Formula One Trend of Design

Front Brakes

The mounting of the front brakes on a Formula One car is one thing that everyone agrees upon; that is, that they should be mounted “outboard” on the wheel hubs. Some years ago when one of the major interests was unsprung weight, attempts were made to mount the brakes “inboard” on the chassis, rather than “outboard” at the ends of the suspension arms. The Lotus 72 was a classic example of “inboard” mounted front brakes, with universally-jointed shafts coupling the brake to the wheel. However, as with rear brakes, the need for reducing the unsprung weight was negated by tyre technology coupled with the reduction in weight of wheels, brake components and suspension members, so that now there is no problem about front brakes, they are mounted “outboard”.

How they are mounted and what type of caliper to use, together with cooling, is another matter, and there is quite a diversity of opinion among Formula One designers. Everyone uses a ventilated cast-iron disc, apart from the experimental carbon-fibre inserted ones that appear occasionally on Brabhams, but there are differences of opinion about whether to use a single caliper containing four brake pads, two each side of the disc, or a pair of smaller calipers each with one pair of pads. A lot of the decisions are made for matters unrelated to actual braking, for the number and positioning of the calipers often is regulated to suit steering and suspension components. Single calipers have been tried mounted at the front of the disc and at the back of the disc, and no change in the feel of the braking or steering has been noticeable, even though it might be thought so in theory. For example, McLaren use a single 4-pad caliper mounted at the front of the disc on the M29, as do Ligier on the JS11, but Tyrrell, Brabham and Ferrari use one 4-pad caliper mounted at the rear of the disc.

Except for Ensign, who were the first to produce the twin caliper layout, everyone mounts their twin calipers fore and aft. The Lotus 79, the ATS, Fittipaldi, Renault, Shadow, Wolf, Merzario, Williams and Arrows all use this positioning. Ensign mount their front one above the horizontal centre-line and their rear one below the centre-line. Lockheed calipers are almost universally used, though Fittipaldi use Brazilian Varga calipers.

Cooling of the disc is affected by feeding air into the hub centre where it passes into an annular ring in the body of the disc and then centrifuges out through the radial slots cast in the disc. With the exception of Brabham and Ligier, everyone uses a scoop protruding forwards to collect cold air and feed it into the annular ring via the centre of the upright. Tyrrell have a slight diversion on this theme in that their air scoop feeds the air directly into the annular ring, ahead of the upright. These scoops all vary enormously, some like the Ferrari being enormous, while those on the Ensign are very small and thin. Brabham use no ducts whatsoever, nor do Ligier, but the French car uses drilled discs.

In all cases the complete assembly of disc and caliper is buried within the front wheel: such are the improvements in heat conduction, brake pad material, caliper design and disc cooling that there is no need to have the assembly out in the air stream. Coupled with the overall design of the front brake assembly is the design of the suspension upright, the hub and wheel fixing and the type of hub bearings used, and in all these spheres there are strong differences of opinion among designers, which is why there is so much variation on the basic front brake for a Formula One car. — D.S.J.

Footnote: this was the situation at the Dutch Grand Prix