THE WORLDS FASTEST SPORTS CAR
Bruce McLaren has his sights set on the ‘69 Can-Am series and the accompanying American dollar. His quest for the ultimate sports car has resulted in the new M8A monocoque.
AFTER winning the 1967 Can-Am series in his all-conquering M6A Chevy-powered sports car, Bruce McLaren went back to his factory at Colnbrook, near London Airport, and set about designing a car that was even quicker. Why? Because in the race at Riverside Jim Hall’s Chaparral had proved to be closely competitive, and McLaren knew he would have to have a better car for 1968. The M8A (the Formula 1 car was the M7A) weighs around 1440lb, which is 25 lb lighter than the ‘67 car, but the aluminium 7-litre dry-sump Chevy V8 engines, modified in McLaren’s own Californian engine division, gives around 650 bhp – nearly 100 hp more than he won races with last season!
Suspension and general styling are obviously similar to the previous car, although the body shape has been smoothed out a lot, and the general ‘negative lift’ lines of the new body means that the currently popular ‘wing’ isn’t really necessary. The smoother lines also mean that this year’s car can run with lower spoilers on the tail. Since tyre profiles are lower than previously the overall lines are lower with the wheel arches less pronounced.
Slots cut in the back of the front wings relieve the high-pressure area directly over the front guards. NASA-type triangular ducts with a lip at the top feed air into side-mounted engine oil-coolers. These ducts are actually built into the doors on either side, and the coolers are mounted level with the engine mounting plate. A separate oil cooler for the gearbox is mounted in the swept-up lip of the tail as it was on the 1967 car.
A larger air-intake slot in the nose feeds air to a wide radiator, and careful interior sculpting has been carried out inside the nose to make sure that the air rushing through the radiator has been put to maximum benefit by being channelled properly upward, thereby creating more down thrust on the front wheels.
The body comes in four pieces – the nose with fitted air ducts, tail section and two doors which also carry the side-screens. The screen has been specially designed to mould up around the driver – almost like a single-seater – and it is now impossible to carry a passenger, even though the passenger’s seat is regulation width. The second seat is now almost covered by this perspex ‘tonneau cover’. McLaren isn’t sure whether this is according to Hoyle, but he reckons to try it out anyway…..
The chassis is monocoque, but unlike the M7A with its four fabricated steel bulkheads, the M8A has only two bulkheads. The forward one is set behind the front suspension, with the steering box mounted on it, making for the shortest-ever steering column. The bulkhead is so far back that a special hole has been cut in it to take the full travel of the clutch and brake pedals.
The broad monocoque is aluminium sheet on the inside and magnesium on the outside, with rubber bag tanks carrying 30 gal of fuel on each side of the chassis. The ‘67 car carried only 45 gals, but this was ample for the thirst of the 6-litre cast iron Chevy V8.
The M8A is powered by a special aluminium 7-litre Chevy V8. “Don’t ask us where we got it from,” says McLaren with a grin, “which should produce around 650 bhp”. The interesting thing about its installation is that, like the Ford Formula 1 engines, it is a stressed part of the car’s chassis. The forward face of the engine bolts to a sheet of magnesium, and A-frames running back from the rear of the chassis (it stops abruptly behind the cockpit) bolt to the rear of the engine. A fabricated sub-frame mounts over the bellhousing and carries the rear suspension, while long radius arms run from the rear up rights forward to the back of the monocoque. Although the monocoque appears to extend back past the cockpit, this extra ‘shelf’ on either side houses the oil tank for the dry-sump set-up, and the various pumps and electrical impedimenta to keep the engine sparkling. In fact, the magneto is mounted vertically behind the injection manifolding on top of the engine vee, and the metering unit for the fuel injection pokes back horizontally from the back of the engine.
The high stacks of the McLaren-modified fuel injection are quite fantastic. They look like a bunch of eight shot-blasted stainless steel lilies curving a full 12 in. above the engine. flower power in a big way … The exhausts run into a pair of big-bore stove-pipes that run out on either side of the gearbox below the body. On the M7A the exhausts curled up over the drive shafts, and exited through the tail bodywork.
The Hewland LG500 gearbox has specially tailored internals for the McLarens. Instead of the normal five cogs, this new box has only four special gears (and reverse) with a high bottom speeder’s control. A sump-puller first gear is not needed since all the Can-Am starts are rolling ones behind a pace car.
The new McLaren wheels are the ultimate in fatties. They get more like buckets with every new model! As tested at Goodwood, the M8A had rear wheels 15 in, in diameter and 15 in. across the rim. A sort of round square, if you know what I mean! And they plan to take a set of 16 in. rims with them as well. Front rims are 9q x 15.
To cope with the increasing number of punctures in racing, the new wheels are knock-ons in place of the normal bolt-on wheels. A specially made bar has been made up to undo the single large locking nut. The Goodyear rears measure 14½ in. across the tread.
The stopping department is very effectively catered for with a set of the biggest disc brakes and callipers you’ve ever seen. Made by Lockheed (who also makes brakes for McLaren’s Formula 1 cars) the big ventilated discs measure 11½ in. across on the rears, and 11< in. on the fronts. The discs are 1 1/16 in. thick. Testing on the cars was delayed when McLaren spun his car into a bank in the wet at Goodwood, the program soon caught up with itself and Hulme and McLaren began attacking their testing records at Goodwood and Silverstone before the cars were shipped to America for the first of the Can-Am races. Article first published World's Fastest Sports Cars No 8
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