Sometimes the old methods are still the best...

Aluminium-skinned 1960s-style monocoque chassis structures were pretty demanding things to make – and particularly to make straight. Past Team Lotus mechanic Cedric Selzer recalls one in particular which he was detailed to set up, only to find that it was impossible without major modification to its suspension pick-up bracketry, simply because the fuselage itself came out of the manufacturing jig with a twist built in. Under the fiendish time pressures of a Formula 1 calendar such things could happen, and did.

At the British Grand Prix at Silverstone in 1969 even as professional a team as Ken Tyrrell’s Equipe Matra International, using cars built by the aerospace-standard fabricators and engineers at Matra Sports, ran into trouble. The dome-riveted MS80 tubs always reminded me of military aircraft or even military vehicle construction. They looked so tough and rugged they appeared bullet-proof, but Jenks reported on Jackie Stewart’s ‘Scottish blood’ as he and Jochen Rindt, in the Lotus 49B, set about fastest time in the third practice session – for which there was a cash prize of £100.

Rindt did a 1:21.4 lap “and was reaching out for his £100 when Stewart went out in his MS80 Matra. Going through Stowe he was well and truly wound up, using all the road and some of the grass verge, and at Woodcote he was right on the limit of adhesion when he saw that a piece of the inside kerb had been dislodged… He was committed to his high-speed line and struck the piece of concrete with his right front wheel. The right rear wheel struck the concrete, the tyre burst, and the Matra spun through the 135mph corner, dissipating its speed remarkably quickly and hit the outside bank going backwards”.

A whack like that commonly binned the suspension and protruding gearbox, but what was far more serious was damage transmitted into the monocoque tub. On the Matra’s right-front the initial impact from the concrete was fed back into the aluminium tub by the trailing member of the lower wishbone. And as that load was smashed back into the inboard pick-up pocket on the tub’s flank, so it tore the outer skin, unzipping it down the vertical rivet line securing an internal bulkhead just there. A long-forgotten photo of that damage sits before me as I write. I bet it was a ******* to mend.

Which is why, over at the Brabham Racing Organisation, Ron Tauranac had been so content for years to retain multi-tubular spaceframe construction. Bend a tube-frame’s corner and it was relatively easy just to cut away the damaged tubes affected and simply weld in new. With a stressed-skin monocoque, and especially one like Matra’s – internally sealed with goo to contain the fuel load without separate rubber bags – such luxury was not an option.