MotoGP: Yamaha Debuts Seamless Gearbox at Brno Test – Shift Times 58% Quicker than Conventional Gearbox

It had been widely rumored that Yamaha would have some important updates to test at its private test being held yesterday and today at Brno.

The biggest expected update to be tested was a seamless gearbox, but though Yamaha Racing Managing Director Lin Jarvis had hinted they might be testing the new gearbox, it was far from certain.

As the test at Brno was a private one, no media were invited who would be able to verify whether the seamless gearbox was being tested or not.

Fortunately, however, the Brno circuit was allowing visitors in to watch the test. And among those was Pavel, who runs the Czech Valentino Rossi fansite http://www.rossi-yamaha.cz/.

Pavel shot some video footage of the private test – thankfully not covered by the blanket ban Dorna has on all coverage of the official tests – and was kind enough to send us the audio from the recordings.

Armed with that audio, we were able to analyze the sound, as we have done previously (on both the Honda and the Yamaha), to try to judge whether Yamaha was indeed testing a seamless gearbox, and if it was, what advantage it was giving the riders.

The answer to the first question is yes they are. Or at least, that is the picture which emerges from the data. Looking at the length of time the bike goes quiet, at the point when the gearchange happens, it is clear that the gearchanges are much faster.

Taking a random sample of clearly audible gearchanges, and measuring the duration the engine is quieter (see the image for an example), we can see that shift times are improved. Assessing the times, gear changes now appear to be taking approximately 0.016 seconds – sixteen thousandths of a second – per shift, rather than the 0.038 found from previous measurements.

That is an improvement of over 0.02 seconds, or 58%. Yamaha’s seamless shift is still not as quick as Honda’s: from measurements made at Jerez, the Honda RC213V was taking just 0.009 seconds to shift between gears, an incredibly short period of time. The Honda is still changing gear in just 56% of the time which Yamaha’s new seamless gearbox takes.

However, that may not be that much of a disadvantage for Yamaha. The real benefit of a seamless gearbox is not so much the shortened shift time – though clearly, that helps – as the extra stability the shorter shift brings to the bike. The difference is clearly visible from track side: the Honda stays smooth as the riders shift up the gears, even when still leaned over.

The Yamaha’s rear gives a little wobble, as the power is disengaged and then reapplied. The hope is that Yamaha’s new seamless gearbox will give the M1 the Honda’s stability, allowing the Yamaha riders to accelerate harder and earlier.

This would improve the one weakness the Yamaha M1 still has compared to the Honda, and give Jorge Lorenzo and Valentino Rossi a better chance of beating the factory Hondas of Dani Pedrosa and Marc Marquez once it is introduced.

When that will be is still unknown. Although the gearbox has undergone extensive reliability testing in Japan, whether the gearbox is race ready remains to be seen.

In a second video, Valentino Rossi was shown having run off the track, and struggling to get the bike back into a usable gear. The engine was still running (just audible in the video), but Rossi’s attempts to get the bike moving again appear to fail, and he has to wait for a Yamaha technician to help push him off the track.

Reports from the track were that the bike made a horrible noise as Rossi was downshifting, just before he ran off track, and that would appear to suggest that the gearbox may have been a problem.

Then there is the question of whether the new seamless gearbox can be retrofitted onto Yamaha’s existing engines. That is up for debate, but early reports suggesting Yamaha was already using the seamless gearbox may be the result of new gearbox casings being used, which have been redesigned to house both the seamless and the conventional transmissions.

Once the gearbox is in use, and when the engine allocation charts show both a new engine and an old engine being used, we will be able to analyze the sound once again, and see which bike is using which gearbox.

Measured times:

Comparison with Yamaha’s conventional gearbox:

Times are approximate, as the audio for the Yamaha seamless, and Honda and conventional Yamaha gear changes were recorded on different devices.

Though the audio should be the same, very small differences may occur. That means the audio could be out by a very small margin, but those differences will be less than 0.001 of a second.

Times are all rounded down to 0.001, meaning the percentages are slightly different due to rounding effects.

Yamaha Testing, Day 1

Yamaha Testing, Day 2

Photo: © 2013 Jensen Beeler / Asphalt & Rubber – Creative Commons – Attribution 3.0

This article was originally published on MotoMatters, and is republished here on Asphalt & Rubber with permission by the author.