Carbon fibre

A black art if ever there was one, the use of carbon and carbon composite materials propelled F1 technology ahead in one huge leap. But the early stages weren’t easy…

Words: Keith Howard. Photography: Charles Best

In the 1980s Formula One abandoned two materials which had served motorsport since its beginnings: cast iron was surpassed for brake discs; and aluminium was eclipsed for structural use. In both cases the replacement material was carbon fibre, but in very different forms.

Carbon-carbon brake discs, and the friction materials used with them, begin as a carbon-fibre blank which is then infiltrated with a pure carbon binding matrix to withstand 700-deg C-plus temperatures. In the carbon-fibre composites that are now the standard material for F1 tubs, by contrast, the fibres are bound together with a tough epoxy resin.

Brabham’s Gordon Murray pioneered the use of both materials but was cautious about the structural application because of concerns over carbon’s crash behaviour. By 1983, when Nelson Piquet won the drivers’ championship in the Brabham-BMW BT52, Murray had worked long and hard to develop carbon-carbon brakes into race winners, but the car’s tub still contained significant amounts of aluminium.

Brabham had been overtaken here by McLaren, where John Barnard took the brave decision to build a carbon monocoque for the MP4 of 1981. In 1984 that boldness paid off when the MP4/2, with carbon tub and carbon brakes, won both Formula One titles. Carbon had finally come of age. But as Murray and Barnard describe below, it had a troublesome upbringing.

Early days
GM: “When we started with carbon-carbon brakes in 1976, Dunlop and I weren’t brave enough to use a structural disc. So we came up with a 3mm-thick central steel disc with 10 pucks of carbon either side. But because of differential expansion the pucks came loose, rubbed on the caliper and boiled the brake fluid. Carlos Pace had an enormous accident at the Osterreichring because of this — he arrived at the end of the straight doing 175mph and had absolutely no brakes.”

JB: “We first tested carbon brakes at Donington in December ’82 with Niki Lauda. We had discs from French company SEP and from Goodrich in California. The difference from the cast-iron brakes was startling. With iron, Niki was hitting the brakes at the 100m board; when we put the carbon on, he was hitting the brakes at about 60m. It was amazing what we were gaining from them. There wasn’t a big difference between the two suppliers’ discs but SEP were keener to follow up with development, so we chose them.”

Solving problems
GM: “We switched to Hitco in 1979 because they wanted to use a structural disc. We went to Riverside in California and stayed for weeks until we’d solved all the major problems. They came up with an edge coating to tackle the oxidation, and by then we’d got on top of the melting wheel bearing grease, blistering paint and setting small mammals alight as we drove past! We’d been laughed at by the other teams, just as we laughed at Renault with the turbo engine’s problems. But we emerged with a package that worked pretty well.”

JB: “We began running carbon brakes in ’83. We were able to run the carbon discs on the Cosworth car and just about get away with it. But when we first ran the turbo engine at Zandvoort, the extra speed pushed the carbon brakes over the top. It wasn’t until we got to Kyalami at the end of the season that SEP supplied us with a fatter disc which had holes drilled around the circumference to vent it. That made all the difference: now they were really raceable.”

Structure beginnings
GM: “We raced carbon fibre on a chassis as early as 1979. There were some pretty horrific accidents with catch fencing poles puncturing monocoques, particularly just in front of the windscreen. Our carbon panel started on the crash box, went over the driver’s feet and right up to the dashboard. We bonded and riveted it to the car so it stiffened the monocoque amazingly, and it gave the driver a much stronger panel in front of him — like the armour plating in a WW2 aircraft.”

JB: “Our first monocoques were male-moulded round an aluminium tool, because I wanted to eliminate joints. They were cured as a single piece, then panels and bulkheads were added inside. The first tub had eight-ply skins, and torsional stiffness was over twice a good aluminium monocoque. But the weight wasn’t that different, so for the second monocoque we went down to four-ply. That first brick-outhouse tub was the one de Cesaris drove in ’81 and kept stuffing!”

Crash concerns
GM: “We lost a year to carbon development because we had two accidents with the BT49 at Monaco in the wet in 1980, where the drivers slid into the barrier at only 20mph or so. The aluminium crunched up nicely but the carbon just shattered. I thought, ‘Whoa, I don’t know enough about this stuff in a crash.’ So I talked Bernie Ecclestone into doing F1’s first, and so far as I know only, full crash test. We took a BT49 to BMW in Germany and ran the car into a concrete block under controlled conditions. We learnt a lot from that: not just about carbon but also about seat belts, driver head and neck injuries, all sorts of things.”

JB: “The worries about carbon’s crash performance were really put to bed at Monza in ’81 when Watson went off, walloped the barrier, split the gearbox case, and I think ripped the engine from the car. The tub stayed in one piece, he stepped out and from that moment people began to think that maybe carbon wasn’t so bad after all.”