Brake Ducts, Tire Cooling, and beyond

[Farnborough]

As I understand it the BBW (brake by wire) used so far has the initial brake application through regeneration for the rear, then as the allowed store capacity in the rules for recovery is reached, the BBW system blends in line pressure to rear calipers .... supposedly in seamless "tapering" such as to be invisible to driver input.

They could have the POSSIBLE addition to dump out through electrical resistance and produce heat instead of filling energy store. This then to be cooled by supplementary system to evacuate. Technically, it wouldn't breach the energy stored allowance as it's wasted. This I don't recall as part of original design.

It would fall straight into that thesis area of the linked yt clip in terms of handling heat transfer at different location from the wheel assembly though.

Effectively it would add inefficiency to the car, which is easier than chasing efficiency. But would likely have a drag penalty for the additional cooling.

It could have the "toggle" effect observers are theorising in how it's deployed though.

Some "theatre" in operation of car build to obscure the real reason by getting people to look at the brake tins a bit of fun to complete the illusion.

Note:- these two post I've copied from the car comparison thread as more logically located here.

[AR3-GP]

I haven’t seen anyone throw some numbers around. Brakes are seeing temperatures in excess of 1000* C. How is what anyone hypothesizing works with that?

The brake disc will only reach 1000* C intermittently. The temperature of the surrounding components tends to be lower as it's a system which is exposed to an airflow that transfers the heat away. Nickel, Tungsten, and various Steel alloys (as well as other unnamed metal alloys) have melting temperatures in excess of 1000C in any case so materials are not a limitation.

Furthermore, brake ducts have rules restricting the deflector and the drums themselves. Furthermore, blown axles are also banned. All this is related to controlling outwash.

Fit what you’re proposing within the rules and the operating parameters.

The descriptions provided so far don't seem to contradict the regulations regarding the brake deflector and the drum as those only govern the geometrical volumes where these components can exist. The "Internal cooling ducts" of the wheel drum are a "Listed Team Component", which means that it is not standardized aero and it is up to the teams to sort independently.

If one were to devise a fully working system with numbers on here for your review, it wouldn't be given away for free...

[TwanV]

No, any liquid in contact with tire would be too easy to find / copy. Does anyone have a reasonable representation about the heat flow of the tire to the road, the rim, how hot things get normally and what amount of cooling at what dT would be needed to shave off any meaningful amount of heat at the tire rim surface? I thought the passive phase change material idea is to be a nice find and most likely what's going on if the heat balance makes sense..shave off high temperature heat flow at the rim by phase change, and releasing that heat using some mechanism involving brake cooling on straights when there's no heat input from hysteresis in the tire and plenty of cooling air. But which material would fit that temperature window of presumably 60 degrees at phase change without any potential to burn up at higher temps?

[AR3-GP]

No, any liquid in contact with tire would be too easy to find / copy. Does anyone have a reasonable representation about the heat flow of the tire to the road, the rim, how hot things get normally and what amount of cooling at what dT would be needed to shave off any meaningful amount of heat at the tire rim surface?

No, but here's a dummy model (sans numbers) that I've found online. It's not specific to F1, but it's the gist of a model that one could further develop.

[Hoffman900]

I haven’t seen anyone throw some numbers around. Brakes are seeing temperatures in excess of 1000* C. How is what anyone hypothesizing works with that?

The brake disc will only reach 1000* C intermittently. The temperature of the surrounding components tends to be lower as it's a system which is exposed to an airflow that transfers the heat away. Nickel, Tungsten, and various Steel alloys (as well as other unnamed metal alloys) have melting temperatures in excess of 1000C in any case so materials are not a limitation.

Furthermore, brake ducts have rules restricting the deflector and the drums themselves. Furthermore, blown axles are also banned. All this is related to controlling outwash.

Fit what you’re proposing within the rules and the operating parameters.

The descriptions provided so far don't seem to contradict the regulations regarding the brake deflector and the drum as those only govern the geometrical volumes where these components can exist. The "Internal cooling ducts" of the wheel drum are a "Listed Team Component", which means that it is not standardized aero and it is up to the teams to sort independently.

