The “Seamless” gearbox was a revolution when it was introduced in MotoGP. Its arrival in series would be a huge surprise and a big step forward in the efficiency of transmission systems. Allowing you to shift gears without cutting the throttle, this gearbox could soon arrive on production motorcycles: at the end of 2020, Ducati had filed a patent which suggested that the future Panigale V4R would be equipped with it, and it is now Yamaha which has just filed a patent application on this subject, concerning the future R1.
MotoGP is a true technological laboratory and proves it to us once again, with technology developed for MotoGP which could once again make its contribution to the production motorcycles of tomorrow.
Manufacturers continue to seek to improve gearboxes. Many brands already offer the option of a quickshift, which allows you to move up and down gears without using the clutch. Honda has had its Dual Clutch Transmission (DCT) system for some time, first used on the VFR1200F and also on the NC750 engines and the Africa Twin's 1100 twin-cylinder engines.
Yamaha's new patent was issued on May 24, 2022 and revealed by the Japanese site Young Machine. The system was used in F1 and MotoGP where Honda was the first brand to use it during the 800cc era. The initial cost of the system was enormous, so much so that Shuhei Nakamoto, vice president of HRC, said at the time: “The Seamless gearbox costs more than my house. »
With such a gearbox, the operation of changing from one gear to another would become very quick. The curious thing about this is that the sketches where the technical architecture of the system was developed are not taken from its MotoGP, but rather based on the Yamaha YZF-R1. The reality is that this new system would be aimed at the brand's road motorcycles and not at competition, where they currently use their own system developed entirely in-house.
The reduction in shift times has the dual objective of reducing the drop in speed to the minimum possible, so as not to lose acceleration when changing to a higher gear, and secondly, to limit load transfers. When changing gears, power transmission is normally interrupted, causing a shock. This shock occurs due to the inertia of the gears at different rotational speeds, being technically called "inertia phase shock". The change in driving force disrupts the behavior of the motorcycle, this shock being more pronounced when the motorcycle is lighter. Gearbox Seamless aims to eliminate these power losses, make it less sensitive to gear changes and, therefore, also make driving more comfortable.
In the Yamaha patent, we can read that "when the gear is changed, the power transmission is not interrupted". Many of us know that gears shift better by cutting off the throttle a little. The system used in MotoGP is designed so that there is no neutral. If Yamaha has found and patented a system that can do this, without the high original production costs, then it has discovered the holy grail for mass production.
From what the drawings show, we can see the principle of the mechanism of engagement of the transmission shaft in the respective gears. Instead of taking the engine's drive directly to the input shaft, like on a normal motorcycle, the clutch connects to an "input hub" which sits on the right end of the input shaft. 'entrance. It transmits torque to one of the two halves of the shaft via two locking bearings.
The primary shaft and gears are essentially a single piece, rotating at the same speed at all times, and have odd ratios. On the secondary shaft, all even gears rotate freely, but inside each gear is a set of four dog rings that lock the gear onto the shaft to transmit power. These are moved on axles which extend outwards from the center of the shaft by a set of internal springs. The clutches only transmit torque in one direction of rotation. Thus, two of the clutches lock for the higher gear (acceleration), while two others lock for the lower gear (deceleration).
MotoGP gearboxes have proven themselves to support powers of around 300 horsepower, but it is true that they have very high costs, due to the quality of construction and the materials used. And then there is the question of its reliability over time, but the Iwata brand has certainly taken all of this into consideration for mass production.
Do we really need a Seamless transmission for the commute to work or the Sunday stroll? The answer is obvious: no. No more than aerodynamic fins or a 200 hp engine. However, for use on the track, a Seamless gearbox makes perfect sense, and it should be remembered that the motorcycles used in the Superbike World Championship are derived from the production models. It's a safe bet that Yamaha or Ducati want to adapt this technical development to their R1 and Panigale V4R, in order to be authorized to use it in racing.
