Formula 1 2024 – WILL CONTAIN SPOILERS

Just watched a YT commenting on the brake regs. Apparently Red Bull had an inertia valve after the brake by wire circuit that then split the braking force left and right. Think of it as a T in the circuit.

There was a little ball in the T that could move left or right as the car went around corners (inertia operated, not powered)  so as you turn left, the ball rolls right partially blocking the right part of the T and pushing more pressure to the left brake. **

This increase the braking on the inside wheel to reduce understeer, similar to the McClaren 3rd pedal back in the day. McClaren reckoned the 3rd pedal was worth up to 1/2 a second a lap.

This was picked up on, and Red Bull stopped using it, about the Chinese GP. Since then, the performance of their car seems to have dropped about 1/2 a second a lap.

**Possibly slightly more technical but this is the basic idea as I understand it

Claiming my £5 from posting the BMW pendulum brake

Fair play I was thinking it was suspension compressiing a brake line /valve or aero related.

 so as you turn left, the ball rolls right partially blocking the right part of the T and pushing more pressure to the left brake.

For that to work, it would have to completely block the brake line, so you’d have normal pressure on one side and zero on the other. As long as the port was open even the tiniest bit, the pressure on each side would equalize. I’m sure it would be possible to make a system with two proportioning valves controlled by a weight so that would limit the pressure to one side, but that would be a much more complicated system than a simple ball blocking off one circuit and hence it would be much harder to disguise as a normal junction.

Surely that would be clearly against the existing rules, so disqualification, as opposed to clarification of the rules forcing them to remove it?

Surely that would be clearly against the existing rules, so disqualification, as opposed to clarification of the rules forcing them to remove it?

Yes, that’s my take on it. None of the reputable publications have mentioned it, it’s just an internet rumour as far as I can tell. It’s quite possible that one of the teams asked if such a system would be allowed, hence the rule clarification, but the assumption that Red Bull must have been cheating because they fell back into the pack (after the other teams introduced upgrade packages) just seems to be fanboi speculation from the internet.

Lots of talk on Twitter from respected journo’s about it…

https://x.com/peterdwindsor/status/1824198674336948377?s=12&t=EQoHg-RGok071Fjc15ZHKw

https://x.com/scarbstech/status/1824228759567814841?s=12&t=EQoHg-RGok071Fjc15ZHKw

Actually, having mulled it a bit, with 4-pot calipers (or 2-pistons per side), you could use this system on one set of pistons per side so the affected wheel would still get 50% of the braking force, assuming two identical sized pistons. By using different sized pistons in each caliper, you could vary the ratio as you wanted. It would be pretty obvious that you were up to something though because you would have two brake hoses to each caliper instead of one (or a very bulky caliper if it was integrated into the brake caliper) and no F1 team would add any extra weight unless it gave some sort of benefit.

Lots of talk on Twitter from respected journo’s about it…

Speculation on the internet, in other words.

Scarborough’s diagram doesn’t quite make sense to me. Contrary to what he says, it wouldn’t just reduce the pressure on the outside wheel, it would reduce it to zero (a simple valve like that will be either on or off as far as pressure is concerned, it’s the pressure that matters here, not the flow volume). However, for the valve to close, the car must be turning before the brakes are applied. If you apply the brakes in a straight line, both brakes will be applied and they will then stay applied even if you turn in with them applied because closing the valve won’t release the pressure that is already applied to the pistons on that side. For it to work during turn-in, the driver would have to brake in a straight line then release the brakes and turn, then reapply the brakes while turning. Problem is, if a driver swerved to avoid a collision and then braked, they would only have the inside brakes operative

…it’s always going to be speculation as the FIA seem incapable of open discussion anymore.

The carpet at FIA HQ must have a massive mound under it with the amount of dirt swept under it.

The ball would not necessarily need to either be open or fully blocking the junction exit. Imagine that the surface the ball seats against has small grooves so there is just a little space for the fluid to squeeze through.

the assumption that Red Bull must have been cheating because they fell back into the pack (after the other teams introduced upgrade packages) just seems to be fanboi speculation – It was immediately after China that the Rebull performance dropped significantly. It ‘could’ be possible that every other teams upgrades yeilded pretty much the same improvement over Red Bull or it could be that Red Bull dropped back.

If you look at the results, especially Checo’s before and after China, there is a big difference. The same for Max but it is masked a bit more by his extreme driving talent.

Location – SP – MV

Bahrain – 2nd – 1st

Saudi  – 2nd – 1st

Austrailia – 5th – DNF

Japan – 2nd – 1st

China – 3rd – 1st

Miami – 4th – 2nd

Emilia – 8th – 1st

Monaco – DNF – 6th

Canada – DNF – 1st

Spain – 8th – 1st

Austria – 7th – 5th

Britain – 17th – 2nd

Hungary – 7th – 5th

Belgium – 7th – 4th

**EDIT *** After typing all that in, this came up on my YT feed – https://www.youtube.com/watch?v=9JKKw8NsPbI

Assuming the system applies more braking to the inside wheel if braking while cornering, you’d best only use the lightest of touches on the brakes  or you will lock up the unweighted wheel – no?

