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ACC Release 7 - Brake Ducts and Tyre damage

Paul Jeffrey

RaceDepartment Editor-in-Chief
ACC Blog - Tyres.jpg

To accompany the latest build of Assetto Corsa Competizione, Kunos physics expert @Aristotelis gives us the rundown on such goodies as brake ducts and tyre damage.

Let today forever be known as Assetto Corsa 'release 7' day! Not content with a massive new build release, the opening of the SRO E-Sport GT Series 'Silver' qualification event and a blog post on the many varied improvements to ratings and weather effects, we now get treated to yet another insightful look at the inner workings of the simulation - this time with a feature on brake ducts and tyre damage.

As has become something of a tradition when a new build is launched, one of the hard working Kunos staff members takes some time out to discuss various aspects of interest introduced as part of the latest build, and this time around it is once again left to Aris to share some insight into the title, helping players get a better understanding of some of the mechanics that go into making Assetto Corsa Competizione the racing simulation that it is today.

Handing over to @Aristotelis, let's hear more about what release 7 has in store for us all...

Brake ducts, car damage, tyre damage and generally how we can make you lose a race and get angry...

ACC v.0.7 brings brake ducts simulation.
Actually brake ducts simulation was always there, but now it is enabled as setup choice. As usual the preset setups have a default brake duct setting, that can work safely pretty much in any condition, different brake duct settings can affect greatly the brake efficiency but also the tyre temperatures and of course up to a point, the aerodynamics of the car.

The obvious functionality of the brake duct is to bring more or less air to the brake discs and keep them in a temperature range that can be effective. Setting 0 is a completely closed duct and can provoke brake fade very very fast, exceeding 1000°C. Never to be used in a real race, but added for simracer's gratification. Setting 6 is completely open and can keep the brakes very cold.

Small and fast note of how the brake heat affects braking performance. The brake discs and pads have a range of optimum friction, just like the tyres. Keeping their temperature between this range, will give you the best possible brake performance. Of course that doesn't mean that it will also stop the car sooner, as this depends on a multitude of reasons like tyre grip, downforce, ABS, setup etc. But it is obvious that a very cold brake system will make your braking zones much longer and the same will happen for a very hot brake system. In addition a very hot brake system will also wear down the pads much faster... but this is a different story for a different release version maybe :p

The brake duct doesn't only change the peak heat temperature but, most importantly it changes how the heat gets dissipated after you release the brakes. A low setting will keep the brakes hot for a longer period of time after your last braking zone, while a higher setting will not only achieve a lower peak temperature but also cool them down faster.

Ideally you want your front brake HUD to show green or slight yellow at the end of your braking zone and your rear, green. Don't judge after just 2,3 braking zones. Do a couple of laps and let the brakes do some heat/cool cycles to arrive at a balanced condition.
MoTeC channels are available for brake heat.

This behaviour brings us to the next very important influence of the brakes. The red hot discs will warm up the rims and then the air inside the tyre. In that way you can use the brake heat to heat your tyres up or try to run a bit colder brakes to keep the tyres from overheating.
Again, a couple of laps are needed to check the heat behaviour of the whole system brakes and tyres.

Also keep in mind that the brake ducts, especially the fronts, get heat from low near the asphalt. That is why they are influenced more by asphalt temperature. This means that you might have the same ambient temperature but an overcast weather will heat the asphalt and thus the brakes, more than a cloudy condition.
Also, the water now influences the brake discs, so under rain conditions it is better if you use a lower brake duct settings.

Finally, as you might have thought, the brake ducts will influence a bit the aerodynamics of the car, both in downforce and most importantly drag. The differences aren’t massive as you might expect, but they will make 3-4kmh difference at the long straight of Paul Ricard and as you know, every little counts.

ACC V.0.7 also brings an industry first tyre damage implementation.
One of the most risky conditions in a racing car, is cold tyres. Everybody has heard pit radio screaming at the driver to warn him that his tyres are cold and he should warm them up. Obviously a well warmed up tyre gives better grip and improves performance so it makes sense to have warm tyres at all costs. Still, there is a much more dangerous situation that occurs on cold tyres. A tyre is inflated with a low pressure so that with heat going up, the tyre will be at the optimum pressure. On the other hand a cold tyre will go even lower in pressure and this means the tyre can flex and move a lot. Riding a stepped kerb on a very low tyre, will make it vibrate and flex a lot. This can provoke carcass damage, can make the tyre lose contact with the rim and small amounts of pressure, eventually creating a vicious cycle that can provoke permanent deflation of the tyre and puncture! All of this is now simulated in ACC.

