The McLaren M7A is a Formula One racing car built by McLaren and used in the world championship between 1968 and 1971. After two relatively unsuccessful years of Formula One competition, the M7A was used to score McLaren's first win at the 1968 Belgian Grand Prix.
Designed by Robin Herd and Gordon Coppuck, the M7A was the first McLaren to be powered by the Cosworth DFV engine, which went on to be used by the team until 1983. The M7B was a development of the M7A (chassis M7A/3), and had outboard fuel tanks riveted to the existing bath-tub monocoque to house the fuel bags, along with wrap-over panel-work similar to the M10, thus creating an interim full-monocoque chassis. The M7C was effectively a Formula 5000 M10A chassis with the horn removed at the rear of the cockpit to enable the fitment of the DFV engine, whilst the M7D was powered by an Alfa-Romeo engine.
The M7A made its Grand Prix debut at the second race of the 1968 world championship. After its victory in Belgium, it took another two wins that year, helping to place McLaren second in the Constructors' Championship.
Background
Bruce McLaren Motor Racing was founded in 1963; Bruce McLaren was a factory driver for the Cooper motor racing team which competed in Formula One, the highest level of international single-seater competition. Since 1966, McLaren and his team had been building and racing their own Formula One cars. Their first two seasons had been relatively unsuccessful, with six points scored (out of a potential 180) and a best result of fourth. The lack of a suitable engine caused problems: the 1966 M2B car's Ford and Serenissima V8 engines both lacked power and the 1967 M5A's British Racing Motors V12 did not arrive until mid-season.
In 1967 Cosworth debuted their DFV engine which was supplied exclusively to the Lotus team. It was immediately successful, winning its first race, and in 1968 it became available for purchase by any manufacturer. McLaren bought five DFV engines at a cost of 7,500 pounds sterling each. Designer Robin Herd was recruited to the team in 1965 before which he had been an aerospace engineer at the National Gas Turbine Establishment (NGTE) where he worked on the Concorde project. His assistant Gordon Coppuck was another ex-NGTE employee. Herd began the design of the M7A towards the end of 1967 but left to join Cosworth before its completion, leaving Coppuck and Bruce McLaren to complete the work.
Design
The M7A was an open-wheeled single-seater with a mid-mounted engine driving the rear wheels. The chassis was a bathtub-type (i.e. open-topped) monocoque initially made from 22-gauge aluminium alloy panels glued and riveted together and to three steel bulkheads. Magnesium alloy was used for the dash panel, battery cover and numerous smaller non-folded panels. The monocoque terminated behind the driver's seat and the engine was used as a stressed member, bolted directly to the rearmost bulkhead. The gearbox was then attached behind the engine, and the rear suspension – consisting of lateral top links, twin radius arms and reversed wishbones– attached to the gearbox and the rear bulkhead. The front suspension – upper and lower lateral links and radius arms – and the steering column were attached to the two bulkheads in front of the driver. Coilover springs and Koni dampers mounted outside of the body were employed front and rear. These were soon after replaced with the more proven Armstrong units.
The outer bodywork was mostly formed by the monocoque, except for the nose and cockpit which were covered by glass-reinforced plastic (GRP) panels; the engine sometimes also had a GRP cover. The wheelbase for the prototype car (M7A/1) was noted as 7ft 9.6", M7A/2 and M7A/3 were subsequently 96.5", just 0.5" longer than its short lived predecessor, the M5A; the front track and the rear track ; weight was . McLaren's own magnesium alloy wheels were used; they were diameter at the rear and 15- or sometimes diameter at the front.
Fuel was stored in tanks running down the side of the chassis, above the driver's legs and behind their seat, totalling capacity. Full capacity was not required for most races so the tank above the driver's legs was usually almost empty. For the M7A's first two world championship races, Bruce McLaren's car was fitted with outboard "pannier" fuel tanks at the side of the cockpit. McLaren had a theory that sports racing cars' handling was superior to that of single-seaters because of the weight distribution of their fuel; the pannier tanks were an attempt to replicate this. According to McLaren mechanic Tyler Alexander this idea was developed in discussion with Lotus boss Colin Chapman. After the car was damaged at the 1968 Monaco Grand Prix, it was rebuilt without the pannier tanks.
The prototype car, M7A/1 was initially fitted with 10.5-inch (266.7mm) diameter solid disc brakes and Girling calipers whilst McLaren awaited delivery of their newly commissioned brake system, which was unusual both in being made by Lockheed when most British Formula One teams used Girling brakes, and in being ventilated. The prototype car was fitted with the all new brake system in early 1968 and subsequent M7A's adopted the same type of brakes. The new Lockheed four-piston lightweight alloy caliper being able to accommodate the larger designed discs which now measured 11.625 inches (295mm) in diameter. Ventilated discs, which are in turn thicker in section, have a hollow area between the two outer disc surfaces to aid cooling – had been tried by Lotus who had suffered from cracking problems caused by rapid heating and cooling. The McLaren team hoped that by being mounted well within the wheels, their discs would retain a more constant temperature.
