The Circuit Gilles-Villeneuve in Montreal retains its reputation as the biggest brake-killer on the F1 calendar, with its relentless sequence of low-speed bends interspersed by high-speed straights. How do the teams ensure their brakes survive the full 70-lap distance without giving up? Mark Hughes and Giorgio Piola provide the answer.
There are many things that make Canada’s track unique – the fact that it sits on an artificial island being one of them. But the crucial point about the circuit’s layout is that the straights are just long enough to allow high terminal speeds, but not long enough to give the brakes enough time to cool before they are needed again. The brake discs on an F1 car are manufactured in carbon fibre as it gives vastly superior friction to the steel brakes that were used up until a couple of decades ago – and they also weigh significantly less.
But the one downside of carbon discs is their very narrow temperature operating band, and this is something the Montreal circuit makes apparent. The disc does not give adequate stopping power until it has reached around 400-degrees Celsius – but at anything much beyond 800-degrees Celsius it begins to oxidise. This process – similar to rusting of metal but in hyper-speed – sees the carbon literally turn to dust and if not controlled the disc would quickly oxidise into nothing. Not something any driver wants to consider…
Because it is so desperately important to keep the temperature of the disc within that narrow band, for Montreal the teams’ special preparations centre around increased cooling capacity to the brakes (even though this costs aerodynamic performance). They are further limited by the regulations on brake disc size. Since 1998 the maximum disc diameter has been 278mm. A maximum width of 28mm was imposed at the same time and this latter limitation remained in place until last year when it was increased to 32mm to allow for the greater performance and weight of the new wider, more aerodynamically-powerful cars that had been legislated in. The limitation on disc size was originally made to limit increases in braking performance that were making overtaking more difficult.
The most obvious way of increasing the cooling of the brakes is to enlarge the brake ducts, forcing more cooling air onto the disc, though this comes at the expense of increased drag which limits straight-line speed.
Ferrari traditionally run much bigger front brake ducts than Mercedes and as a consequence the brakes can usually be pushed harder for longer. This difference can be seen quite clearly in the comparison between the Ferrari’s traditionally-shaped, semi-oval ducts and the Mercedes’ slim envelope-type openings.
Ferrari’s Monaco brake arrangement (the inset area shown in yellow is the area of un-drilled carbon)
and their Canada layout, with extra cooling holes in the drum surrounding the disc
The sort of Montreal-specific measures that teams make can be seen in the comparison between Ferrari’s Monaco and Montreal arrangement from last year. For Montreal the cooling holes in the drum surrounding the disc are opened out and the arrangement of the Brembo disc’s cooling holes is changed. There is a greater area of un-drilled carbon at the outer edges to give greater strength and the holes are arranged asymmetrically.
As ever in F1, it’s all about achieving the ultimate combination of performance with sufficient reliability. Montreal reveals that challenge in the area of braking more than any other track.