The reasons why the ventilation of Formula 1 car brakes is such a delicate and crucial aspect for teams.

Every Formula 1 car is the result of thousands of hours of study, countless computer calculations, simulations, and tests, as well as several wind tunnel sessions necessary to optimize every smallest component, even though the regulations set usage limits: a maximum of 1,200 wind tunnel occupancy, with 960 tests and 240 hours of Wind on Time.


The braking systems are no exception, and Brembo subjects all components supplied to Formula 1 teams to rigorous and sophisticated tests and simulations. There are tests to measure caliper pressure, others where it is evaluated together with torque: these tests are carried out by applying 50 percent more force than the maximum value hypothesized in design. On the dynamic bench designed by Brembo, the entire braking system, including the pedal box and suspensions, is tested, simulating a race. If the sensors give a positive result, the brake is approved and can be mass-produced and delivered to the teams for the entire championship. Despite all the calculations and static and dynamic tests, the history of racing is rich in unexpected events that have caused unforeseen problems, compromising the success of a Grand Prix.


In most cases, the triggering cause was external and independent of the team’s actions, such as a component detaching from another car: famous is the camera that detached from Jean Alesi’s Ferrari at the 1995 Italian GP and hit the suspension arm of the twin car, forcing Gerhard Berger to retire.

Sometimes, however, the failures were caused by factors unrelated to other cars on the track: such as an animal invasion or an object coming from the stands. The Alpine Renault knows something about this, as in 2021, at the Bahrain GP, it stopped Fernando Alonso after only 33 laps to avoid worse troubles for his A521.
 

All because of a sandwich wrapper that got stuck in the rear brake air intakes of the French car, causing overheating that ended up undermining the braking system’s operation.


The engineers in the pits noticed that something was wrong through telemetry and opted for retirement as continuing would have been a gamble for the driver’s and his colleagues’ safety.


The history of Formula 1 and Alonso himself are not new to such episodes: in 2015 during the Spanish GP with McLaren, Alonso was forced to abandon the race on lap 25 after moments of fear - “the rear brakes didn’t seem to work anymore,” the driver had communicated to the pits.


The malfunction was caused by a tear-off visor that had gotten into the air intake: the small piece of transparent plastic was found at the bottom of the car. The same happened at the 2022 Belgian GP, with Charles Leclerc as the victim: the visor penetrated the right front brake air intake on the first lap, producing smoke, but fortunately, the subsequent pit stop allowed it to be removed.


Thanks to multiple sensors placed in various points of the car, teams know the temperature of discs and calipers at all times. Based on this data, any alerts are sent to the driver to modify the brake balance of the car or manage the system: this communication occurs when anomalies are recorded compared to predictions.

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The importance of brake air intakes


But how do brake air intakes work and what happens in case of accidental obstruction? Around the wheel corners of Formula 1 cars, we have seen increasingly sophisticated carbon brake ducts develop over time, with air intakes, flaps, and flow deflectors designed ad hoc, capable not only of cooling the braking system but also performing aerodynamic functions.


This is because, by cleaning the air from the turbulence generated by the rotating motion of the tire, it is possible to reduce the drag of the car or increase its aerodynamic load. In the presence of an obstruction of even just one of the air intakes, the disc and pads are forced to operate constantly at temperatures higher than the optimal operating ones.


This results in their oxidation, and within a handful of intense braking events, the temperature of the friction material risks skyrocketing. The accidental lack of ventilation can therefore first compromise the brake fluid and then the friction material.


In addition to wearing out very quickly, the friction material begins to burn, eroding part of the disc, while the brake fluid boils, generating the phenomenon of vapor lock. If the car continues to run in such conditions and the driver presses harder on the brake pedal, the wear reaches the ventilation holes, risking the explosion of the disc.


The aluminum used to make the brake calipers melts at 700°C. However, Brembo’s six-piston Formula 1 calipers have a guarantee threshold of 210°C, which is significant but lower than the minimum operating temperature for the discs, whose usage range is between 350°C and 1,000°C.


Unlike discs and pads, which reach very high temperatures in the most extreme conditions like the Canadian GP, whose layout involves many hard and close braking points, Brembo calipers never exceed 200°C.

The puzzle of optimal temperature


On the Gilles-Villeneuve circuit as well as on the tracks of Abu Dhabi, Mexico City, and Singapore, the role of brake air intakes becomes fundamental because the sequence of violent braking without long straights to allow the braking systems to cool down requires directing large quantities of air inside them.


Conversely, on tracks like Silverstone, Suzuka, or Interlagos, there is the opposite risk, namely the failure to reach the ideal operating temperature of the brakes, with the consequent risk of the glazing phenomenon of the friction material.


In such conditions, the brakes need less air, and the air intakes are “partially closed,” effectively reducing the airflow directed to the brakes. On paper, these choices seem logical, but the wheel corner of a Formula 1 car includes many elements, each with different needs.

Additionally, the impact on tire performance, the operating temperature of the power unit, and drag on the straights must be considered.
In short, a real balancing act, to which an additional variable is added: the number of ventilation holes in the brake discs. Designed through CFD (Computational Fluid Dynamics) calculations, they are the result of a synergistic study between the disc manufacturer and the car constructors.


Depending on the air intakes used in a season or modified for a specific GP, teams choose the disc version they consider best. For the front, Brembo had produced discs with up to 1480 holes, but since 2022 a minimum diameter of 3 mm has been established, which has reduced the number of holes in the front discs to between 1,000 and 1,100.
 

The teams supplied by Brembo use two different types of carbon discs: “wide spline” and “single sided spline.” In the “wide spline” specification, the thickness of the drive - the part in contact with the bell - is equal to the thickness of the disc, while in the “single sided spline” specification, the thickness of the drive is less than the thickness of the disc.
 

This second solution can favor a different ventilation strategy for the disc and better packaging of the wheel corner but at the expense of optimal mechanical stress on the carbon, which limits the possible drilling for ventilation. The choice of one solution or the other depends on the needs of each team based on the design of the individual cars.