot. Thus, the dual clutch gradually conquered the car market. And today it is installed on cars of such well-known manufacturers as Ford, BMW, Porsche, Mercedes, Audi, Mitsubishi, VW.

Operating principle

In simple terms, in the case of a dual-clutch gearbox there is a pair of conventional mechanical boxes that work alternately. The design has 2 shafts (internal and external). Unlike the "automatic", there is no torque converter.

The system can "boast" of the rudiments of intelligence: as soon as the first gear is turned on, the second one is immediately prepared. At the same time, one “semi-box” is responsible for even gears, the other for odd ones. When switching, the first clutch opens and the parallel one starts to work. The electronic unit takes into account:

• ✅ speed of the transmission shaft
  
• ✅ the position of the gas pedal and gear lever
  
• ✅ wheel speed
  

At the moment of shifting, both the first and second clutches remain connected to the engine for a fraction of a second. That is, it is still connected to the drive axle. Therefore, jerks and failures are absent. Switching and all related “procedures” take no more than 0,2 seconds. Manufacturers produce 2 types of double clutch designs.

"Wet" transmission

An example is the DSG 6 from VW. Here all nodes are placed in an oil bath. Thanks to this solution, there is a rapid cooling and a decrease in friction of the contacting parts, which slows down their wear. "Wet" dual clutch is most often installed on powerful cars with high torque (more than 250 N * m). These are sports cars and less often - "civilian" cars.

"Dry" clutch

There is no oil bath in the box, cooling can be difficult - heat is removed only by dissipation. But there are a number of advantages. The first of these is the simplicity of the design, associated with the absence of an oil pump that consumes energy and reduces engine power. Other advantages follow from this advantage - compactness, relatively low weight (70 kg versus 91) and higher efficiency. But due to difficulties with cooling, the design is installed on machines with a small torque.

Advantages and disadvantages of dual clutch

The first plus is the smoothness of gear shifting: there are no usual twitches, jerks and gas release. The next argument in favor of dual clutch is reduced fuel consumption, reaching 10% (when compared with a 5-speed "automatic"). This became possible due to the continuity of the transmission of torque from the motor to the transmission. It is also worth noting the improved dynamics without power failures during straight-line acceleration. The dual clutch is ideal for cars with engines between 200 and 500 hp. With. And the last plus is the ability for the driver to choose manual or automatic switching modes.

And what about the cons? The double clutch lasts a long time, but the time comes and its components wear out or an “unscheduled” breakdown occurs. That's when the owners of cars with such a transmission begin to have problems. Firstly, it is not easy to find a specialized car service that is ready to take on such repairs. Secondly, not only it, but also maintenance is expensive. And thirdly, the high cost of parts and assemblies. But manufacturers are looking for a way out of this situation. For example, Schaeffler offers its own double clutch repair technology called LuK RepSet 2CT. These are special tools, training, seminars, etc. Simpler car services can solve the problem in their own way - for example, offer the client a contract (used) mechanism.

Dual clutch service life

The transmission resource is influenced by many factors. The first is the type of machine. On SUVs and premium sedans that are under heavy load, it is worth thinking about repairing the clutch earlier than owners of ordinary cars. A wet, oil-cooled transmission will last longer than a dry one. Poor maintenance and constant driving in the city with its traffic jams and frequent gear changes will not add a resource. Aggressive driving style negatively affects the durability of the double clutch. Plus, it is worth considering the state of Russian roads. According to dealers, dual clutch problems can start after 60-80 thousand km of run. But in most cases, wear of parts becomes serious at around 100-150 thousand km. How much does a double clutch repair cost?

DSG 6 and DSG 7

This transmission is installed on vehicles manufactured by the VW Group. Brands "Volkswagen", "Skoda" and others. The most common causes of DSG 6 wet clutch failure are:

• ✅ wear of friction clutches
  
• ✅ destruction of bearings
  
• ✅ failures in the electronic unit
  

The cost of the original DSG 6 clutch is around 27-32 thousand rubles. Add here the work of removing, installing, adapting (16-18 thousand rubles), a set of gaskets, filters and oil (VAG. 1 l - 2400 rubles, full refueling 6,9 liters, total 16 thousand rubles). That is, the minimum cost is 60 thousand rubles.

For the repair of DSG 7, prices are also not very attractive. For example, the cost of a clutch kit 0AM 198 142 AA averages 43-47 thousand rubles, but there is another, inexpensive set - DSG-7 SACHS 3000943001, which will cost 43-44 thousand rubles. The cost of work (with removal, installation, adaptation) is 8-9 thousand rubles. Total: at least 51 thousand rubles.

Dual clutch on a Ford

It was named Power Shift and has been installed on cars since 2007. Among other companies that also use this transmission are Volvo, Jaguar, Mazda. The 6DCT450 clutch is "wet". If the faults are minor, it will be repaired without removing it. The cost of work in this case is from 15 to 19 thousand rubles. Dismantling the gearbox and installing it will add another 11 thousand. The final cost depends on the parts being replaced. But if you decide to change the clutch assembly, a complete set, for example, on YandexMarket, will cost 75-90 thousand rubles.

Mitsubishi

Here prices are not the same as in previous cases. For example, for Mitsubishi Lancer, the LuK 620316900 clutch kit costs 14-15 thousand rubles, and LuK 623356809 is already 43-44 thousand. There is also a cheaper option - the KraftTech W20200F kit for the same model costs from 5-6 thousand rubles. (bearing, basket and disk). The cost of repairing the clutch, which includes removal / installation, cleaning, is 8-9 thousand rubles. If you take the clutch kit from LuK, the cost of repairs can be 53 thousand rubles. and more. If you do not need a set, but some individual parts, the amount may decrease - it all depends on the manufacturer.

BMW

A clutch kit from LuK for models 320i (factory index E36), 520i (E34) will cost 24-25 thousand rubles. If you only have to change the clutch disc, Sachs offers an inexpensive option for the BMW 5, 6 and 7 series - 7,5-8 thousand rubles. A set from Edel Racing, which includes a pair of sintered metal-ceramic discs with a diameter of 215 mm, will cost 53-54 thousand rubles. However, the original complete set of double clutch costs from 107 thousand rubles. and higher. For example, GS7D36SG wheels from Even cost 129 thousand rubles. Work on replacing the clutch assembly will cost 8,5-9,5 thousand rubles.



As you can see, the price of repairs on different brands of cars depends heavily on the number of parts purchased and their manufacturer. The cost of replacing the double clutch is approximately the same - from 8 to 9 thousand rubles. The exception is Ford - up to 15 thousand rubles.