Lewis Hamilton’s dramatic victory in the final laps of the Canadian Grand Prix meansthere have been seven different winners in seven races in this mostincredible of Formula 1 seasons.Making the call to remain on a two-stopstrategy, Hamilton pitted from the lead on for a fresh set of tires before reeling in andpassing Sebastian Vettel and Fernando Alonso. The win owed much to the tire strategy Italked about in my Bahrain column. Alonso and Vettel’s error in opting for aone-stopper cost them dearly and allowed Romain Grosjean and Sergio Perez to take theremaining podium places. But while tire strategy ultimately decided theoutcome of the race, the Circuit Gilles Villeneuve is also regarded as the ultimate testof a car’s brakes, with its mixture of long straights and tight hairpins. There areseven extreme braking areas over a single lap, the brakes applied around 10% of the laptime. Decelerating from 200 mph to 60 mph in two seconds at the hairpin puts seriousstress on the brakes and is enough to take the moisture from a driver’s eyes andsplash tears onto the front of his visor.Before applying the brakes, the diskshave cooled on the straights to 450 degrees Celsius, but once they’re used, theyheat to 1,200 Celsius instantly, about the same temperature as lava. Above 650 degrees,the wear is accelerated as the carbon oxidizes, so it’s vital the brake ducts getenough cooling to keep wear in check.Brake ducts work by drawing air throughthe ducts and out over the brakes and the wheel bearings to regulate temperature. Whiletheir primary purpose is to cool the red-hot brakes, they are also used to cool the wheelbearings, which are prone to overheating. A brake duct takes in a huge amount of air andthe front brakes require more cooling. At 200 mph, the front ducts swallow a massive 400liters of air per second and of this, about a third passes through the disc and the restis used for surface cooling. If we equate the same volume to water, it would require sixfire engines pumping at maximum capacity for just a single brake duct!Thedemands placed on brakes differ from circuit to circuit, and for an extreme brakingcircuit such as Montreal’s, larger ducts are required than for a circuit such asSilverstone, where the driver isn’t required to brake hard at any point. But thebigger the brake duct is, the more downforce is lost, so race engineers will always try torun as small a duct as possible or look for little innovations.One ofFerrari’s new features for the Canadian race were front brake ducts that almosteliminated the hole that takes in the air. Instead, the design employed a shield in frontof the tire that took air into the brakes between the tire and the turning vane in anattempt to reduce the drag created by a conventional hole. Red Bull also tried to find aloophole in the regulations by cutting holes in the wheel hub in a further effort to coolthe brakes in Montreal. But the sport’s governing body, the FIA, claimed the holescreated an aerodynamic advantage that did not contribute to the cooling of the brakes.Unlike in your own road car, the balance between the front and rear brake effortis varied throughout the process to get optimum stopping power. Drivers will also tinkerwith brake balance from one corner to another, and you often see the drivers adjusting thebrake balance in the cockpit before a corner. The driver always uses his left foot forbraking because the clutch is operated automatically for down changes, as I explained inmy last column. As thereis no servo to assist the driver, he will be applying 140 kilograms to the pedal with hisleft leg -- the equivalent to lifting around twice his own weight with one leg.So next time you’re pulling up to the traffic lights on your daily commute orweekend drive, spare a thought for the Formula 1 drivers who put their bodies under suchenormous stress as they experience similar g-forces under braking to those of a U.S. AirForce fighter pilot. Continue Reading

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