In ACC brake setup, the most common mistake is starting from ABS and brake bias, as if finding “the right number” were enough to go faster. In reality, the logic is much clearer: first you build the correct thermal window, then you choose brake pads and ducts, then you fine-tune ABS and bias, and finally you verify everything with telemetry and brake-release technique. If you skip one of these steps, you risk fixing a temperature problem with electronics, or blaming the setup when the real limit is your foot or pedal calibration.
The Correct Brake Setup Hierarchy
The first question is not “how much rotation do I want on entry?”, but “are the brakes working in the correct window?”. The most common baseline is simple: at the front, you generally want to stay around 600–650°C, while the rear reference is close to 450°C, with the HUD indicator staying in the green zone. Small peaks above these values can happen, but if they become frequent, overheating, accelerated wear and reduced braking consistency start to appear.
This is where brake ducts come into play. If you open them, you increase cooling. If you close them, the brakes run hotter and you can gain a little top speed because you create less drag. On fast circuits, the goal is usually to close them as much as possible while still staying in the correct window. On stop-and-go tracks or in hot conditions, it is usually better to open them more.
The key point is that ducts do not affect only the brake discs. They also influence tyre carcass temperature and therefore the behaviour of the whole car package. For this reason, brakes and tyres should never be treated as two separate systems. While working on setup, you need to watch both the brake widget and the tyre widget.
A useful practical detail is this: brake temperature should be judged on the longest section between two braking zones, not only at the end of a braking phase. If the indicator turns blue there, the brakes are too cold, even if they briefly reached green at peak braking. It is a small detail, but it completely changes how you read the problem.
Brake temperature must be read together with duct settings:
more open ducts increase cooling but also drag; closed ducts reduce drag, but increase overheating risk.
Ducts and Brake Pads Are the Real Foundation
Once you understand the thermal logic, brake pad choice stops being random. Pad 1 is the qualifying, hotlap and short-stint option: it has strong bite, but it is more temperature-sensitive and wears faster. Pad 2 is the most universal choice: less nervous, more consistent, easier to manage over long stints and often the best solution for drivers who want predictability. Pad 3 is mainly useful in very wet or very cold conditions, while Pad 4 is essentially an extreme wear simulation, useful for training but not something you would normally choose for racing. For GT4 cars, the picture is even clearer: Pad 2 is the recommended choice in almost every real-use scenario.
The correct method is therefore this: first choose the pad according to session type and weather, then adjust the ducts to make that pad work properly. In ACC, brake ducts are adjustable from 0 to 6. With 0, overheating comes very quickly. With 6, the risk is that the brakes never really enter the useful window.
As a practical rule, more aggressive pads require more cooling, while endurance or wet-weather pads can tolerate a more closed duct setting. A good starting point is often 3, then moving to 4 or higher when ambient temperature rises above roughly 26°C. But this should be treated as a baseline, not as a fixed rule: every car, track and driving style changes the real cooling requirement.
If you do this in the wrong order and try to “save” the wrong pad with ducts, the setup always becomes a poor compromise.
that pad works in the right window: choose the compound first, then adjust cooling.
ABS and Brake Bias Define the Braking Character
Only at this point does it make sense to talk about ABS and brake bias. ABS does not magically shorten braking distance. Its main role is to make the car more stable when load changes and grip is not perfect. A higher value gives the driver more margin, but tends to extend the braking phase. A lower value can shorten braking, but requires more precision and better load management.
Brake bias works alongside it. More front bias means a calmer, safer car, but also a stronger tendency to understeer on entry. More rear bias gives more rotation, but also increases the risk of instability. In other words, ABS decides how much the car protects you, while bias decides how much the car rotates while you are still braking.
The practical consequence is that these two values should be changed in small steps and always one at a time. If the car moves too much under braking, the steering wheel vibrates heavily, or braking becomes messy, the first sensible tests are often +1 ABS and a 0.2–0.4% brake bias move towards the front.
If, instead, the car feels too planted and does not want to rotate, you can give it back a little freedom by removing some front bias, but only after checking that the real issue is not a brake release that is too abrupt.
A key concept remains: ABS should be a safety net, not a constant crutch. If it intervenes too often, you are already losing quality in deceleration and in the corner-entry phase.
ABS and brake bias define braking behavior: stability versus rotation.
Telemetry and Technique Tell You If the Work Is Really Correct
The final proof does not come from steering-wheel feeling, but from the brake trace. ACC can export telemetry to external analysis software and, with modern live-comparison tools, it is possible to overlay speed, throttle, brake and other channels to understand where time is really being lost.
A good brake trace starts with a fast and decisive application, reaches peak pressure early, then tapers off progressively as steering angle increases. If the peak has a jagged or irregular top, you are probably making the ABS work too much. If the curve drops to zero too early, you are releasing the brake suddenly and unloading the car exactly when it should start rotating.
Effective trail braking is the opposite: you keep reducing pressure while beginning to steer, keeping load on the front axle without saturating it.
There is also one final step that many drivers skip, but it changes everything: pedal calibration. If the pedal does not allow you to repeat the same pressure lap after lap, every discussion about bias and ABS becomes more confused.
With load-cell or hydraulic pedals, Brake Gamma should generally stay linear at 1.00. With potentiometer pedals, a higher value can make sense, usually between 2.50 and 3.50. The Maximum Limit can also help drivers who struggle to reach 100% brake pressure consistently.
In practice, inconsistent braking does not always come from the car. Very often, it comes from a pedal that is not yet being used in the right way.
Effective braking is not only about steering-wheel feel:
telemetry shows whether the brake peak is clean, the release is progressive and the pedal is calibrated correctly.
The most effective way to set up brakes in ACC is always to follow the same sequence. Choose the right pad for the session and weather. Bring the brakes into the correct window with ducts, looking at the longest section between two braking zones and not only at the peak. Use ABS and bias to find the compromise between safety and rotation. Finally, check telemetry and brake trace to understand whether the problem is really in the setup or in your foot.
When temperature stays where it should, the HUD does not fall into blue, ABS does not hammer unnecessarily and the car accepts trail braking without becoming unstable, you have found a brake setup that is not only comfortable: it is fast, repeatable and ready for racing.
