Until the practice for the Dutch Grand Prix at Zandvoort the only new things to appear from Bourne had been various mechanical items fitted to last year’s cars. In Holland the all-new 1963 car made its first appearance, and a week later it took part, and finished third, in its first race, the French Grand Prix at Reims.
At the end of 1962, when the B.R.M. team had won the manufacturers Championship, they had finalised their rear-engined V8 car and during the winter they redesigned the bottom-end of the engine, using a single-plane crankshaft, as normally used on horizontally-opposed engines. This arrangement allowed them to use a comparatively simple tuned-exhaust system for each bank of cylinders, in place of the various types of stub pipes used previously. To start the 1963 season the team used last year’s chassis and gearbox, with the new engines, and at Spa they tried out their new 6-speed gearbox, designed and built at Bourne, like almost everything else on the B.R.M.
This gearbox was for the 1963 car, but was so designed that it could be used on the earlier chassis. The all-new car was ready for serious testing just before the Le Mans weekend, and Graham Hill flew back from his turbine commitments to try the new car before it was taken to Zandvoort for its first appearance in public.
Most Grand Prix cars designers have been well aware of the shortcomings of the small-diameter tubing space-frame, which replaced the earlier type of tubular ladder-frame. If you design a perfect space-frame, triangulated in all directions then there is no space in which to put the driver, or the engine! It is possible to arrange the design such that it encases the engine, but there must always be a gap in the triangulation into which the driver is inserted, and this gap in the frame is the weakest point in the design, especially in the event of a crash. This factor being brought to the notice of a lot of people after the accident to Stirling Moss, for his car folded about the cockpit area.
Colin Chapman overcame this disadvantage of the space-frame with his “monocoque” design in the Lotus 25, in which the cockpit area was as strong as any other part of the frame, and in addition he did away with the necessity for encasing the engine in a framework of tubes, easing servicing and maintenance. Tony Rudd of B.R.M. who was responsible for the design of their 1963 car, had all these things in mind, but approached the matter from a different angle to that of Chapman. A stressed-skin structure of Duralamin sheet forms the centre section of the car, from the driver’s feet back to the rear of his seat, but whereas the Lotus is in the form of a stressed-skin bath on which an unstressed lid is fitted, the B.R.M. is a single structure in the form of a tube. At the front of this tube is a steel sheet bulkhead, riveted in place and to this is riveted and welded a very light tubular framework that carries the front suspension. To the lower part of the rear bulkhead of the centre-section is riveted and welded another tubular frame that runs back to the tube and sheet steel framework that carries the rear suspension.
In the gap above this lower tubular frame is mounted the engine on a further tubular framework that bolts into place between the upper part of the centre bulkhead and the rear suspension frame, so that the complete chassis is a combination of stressed-skin and tubular space-frame. Following Chapman’s lead the front suspension has the coil spring units mounted inboard, and operated by rocker-arm top wishbones of the double-wishbone suspension layout.
The rear suspension is very similar to the 1962 B.R.M. cars in that it has a double-wishbone layout, but the coil spring/damper units are mounted inboard above the final drive unit, and inclined towards each other at their top ends, and are anchored to the tubular framework over the engine. The lower ends are fixed to a link pivoted on the chassis, and a further tubular link connects the spring unit to the outer end of the lower wishbone, so that the springs are compressed by this “pushrod,” and the arc of travel is controlled by the link pivoting on the chassis. The Dunlop disc brakes are all hub mounted, Dunlop bolt-on wheels to B.R.M. design are used at the front, and knock-off hubs are used at the rear, again for Dunlop-built wheels.
Within the walls of the centre-section are carried rubber fuel tanks, of aircraft pattern, and also rubber oil tanks, which are a new innovation. An oil cooler is mounted below the driving seat and cooling air for this element is ducted along the stressed-skin centre section from a scoop under the nose aperture. This layout assists in weight saving by doing away with long oilpipes, and also helps in achieving a rearward weight distribution.
The well-proven B.R.M. V8 engine is used, running on Lucas transistor ignition and Lucas low-pressure port fuel-injection. The water radiator is in the nose of the car, and just behind it are two newly designed lightweight Lucas 6-volt batteries. On the rear of the engine is bolted the 1963 B.R.M. 6-speed gearbox, as tried out by Ginther on one of the 1962 cars in recent races, and this is operated by a mechanical linkage from a left-hand gear lever in the cockpit, the clutch operation being by hydraulic means. The main fuel pump, fuel tank switch, starter button and fuel pressure gauge are all mounted in a panel that forms part of the cockpit floor, between the driver’s knees, while the main instrument panel carries oil temperature gauge, tachometer and a dual gauge for oil pressure and water temperature.
An interesting day was spent at Zandvoort watching this new car and one of the 1962 cars circulating together, during a private testing session, and it was noticeable how different were the two cornering methods. The new car seemed to be deriving most of its cornering power from the cornering force being generated by the outside front tyre plus a combined force from the two rear tyres, but the rear ones were also capable of applying a forward thrust while still generating a cornering force. On the 1962 car, both front tyres were contributing a cornering force, as were the rear ones, but any application of forward thrust to the rear tyres while they were still generating a cornering force, appeared to provoke breakaway on the rear tyres rather too easily.
All this is, of course, in the broadest sense of the theory of cornering, but put simply, it means that the 1963 car can cope with a greater amount of acceleration through a given corner than the older design. It also calls for a different driving technique to get the best from the new design. The ways of a designer are not simple, for this improved cornering brought other problems in its wake, which had to be experimented with until a healthy compromise could be found; two major ones being a tendency to lift the inside front wheel, and a distinct “lightness” at the front end under some circumstances, but all these things are the result of variables which are adjustable and come under the heading of “chassis tuning.”
The overall weight of this new car is a great deal less than the 1962 cars, which was one of the objects of the exercise, naturally enough, but it is still not down to the minimum limit of 450 kilogrammes for Grand Prix cars. Dimensions of the car are: Wheelbase: 7 ft. 6 in. Front track: 4 ft. 5 in. Rear track: 4 ft. 4 3/4 in. Front tyres: 5.00 x 15 in. Rear tyres: 6.50 x 15 in.—D. S. J.