The Story Behind the Development of the Honda E-Clutch

The Honda E-Clutch is the world's first technology that allows the driver to choose whether or not to use the clutch lever at any time. It took ten years of last-minute development to finally bring it to market. The trump card for reducing size and weight was the technology of ASIMO! Let us tell you the story of the painstaking development as highlighted in this interview.

No lever is needed from start to stop, but it can be operated manually instantly!

The Honda E-Clutch is the world's first technology that allows the rider to use or not use the clutch lever. From starting to half-clutching and stopping, the driver does not have to hold the lever and can instantly switch to manual operation when he or she wants to use the lever. It is a system that is easy to use but does not compromise the enjoyment of riding at all.

It is expected to be installed on the 2024 CB650R/CBR650R and is also expected to be available in Japan. It can also be installed on existing engines, and its use is expected to expand further in the future.
※ See separate article for details.

We interviewed the development team at a press launch in Tokyo. We were able to hear the passionate thoughts of the engineers who, against the backdrop of internal opposition, achieved half the cost, half the weight, and half the space, and brought the car to market.

From left to right: Junichi Sakamoto, general manager of the large motorcycle category; Junya Ono, E-clutch development manager; Tatsuya Ryuzaki, E-clutch control project leader; Asuka Ito, E-clutch drive train research project leader.

You can do more things with a manual, and the SR400 at the source.

The SR400 requires all operations to be done by yourself. Mr Ono, who is in charge of E-clutch development, says that this may be partly connected to the new E-clutch.
His favorite bike is a 2005 SR400. He bought it when he was a university student and still uses it to commute to work. The SR has a heavy clutch and can only be kick-started. His love for such analog bikes seems to be at the root of the E-clutch.

Mr Ono joined the company in 2009 with a desire to develop new two-wheel drive systems such as the HFT on the DN-01. He was assigned to advanced research on two-wheel drive systems and eventually became a development manager.

The development of the E-clutch started around 2014. This was around the time when the DCT (dual clutch transmission) for motorbikes, which was introduced in 2011, was finally becoming popular. However, DCT was only available in large models. The E-clutch was finally developed in response to the demand for a system that did not require the clutch lever to be operated and that could be used to do more things in a manual transmission.

DCTs have a mechanism that turns the engine oil pump and controls the clutch with the hydraulic pressure generated, which inevitably causes weight and loss. We thought about whether it would be possible to wipe out these aspects and make it more applicable to manual transmissions (Mr Ono).

The DCT is the main function of the automatic transmission, but the E-Clutch controls the clutch and allows for a greater variety of operations.

The clutch is optimally and delicately controlled by sending current to two motors on the right-hand side of the engine. The clutch is connected and disconnected based on a variety of information, including vehicle speed and throttle position.

The system for both electronic control and manual operation is surprisingly simple. The engine-side clutch lever (release section) is divided into three sections, with the brown section disengaging the clutch when motor control is used and the blue section when manual operation is used.

The impossible task of halving the cost, weight, and size!

However, there was much opposition from within the company. Currently, in models where DCT and manual transmission are sold together, up to 60% of users opt for the DCT version. However, when the development of the E-clutch began in 2014, it was not very popular and only accounted for 20-25% of sales.

Mr. Sakamoto, who is in charge of business planning for large motorbikes, says that at that time, the main group buying large motorbikes was the Boomer group, now over 60 years old, and they were looking for a sport that they could enjoy using all their senses and the whole body.

The DCT also struggled considerably to spread, and when it was proposed that sports could be enjoyed without operating the clutch lever, it was difficult to gain understanding within the company.

A prototype version existed from the beginning, and in the early stages, it was large and heavy enough to be placed on the rear seat. However, it was well received by those who drove it, even within the company. Sakamoto himself said that when he was given a ride in the prototype, he thought it was a good idea.

However, no decision was made on whether sales could be expected, and development continued into the 2020s without the go-ahead. Finally, the go-ahead was given by senior management.

However, we were instructed to 'halve the cost, weight and space'. Looking back, perhaps they meant that we should just give up," laughs Sakamoto.

One of the reasons behind the move towards commercialisation is that in recent years the main group of motorbike buyers has been replaced by Generation Y (the generation born between the 1980s and early 2000s). In other words, the number of riders who accept easy operation has increased. In addition, as development continued over a long period and test rides continued within the company, the number of members who supported and encouraged the development of the bike also increased.

If they miss this opportunity, they may not get another chance. However, the time available for mass production is very limited. So we proceeded with the development of a commercial version in a very short time. We didn't want to have a situation where we stood in the batter's box and the ball came to us, but we couldn't swing it in time.
It was very hard work to get it there in time (Ono).

The E-clutch system is compact. The overhang is minimal compared to the manual version.

It seems to be almost impossible to catch when the foot is on it. Even if they touch when the feet are on the ground, the top part is made of soft rubber.

Asimo's motor control technology contributes to the lightweight, compact, and simplified system!

