A faulty software program was the culprit of the gear selection issue, while the jerkiness may be innate to the car or due to manufacturing clearances that push the transmission too much. Moreover, people found the transmission to be harsher than expected, with others experiencing quite a bit of slippage. A recall has been issued in South Korea, because the transmission refused to use the odd-geared shaft, hence being stuck in the second, fourth, and sixth. Volkswagen recalled 1.6 million cars fitted with a dual-clutch transmission in 2013, while Kia had a bunch of issues with their dry 7-speed DCT transmission quite recently. There has been a myriad of issues across the years regarding them. Problems With DCTsĪ problem with dual-clutch transmissions is that they can be quite finicky. There are also some other nuances, like how a wet clutch has multiple discs, while a dry clutch is a manual transmission clutch, or how these wet clutches need their oil changed occasionally. That’s the case since a wet clutch is covered in a film of oil that provides better heat dissipation, thoroughly needed when engines surpass 500 bhp. Wet clutches can withstand more torque, hence they’re common on powerful sports cars. The main difference between the two is, apart from the engineering behind building the clutch, how much torque they can handle. Dry and Wet Clutchesĭesign-wise, they come in two similar variants: dry clutches and wet clutches. ![]() This can happen to the most basic of tasks. An extreme example would be you trying to upshift while slowing down. If your car guesses the wrong gear, it will take a while until the proper gearshift takes place, resulting in an annoying bog-down and a seeming lack of response. The car’s computer tries to predict what gear you may need and prepare said gear beforehand to minimize shift times. However, choosing the gear is challenging and is a significant bother for several dual-clutch transmission owners. This can happen in a few tenths of a second. This process can be so fast that one clutch doesn’t need to disengage fully so that the second clutch can engage. Seeing how we have two clutches, whenever we choose to disengage one clutch, the other one can engage at precisely the same time, thus having little to no downtime in between shifts. What makes dual-clutch transmissions special is how fast they can shift and how they can shift under load. It all depends on the engine’s power, the platform’s available volume, and the car’s architecture. Whatever the design choice may be, once the force reaches the output shaft it will eventually reach the wheels. These two input shafts can have their output shaft or share the same one. This is the core of a dual-clutch transmission.įurthermore, some particularities depend on the manufacturer and the goal. Usually, the odd-geared shaft is solid, while the even-geared shaft is hollow and houses the odd-geared one. Thus, they can share the same space and the same rotation axis but rotate at different speeds. One input shaft is solid, while the other is a hollow shaft that houses the solid one. These two manual transmissions, even if it may look like they have the same input shaft, they don’t. ![]() ![]() Input and Output ShaftsĪs we know, transmissions have an input shaft that is connected to the engine and the clutch, and an output shaft, that goes to the wheels. However, its internal design is a bit more complicated, even if they truly are two manual transmissions stuck together and electronically controlled. That’s because the shifts are electronically controlled thus the clutches take care of themselves. Seeing how we have two manual transmissions, we have two clutches, hence the dual-clutch transmission name. Thus, each manual gearbox has all its explicit components, like synchronizers and, more importantly, a clutch. One manual gearbox takes care of the odd gears, while the other one takes care of the even gears. Design-wise, a dual-clutch transmission is two manual gearboxes combined into one. Two Manuals Equal One DCT Schematic diagram of a type of dual-clutch gearbox: M: Motor A: Primary drive and driving shaft B: Dual-clutch C: Driven shaft D: Layshaft, hollow, even gears E: Layshaft, odd gears F: Outputĭual-clutch transmissions aren’t all that complicated, at least, conceptually.
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