ANALYSIS: How does longitudinal acceleration reveal Norris' brake problems in Shanghai?

Championship runaway leader Lando Norris was forced to nurse his car in the closing stages of last Sunday's Chinese Grand Prix, with brake issues causing a stir in his otherwise quiet race. F1Technical's senior writer Balazs Szabo analyses Norris' issue in the dying stages of the Shanghai round.

Despite McLaren dominant form at the Chinese Grand Prix, Lando Norris faced a “nightmare” scenario in the closing stages the 56-lap race, with a brake issue disrupting his last laps.

Although the team confirmed that they could see the issue on the data, they could do little to mitigate the problem, but they could only offer some advice Norris to manage the issue by avoiding any hard braking.

McLaren team boss Stella was left dissatisfied with the impact the issue had on Norris’ race, but he praised the British driver to get around the issue in the closing stages of the race.

“We are happy with the one-two, but we had a failure on Lando’s car with the brake pedal that we had to manage over the last twenty laps,” he said.

“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.”

The diagram provided by F1DataAnalysis shows the seriousness of Norris' brake issues. The most evident sign is the drop in pace. Although Stella revealed that the issue became evident 20 laps from the end of the race, Norris still chased maximum lap time until Lap 53.

However, his pace dropped by 1.4s, 3.5s and 3.9s on the following three laps which ultimately enabled third-place George Russel to close in within two seconds when the chequered flag fell.

The throttle application shows that Norris started the lift-and-cost process ever more earlier on the closing three laps. Ultimately, the Briton started to lift and coast approximately 180m earlier on the last three laps into the final hairpin.

“You could brake, but very, very gently," Stella explained. "So what was 100-metre braking, became 200 metres, and towards the end, it was 300 metres because Lando needed to lift the throttle, coast to a certain speed and then apply very gentle brake pressure. That was to avoid the leak becoming too fast."

Interestingly, there is a slight hesitation on the last tour. Norris wanted to start to decrease the throttle pressure even earlier than on Laps 54 and 55, albeit with Russell inching closer and closer, he decided the accelerate again for a split second before completely coming off the throttle pedal.

The longitudinal deceleration also clearly shows how Norris wanted to manage the issue which became "critical" for the dying stages of the race. While most of the corners of the Shanghai International Circuit are medium-speed turns that do not require heavy brake application, there is an elongated braking phase into the complex of Turn 1 and 2 while Turns 11 and 14 are usual heavy braking zones.

In Turn 11, the acceleration forces came down from 4.3g to just 2.2g while it decreased from 2.7g to just 1.7g into the last hairpin.

Stella refused to reveal the exact cause of the issue, but he offered some explanation for how Norris had to adapt his driving to mitigate the brake pedal issue.

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

“The brake pedal was going long, and what we needed to do was to avoid the peak pressure, so Lando needed to brake with less and less and less peak pressure.

“It got to the point over the final laps where he was just coasting for a long time, off throttle, and then just applying minimum brake pressure to stop the car and go around the corner," Stella said.