If one were to devise a fully working system with numbers on here for your review, it wouldn't be given away for free...

We run caliper tape on GT cars. 200* C + is pretty consistent on calipers.

You can assume the caliper, brackets, the hubs, parts of the upright, etc are all floating around 150-170* C.

Not sure about F1, but most racing tire compound tires want to be around 95-100* C tread temp.

[DiogoBrand]

Newey invented the blown diffusor. As this was forbidden, the coanda was used...and so on...

Blown diffusers were around in the 80s...

I have a running joke with friends that Newey gets credit for inventing everything

Pretty much nothing is "Invented" in F1 these days, everything is "reinvented" or "adapted" for different conditions. There's a video somewhere of Willem Toet telling the story of how the blown diffuser concept resulted in a discussion between aero and engine departments on his team at the time, aero wanted a narrower exhaust to accelerate it and help with diffuser performance and engine department arguing that it would result in too big a hit on power.
So even though I'm not someone that thinks Newey is an airbender that can see air with his bare eyes and perform miracles, you have to give him credit for adapting the concept to the regulations at the time.

[Hoffman900]

Blown diffusers were around in the 80s...

I have a running joke with friends that Newey gets credit for inventing everything

Pretty much nothing is "Invented" in F1 these days, everything is "reinvented" or "adapted" for different conditions. There's a video somewhere of Willem Toet telling the story of how the blown diffuser concept resulted in a discussion between aero and engine departments on his team at the time, aero wanted a narrower exhaust to accelerate it and help with diffuser performance and engine department arguing that it would result in too big a hit on power.
So even though I'm not someone that thinks Newey is an airbender that can see air with his bare eyes and perform miracles, you have to give him credit for adapting the concept to the regulations at the time.

People make these decisions all the time though in racing. Most just aren’t exposed to it.

I have contacts in one of the NASCAR teams, and I know their most powerful headers are not used on the car, because they don’t produce the most downforce. In NASCAR where everything is tightly controlled, how you layout the exhaust tubing can influence under car flow and the flow out the engine bay underneath. Less power but more downforce for a lot of cars is often faster (to a point).

My point being, is Newey gets a lot of credit for stuff he never did or was the sole brain child behind. He’s great, one of the best ever, but he’s just one guy. He doesn’t bend air and he doesn’t perform miracles. His probably biggest advantage, and he’s said this himself, is he better understands the complete package; chassis, air, and driver, and how they interact and the compromises needed than most contemporary designers. That’s because he worked as an actual pitwall race engineer (in Indy Car) in an era when everyone did more than one thing. Today, people are so specialized they may struggle to see the forest for the trees. The majority of people working on the car design side of F1 now probably never or VERY rarely get to any race track, let alone be involved in any of that stuff.

[Watto]

We are assuming that McLaren is somehow using brake heat to heat up the tires, then once they're up to temperature they're isolating them to prevent overheating, but is there any evidence that they're doing something special to bring the tires up to temperature?
I mean, maybe heating up the tires is not such a challenge, and the brake ducts are only acting to isolate brake heat from the tires, not switching on and off to do two different functions at different times. They do have an advantage in keeping the tires cool over a qualifying lap when temperatures are high, but I don't see them having a big advantage in qualifying or race pace otherwise.

I think a few have pointed out one of Red Bulls biggest issues a few years ago when they dominated the season was the struggle to bring tyres upto temps for quali. Race was it was always good and okay for quali but the current McLaren seems to have tyres that get upto temp for quali and not overhear during a race. Even on restarts they McLaren seens pretty quick. Some thought too of both Lando and Oscar have had some good race starts this year - Lando had trouble getting it off the line last year often lost places this year he has been pretty good off the line so maybe something McLaren have worked on and possible having tyres in their window pretty quickly.

[AR3-GP]

I doubt PCM technology because liquid cooling of the brakes is forbidden according to article 11.5.