So I would want a non-linear response to the brake pedal too, to minimise that. And the front brakes to engage before the rear in that pedal travel (which they may do anyway).

Have the Red Bulls been locking inside wheels more than other cars?

I’m struggling to envisage a system where a little ball reliably rolls side to side in an oil based system – especially when the cars barely roll through corners.

(Plus as soon as the brake pedal is pressed the system is much more pressurised)

But I’m obvs not an F1 engineer!

little ball reliably rolls side to side in an oil based system – especially when the cars barely roll through corners

I don’t think it would be rolling because the car was leaning over, but because it wants to go straight on while the car is turning.

As someone else said, if you apply all/most/more of the braking force to the inside wheel it’s far more likely to lock up as it unweights.

The ball would not necessarily need to either be open or fully blocking the junction exit. Imagine that the surface the ball seats against has small grooves so there is just a little space for the fluid to squeeze through.

If there’s any space for fluid to flow, the pressure will equalize on both sides. Brake systems aren’t intended to carry large flows, they just transfer pressure, which doesn’t require any flow once the pistons have extended and compressed the pads against the rotor. The cross-sectional area of the port that the pressure is transferred through doesn’t matter so the port has to be fully closed if you want a pressure differential from side to side. Partially closing it won’t give a pressure differential.

As someone else said, if you apply all/most/more of the braking force to the inside wheel it’s far more likely to lock up as it unweights.

From what I remember about the McLaren system, the drivers would drag the brake on the inside wheel through the corner. It was intended to aid with cornering, not to slow the car. The inside brake disks would glow red hot, I think that’s how the other teams figured out what was happening.

So, I think in this case, the driver would brake and turn into the corner normally with both wheels receiving equal braking force. Then the driver would lift off the brakes and the inertia valve would block off the pressure to the outside wheel, then the driver would drag the brakes through the corner and the asymmetric braking would help rotate the car.

What if it was in a slightly flexible line or orifice

So if the ball blocked a port, more pressure would be needed for fluid to overcome the resistance. If it was a flexible tube, there could be a larger outer tube to limit loss in braking power as the flexible tube expands during braking.

Ignore me the ball would get stuck

What if it was in a slightly flexible line or orifice

So if the ball blocked a port, more pressure would be needed for fluid to overcome the resistance. If it was a flexible tube, there could be a larger outer tube to limit loss in braking power as the flexible tube expands during braking.

If the port is open at all, the pressure on each side will equalize. If the brake hoses are too flexible, you’ll get a mushy pedal feel. I can’t imagine that teams would want spongy brakes.

It’s interesting that it’s all rumour and innuendo so far and no proper journalist is touching it.  They must be digging and digging tho.   Andrew Benson will be trying harder than anyone, he seems to really hate Horner ?

thols2 – I think what you are saying about pressure equalizing and limited flow makes sense but the drop in performance, number of rumours and the new regs seem to suggest that something was happening. I was basically quoting from the YT videos I have seen and the sources that they quote. Agreed that they are not hard evidence.

Article from Mark Hughes*…

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

…Red Bull talked of as main user, but also that McLaren and Mercedes could be using a similar system. We’ll see how they all fare in twisty Zandvort! 🙂

*subs only but you can register to view.

*subs only but you can register to view.

Or just open in an incognito window in Chrome

If the port is open at all, the pressure on each side will equalize

The system would control a pressure regulating valve, not a flow regulating valve, so the brakes can be biased as needed to aid the steering of the car

The system would control a pressure regulating valve, not a flow regulating valve,

The diagram that Craig Scarborough had was of a flow regulating valve closed by inertia.

That Mark Hughes article references braking the outside wheel more, which makes more sense

That Mark Hughes article references braking the outside wheel more, which makes more sense

Possibly, but something that moves by interia – the car entering a corner – can be made to act on either side depending on your design I guess.

I understand the outside wheel would be more loaded so could take more braking but wouldn’t that pull the car on a wider line rather than tighter, thus increasing understeer?

I am guessing but I would have thought that you wanted the inside wheels braking more than the outside and then use the driver to control the lock up point.

He talks about it being a handbrake turn effect….dunno, don’t really understand it.

Good job I’m not an engineer in F1 really.

The original McLaren system braked the inside rear wheel. Drivers apparently had to learn to stay on the throttle slightly to avoid locking the inside wheel. The outside wheel being driven would also tend to turn the car into the corner.

https://www.autoevolution.com/news/mclaren-mp4-12-the-f1-car-that-used-two-different-brake-pedals-207645.html

The diagram that Craig Scarborough had was of a flow regulating valve closed by inertia.

