How and why Lewis Hamilton and Charles Leclerc were disqualified at F1’s U.S. GP

When representatives from Mercedes and Ferrari were called to see the FIA stewards after Sunday’s United States Grand Prix, they knew their fate was sealed.


Lewis Hamilton and Charles Leclerc’s cars had both failed a post-race inspection during which officials found the skid plank on both chassis had worn down too much, putting them in breach of the technical regulations.


In an era where the teams meticulously check their cars throughout a race weekend to ensure compliance, getting thrown out of the final results for a technical infringement is rare: Not since Romain Grosjean’s exclusion from the Italian Grand Prix in 2018 has a driver been disqualified from a race for such an issue.


Hamilton and Leclerc published a shared Instagram post on Monday morning, showing them sat together during Friday’s FIA press conference, looking bored and emotionless. The caption simply read: “Mood.”



It was a gutting end to both of their weekends. But how did two cars from different teams end up getting disqualified for the same rule breach on Sunday in Austin?


How the scrutineering process works

Both Hamilton and Leclerc’s cars breached Article 3.5.9 e) of the FIA’s technical regulations. This rule outlines the required thickness and dimensions of the planks underneath the cars. That’s “10mm ± 0.2mm” before a race, while a “minimum thickness of 9mm will be accepted due to wear” in a race. Similar design restrictions govern all parts of the F1 cars.


The plank on the underside of an F1 car is made of a composite material called Jabroc, a kind of strengthened beechwood. Its primary purpose is for safety, stopping the cars from bottoming into the circuit.


The point of the plank wear rule is to ensure teams are not running their cars too close to the ground. This can offer a performance benefit by increasing the downforce generated by the floors, which are especially powerful under the current ‘ground effect’ regulations.


After each race, the FIA conducts an extensive scrutineering process that checks various aspects of all cars. This information is detailed in a post-race report issued by the FIA’s technical delegate, Jo Bauer, which is sent to all competitors and made available to the media.


All 20 cars are weighed and undergo inspections for things such as tire pressures, fuel samples, torque control and oil consumption. A number of cars are also randomly selected for additional technical checks. After the race in Austin, the cars of Sergio Pérez, Lando Norris and Yuki Tsunoda were selected for aerodynamic component and bodywork checks to ensure compliance with the technical regulations, covering a total of 19 areas including the front wings, rear wings and sidepods.


These were separate to the physical floor and plank wear inspections, which are routine at races — they most recently happened in Singapore — and this weekend were conducted on four cars: Max Verstappen’s Red Bull, Norris’s McLaren, Hamilton’s Mercedes and Leclerc’s Ferrari. These were again chosen at random. It just so happened that two of the four were in breach.




Had the FIA not checked the planks on Hamilton and Leclerc’s cars, both would have escaped detection and disqualification.


Team representatives typically go into hearings with the stewards armed with all the arguments possible to escape sanction. On this occasion, there was little Mercedes or Ferrari could do. The document confirming the disqualification stated both teams “acknowledged that the measurement performed by the FIA Technical Team was correct.”


Ferrari’s sporting director, Diego Ioverno, explained that Leclerc’s car was only “a few tenths” outside the requirements. “The code doesn’t allow anything else than disqualification in this case,” he said. It’s a black and white rule, and they were on the wrong side of it.


Why was plank wear a problem?

Two key factors contributed to the high levels of plank wear on both cars in Austin: the sprint weekend format and the bumpiness of the track.


As teams make setup tweaks through a race weekend, they will check and inspect the planks on their cars to measure the levels of wear using sensors. This will help inform them how much the car is bottoming out, which has become an increasing issue under the updated technical regulations from 2022.


But the sprint weekend format provided only a single one-hour practice session for the teams to refine their cars before locking in their setups. From the start of qualifying on Friday, the car setups could not be changed without requiring a pit lane start, a major disadvantage especially for teams starting high up the grid. On a normal weekend, it is possible that both Mercedes and Ferrari would have realized wear levels were too high on the planks and increased their ride height accordingly.


Ioverno explained that Ferrari did lift the ride height on its cars during FP1 in response to the bumpy asphalt at the Circuit of The Americas, something that has been a recurring issue over the years. After the race, Verstappen said COTA was “better suited to a rally car” and needed to be repaved to make it smoother for the drivers.


“In the past, more or less everyone failed the suspensions, failed the chassis,” Ioverno said. “We knew it would have been tricky, and this is the reason why we lifted the car throughout FP1. From our consideration, it should have been OK. It turned out we were anyhow too marginal.”


It meant as both Hamilton and Leclerc’s cars dealt with the bumps over the 56-lap race, running heavy fuel and dealing with a higher wind than earlier in the weekend, which also impacts the ride of the car, the levels of wear went just beyond the permitted amount.


F1 teams will always try and push the technical regulations to the limit in an effort to beat their rivals. But on this occasion, the factors combined to push Hamilton and Leclerc’s cars too far.


“With hindsight, we may have lifted even more the car,” Ioverno said. “But we would have lost performance. We are here always to try and optimize our own performance.”

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