Formula One is a tricky business where anyone hungry for success is willing to achieve it in slightly shady ways. Innovation is what wins championships, and occasionally, the line between inventiveness and underhanded trickery blurs. In 1997, McLaren drivers Mika Hakkinen and David Coulthard welcomed genius aerodynamicist Adrian Newey into their team, who brought a few tricky upgrades to their car.

With a cleverly-hidden third pedal, McLaren’s drivers were able to control the inside-rear brakes independently of the fronts. This ingenious device, which would be operated in conjunction with the throttle primarily, would help trim wheelspin at the corner exit, and help minimize understeer at the entry to mid-corner phase. While this might sound remarkable, it is essentially what the stability systems used in production cars provide.

Engineer Steve Nichols came up with the idea the previous season, and though there were concerns about the technique involved, both Hakkinen and Coulthard adjusted quickly to it. While the plumbing was fairly simple – just involving an extra master cylinder at the rear and a split brake line – it relied on a specific pad material to work well. “A progressive material with a flat friction/temperature curve,” according to Adrian Newey, helped the drivers manipulate the brakes delicately when they were needed. If flirting with the limit of adhesion, the drivers could easily upset the balance with a grabby set of pads. In fact, that was the secret to its success – some rival teams mimicked the design but failed to realize the importance of a pad that grabbed gently and progressively, and never benefited from the system.

Another advantage of using this setup offered was the ability to run a setup that edged towards understeer. This meant greater stability under braking, reduced rear tire wear, and added speed in the faster sections, while still keeping that incisive nose. Ultimately, this gadget could trim the lap time by a few tenths!

Neither David Coulthard nor Mika Hakkinen enjoyed a car that emphasized rear-traction – that was more Alain Prost’s or Niki Lauda’s preference – but they could manage the setup with the added maneuverability provided by the rear braking. Additionally, this stable setup allowed the two drivers to maintain their tires since the car was less likely to snap-oversteer into and out of the corner.

Since the Austrian Grand Prix that year, clever observers had noticed that the McLaren cars behaving oddly: the rear brakes had been spotted glowing well-past corner exit. When both McLarens failed at the 1997 Luxembourg Grand Prix, photographer Darren Heath crept over to Hakkinen’s stopped car on the start-finish straight and snapped a shot of the cockpit’s footwell. When Heath developed his film, he saw precisely what he had guessed: a third pedal. Keep in mind that the entire field had adopted paddle-shifted gearboxes by that time, so seeing what looked like a clutch in the pedalbox was odd.

It was not controversial from the get-go, since the McLarens were not in top form in ’97. Running mid-pack would be a more appropriate way to describe their performance that year and the years prior; Coulthard’s victory at Australia was the first victory McLaren enjoyed since losing Ayrton Senna in 1993. As they weren’t much of a threat, the leading teams didn’t protest strongly and the FIA allowed the device for the rest of the season.

However, 1998 was a different story entirely. Having won the last race of the previous season, the major players had an eye on McLaren, but when Hakkinen and Coulthard lapped the entire field at the first race of the 1998 season, the situation became dire. Like anything that seems to be giving an unfair advantage, it was immediately campaigned against by Ferrari, who attested it was an illegal type of steering system.

McLaren’s Ron Dennis argued that the device added no new functionality, but merely offered another way of manipulating the brakes. However, the FIA decided that the system was, in effect, a three-wheel steering system, and despite a prior year of legality, it was deemed illegal at the second race of the season. Not a particularly good way to start a season, but the changes didn’t stop McLaren from running away with both the drivers’ and constructors’ titles that year.

The system might’ve been scrapped in Formula One, but with the beginning of a new line of production cars launched thirteen years later, it found a new home. The brake-steer system, also known to some as the “fiddle brake,” is used in McLaren’s MP4-12C road car, as well as its successors; the 650S, the 675LT, and the P1. This design allows for crisp, immediate turn-in without much understeer, and even with an open differential in the back, puts down the twin-turbo V8’s incredible grunt with ease.

As is always the case with motorsport, at least half of the game comes down to the equipment. If any team, no matter their principles, manages to find a margin as large as three tenths per lap with one tweak or another, they’ll do what they can to circumvent the rules. However, once something outlandish has been seen to work, you can bet the farm on another team protesting it.

Perhaps what’s more interesting is the direct link from motorsport to road-going vehicles. In the case of the fiddle brake, a genuine component took an influence from racing which eventually trickled down into road cars, or vice-versa. Rarely nowadays do we see that sort of thing, since modern racing cars seem to be 90 percent aerodynamics. It’s doubtful a double diffuser will make much sense on the next generation of econoboxes, but what do I know?