It’s just a simplified diagram. A proper hydraulics diagram wouldn’t make sense to most readers

It’s just a simplified diagram.

It’s not simplified, it’s a diagram of a flow regulating valve turned on or off by lateral acceleration. When the car is cornering hard enough to close the valve, the outside brake is disabled and the driver can feather the brake to help rotate the car. The brakes will work symmetrically under straight line braking, then the driver needs to lift off the pedal as he turns in to release the outside brake, then feather the brakes to use the inside brake to help turn the car.

This all sounds a bit odd.

I don’t follow the Scarbs diagram either: my interpretation is as per hols2’s, ie that it has either no effect on pressure and/or will completely freeze one caliper at some point.

I also don’t follow Mark Hughes’ thoughts. I don’t see how a “handbrake turn effect” is relevant: the handbrake turn works by locking the rear wheels so that they have a lot less retardation than the front wheels. Until the wheels lock, there is no handbrake turn as such, it’s effectively just a bit more rear brake balance. And he talks about how applying more braking to the outer rear wheel induces a turning effect into the corner—that makes no sense either: the opposite is true.

What’s more, the regulations as I read them relate to asymmetric forces at a single caliper. Maybe I read them wrongly. But the regulation relates to “a given brake disc” and “a given axle”. There is no single rear (or front) axle, there is one per wheel. So I don’t get why all these rumours seem to relate to differential forces between the two wheels. I’ve always interpreted it as relating to differential forces across two sides of a single disc.

Edit: looking through the regulations, they use “axle” both to refer to the four physical axles at each wheel and to the two virtual axles front and rear. Quite why they’ve made that term ambiguous is a bit baffling, but I guess it makes a nice loophole to work with if you’re confident you can argue it in court if needed,

Gary Anderson has an article that explains one way an inertia valve could help by causing the inside rear brake to drag through corners. The brakes would all receive full pressure when braking in a straight line, but turning would activate the inertia valve which would prevent the inside rear brake from releasing. The driver would have to keep some pressure on the brake pedal as he turned in, then would release the pedal. As long as the car was turning above a preset g-level, the inside rear brake would keep dragging. The amount of braking could be adjusted by changing the weight and/or spring. Once the car stopped turning, the valve would open and the brake would stop dragging.

Important point is that the changed wording was apparently copied from the new 2026 regs, so there’s no evidence that it was done in response to finding that anyone was actually using asymmetric braking, they may be just closing off a loophole before anyone tries it.

https://www.the-race.com/formula-1/f1-intriguing-new-brake-rule-tweak-gary-anderson/

The interesting thing about that sort of device is that if it were to stick, it would cause exactly the issue that Verstappen had in Australia. Obviously, it’s not the only thing that could cause it, but Brembo (whose discs and calipers are used by the entire grid IIRC) publicly stated it wasn’t an issue with their components and there was no hint that it was something simple like debris caught under a pad. Red Bull never revealed what the cause was. Besides, when was the last time a single F1 caliper locked on like that? Not sure I’ve ever even seen it. For sure, you’d be jumping to conclusions to think case closed, but a passively-controlled valve failing to disengage seems to be one very plausible explanation.

If I were designing it I would design it to leak slightly so that the pressure equalised slowly. That would give a larger effect on turn in but lessening through the corner and minimising the chances of it locking a brake on.

It would also operate on the rear inside wheel, both allowing the front to track nicely, and to allow throttle balance of the effect.

As you straightened and accelerated the effect would tail off beautifully.

It might however lead to slightly different cornering lines. Anyone noticed anything odd about RB or MV cornering lines? In particular do MV and SP have different cornering styles that might make this work for one and not the other?

If I were designing it I would design it to leak slightly so that the pressure equalised slowly.

Yes, Gary Anderson says they did something similar back at Jordan, where they could tune the brake release for different wheels. Given the engineering resources the teams have, I’m sure they would figure out clever ways to optimize the system beyond being an on-off switch.

it would cause exactly the issue that Verstappen had in Australia.

Or Piastri at Hungary in a long fast corner when all of sudden he decided that he couldn’t brake, and allowed Norris to gain 3 seconds on him, and all the farrago that followed. In his radio transmission he said basically, “yeah it’s OK, I know what I did wrong” which some folks have translated as Piastri getting the brake setting wrong and not wanting to publicly broadcast that he’d done so.

If it was just a rule change why is there such a song and dance being made about it? Rule clarifications must happen all the time with no one batting an eyelid.

This weekend will be revealing though – it’s the sort of system that could work a treat around Zandvoort.

Motorsport.com are saying that an FIA spokesperson told them nobody was using such a system.

Could just be that a team wanted to use it and asked for clarification.

Motorsport.com are saying that an FIA spokesperson told them nobody was using such a system.

Could just be that a team wanted to use it and asked for clarification.

Yes, replicating the McLaren brake steer functionality without checking that it was legal first would be pretty dumb, especially for Red Bull who had an utterly dominant car last year.