Return Of The Hondamatic?

[Hugh Janus]

New patent filings may mean a clutchless transmission is in the works for Honda’s CB1100. (Honda /)

Quickshifters on new bikes mean we’re getting increasingly comfortable with the idea of clutchless gear changes but Honda was decades ahead of the game when it introduced the CB750A in 1976 with its Hondamatic transmission. Now the firm appears to be working on a natural successor to that model, having filed patents for a semi-automatic version of the CB1100.

While the new design shares the original Hondamatic’s control layout—with a manual, foot-operated gearshift but no clutch lever—it works completely differently and features an arrangement that would allow virtually any modern bike to be fitted with the same system.

An actuator hidden under the fuel tank would generate hydraulic pressure to engage the clutch. (Honda /)

The first Hondamatic might have dispensed with the clutch lever but it also lost out when it came to ratios. It featured a car-style torque converter instead of a clutch and just two speeds in a purpose-made transmission. The new design instead uses a conventional six-speed gearbox allied to a simple set of electronics and hydraulics that control the clutch automatically.

RELATED: Best Standard: Honda CB1100

The first main component is an actuator mounted just behind the steering head, hidden under the fuel tank. It’s an electric motor that generates hydraulic pressure—basically an automated clutch master cylinder. It even keeps the same bar-mounted clutch fluid reservoir, but simply eliminates the lever itself. The difference is in the application: Whereas you normally disengage the clutch by applying hydraulic pressure, the new design works the other way around. The clutch defaults to a disengaged state, and is engaged when the pressure is applied. That creates a fail-safe of sorts, since any electrical or hydraulic problem would lead to a loss of drive rather than an unexpected—and potentially more dangerous—clutch engagement.

A valve unit closes the hydraulic system once the clutch is engaged, so drive can continue without running the actuator constantly. (Honda /)

The second main part is a valve unit mounted by the clutch slave cylinder. This features a solenoid-operated valve that closes the hydraulic system once the clutch is engaged—allowing drive to continue without constantly running the master cylinder actuator. It also means that the clutch can be disengaged instantly by removing electric power to the solenoid, in turn opening the valve and releasing the hydraulic pressure in the system.

Again, in the case of an electrical failure, it would fail in a safe, disengaged mode.

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The system’s main job is to engage the clutch when you pull away and to disengage it when coming to a stop. Once you’re riding, there’s a relatively conventional up-and-down quickshifter using a load sensor on the gear lever itself as well as inputs including gear position, throttle opening, vehicle speed, and rpm to alter the ignition and throttle position, including blipping to rev-match during downshifts. Unlike a normal quickshifter, the system also has the option of disengaging the clutch to assist in rev-matching during downshifts or to soften upshifts.

Once the bike is in motion, additional sensors and inputs provide info to alter ignition and throttle positions. (Honda /)

While the CB1100 might not appear to be the most obvious bike to benefit from a system like this, it has the benefit of being a clear descendant of the original CB750 that first introduced Hondamatic back in 1976.

Will Honda’s new system signal clutchless gearshifts for future CB1100s? (Cycle World /)

More importantly, though, the entire setup is made of modular components that could be easily redesigned and be fitted to virtually any conventional bike. Unlike Honda’s existing semi-automatic DCT gearbox, as used on the NC750 range and Africa Twin, there’s no need for a completely new set of transmission internals and complex actuators to allow push-button gear changes or fully automated shifting. Over the last decade DCT has proven there is a market for bikes without a conventional clutch lever, and this system has the potential to bring most of the same benefits to a much wider range of models and at a significantly lower price.

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