The MCL39 is the car of the moment, coming off a dominant one-two finish in Miami, where at times it showed a race pace advantage of more than a second per lap. Fans and rivals are wondering what the secret of the Woking car is, focusing their attention on the brake cooling ducts, which have proven particularly effective at managing tire temperatures. Nothing illegal, according to the FIA, which, as reported by The Race, inspected the MCL39’s brake ducts after the Miami race — an area McLaren has been investing time and resources in over the past three years.
The importance of the brake ducts
Brake system cooling is one of the most important areas in modern Formula 1. In addition to ensuring proper cooling of the discs and calipers, the design of the ducts impacts external aerodynamics, both in terms of drag and the management of turbulence and hot air exiting behind the wheels. Even more crucial is the ability to design the channels in a way that can cool the tire from inside the rim, isolating it from the braking system — or, conversely, heating it by using brake heat.
There is nothing secret about this; it is a practice common to all teams, as noted by those who work closely with tires. “The FIA has been trying to limit this kind of practice,” said Pirelli Motorsport director Mario Isola, speaking earlier this season on the program The Tech Formula. “In the past, with 13-inch rims, the tire was very close to the brake ducts, and teams built very complex systems to heat or cool the tire, depending on the need. Now this is more difficult, because with 18-inch wheels there’s more space between the brakes and the rim, and there are regulatory limits — but teams are still trying to extract performance in this area.”
McLaren, years of investment
By reviewing the development documents from the past three years — coinciding with McLaren’s rise that began in 2023 — it becomes clear how much the team has invested in brake cooling. Development declarations to the FIA are always open to interpretation, covering both general upgrades and track-specific adaptations. Each team also chooses how transparent to be when listing updates, taking advantage of the fact that only externally visible changes are required to be reported. Ferrari, for example, has never declared any brake cooling updates, clearly making internal duct changes instead.
Excluding Ferrari, the past three years show that McLaren has worked more on brake cooling than any other top team. Since 2023, only counting in-season updates, the Woking team has modified the front ducts nine times and the rear ducts three times. Red Bull has made three rear and seven front duct updates, while Mercedes has brought five front duct updates. It’s also notable that each of the three major development packages introduced by McLaren in 2024 — in Miami, Zandvoort, and Austin — included revisions to brake cooling, with further updates arriving in Australia at the start of the 2025 season.
McLaren updates
Barcelona 2023: front ducts
Monza 2023: front ducts
Singapore 2023: rear ducts
Mexico 2023: front ducts
Japan 2024: front ducts
Miami 2024: front ducts
Zandvoort 2024: front ducts
Monza 2024: front ducts
Austin 2024: front and rear ducts
Australia 2025: front ducts
Red Bull updates
Silverstone 2023: front ducts
Budapest 2023: front and rear ducts
Japan 2024: front ducts
Imola 2024: rear ducts
Montreal 2024: front ducts
Budapest 2024: front ducts
Singapore 2024: front ducts
Mexico 2024: front ducts
Japan 2025: rear ducts
Mercedes updates
Baku 2023: front ducts
Singapore 2023: front ducts
Imola 2024: front ducts
Montreal 2024: front ducts
Silverstone 2024: front ducts
More than just brakes
Woking is now reaping the rewards of years of investment in a very profitable area, but it would be wrong to attribute the MCL39’s advantage solely to the brake ducts. The car’s excellent tire management also stems from abundant aerodynamic downforce and good balance — characteristics that prevent sliding and overheating of the tires. McLaren’s technical superiority is comprehensive, limited only by driveability issues in qualifying, which, however, disappear in race conditions where the car’s strength truly emerges.
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