K I W I M A D E www.engineeringnews.co.nz 7 To start the story we go back to 1967. This was the year of the McLaren M6A, the first of the orange elephants, as they were affectionately known and of course, the first year that Bruce McLaren and his team won the highly coveted Can-Am Championship. After winning the Can-Am series in the allconquering M6A, Bruce McLaren set about designing an even quicker car. Why? Because at the Riverside race, Jim Hall’s Chaparral had proved to be competitive and McLaren knew he needed a better car for 1968. The monocoque chassis M6A was hugely successful in 1967. At the season’s end, the McLaren factory took Denny Hulme’s M6A, which had run a small block Chevrolet engine, and mounted a big block 427 cubic inch Chevy motor to create the first M8A, with the engine as a semi-stressed member. Power was increased from 516bhp to 640bhp and with wider tyres and better body aerodynamics, the new M8A was going to lap about 3 percent faster. The M8A (the Formula 1 car was the M7A) weighs in at around 1440lb (645kg), which was 25lb (11kg) lighter than the ‘67 car, but the aluminium 7-litre dry-sump Chevy V8 engines, modified in McLaren’s own Californian engine division, give around 650bhp - nearly 100bhp more than last season’s winning car! Suspension and general styling were similar to the previous car, although the body shape was wider and lower than the M6A. Because tyre profiles were lower than before, the wheel arches were less pronounced for better forward vision. Slots above the front guards relieved the highpressure area beneath and NASA-type triangular ducts fed air into side-mounted aluminium engine oil-coolers. A separate oil cooler for the gearbox was mounted in the swept-up lip of the tail as it was on the 1967 car. A larger air-intake slot in the nose fed a wide aluminium radiator, and careful interior sculpting inside the nose ensured that the air rushing through the radiator created down force on the front wheels. The body was in four pieces, nose, tail section and the two doors which carried the sidescreens. The screen was moulded up around the driver, almost like a single-seater, making it impossible to carry a passenger. The regulation passenger seat was almost covered by a perspex ‘tonneau cover’. McLaren wasn’t sure whether this was legal, but he reckoned he would try it out anyway... The chassis was monocoque, but unlike the M7A (the Formula 1 car), with its four fabricated steel bulkheads, the M8A had only two bulkheads. The broad monocoque was aluminium sheet on the inside and magnesium on the outside, with two rubber bag tanks carrying 30 gal of fuel per side. The M8A was powered by a special aluminium 7-litre Chevy V8. “Don’t ask us where we got it from,” said McLaren with a grin. “It should produce around 650bhp”. The interesting thing about its installation was that, like the Ford Formula 1 engines, it was a stressed part of the car’s chassis. The forward face of the engine bolted to a sheet of magnesium, and A-frames running back from the rear of the chassis (it stops abruptly behind the cockpit) bolted to the rear of the engine. A fabricated sub-frame mounted over the bell housing and carried the rear suspension, while long radius arms ran from the rear uprights to the back of the monocoque. Although the monocoque appeared to extend back past the cockpit, this extra ‘shelf’ on either side housed the oil tank for the dry-sump set-up and the various pumps and electrical paraphernalia needed to keep the engine sparking. The magneto was mounted vertically behind the inlet manifold and the metering unit poked back horizontally above the engine. The high stacks of the McLaren-modified fuel injection looked like eight shot-blasted stainless steel lilies curving a full 12 in (30cm) above the engine. The exhausts ran into a pair of big-bore stove-pipes that ran out on either side of the gearbox below the body. A Hewland LG500 gearbox with specially tailored internals for the McLaren completed the drivetrain. Instead of the normal five cogs, this new box had only four special gears (and reverse) with a relatively high first gear for Can-Am rolling starts. The McLaren wheels got wider too and became knock-ons for ease of changing. As tested at Goodwood, the M8A had rear wheels 15” diameter and 15” across the rim and they planned to take a set of 16” rims with them to races as well. Front rims were 9” x 15”. The stopping department was catered for with a set of the biggest disc brakes and callipers seen at that time. Made by Lockheed (who also made brakes for McLaren’s Formula 1 cars) the big ventilated discs measured 11½” (29cm) across on the rears, and 11” (28cm) on the fronts. The discs were 1 1/16” (27mm) thick. M8A-2, Denny Hulme’s car, was constructed at the McLaren factory in England in early 1968 by the team, which included New Zealander’s Colin Beanland, Cary Taylor, George Begg and Chris Charles. The two M8As were only just ready in time for the opening round of the 1968 Can- Am series in North America. The 1968 Can-Am proved a very successful year for McLaren, with M8A-2 winning the series with Denny Hulme driving and Bruce McLaren coming in second. For 1969 the M8 was developed further with a high wing, cut-away front fenders and a 430 cubic inch, nearly 700bhp, screamer of a big block engine. Hulme’s M8A-2 was upgraded and modified to the “B” specification to become the team’s spare car. At the Riverside meeting, McLaren had a bad smash in his M8B, when a rear wishbone broke and damaged his car badly. He took over the spare car for the final round in Texas and secured the 1969 title in M8A-2 and was clocked at 210mph on the banked circuit. During the 1969 Can-Am season the spare car was also driven by Jack Brabham, Chris Amon and Dan Gurney. When the team offered M8A–2 for sale, it was very quickly purchased by Lothar Motschenbacher. Motschenbacher’s first race of the season was at Mosport on June 14th 1970, where Motschenbacher came in second to Dan Gurney in the works McLaren M8D. At Elkhart Lake in Wisconsin, Motschenbacher went off through the trees, hitting an embankment and effectively writing off the now red M8B. Investigations showed that a left rear wheel spindle had snapped and the two year old, badly
EN feb16-HR-nocrops
To see the actual publication please follow the link above