Revealed: The truth behind the FIA’s mid-season brakes rule change

The McLaren drivers and Max Verstappen

The FIA making an addendum to the rules regarding Formula 1 braking systems raised eyebrows over the F1 2024 summer break, leading to some conspiracy theories.

Having been approved by the World Motorsport Council at the end of July, the FIA published an updated edition of the 2024 Technical Regulations on July 31 which included an eye-catching addition to the rules regarding F1 braking systems.

What was the change made by the FIA in the F1 2024 Technical Regulations?

Tucked away in the depths of the updated Technical Regulations, rules which are immediately binding, was an additional sentence in the area related to F1 braking systems – a sentence with potentially huge meaning.

Article 11.1.2, in the original regulations for this year, stated: “The brake system must be designed so that within each circuit, the forces applied to the brake pads are the same magnitude and act as opposing pairs on a given brake disc.”

The updated Article kept the aforementioned sentence, but included an additional clarification that stated: “Any system or mechanism which can produce systematically or intentionally, asymmetric braking torques for a given axle is forbidden.”

So why was this change made in the middle of the season?

After all, with the rule now bound into the regulations, any team using such a system would face race and championship-defining penalties – but did this mean a team had been running such a system prior to the July 31 introduction?

Why would an F1 team want asymmetric braking?

With the current generation of F1 cars particularly prone to understeer, a way to counteract that would be if it was possible to slow down one rear wheel more than the other.

It’s not a new or novel idea, and it’s something McLaren experimented with – to growing success – in 1997 and early ’98 before it was banned on the grounds of it being a four-wheel steering system.

Both the braking and steering technical regulations were updated in 1999 to close off what McLaren was doing, but the possibility of a similar system being used through a different method had been identified – something that’s particularly pertinent as the F1 teams battle to find ways to make their cars less afflicted by understeer.

Being able to slow down one rear wheel more than the other would allow for stronger turn-in and would thus pay off in lap time – if such a system were completely above board.

More on the FIA and F1’s braking systems

Explained: How the FIA develops potential new F1 rules and regulations

‘Fiddle brake’ banned: The controversial McLaren braking system banned by the FIA

Were any teams running an asymmetrical brake system?

There’s no evidence to suggest that any of the F1 teams were using any such system.

Given the sudden and surprising nature of the rule clarification, it’s no surprise that some theories have been offered up – particularly regarding the coincidental drop-off in the relative competitiveness of the Red Bull RB20 this year.

Respected F1 journalist Peter Windsor took to X (formerly Twitter) over the summer break to speculate on this possibility, saying: “Looks as though [Red Bull] might have been running a clever rear cross-brake inertia valve before they were obliged to remove it before Miami. This could explain Max’s [right-rear] brake drama in Melbourne and his turn-in grief since China.”

Windsor chose to highlight the brake caliper issue that Verstappen encountered early on in Australia, which resulted in a brake fire for Verstappen after his right-rear caliper seized.

At the time, brake manufacturer Brembo told PlanetF1.com that, on their side, there were no issues with the components or materials used in the manufacturing of their supplied parts.

Brembo stated the cause of the problems encountered by Verstappen was “not attributable” to their materials or components, nor to component anomalies or a malfunction in the materials used to make the components.

Red Bull mechanic Calum Nicholas bluntly dismissed Windsor’s theory on X, saying: “Yea [sic]… this is bulls**t…. Unsurprisingly.”

Weighing in on Windsor’s hypothesis, technical journalist Craig Scarborough explained how such a valve could work to alter the amount of pressure across the rear braking system, offering diagrams to showcase the idea.

“This makes sense and underlined by the tech reg change,” he said.

“A return of the Newey fiddle brake, but automatic & creating a turning moment with the rear brakes. A simple weighted valve in the rear brake splitter could do this. Altering the effort between the calipers as the car turns.”

This makes sense and underlined by the tech reg change.
A return of the Newey fiddle brake, but automatic & creating a turning moment with the rear brakes.
A simple weighted valve in the rear brake splitter could do this.
Altering the effort between the calipers as the car turns pic.twitter.com/XY3onkG51w

— Craig Scarborough (@ScarbsTech) August 15, 2024

The existing regulations suggest such a system wouldn’t have been legal in the first place, given the prescription on how forces applied to the pads across a circuit (per axle) must be of the same magnitude.

‘Powered devices’, of which a simple G-activated valve wouldn’t qualify, are also explicitly banned, while the rules pertaining to calipers state: “No braking system may be designed to increase the pressure in the brake calipers above that achieved by the driver applied force to the pedal under all conditions.”

These rules would seem to have closed down any possibility of a team running such a system and sources with close knowledge of the situation have told PlanetF1.com that, according to the opinions and understanding of leading technical staff at the teams and within the governing body, a system to vary the pressure being applied to the pads or increase the pressure in the brake calipers beyond the driver’s own input was already viewed as illegal.

But the grey area of having a system capable of producing asymmetric forces, whether used or not, has now been expressly forbidden by the FIA’s rule tweak – if a system such as the one theorised by Scarborough were to be found, the updated rule wording allows the FIA to take action against the relevant team rather than having to figure out whether the said system was used and produces an effect rendered illegal by the wording without the addendum.

Put simply, it’s cutting out the theoretical – if you have such a system on your car, it is illegal.

The rule ‘change’ is merely a clarification and tightening of existing rules – and the FIA has expressly confirmed no team was running a system in contravention of them.

Rather than there being a more cloak-and-dagger reason behind Red Bull’s relative drop in performance, the Milton Keynes-based squad’s own explanations of the other teams making big strides forward while, simultaneously, struggling to unlock its own upgrade potential, is the true picture.

But given the slight grey area left open by its own regulations, the FIA acted now, rather than waiting for a future rulebook – resulting in the guesswork behind the rule change.

The plan had been to make the rules pertaining to brake systems tighter by the time the new 2026 rulebooks came into force but, with teams requesting clarification on the matter in recent discussions, the FIA introduced it as a clarification at the earliest opportunity.

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