When the pressure goes under 24psi, you will get a warning from pitradio to keep an eye on it and avoid kerbs. You should really avoid kerbs at all costs when the pressure is so low. If you ride and slide over stepped kerbs with such a low kerb, the tyre might lose pressure. If the pitradio understands that you lost a good amount it will warn you again. It’s up to you of course to do a pitstop and put new tyres or raise the pressures, or risk it and stay out trying to heat up your tyres and raise your pressures. But don’t blame us if over a kerb the tyre will instantly deflate and you’ll end up spinning with no grip… or tyre.

Go outside the track and rejoining, running wide on grass and sand traps can also provoke similar tyre damage situations. All in all, the more you abuse your tyres when not in correct pressures, the more risk you have to get a puncture or at least to seriously compromise your tyres life.

A typical scenario of what you might experience: You start with slick tyres and correct pressures. Dynamic weather changes and you get night time cloudy with lower temperature or slight rain. You think you can handle it with slicks and decide to stay out. The grip is not bad but the tyres lose temperature and pressure fast. You get a warning from the pit radio which you ignore and you keep pushing on the kerbs. Another different warning, this time the pit radio says they detect a slow puncture or simply you’re losing pressure. Another kerb, and another and then that frightening sound of a tyre exploding, sparks from the under tray scratching the asphalt and your car spinning without control… maybe you should have made that pitstop for rain tyres.

Obviously the system is brand new and needs tweaking, so we appreciate your feedback. There is nothing random in the system, all of it depends on your actions, but some of the causes and effects are not predictable. You can never tell how your tyres hit the kerb or what impact they got in the re-entry from the grass, so some effects might seem random to you, but they are not.
We think it adds extra depth of simulation, realism and decision making while racing.

Finally with ACC v.0.7 we also activate the classic damage. Aero damage, drag and downforce, suspension bends, and total crash can happen. It’s a good system, fairly simple, does the job. We will try to improve on that too, in the near future.

Hope you will enjoy.
Assetto Corsa Competizione is currently at release stage 7 and available on Steam Early Access now.

For more Assetto Corsa Competizione news and discussion, head over to the ACC Sub Forum here at RaceDepartment. If you enjoy online racing yourself, you might enjoy our ACC League and Club Racing forum, a place to take in clean, fair and competitive online racing in this sim.

SRO E-Sport GT Series – Check out the latest news HERE.

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Isaac Chavira

Livery Designer
I'm tripping out over YouTuber Nicki Thiim racing for Aston Martin! I hope Jimmy Broadbent gets a drive soon. And he drives No.76 which is the car number I always pick.


TheReaper GT

Learning stuff, eating cookies. :D
I'm tripping out over YouTuber Nicki Thiim racing for Aston Martin! I hope Jimmy Broadbent gets a drive soon. And he drives No.76 which is the car number I always pick.

View attachment 299635
To be fair Nicki drives in real life wayyy before he got into simracing. Nicki have a WEC title and a Le Mans Class win. He is one of the best GT drivers in the world (toggle Jezza's voice). Also, he's father was a DTM legend :D


I'm tripping out over YouTuber Nicki Thiim racing for Aston Martin! I hope Jimmy Broadbent gets a drive soon. And he drives No.76 which is the car number I always pick.

View attachment 299635
Nicki isnt really a youtuber, hes a full time pro driver that has a Le Mans class win and a WEC class title and always has been and just does twitch/youtube for fun where as jimmy is just a simracer and there is no way he would get a seat in a pro car in BES or BSS
I have got sound issues. Game also CTD. It's far from v1.0
Strangely I got this to, but only once or twice after the update to 0.7 last night. I believe it was a CTD with AC2 fault and the other time the audio got stuck, then the whole game froze and crashed the computer eventually.
Did a few hours of racing after a reboot and never had any issues again. Strange things do happen.
Well yesterday i started avoiding the kerbs when going out with low pressure tyres, and doing like real life to heat the tyres.
So i did a race in the gtr18 in zolder, was in first everything was fine until the moment that the engineer said that i had a low pressure tyre so i did quick check of the app, i had my rear left tyre with less 2,6psi than the right one it was almost 24psi and this happened from constantly abusing the kerbs during the race, i tried to raise the temperature of the tyre but i was just sliding in almost every corner, i changing brake bias and tc to a more safe place but was hopeless, at the end i won the race but i wish i had a puncture, it would be amazing,
So amazing work Kunos love that we need to give love to the tyres.

Just one question is tyre wear in game already?