Racing ABS: The anti-lock braking system in motorsport

Oct 10, 2018
Stuttgart

Mercedes-Benz racing driver Roland Asch stunned his competitors with the excellent braking performance of his AMG Mercedes racing tourer in the German Touring Car Championship (DTM) invitation race at Kyalami in South Africa on 18 November 1990. This was because the Stuttgart brand used the racing ABS jointly developed with Bosch for the first time in a race. Asch achieved pole position in the first heat and went on to finish in second place. The racing driver nicknamed “Swabian Arrow” then won the second heat. This gave Roland Asch victory in the general classification of the race in Kyalami, driving a racing tourer based on the Mercedes-Benz 190 E 2.5-16 Evolution II.

Development of the anti-lock braking system for racing cars started soon after the introduction of ABS in series production. Ayrton Senna got a foretaste of the effect the system could have in spring 1984 during test driving for the opening race on the new Grand Prix circuit at the Nürburgring. This premiere on 12 May 1984 was celebrated with a race involving 20 Nürburgring champions in 20 identical Mercedes-Benz 190 E 2.3-16 (W 201) models.

Senna went on to win the race in May. But during the test drive, the Brazilian racing driver’s initial reaction was one of shock: “ The brakes are broken.” That’s because Senna had never before driven a racing car with ABS, which is why the pulsing brake pedal irritated him when ABS was activated. Project head Gerhard Lepler calmed him down and gave him a tip: “Just keep your foot right down on the pedal.” However, legend has it that Senna never really warmed to racing ABS. It was a totally different story with Niki Lauda, though, who won the Formula 1 world title for the third time in 1984: When the vehicle concept for the opening race was presented to him and the installed ABS was explained, he declared the anti-lock braking system to be “the best invention since the invention of the wheel”.

But Mercedes-Benz project lead Lepler was still not satisfied with the performance of the racing ABS. It wasn’t just the pulsing brake pedal that was annoying; ABS also had a problem when the wheels left the track after hitting a bump. In this instance, the sensors no longer detected any adhesion and signalled black ice-like friction conditions to the control unit. This led to the brake pressure being reduced drastically at first and then built up again, albeit far too slowly for motor racing. Fine tuning initially brought about a slight improvement. But it wasn’t until the arrival of the new electronic control system jointly developed with Bosch, including a programmable control unit, that the racing ABS was able to deliver truly impressive performance. This setup made it possible to suppress the pulsing of the brake pedal during ABS activation and the sudden yielding after hitting bumps on the race track.

So it was with this fully developed version of racing ABS that Roland Asch took his place on the start grid at Kyalami in 1990. German car magazine “Auto Motor und Sport” reported on the race in issue 25/1990: “Asch jumped for joy onto the roof of the car and couldn’t stop singing the praises of his ABS car: ‘ABS is incredibly good, I can focus fully on driving and don’t need to shuffle over to the brake until the last second,’ he said.”

Mercedes-Benz equipped its DTM touring race cars with the advanced system in the 1991 season. For the following year, the amount of force the driver needed to apply on the brake pedal, which increased significantly when ABS was introduced, was reduced again. Mercedes-Benz racing tourers with ABS lined up at the start in the following seasons of the German Touring Car Championship and the International Touring Car Championship (ITC) until its discontinuation in 1996.

A similar system was introduced in Formula 1 at almost the same time as in the DTM. Here the system measured the pressure the driver exerted on the brake pedal and distributed the braking pressure to the wheels to prevent them from locking up. This meant that the drivers were able to brake fully when driving at top speed, even at the end of a long straight. ABS was banned from motorsport’s premier class at the end of 1993, the argument being that piloting a racing car equipped with ABS required less skill.

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