During the 1968 season, wings – which press the car and tyres towards the ground thereby increasing cornering speeds and reducing braking distances – first appeared on Formula One cars in races. Teams experimented with various wing set-ups and the governing body of the sport, the CSI, regulated their use. McLaren had first experimented with wings on their 1965 M2A Formula One development car but didn't use them on the following season's racing car, the M2B. The M7A and its variants wore a variety of wing configurations, as described in the racing history section.
The DFV engine, whose development was funded by Ford and which was designed and constructed by Cosworth, was normally aspirated with eight cylinders arranged in a v configuration (i.e. a V8) of 90 degrees. The block was made from aluminium alloy and the cylinder liners from iron. It had four valves per cylinder, actuated by double overhead camshafts. Liquid-cooling was provided by a radiator situated in the nose which vented through ducts in the upper body surface whilst the engine oil was cooled by a radiator mounted on top of the gearbox at the rear. Peak power was at 9,000 rpm. The gearbox was a Hewland DG300.
The works cars were painted Traffic Yellow, a British Standard colour, number 368 on the 381C scale which was used in the paint and fibreglass gel-coat industry. This yellow/orange colour was later incorrectly described as papaya however in reality it was only ever known as McLaren Orange by the factory; it was not a national racing colour, however, the colour would continue to be used on works McLaren cars until Yardley sponsorship was obtained in 1972.
Variants
M7B
The M7B was a one-off conversion of M7A/3, the car which, in its original specification, brought the first F1 Grand Prix win for McLaren Cars at the Belgian GP in 1968. The fuel was stored low and centrally in bags which were housed inside L72 aluminium pontoons, riveted either side of the cockpit and terminating at the engine by a new, full width magnesium bulkhead. This was another result of Bruce McLaren's theory about improving the car's handling by altering the fuel weight distribution. Author and former McLaren secretary Eoin Young said that another purpose of the outboard tanks was to make room for a four-wheel-drive system.
M7C
The chief distinguishing characteristic of M7C was its fully enclosed monocoque which gave greater torsional rigidity than the bathtub chassis. The chassis was identical to McLaren's M10A Formula 5000 car, save for the removal of the horns at the rear of the monocoque, which itself was derived from the M7A. One was made.
M7D
The M7D was commissioned by Alfa Romeo's Autodelta competition department and was powered by a 3.0 litre V8 engine from Alfa Romeo's T33 sports car. The engine is variously cited as producing peak power of between and (the highest figure said to be produced at 10,500 rpm), with good levels of torque, but McLaren found that performance varied significantly between units. The wheelbase remained similar at 96" however a new mounting point was created for the alternator which, unlike the DFV arrangement, was not integrated with the engine. One M7D was built up on a new chassis based on the M7 series design.
Racing history
For the 1968 Formula One season, after two years of driving the team's sole entry, Bruce McLaren was partnered by Denny Hulme. Hulme was world champion with the Brabham team in 1967 and had raced for McLaren that year in Can-Am, a North American sports car racing series. For the first round of the 1968 world championship – the South African Grand Prix, which was held in January, four months before the second round – only Hulme competed, using the M5A to finish fifth. The M7A's first race was the Race of Champions at Brands Hatch, run to Formula One rules but not part of the world championship. There, McLaren won from pole position while Hulme was third. Another victory came at the non-championship BRDC International Trophy at Silverstone, this time with Hulme finishing first and McLaren second. In the M7A's championship debut in Spain, Hulme was second and McLaren retired, then in Monaco McLaren crashed and Hulme was fifth and last. At the Belgian Grand Prix, they were fifth and sixth on the grid. Hulme took the lead and held it until a half shaft failed two thirds of the way in. McLaren was then second behind Jackie Stewart's Matra but Stewart had to make a pit stop for fuel on the final lap, giving McLaren the win, although he initially believed he had finished second. It was the McLaren team's first world championship victory and Bruce McLaren became the second driver, after Jack Brabham, to win in a car bearing their own name; it was also the last win of his career.
After Belgium, McLaren's Goodyear tyres suffered a slump in competitiveness and the team and their car fell behind rivals Graham Hill in his Lotus and Stewart in his Matra. At the Dutch Grand Prix McLaren crashed out and Hulme retired with ignition failure. After Lotus had begun the first experimentation with wings in Monaco and Ferrari and Brabham had debuted full height wings in Belgium, McLaren fitted a rear wing to their car for the French Grand Prix. However, mounted above the engine on the sprung mass of the car, it was not as effective as Lotus's wing mounted on the unsprung suspension components. In France Hulme was fourth, then fifth in Britain but both cars were out of the points-earning positions at the German Grand Prix.