Mercedes break down “mistake” over Hamilton’s ‘illegal plank’ at US GP

Hamilton drove impressively in Texas but a podium finish vanished when it was discovered that the plank beneath his car had excessively worn out.

Mercedes technical director James Allison said: “The skid blocks are basically little discs of metal that are put into the plank material.

“At the end of the race, there has to be a guaranteed thickness. 

“They begin the race at 10mm thick and, by the time you get to the end of the race they must be no less than 9mm.

“You are allowed a certain amount of erosion of that skid block by touching the ground. 

“But no more than 1mm or else if your car is inspected, and found to be below that 9mm, then you will have been deemed to be running your car too low and you’ll be disqualified. 

“That is what happened in our case.”

Mercedes brought a major floor upgrade to last weekend’s F1 United States Grand Prix which appeared to be working well, until Hamilton was disqualified.

The question left lingering was whether the upgrade added competitiveness, or whether it was only because the W14 was too low.

Allison backed the upgrade: “The weekend was a very cast-iron vote of confidence in favour of what we put on the car.

“That gives us great hope for the races that remain. 

“But, the disqualification had everything to do with the setup and the bumpiness of the track - amplified by the fact that it was a sprint weekend.”

The complexity of the sprint format contributed to Mercedes’ error.

“Austin is a track with a very bumpy surface,” Allison said. 

“Therefore you are a bit more vulnerable to bumping the car on the ground. We just simply didn’t take enough margin at the end of Free Practice 1.

“When we had done our setup, we checked the plank and everything all looked fine. Untouched after FP1 running. 

“But the results of the race speak for themselves. We were illegal so, clearly, we should have had our car set a little bit higher up to give ourselves a little bit more margin. 

“It’s of course a mistake. It’s an understandable sort of mistake in a sprint weekend where it’s so much harder to get that stuff right, especially on a bumpy track. 

“But a lesson for us in the future is to make sure that we take more margin, especially at a track like that with all its bumps.”

F1 returns for the Mexico City Grand Prix this weekend.