Some Le Mans cars

LAST month we printed a very brief and hasty report on the Le Mans 24-hour race, due to printing schedules being unable to wait longer than a day after the race, so in consequence details of the more interesting cars that were competing had to be omitted. As some of these cars are unlikely to appear again this season, and may never be seen again even next year, it is worthwhile at this late date giving a few notes on them.

Of the great Ford entry the two most exciting cars were the 7-litre GT Prototype coupés driven by Miles/McLaren and Phil Hill/Amon. These were normal GT 40 coupés into which big Galaxie V8 engines were fitted, these power units being developed by Shelby American from the Daytona N.A.S.C.A.R. type of engine. A dry sump oil system was made by the simple expedient of driving by Gilmer belt, an external scavenge pump, which transferred the oil to a tank in the front of the car. This tank had a perspex window in the front for easy checking of oil level, and the normal steel engine sump was replaced by a shallow aluminium one. The cast-iron cylinder heads were replaced by aluminium ones to the same design, the rockers on these big engines being carried on shafts instead of pedestals as on the 4.7-litre and 5.3-litre Ford V8 engines. A one-piece inlet manifold filled the vee of the engine and a single 4-choke Holley carburetter was used, while a Coventry-Climax cross-over type of exhaust system was employed, ending in two large-diameter tail pipes. The exhaust note of these big 7-litres, turning over at 6,500 r.p.m., was anything but a rumbling V8, they had a scream like a Climax V8. In Daytona form these Galaxie Ford V8 racing engines develop 525 b.h.p. and can run 500 miles in that state of tune. For Le Mans they were detuned to about 455 b.h.p. and it was felt that they should run 24 hours at that without any troubles and the insignificant looking 4-choke carburetter was quite sufficient to produce this power, there being no need for exotic multi-carburetter layouts.

To transmit this power to the rear wheels, Ford Advanced Concepts of Detroit designed a gearbox/rear axle unit around the four gears and crown wheel and pinion of a Daytona Galaxies, the casting for the casing being made by a local firm in Detroit named KAR KRAFT. The rest of the chassis and suspension followed normal Ford GT 40 practice, but the body had a much longer nose section with all the air going through a single inlet, instead of a multitude of slots and openings as on the 4.7-litre cars. Some of the air was deflected by flexible ducting directly on to the front brake discs and the radiator air came out of an opening in front of the windscreen. Although these cars were supposed to have been tested in America at over 200 m.p.h., when they came to the Mulsanne straight they did around 190 m.p.h. and were so unstable that all manner of "tweaks" were applied to the aerodynamics. In the end they were made stable by the addition of deflectors under the nose to push the air away from the underside of the car, the addition of spoilers on the tail and two fins down the back of the car, from the rear window to the tail.

These bodges seemed to effect a cure and the removal of the enormous anti-roll bar from the back suspension helped with cornering, so that the cars could use most of their potential, but as we saw in the first hour, their fuel consumption was out of all proportion to their performance. A typical instance of the fact that the Ford people still have a lot to learn about 24-hour races and the speed of Le Mans was shown by the mechanics covering all the body joints with masking tape just before the start. Presumably this was in the interests of drag coefficients, but it stayed in place for barely an hour. Such detail stuff may pay off on a flying mile at Bonneville with a Hot-Rod, but it's a waste of time in a 24-hour race. These big Fords had a starting line weight, with fuel and oil, of 2,662 lb., against the 4-litre P2 Ferrari which weighed 2,245 lb., a handicap of over 400 lb. In practice, after the handling had been improved Ken Miles tried using all the available b.h.p, out of Arnage corner and promptly broke the differential. For the race, both gearbox/axle units were changed and on the Phil Hill car the replacement box did not fit exactly to the drawing and this caused the gear-change linkage to be assembled incorrectly, a locating pin on the selector rod not engaging in its register so that turning motion on the selector shaft was done purely by friction, and that didn't last for long. This caused the car to have a long pit stop, but when it got going the clutch began to slip, so that was that. The other 7-litre car suffered a broken gearbox, going round in top gear until that gave up the unequal struggle. When this gearbox trouble began one of the drivers summed it up by saying "I think the layshaft is lying in the bottom of the casing." The Galaxie gears may be strong enough for N.A.S.C.A.R. racing but they could not stand up to the loads imposed by Le Mans.

Another car that made its first appearance at Le Mans was the 5-litre Maserati V8, actually 5,054 c.c. by reason of enlarged bores, the extra capacity putting it in the next category for fuel tank capacity, for the Le Mans regulations limit tank capacity according to engine size. This Maserati Tipo 65 was only begun on May 1st and was a completely new car from the drawing board of Guillo Alfirei. The chassis was a true space-frame made of very small diameter tubing on the same principles as the "Birdcage" cars of a few years ago, but on this new car the V8 engine was installed behind the driver's cockpit and in front of the rear axle. After the engine is lowered into the cage of tubes a removable structure is bolted in over the top of the engine to complete the space-frame. A 5-speed axle/gearbox unit sticks out the back, there being a torsional shaft between the engine and the clutch which is in the extreme rear of the gearbox, the drive then passing forwards through the gearbox to the crown wheel and pinion. Independent suspension is used all round with double wishbones and coil springs at the front and a typical Grand Prix car layout at the back with a lower wishbone, transverse top link and a pair of radius rods on each side with longitudinal torsion bars and light coil springs. All four Girling disc brakes are mounted just inboard of the hub carriers, this arrangement permitting discs larger than the inside of the wire-spoke wheels.

The V8 engine uses Lucas fuel injection and develops 430 b.h.p. at 6,500 r.p.m. The car was undoubtedly fast at Le Mans, but its directional stability, left a lot to be desired and on the first time out in practice Siffert could be seen going down the Mulsanne Straight at about 160 m.p.h. astride the central dotted white line in the road, looking as if he did not want to go much faster or deviate from the straight and narrow.

Another interesting car that is unlikely to race anywhere else is the Rover B.R.M. gas turbine driven car. Since its demonstration run in 1963 the car has been built with a very pretty coupé body and the Rover gas-turbine has been fitted with a heat exchanger to raise the inlet temperature of the ingoing air and to improve fuel consumption. As in 1963 the works drivers drove the turbine car, this year the pair being Graham Hill and Jackie Stewart. As in 1963 the car ran quietly and consistently throughout the 24 hours and as it crossed the finishing line it received an enormous ovation from the French crowds, which most have been truly heart-warming to the Rover team. The only trouble the car experienced was the entry of some foreign body into the compressor, which damaged some of the compressor vanes and this caused the turbine inlet temperature to increase. To keep the turbine inlet temperature at a reasonable level the compressor speed was reduced and consequently the power output was reduced, but despite this the car ran faultlessly for the 24 hours.

After the race the engine was dismantled and inspected and with the exception of the damaged compressor impeller all the components were in first class condition. The Corning ceramic heat exchanger discs were also in perfect condition except for a score mark on one disc caused by the passage of a foreign body. In the 24 hours the Rover-B.R.M. covered 2,370 miles and averaged a fuel consumption of 13.52 m.p.g. It finished 10th overall and won the Motor trophy for the highest placed British car. As a technical exercise and a demonstration of Rover engineering the car more than proved itself and was a fine example of British engineering.—D. S. J.