Dual Clutch Transmissions (DCT) are still a relatively rare breed, though in the past few years we have been inundated with them in high end automobiles. By using a separate clutch for odd and even gears, gears can be changed without interrupting power by applying the engine's torque to the next gear just as it is being disconnected from the previous one. This enables quicker and smoother gear changes and delivers better fuel economy while reducing emissions. Honda’s newly-announced, fully-automatic motorcycle DCT is a first for large-displacement sport bikes and will debut on the new VFR set for release in 2010.
Honda’s DCT is light and compact, making it suitable for use with existing engines without substantial layout modification. Not surprisingly, the simultaneous feeding in and out of the power to each clutch is done electronically, offering the precise acceleration control necessary for motorcyles with their limited cornering tire adhesion. What it will be like to ride with such a set-up is still unknown, but theoretically, the smooth, seamless gear changes should enable greater stability downchanging for corners under brakes, gear changing through the apex, and smoother exiting of corners – all likely to get you through a corner faster and smoother.
Honda seems completely confident that its new internally-developed transmission (with more than 100 patents pending) will not only be better, but that it will be embraced by the motorcycle community as it intends to introduce the DCT to more of its large-displacement motorcycles, particularly sports models destined for use in developed countries. It certainly would not be committing to such a radical change in its premium sports motorcycles unless it was convinced of the benefits and ease-of-use, as the new technology impacts the most critical area of safety and enjoyment of riding a motorcycle.
In order to suit a variety of riding styles, the transmission is equipped with three operating modes, two full-auto modes (D-mode for regular operation and S-mode for sporty riding); and a six-speed manual mode, which delivers the same shift feel as a manual transmission.
The new transmission features a Dual Clutch Transmission configuration in which independent clutches are employed for the odd gears (first, third, fifth) and the even gears (second, fourth, sixth), respectively. The two clutches operate alternately to effect gear changes. For example, when changing from first to second gear, the computer detects the up-shift and engages second gear, then releases the first-gear clutch while engaging the second-gear clutch to achieve a seamless gear change.
While some dual-clutch transmissions tend to be bulky, the new system employs original technologies such as dual input shafts, exclusive in-line clutch design, and concentration of hydraulic circuitry beneath the engine cover to achieve a compact design. Compactness and lightness is further enhanced through the use of a simple shift mechanism design based on that of a conventional motorcycle shift drum. Optimized shift scheduling achieves fuel economy equal to or better than that of a fully manual transmission, enabling the Dual Clutch Transmission to deliver both sporty riding and environmental performance combined.