Car
What is the plank assembly and skid block and why are they so important in F1 and F2?
by Samarth Kanal
3min read
A long piece of wood attached to the bottom of the Formula 2 car might not seem like such a crucial piece of equipment, but the plank does have an important part to play within F2 and other single-seater series such as Formula 1.
The plank assembly and skid block, a related part on an F1 car, recently made headlines in F1 when Ferrari’s Lewis Hamilton was disqualified from the 2025 Chinese Grand Prix - before Haas’s Nico Hulkenberg was disqualified for a similar infringement in Bahrain.
In F2 Richard Verschoor was similarly disqualified from the 2024 Hungarian sprint race.
The plank can therefore play a huge part in race results - but why is that?
Lewis Hamilton’s Mercedes F1 car being lifted by a crane after a crash in Monaco in 2023, showing the plank underneath the car
An F2 crash in 2010 showing the plank’s mounting on the underside of the car. The driver escaped unharmed.
The importance of ride height to F1 and F2 cars
With Venturi tunnels underneath their floors, and long diffusers, the underbodies of F1 and F2 cars are pivotal in producing downforce.
Downforce is generated by a surface when there’s a zone of high-pressure airflow above the surface and an area of low-pressure airflow below it. Bernoulli’s principle states that an increase in speed of a fluid (air, in this case) corresponds to a decrease in pressure.
Venturi tunnels are therefore used underneath the F2 and F1 cars to speed up airflow and create that low-pressure zone and, therefore, downforce.
To maximise downforce (and ensure consistent downforce) from the underfloor, it is important to have the cars running as low as possible to the ground, effectively creating a seal for the air to flow through the Venturi tunnels before it is sucked to the rear of the car by the diffuser.
The plank or skid block was introduced in F1 after Ayrton Senna’s death at the 1994 San Marino Grand Prix at Imola. Junior series such as GP2 introduced the plank shortly after and FIA Formula 2 has used the plank since 2017.
The plank assembly is used to control how low teams can run their cars, therefore limiting cornering speeds - but also guarding against the cars hitting the surface of the track and rebounding, which can lead to a sudden and critical loss of downforce.
How is the plank assembly used to control ride height in F2 and F1?
F1 and F2 technical regulations dictate where the plank must lie. It is fitted flush to the floor with no gaps and situated in the centre of the car lying between the front and rear axle - with specific gaps between both of those axles.
In F2, the thickness of the plank assembly must measure 5 millimetres with a tolerance of 0.5mm each way.
After an F2 race, the thickness of the plank must measure at least 4mm - and this thickness is measured at one of three holes that measure 80mm in diameter.
A diagram showing how the skid block works and how it is measured in Formula 2
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If the plank is worn too thin, as it was after the 2024 Hungarian Grand Prix when Verschoor’s car was found to have a plank measurement of 3.7mm at the rearmost hole, then the driver will most likely be disqualified.
In F1, the plank must be 10mm with a tolerance of just 0.2mm each way and a minimum thickness of 9mm is allowed after a session. It is also reinforced with a skid block at the rear of the car to ensure sufficient ride height measurement across the length of the underfloor.
After the 2025 Chinese Grand Prix, Hamilton’s Ferrari was found to have a plank measuring 8.6mm in thickness at the centreline - which led to him being disqualified. Hulkenberg was disqualified in Bahrain as his Haas plank assembly was 8.4mm at its thinnest point.
What are F1 and F2 plank assemblies made of?
In F1, planks are made out of Permaglass, a glass reinforced composite, while the rear of the car also has a titanium alloy skid block, which contributes to the sparks that are visible when the car is running at high speed, particularly in a straight line.
In F2, planks are formed out of a material called Jabroc. This is a composite formed of high density layers of beechwood pressed together and impregnated with resin. This is much cheaper to produce than titanium and Permaglass. Compared to cheaper materials such as steel it is much lighter - around 80% so.
A mechanic working on a car’s plank in the pitlane
The F2 plank generally comes in two pieces - a shorter front piece and a longer rear rectangular section - that are then glued to the plank floor before it is attached to the car.
Teams have to declare the serial numbers of their two allocated planks to the FIA and register the part to stop them swapping it out between sessions. To ensure structural integrity of the plank assembly between races, F2 teams must use new planks for every round - with penalties applied if teams do not comply to these regulations.
It’s far from the most glamorous part of a racing car, but plank assemblies play a central role in ensuring safety and parity in championships like F1 and F2 - and teams face harsh penalties if they’re found to have transgressed these rules.
