Analysis: The real story behind Mercedes' gearbox dramas
Suffering one reliability problem in Formula 1 can sometimes be down to bad luck, but when a team suffers two on the same component almost simultaneously, that is often a sign that something major has gone wrong.
So when Mercedes announced ahead of qualifying for the British Grand Prix that Valtteri Bottas needed a gearbox change – just one week after Lewis Hamilton had to do the same in Austria – alarm bells began to ring.
For while there had been suspicions after Baku (denied by Mercedes) that Hamilton’s failure could have been caused by the bash he got from Sebastian Vettel, it was clear when Bottas’ system needed changing too that this was something far more critical.
And inevitably it prompted questions about whether there was some serious fault with the Mercedes design that left the door open for even more penalties down the line – especially because gearboxes have to last six full weekends.
Mercedes’ demeanour was not one of panic, though. Indeed, while on the outside the situation could have seemed dramatic, the team itself knew it was one that could be easily rectified.
In simple terms, Mercedes had been too aggressive with the timing of its seamless shift system – and that had damaged the gearbox internals.
Mercedes technical director James Allison said that the team’s bid to extract every element of performance out of the car had resulted in it pushing too hard to shave milliseconds off its shift times.
“In the old days, you’d be in a gear, then you’d be out of a gear and then you’d be in another gear and you’d just lose drive all the time that the gears were in transit from one to the other,” he explained.
“In a seamless shift you are in one gear and then the next one takes over instantly - so there isn’t a loss of drive.
“However, if you imagine the gearbox, when you are shifting up, it’s spinning at a high speed in a lower gear, then you want to upshift the box, all that rotating inertia has to slow down to meet the next gear.
"So seamless though it is, there is still an amount of spinning stuff that needs to be slowed down to meet the next gear.
"Now you can do that gently or you can just let the whole thing go ‘hhhuuurrrgggghhhh’ and sort of wind up and then spin that wind back into the wheels.
“The gentle [way] is done by cutting the torque from the engine, to soften the wind that would occur. The harsh is just letting rip. I can say this because it’s not a sort of thing that no-one else has thought of, it’s a standard thing in F1. It’s just a question of how bold you are with it.”
Mercedes, in the end, simply went too bold. And while it has a thorough reliability sign-off when it comes to development, Allison says the team was caught out by the real world throwing up things – like G-forces – that cannot be simulated on dynos.
“We have a process for signing off any new strategy or any new design and that process is actually quite cautious from an engineering point of view,” he said.
“We try to put it on the track as much as we can, but the opportunities for track running in a risk-free way are limited. So we have dynamometers back in the factory where we can create a fairly good representation of reality.
“We did all of our normal process to prove off a layer of greater aggression with the shift settings than we had used previously. But, despite the fact that everything looked fine in our sign-off process, sadly that particular plan didn’t survive contact with the enemy on the track - where things were a little different, where the g-loads moved the oil around the box differently than you can simulate in a dynamometer.
“So we just overstepped the mark by the tiniest of margins and paid a price."
What the gearbox situation shows is that Mercedes is having to push the limits of its cars perhaps harder than it has done in recent years.
For after three years of dominance in F1, Mercedes is entering new territory this year – where the fight is not just between its two drivers but against Ferrari. And with tenths of a second separating success from defeat, any area where performance can be found needs to be pursued.
Mercedes boss Toto Wolff explains about the efforts that fuel and lubricants supplier Petronas has done: “For me, it is amazing that there are fluids you can extract performance from that I didn’t even know were in the car
“And it adds up. You can find five milliseconds on a cooling product, you can find 15 milliseconds on a hydraulic oil. With the formula of oils and fuels and the density, you can extract so much more performance out of all these crucial parts of the internal combustion engine.
“The gearbox is another good example. Running the right oil in the gearbox can give you a performance advantage, it can give you a weight advantage, it can allow you to race more aggressively in terms of gearshifts. And sometimes as a team you get over-confident.
“That has happened to us on the gearbox. We’ve probably run it too hard and when we stuck the nose in after Baku, we realised.”
Wolff, though, is ultimately proud that Mercedes has maintained strong form throughout a regulation change. He knows that the team has now paid a price for pushing too hard, but reining the aggression in a bit solves its problem on this front.
“Our objective was to come out on top after a year of regulatory change,” he said. “As far as I know, there has been no team in the past that was dominant over a couple of years and has stayed on top through a regulatory change. And this was our objective, to achieve that.
“So you can say it’s not us alone any more. It is probably better for the sport and for the entertainment factor that Ferrari is part of the mix now, but we are pushing so hard.
"And by pushing and trying to keep the development curve steep, you get setbacks. Headrests that become undone, gearboxes that break because you try to extract the last bit of bits that normally have no performance relevance any more, or not a lot. But they do.”
For teams, just like for the drivers themselves out on track, sometimes the price of finding the limits is that you have to pay the consequences for overstepping the mark.
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Analysis: The real story behind Mercedes' gearbox dramas
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