[AR3-GP]

I thought there was something strange about Mclaren's comments after the Chinese GP where Lando Norris faced an unspecified brake system failure.

“Lando and the team did a great job in managing the situation and adapting the driving style to the problem, which then got worse to the point where it put the result at risk, which is unacceptable from a reliability point of view, we need to do better.”

Stella gave a limited explanation behind the issue, but sought privacy rather than disclosing the whole picture.

“We understand what the problem is, which I can’t disclose for IP reasons,” he said.

“But fundamentally, it had to do with a leak in one of the components, not in the brake line, but somewhere else, and the main action required was to limit the peak brake pressure.”

https://www.motorsportweek.com/2025/03/ ... -in-china/


Brake systems are well known and you are not going to find any big differences between the cars. What is the reason of being so secretive here?




I'm not so sure how to connect the dots in a way that satisfies the regulations. I think that the brake fluid could be used to conduct heat away from the brake tins but any further details are complex. While liquid cooling is forbidden, brake fluid is unavoidable.

According to AMUS report:

Based on thermal imaging camera images, Red Bull has virtually black on white that the McLaren's brake linings stay cooler on the outside than on any other car. And that naturally affects tire temperatures. McLaren clearly has absolute control over this. And that could be the match winner, both for a single lap and for the entire race. Because the tires don't overheat and therefore don't lose grip.



Red Bull is convinced that it's impossible to cool its tires with air alone.

Correct me if I'm wrong but I see nothing in the regulations that would forbid you from cooling the brake fluid. Brake fluid absorbs heat from the caliber and the lines. It can boil if it gets too hot. So maybe one could justify the use of a heat exchanger in the circuit under safety pretenses. Maybe the fluid itself has been highly modified for such purpose. Could be something. Could be nothing.

[Hoffman900]

Brake fluid doesn’t move anymore than the caliper’s pistons. You’re talking few mm’s of travel. That’s how hydraulics work.

When fluid boils, it’s very localized (usually inside the caliper).

[AR3-GP]

Brake fluid doesn’t move. That’s how hydraulics work.

It doesn't need to move to conduct heat. It's a fluid. Establish a temperature gradient and heat "flows". I know that you could transfer much more heat if you could circulate it, but that is not an insurmountable challenge either. Fluids can be circulated under high pressure (gas pipelines work, somehow). This is where it all starts to get dodgy though. What would such a system look like to the FIA?

I'm also not claiming this is exactly how a system would work, but there could be possibilities along these lines. Maybe one could develop a bespoke brake fluid for such purposes.

Mclaren is clearly doing something that no one has thought of yet. So it's time to think outside of the box.

[FittingMechanics]

I doubt PCM technology because liquid cooling of the brakes is forbidden according to article 11.5.

https://i.postimg.cc/CMQtHJ56/image.png

Idea of PCM is not to use it for cooling of the brakes, it would be used to serve as a barrier between hot brakes and the wheels. Kind of like a insulator but that starts working at certain temperature, so you can gets some heat into the tire but not more than that.

Not sure if that would fall under "no liquid cooling", maybe, who knows.

[Farnborough]

If they were to make use of regeneration in more capacity now ....... shunting excess out to resistor pack for cooling in tandem with pre-existing battery store cooling "pack" ..... ultimately to comply with regeneration cap. Then that woukd play into next years regulations of higher recovery rate for chassis/driver dynamic.

It simply wouldn't make heat in the same quantity as others at disc, drum, wheel location in the first place.

Speculation of cooling may be looking in the wrong place.

[Alexf1]

I doubt PCM technology because liquid cooling of the brakes is forbidden according to article 11.5.

https://i.postimg.cc/CMQtHJ56/image.png

Idea of PCM is not to use it for cooling of the brakes, it would be used to serve as a barrier between hot brakes and the wheels. Kind of like a insulator but that starts working at certain temperature, so you can gets some heat into the tire but not more than that.

Not sure if that would fall under "no liquid cooling", maybe, who knows.

A material inside the brake drum which at some point is liquid would