MPH: The clues as to which F1 team had now-illegal brake system

F1

At least one F1 team is suspected of using an asymmetric braking system that has been specifically outlawed over the summer break. Mark Hughes looks at where the evidence points

Red Bull F1 car with McLaren and Mercedes on track at the 2024 F1 Belgian Grand Prix

Revised brake regulation could affect the battle at the front

Grand Prix Photo

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Mark Hughes

During the off-season the FIA took the opportunity of tightening up one of its technical regulations, namely that concerning asymmetric braking.

The relevant regulation states (with the newly-added wording in italics): “The braking system must be designed so that, within each circuit, the forces applied to the brake pads are of the same magnitude and act as opposing pairs on a given brake disc. Any system or mechanism that can systematically or intentionally produce asymmetric braking torques for a given axle is prohibited.”

A key generic limitation of this generation of ground effect cars is that they understeer at low speeds. F1 cars have done that for years, but now they really do it. The aerodynamic centre of pressure is a long way back in the wheelbase at low speeds thanks to the regulation placement of the choke point of the underbody’s venturi. Countering that with more front wing will ease the understeer but bring big problems at higher speeds when that big wing gets close to the ground as the car is pressed down on its suspension. With the wing then working in ground effect it becomes very powerful, shooting the car’s centre of aero pressure forwards and promoting rear instability on corner entry in particular. There’s not enough front end at low speeds, but too much at high.

Ferrari of Charles Leclerc cornering in 2024 F1 Belgian Grand Prix

Current-generation F1 cars are afflicted by understeer in low-speed corners

Asymmetric braking on the rear axle would be a neat way of resolving this conflict. By applying greater force to the outside rear than the inside, the car could be made to pivot into the slow corners. If this was related to how much steering lock was applied, then it could be set up to heavily rotate the car only into low-speed corners without coming into effect at the lesser steering angles needed for high-speed corners.

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It would be an exaggeration of the effect of loosening the differential but working earlier in the turn. Essentially it would give a mild handbrake turn effect, so giving you the low-speed agility without having to make the front wing work so hard that it becomes a problem at high speed. It revisits McLaren’s 1998 banned ‘fiddle brake’ (an extra rear brake on each wheel operated by an extra pedal and a switch to determine which side was being applied) but in a generation of car in which that low corner agility is more sorely needed.

Inevitably when the revised regulation was announced, speculation was rife about which team or teams may have been using such a system. There have even been stories linking it to one team, but the details are vague and the supposed timings suspect. Not that it would have been breaking the letter of the regulations as they were. But there’s no ambiguity now.

There have, though, been several incidents through the season (and even last season), which might be seen as supporting the possibility of asymmetric braking having been used. Let’s run through three of the top teams: Red Bull, McLaren and Mercedes.

Red Bull

In Melbourne this year Max Verstappen retired from the race on lap two with his left-rear brakes ablaze after a reported preparation error resulted in the Red Bull’s caliper sticking on. Before he pulled in, it was giving Verstappen way too much of a handbrake effect and his wrestle for control of the car through Turn 3 is what allowed Carlos Sainz to pounce and take the lead. Twelve months earlier at the same track Verstappen and team-mate Sergio Perez were troubled in Friday practice by a rear caliper taking too long to release and giving some entry instability. Perez crashed out of Q1 insisting the problem was still there, but the team insisted it could find no technical problem with the car.

Smoke from Red Bull of Max Verstappen at the 2024 Australian Grand Prix

A sticking caliper brought Verstappen's Australian Grand Prix to a premature and smoky end

Scott Barbour/AFP via Getty Images

Oscar Piastri sprays champagne on the F1 podium after winning 2024 Hungarian Grand Prix

Piastri won in Hungary, despite running off track

McLaren

Sparks from Mercedes of Lewis Hamilton

Mercedes took time to get the right set-up at Spa

Mercedes-AMG

McLaren

Recall that in Hungary the only reason there was any controversy between Oscar Piastri and Lando Norris around the second McLaren pit stops was that shortly before the stops Piastri had lost a big chunk of the 5sec lead he had established over Norris, with a big sudden snap into the fast Turn 11 which ran him onto the run-off area. Afterwards Piastri reported that he understood what he had done wrong. As he’d dropped those 3sec his alarmed race engineer asked if all was ok. “Yep,” replied Oscar. He didn’t seem up for broadcasting over the radio what the problem may have been. Just a simple driving misjudgement? Or a setting error for a fast corner after a series of slow ones?

Mercedes

Recall how the cars were all at sea on Friday at Spa, with bouncing and balance problems? But very quick and well-balanced on Saturday and Sunday, good enough to cross the line 1-2.  The problem on Friday, the team explained, was a ‘mismatch between certain mechanical aspects and the aerodynamic set up’. That sure could be interpreted as getting asymmetric braking set up appropriate to the track. It could just as easily – as with the Red Bull and McLaren examples – be something else.

No Ferrari incidents of a similar nature spring to mind. It will be interesting to monitor the post-break competitive order.

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