Last weekend, Valtteri Bottas’ race in the Monaco Grand Prix had to end with more than half the distance left due to a pit stop failure where the mechanics were unable to remove his car’s front right wheel.
In footage released afterwards we could see little snippets of aluminum shearing off the wheel nut, where the gun’s force made it smooth, rather than connecting to the teeth to loosen the nut and remove said tyre.
James Vowles, chief strategist, explained: “Our nuts are what we call captive, they are maintained within the wheel and the tyre, so as the wheel comes off the nut goes with it.
“This nut has to hold a wheel to the car such it can cope with 5g forces in braking and laterally as well. It’s a huge amount of force going through the axle and the nut and clearly, we can never have it coming loose. So, the gun is an incredibly powerful gun, such that you can actually see the mechanics having to restrain themselves holding themselves to the ground otherwise they get rotated with it at the same time.”
James added that the gun’s action required a perfect alignment to the nut for it to work as it is supposed to do.
“It’s an impact force and what happens is the nut typically loosens in four or five impacts against it, a hammering action.
“What happened is we came on slightly angled, so when the socket was now connected to the nut, it slightly angled relative to it and as a result of that, now instead of distributing the load across all of the nut it was across a small section and that tore the metal clean off and in fact all of the metal was now removed from the nut. As a result of that, the nut was in place and we were unable to remove it.”
The machining was so severe that the team were unable to remove the wheel in Monaco and were expecting to be able to do so back at the Mercedes factory.
“Clearly, it’s a circumstance that cost Valtteri dearly and cost the team dearly,” Vowles said. “One that we are going to put steps in place to mitigate.”