KM Tech Corner - Brake Bias: Episode Four

Imagine exiting the famous Parabolica with the perfect racing line, on the rev limiter and speeding towards Variante Del Rettifilo at full throttle… Then 50 metres from the first chicane, the driver slams his foot on the brake pedal at the braking point. The driver and car both experience heavy braking loads with over 4.0G of force– enough to throw the driver forward in the car at quite a pace.

These forces and pressures help explain why the correct brake bias is so important during an endurance race.

Watching spectators are likely to notice the Brembo brakes illuminating bright orange as the friction between the brake pads and discs generate immense heat when the car decelerates to slower speeds and tackles the chicanes in the quickest time possible. Having a swing in brake bias too much in one direction will affect the car’s handling entering those corners.

Rule 1: In short, the brake bias is a representation of torque values at both the front and rear of the car. They are given in percentage form. For example, Kaspersky Motorsport has a default brake bias of 55/45 – meaning the rear wheels are expected to produce 55% of the braking and the front will produce 45%.

The focus at every racetrack is to find the optimum braking bias to keep the car grounded and stable under braking. Braking pressures distributed between the front and rear brakes can be adjusted on track according to the feeling of the driver and car, which makes testing and the free practice events vital to understand the performance of the car during the race.

Before every race weekend starts the team will set the car’s brake bias to the default position of 55/45. As the driver gets a feel for the car, the ultimate goal of the brake bias is to adjust the forces applied when braking to maximize the overall braking efficiency. The mechanics of the brakes with the Ferrari 488 GT3 largely stay the same as last season’s 458 GT3 with no major differences between set-ups, so drivers may have early indications of car handling thanks to their experiences on-track last year.

Note: The brake bias of the car can be adjusted inside the driver’s cockpit by turning a switch clockwise or anti-clockwise. A clockwise turn adjusts brake bias to the rear and anti-clockwise adjusts the front brake bias.

There is no set formula when the Kaspersky Motorsport team prepares the brake set-up. Like Formula 1, engineers can advise their drivers on the ideal brake bias settings, but ultimately the decision remains largely with the driver. This kind of fine-tuning by the drivers is exactly what Free Practice sessions are designed for.

The driver’s feedback

Our Chief Race Engineer can only see the telemetry and cannot feel the drive, nor experience oversteer or understeer as drivers make changes to the brake bias. Instead, he advises the drivers using past historical data and the live performance of the car as he sees it through the timing sheet and telemetry.

So, feedback from the Kaspersky Motorsport drivers is important and the only way the team can understand the behavior of the car on the many types of circuits that they will race on this year .

At the end of the Free Practice and Bronze Test sessions, the team gathers for a full debrief to discuss any changes that have been made on track. Drivers may report that they have adjusted bias two clicks clockwise or one click anti-clockwise for example, and so the drivers play an integral role in setting up the brake bias for each race.

Drivers will also deliver more insight and higher levels of detail when making changes on the 488 GT3’s balance according to track conditions. For example, from dry to wet conditions, the Chief Race Engineer can recommend that the driver turn 3-clicks clockwise to adjust brake bias to the rear, so that the car will sit on the track better, give better traction and minimise oversteer on the entry to the corner.

Top tip: The Kaspersky Motorsport team starts with a standard brake balance – 55/45. This allows the team to adjust as required throughout the Free Practice sessions, and also look at historic data to make the all important brake balance changes for that race weekend.

Interestingly, as well as understanding the car and learning it’s various braking points while trying to apply the necessary pressure to slow the car down without ‘locking up’ or dealing with oversteer, drivers can also adapt to the behavior of the car under braking. For example, Marco Cioci rarely modifies the brake bias over race weekends. Instead, he prefers to either adjust his brake bias at the start of the session or modify his braking behavior to stabilize the car into corners. Marco has a very unique style, but one that works.

Getting it right

The Chief Race Engineer is always trying to find the best set-up to give the team the optimum on-track performance. His biggest challenge comes at the Total 24 Hours of Spa race, the highlight of the Blancpain Endurance Series. “For 24 hours you have to concentrate on the maintenance of a consistent brake bias and watch the track and race evolve over the time to then make those needed adjustments”.

For example, Spa-Francorchamps can be a difficult set-up challenge due to the changing track conditions. The set-up and brake balance changes rapidly due to the ever-changing weather conditions in Belgium and the tyre marbles that decorate the edges of the track. As mentioned above, the team will start the race with the standard brake balance setting, but then towards the end of the Total 24 Hours of Spa, adjust 2 clicks anti-clockwise to put more emphasis on the front brake bias, as more grip is required to dance over the tyre marbles.

There are several elements that the Kaspersky Motorsport team will need to get right before they accelerate out of the pit lane, with the brake bias being just one component part. Join us for the next instalment in the Kaspersky Motorsport tech corner series as we take you on a track walk and discuss the key points that the Kaspersky Motorsport team looks out for to help the driver set-up his Ferrari 488 GT3.

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