ACC getting many changes in version 1.9 this week

ACC Update 1.9: Tyre Model and Physics Changes

Assetto Corsa Competizione

This weekend, Assetto Corsa Competizione developer, Aristotelis Vasilakos detailed some of the changes coming to ACC in Update 1.9. Here are some of the highlights.

Image Credit: Kunos Simulazioni

Everyone that follows simracing is aware that Kunos is releasing Update 1.9 for Assetto Corsa Competizione this week. Supposedly the “biggest update ever” for the game, the community is understandably feeling the hype. But until recently, we still didn’t know what would be included in the new version of the game.

To change that, ACC Head of Vehicle and Handling R&D, Aristotelis Vasilakos took to his Youtube channel this weekend. In a pair of live streams, he spent nearly four hours over Saturday and Sunday showing off his team’s work. From a near-complete overhaul to the ACC tyre model to changes in the way suspension components interact with the car, tyres and track surface, there is plenty to discuss.

Goodbye Pinhead Tyre Pressures

Among the changes, Kunos front man Aris was keen to point out the major overhaul affecting the tyre model. Assetto Corsa Competizione has always received praise for its tyres, but the Italian team evidently believes more is possible.

Since launch, pressures have been a huge talking point in the ACC community. The famous 27.5 psi figure is surely etched into everyone’s minds. But it’s time to forget that number and be a little more adaptable. According to Aris, there will no longer be a perfect pressure figure that gives optimum grip. A wider pressure window of between 26-27 is advised while some cars may even find more speed above or below that bracket.

Depending on track temperatures, grip levels and the suspension and alignment setups, pressures will change. The key will be to balance the low-speed grip offered by a low-pressure tyre with the high-speed agility of a high-pressure tyre. These will also severely impact the second main tweak to the model, temperature.

Managing Tyre Temps

Tyre temperature in ACC has also always been a black and white affair. You’re either on the pinhead of perfection or falling off the cliff. But, with Update 1.9, the changes mean ACC players have more freedom in their tyre temperature. Stay within the window of 70-100°C and you should be good. It’s important to note that this is a core temperature guide as tyre surface temperatures will fluctuate much more in the new update.

When flying down long straights, the surface will drop by as much as 30°C. Whilst on twisty sections that work the tyre more, you’ll see peaks of well over 120°C. The key here, according to Kunos’ presentation, is to manage the temperature spread across the entire tyre surface. Avoid large differences between the inside and outside side walls as this will negatively affect core temperature, grip and wear.

Unrealistic Setups in ACC 1.9?

These changes are being introduced for two reasons. Firstly according to Aris, these wider windows will force simracers to feel what the car is doing underneath them. Too often simracers “drive to the numbers” according to the Kunos Head of Vehicle and Handling R&D.

But the new physics tweaks should also deal with so-called ‘alien setups.’ Pushing odd toe and camber values that would never exist in real life, they result in the game distancing itself from the sport it replicates. The tyre temperature changes specifically should root out these unrealistic setups that provide top level drivers with unachievably fast cars. It is this key issue that pushed our editor Champion Joe to call ACC a pay to win game.

More Compliant on the Kerbs

In previous versions of Assetto Corsa Competizione, cars would often hit kerbs and bounce in an aggressive way. For the most part, this was due to way in which Kunos set up the simulator’s bump stops. Whilst in real life these are designed to limit the travel of a suspension spring to avoid carbon fibre crashing into the tarmac, ACC featured a seemingly endless bump stop. Therefore, the limit on suspension travel would be determined by the softness of a spring and its length.

The result of such a feature was that, with softer setups, cars would run along the ground in an unrealistic way. Producing less drag, this was another ‘alien setup’ possibility that the pros used to gain an advantage. With stiffer setups, the spring would act as the limiting factor of suspension travel and rebound values would launch the car in a nasty way on bumps and kerbs.

With ACC 1.9, changes to the bump stop window mean there is a limit to its compliance. Once it reaches its limit, it will no longer compress infinitely. Instead, it will hit its maximum and allow the car to rebound in its own time. This should make for a more compliant ride on bumpy surfaces and avoid random spins when driving in places which were forbidden ground in version 1.8.

More Changes Coming to ACC

With tyres and bump stops firmly headlining the changelog for Assetto Corsa Competizione 1.9, Kunos has seemingly reworked the entire sim around these key changes. With overhauls to the way the bump stop works, everything around the suspension has been worked on, including the dampers.

The main effect players should notice from this is how slow dampers alter the car’s aero balance. Inputs and surface changes will change the car’s pitch in a better way making for the aero balance to slightly shift. Fast damper settings now work in harmony with the new bump stops to ride kerbs and track elevation better.

Finally, greater flexibility in the tyres means the force feedback has also received quite the overhaul. Players should reportedly feel more forces in the wheel as the tyre contorts under acceleration, braking and cornering. However, ACC‘s force feedback has always focused on the feeling from the front axle. So it will be interesting to see just how much one feels the new rear end-bias rotation in update 1.9.

It seems that the changes Aris highlighted in his streams are just the tip of the iceberg. Sure, physics overhauls to root out buggy setups and create a fairer playing field are nice. But, several other new features or tweaks could be in the pipeline. We won’t have long to wait to find out. Update 1.9 of Assetto Corsa Competizione releases alongside the 2023 GT World Challenge DLC on Wednesday 19 April.

Are you excited for the changes coming in Update 1.9 for ACC? Tell us on Twitter at @OverTake_gg or in the comments down below!

A petrol head and motorsports fan since the early days, sim racing has been a passion of mine for a number of years. The perfect way to immerse myself in my true dream job; racing driver. With lots of experience jotting down words about the car industry, I am happy to share my passion for pretend race cars here on Overtake!