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Honda’s DCT Challenges & Success 10 Years After Its Debut

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Honda-dual-clutch-transmission-dct-10-ye

Honda is celebrating a new milestone, reaching a full decade since its Dual Clutch Transmission (DCT) technology debuted in its two-wheeled product lineup. Having first appeared in dealerships on the VFR1200F sport tourer, DCT is now offered in several other Honda motorcycles including their most popular adventure bike—the Africa Twin. 

Although automatic transmission is shunned by many motorcycle riders, Honda has seen enough demand for the technology to justify its continued application. In 2019, 45% of Africa Twins, 52% of NC750X’s and 67% of Gold Wings sold in Europe were the DCT version, accounting for a significant portion of the sales of models offered with the option. Overall, Team Red has sold over 140,000 machines in Europe alone.

Honda Dual-Clutch Transmission hits decade mark

Its success has been in large part due to a constant evolution of the technology, with refinements to the smoothness and timing of the gear shifts, and adaptations to match the riding characteristics required of a broad range of models. Examples include an off-road-focused G switch addition for the Africa Twin, and synchronization with Hill Start Assist, Walking Mode and Idling Stop on the flagship GL1800 Gold Wing luxury tourer.

Honda Dual-Clutch Transmission evolution
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Some of the benefits of DCT Honda highlights are that it allows the rider to focus more on their riding line, braking points, cornering and acceleration. Other advantages include reduced rider fatigue, no stalls and greatly reduced pitching of the motorcycle during gear changes.

Simply explained, DCT is an automated, electro-hydraulic clutch and shift operation gearbox. A pair of independent clutch packs are connected to separate gear sets; one clutch works with startup, 1st, 3rd and 5th gears, the other with 2nd, 4th and 6th. Shifting can be done manually by using the paddle-shifters; or in Automatic mode by software triggers based on vehicle speed, engine rpm and throttle opening angle. During a gear change, as one clutch disengages, the other simultaneously engages the target gear to ensure an ultra-fast and seamless shift, with no loss of drive to the rear wheel.

Honda DCT is used in several motorcycle models

The driving force behind Honda’s DCT technology is Dai Arai, who joined Honda in 1999. Here is what Arai has to say about its application and the challenges faced over a decade of developing DCT for bikes:

What is the origin of DCT?

Before my time at Honda, there were other automatic transmissions such as the ‘Hondamatic’ gearbox in the 1970s which relied on a torque converter, and the Human Friendly Transmission on the DN01.

So before the VFR1200F came with the first DCT, the idea of making an automatic transmission was around for many years.

The big difference with DCT is that it involves much less losses than the previous systems, so it gives a much more direct and sporty feeling.

What was the hardest problem to solve?

Everything on the development of the very first DCT for the VFR1200F was a real struggle.

No-one had ever done it before, so it was so difficult from both the hardware and software point of view. It was really the first time transmission engineers had been involved in electronic controls.

Honda-dual-clutch-transmission-dct-10-ye

With the hardware, we had to develop a crankshaft case that could be used for both DCT and manual transmission engines, to allow us to prepare MT and DCT variants in the same frame. So we used two mainshafts with one inside the other to keep the package compact. Giving that small package the required strength and durability was a big challenge.

There was also the challenge of reducing the noise of the gear shift. Because the gear mechanism itself is the same as a manual bike, the DCT makes the exact same ‘pre-engagement’ noise from the gear dogs as on a manual shift. For some riders, hearing this shifting sound in automatic modes without the normal ‘manual’ inputs into a gear change could sound strange, so reducing that sound was a big extra challenge. 

On the software side, programming the gear shift schedules for this new kind of technology was a real challenge. No-one had attempted to make such a system, and it takes thousands of hours to come up with the right programmes for the shift schedules.

What do you think has been the biggest single improvement throughout the decade of DCT?

It’s not possible to pinpoint one particular change as most important. That’s because the system has evolved consistently over the decade, with different changes being introduced that not only improved DCT itself, but also made it bring out more and more the different riding characteristics required of each different model.

One of the first big steps was the automatic return to Automatic mode if you used the manual triggers as an override to select a gear. It’s a lot of programming to make the return to automatic as intuitive as possible, because you have to calculate the riding situation and therefore the rider’s intention – was it a downshift coming into a tight corner, a downshift to overtake on a straight road, etc. It’s not just a question of returning the system to Automatic after a certain number of seconds.

Later, we refined the way that the throttle blips on the downshift to accurately match the revs and make those shifts really smooth. These changes involved a lot of synchronization with the PGM-FI fuel injection controls.

We also introduced the ‘Adaptive Clutch Capability Control’ which uses the electronic control of the DCT system to ‘slip’ the clutch a little when the throttle position is changed initially from a fully closed or fully opened position. That really helped smooth out the bike behaviour.

Honda-dual-clutch-transmission-dct-10-ye

On the other hand, the ‘G’ switch introduced on the CRF1000L Africa Twin and later the X-ADV reduces the amount of clutch slip to give a more direct feeling for rear wheel traction. Especially off-road, this can allow riders to do controlled slides.

We’ve also linked the system with riding modes thanks to Throttle by Wire on the Gold Wing, which also helps to shorten the shifting time.

And on the latest CRF1100L Africa Twin, linking with the IMU really helps refine the gear shift timing through corners, as the IMU gives definitive information about lean angle.

So the system has developed continuously, and will continue to do so. That’s one of its great advantages – it can be continuously improved.

How is control differentiated model by model? 

Mainly, the different programmes for the shift timing. Each model is different. For example, the shift pattern on the X-ADV is much sportier than on the Integra, as it upshifts at higher rpm and downshifts also at higher rpm for more engine braking.

Every single DCT model is programmed with a different shift timing pattern to add character and taste in the riding feel.

What would you like to see as the next application for DCT? 

ricky-brabec-dakar-2020-stage-10-dppimed

Personally, I’d love to see DCT on our Dakar Rally bike. That kind of riding – where fatigue is possible, and concentration so important – means the system has a big benefit.

Off-road, people are often surprised at how much DCT can help them – working a clutch lever standing up is not so easy, and uses up a lot of energy and concentration. Also, of course, with DCT the rider cannot stall in difficult situations.

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