In a dramatic development at the 2025 Miami Grand Prix, McLaren’s innovative rear brake design, which had sparked heated controversy among rival teams, was emphatically fixed by the FIA following an intense post-race inspection. The decision silenced doubters and reaffirmed McLaren’s technical prowess as the team continues to dominate the Formula 1 season with its MCL39 car. The ruling not only cements McLaren’s position atop the constructors’ championship, but also sets the stage for a fierce technical battle as the rivals race to match their advantage.
The controversy began when Red Bull, led by team principal Christian Horner, raised concerns about McLaren’s ability to maintain exceptionally low rear tyre temperatures. Thermal imaging, reportedly obtained by Red Bull from a third party, revealed “cold spots” on McLaren’s rear brake drums, leading to speculation about potential rule violations. Some rivals even suggested McLaren might be injecting water into their Pirelli tyres to cool their brakes, a practice strictly prohibited under F1 regulations. These allegations prompted the FIA to conduct a forensic examination of the MCL39’s brake system after McLaren’s commanding 1-2 in Miami, with Oscar Piastri leading Lando Norris across the line.
The FIA’s inspection, described as one of the most thorough in recent memory, focused on the channels and internal materials inside McLaren’s brake drums. Rivals had theorised that McLaren could have used phase-shifting materials or intricate airflow management to gain their cooling advantage. However, the FIA’s findings, as reported by The Race , confirmed that McLaren’s design is entirely legal, relying on an “intelligent but compliant” concept that exploits pressure dynamics within the braking system. No evidence of liquid cooling or moveable aerodynamic devices – both of which are banned under F1 rules – was found, putting the speculation to rest.
McLaren CEO Zak Brown, who had been brandishing a bottle of “water” during the Miami weekend, hailed the ruling as vindication. “We have always been confident in our engineering,” Brown said. “This is a testament to our team’s innovation in the rules.” Brown also called for reforms to the protest process, suggesting teams should face a financial penalty for unfounded complaints, a position echoed by FIA president Mohammed Ben Sulayem.
For McLaren’s rivals, the decision is a wake-up call. Red Bull, Ferrari and others now face the challenge of replicating McLaren’s braking system without violating regulations. The ruling has also increased scrutiny on Red Bull, with some suggesting their focus on McLaren’s design may be a distraction from their own performance struggles as Max Verstappen battles tyre wear issues.
As the F1 circus heads to the Emilia Romagna Grand Prix, McLaren’s scrapped brake design ensures they can push forward without costly redesigns, maintaining their edge in tyre management, a critical factor on demanding circuits like Monaco and Singapore. With five wins from six races, McLaren’s dominance is undisputed and the FIA’s decision has only encouraged their charge towards another championship title.