Nevertheless, halving cost, weight, and space is no mean feat. A major turning point in weight and size was the essence of Honda Robotics. Honda's humanoid robotics technology, as exemplified by ASIMO, has played a major role in the system configuration and actuator control.

The E-clutch consists of first the motor, then the reduction gear, and finally the clutch lever on the engine side. The system is completely different from a DCT, where the clutch is controlled by hydraulics, as the motor provides direct control.

The technology of controlling something with a motor is similar to robotics. The basics of robotics technology are in areas such as precise position control and the successful control of force when in contact with a human being.

E-clutches have various frictions from the motor to the clutch, but by applying robotics technology, it is possible to predict, learn, and control them well (Ono).

This has made the system smaller, lighter, and simpler.

Honda has been researching robot technology for some time and launched the definitive Asimo in 2000. It appeared in shows and other events and became popular, but ended its demonstration in 2022.

As well as balancing and walking on two legs, they were also capable of complex movements such as running, twisting the lid of a water bottle, and giving way to others.

The e-clutch system was disassembled. The motor moves the clutch release via the reduction gear. Robotics technology facilitates friction prediction and learning.

Despite internal opposition, Thai production cuts costs

Even though the technical aspects could be cleared, the cost hurdles were high.

Mr Tatsuzaki, the control design project leader for the E-clutch, is primarily responsible for the motor control unit (MCU) that controls the clutch.

Cooperation with suppliers with whom we have not had much contact to reduce costs. The control unit uses a vast amount of sophisticated software, but because it is a new supplier, it is not possible to make use of the existing assets. It was also necessary to design a new electronic base for the control unit.

Mr. Tatsuzaki says that there was a lot of pressure because we had come within a development span that even his superiors were against. There was also the difficulty of adapting it to an existing vehicle that was not completely brand new.

The MCU is a separate unit, mounted together with the engine control unit (ECU) in a plastic tray under the tank. It is slightly larger than a business card, with the thickest part measuring around 3 cm.

Mr Ito, the Driveline Research Project Leader, also said that the schedule was tight. In addition to the new supplier mentioned above, another factor was that production was at a factory in Thailand. It was a struggle to negotiate and adjust the schedule, and it was like someone had to cover what someone else couldn't pick up, so I don't know how we didn't miss anything. Every week we said we couldn't do it anymore.

In addition, as Honda's theory had been that new mechanisms should originate in Japan, there were objections to Thai production from within the company. However, it was difficult to reduce costs without using Thailand (Ito).

The CBR650R/CB650R are produced using the knockdown method, with parts transported from Thailand and assembled at the Kumamoto plant in Japan. The E-clutch unit is also guaranteed by Thai Honda and then checked as a complete bike in Japan.

The Japanese version of the new CB650R with E-clutch. The livery is exclusive to Japan. Rumour has it that a manual clutch version will arrive in Japan in spring, followed a few months later by the E-clutch version.

A full-cowl version, the CBR650R, is also available with an E-clutch version (photo: European specifications). The Japanese version is undisclosed but is expected to appear in Japan.

Further miniaturization and increased performance in conjunction with the electric brain.

Thus, in November 2023, the E-Clutch was officially presented at the European show.

However, he says that it was only fairly recently that the system became closer to what it is today. We had a lot of internal test drives, and eventually, we brought it to Europe and so on, and it was like we had more and more allies, and finally, we pushed it in and got to the finish line. It was exactly the right time to bring it out, and I think we made the development team feel hard done by and sorry for them. But they didn't give up and kept working on it for 10 years without it seeing the light of day in the world (Sakamoto).

The E-clutch was finally realized after overcoming various size, weight, and cost issues.
Therefore, further expansion of models equipped with the clutch is expected in the future. We asked Mr Ono about prospects.

If I were to speak only of my wishes, I would like to create a system that can fit better into the engine. The current E-clutch is designed to be fitted to existing engines, but I think there are parts of the system that could be done better if it were to be fitted from the outset.

For example, he says, it could be possible to further reduce the size of the vehicle through dedicated design. He also says that in 1000cc supersports, which are equipped with a large number of electronic devices such as IMUs (inertial sensors), performance can be enhanced by co-operating with the electric brain.

Note that in the case of hydraulic clutches, the structure is different and the system is likely to have to be modified.

Incidentally, the durability is equivalent to that of a manual clutch. The possibility of retrofitting to vehicles already in use by users is a dream come true.

In this interview, we heard the passionate story of the engineers' persistence in realizing the world's first technology. The development team, who have already driven the clutch several times, are confident that nothing has been lost in the enjoyment of the manual clutch. We are suddenly looking forward to the day when we can try out the E-clutch.

2024 CBR1000RR-R (European specifications). It would be awesome if the SS, with its 218 hp maximum output and full of electric brains, could be combined with an E-clutch that is quick and has a little shifting shock. Of course, we also expect to see it mounted on 250-class and other small-displacement vehicles.