A New Standard in Grand Prix Design
Everyone interested in Grand Prix racing has been awaiting the appearance of the new Mercédès-Benz with great expectations, remembering the peak of perfection that the 1939 Grand Prix cars had reached. With Herr Uhlenhaut still in charge of design, and Alfred Neubauer as team chief, it was reasonable to expect the 1954 Formula I team to be the equal of any of its rivals and also the season of racing with the 300SL sports cars in 1952 was an obvious practice for both design and organisation departments of Mercédès-Benz. The thoroughness with which the sportscar field was attacked, with well-earned results as well as lucky ones, gave indication of what one might expect when the Grand Prix team was put into action.
Keeping to their promise of three cars for the French Grand Prix at Reims, the Mercédès-Benz team made their first public appearance in a race on July 4th, against the reigning champions of Formula I, and achieved the result of first and second, which positions were held front the fall of the flag to the finish, and the third car set a new lap record before retiring with mechanical trouble when third. Clearly Mercédès-Benz were on form and these cars which could beat Ferrari, Maserati and Gordini on their first outing were worthy of close inspection.
The general shape of the cars, with all-enveloping body, is already well known to readers of Motor Sport, but what that body conceals is what interests. Taking the power unit first of all, this is a straight eight-cylinder of 76-mm. bore and 68.8-mm. stroke, giving a capacity of 2,496 c.c. and running to 8,500 r.p.m. The engine is mounted on its side, some 20 degrees from the full horizontal, but for the purpose of describing the power unit it will be simpler to visualise it as a normal upright straight-eight.
Two overhead camshafts are driven by a train of gears from the centre of the crankshaft and viewing the engine in the direction of travel, inlet is on the left and exhaust on the right, but the inlet ports run down between the camshafts as on Bristol/B.M.W., while the exhaust ports are normally situated on the side of the head. For each cylinder there are two sparking plugs, placed one either side of the inlet port, while on the side of the head, where a normal inlet port would be, is the injector nozzle, for the Mercédès-Benz fuel-injection system.
The eight inlet ports are coupled to a long tube some 6 in, in diameter by means of pipes joining thin tube tangentially, and this collector box runs forward to a throttle valve, and the air-intake from the nose, engine speed being controlled by this butterfly throttle valve in the intake. A Bosch injector pump, very similar to a diesel pump, is driven from the central gear train with each of its eight plungers feeding an injector nozzle. This pump is mounted on the cylinder block and next to it is a double magneto, also Bosch, each part supplying current to eight plugs. Now, having visualised our twin o.h.c. straight-eight, with Bristol B.M.W. valve layout, we turn it through 70 degrees to the off side of the car so that it is virtually horizontal; the inlet collector is now on the side of the engine compartment, the exhaust ports underneath and the magnetos and injector pump are on top of the power unit. The crankshaft in now well to the left of the car’s centre-line and from the clutch, mounted on the end of the crankshaft, the transmission shaft runs back under the driver’s legs and into the centre of the rear axle assembly, under the differential and into the gearbox. The gearbox is a five-speed unit, operated by a right-hand lever in a very large gate, and the complete gearbox is mounted on the rear of the differential housing, which is itself mounted on the chassis frame, the rear wheels being independently sprung.
The chassis frame is of the space-frame type, bearing a close resemblance in conception to that of the 300SL, and the main members are one across the car, in front of the engine, and one above the rear axle assembly. These two are about 4 in. diameter and form the basis of the multi-tube structure, and apart from these two tubes the rest of the frame consists of tubing of between 1 in. diameter and 3/4in, diameter, depending on the work the tube has to do. Unlike Ferrari and Maserati, who make a space-frame using the same type of tube throughout so that clearly some tubes are grossly under-stressed and therefore unnecessarily heavy, Mercédès-Benz have gone into the frame in such detail that each tube is stressed correctly and is only in tension or compression, unlike Maserati, for example, where many of the tubes give strength in bending, which defeats the of the objects of a theoretical space-frame. The result of Mercédès-Benz design is a frame of very light weight and extreme finesse.
The two large tubes previously mentioned do more work than just cross-members, for they carry the mountings for the telescopic shock-absorbers and the front one also has the steering box built into it on the left and part of the air-intake duct on the right. At the cockpit the frame is almost out to the full width of the car, which rather dispels any possibility of fitting a normal Grand Prix body. All four brakes are mounted inboard and are of immense proportions, those at the front being nearly 24 in. overall diameter, with it least 4 in. wide linings. The complete assemblies are mounted on the chassis frame and the drums have fine radial finning, on the principle used on the 300SL, with aluminium shrouds welded on to give a turbo-flow effect. The front brakes clear the front of the engine by barely 1 in., clear indication of the way the car has been designed as a complete unit, and are coupled to the wheels by very small diameter shafts and Mercédès-Benz universal joints. Due to the size of the front brakes, they are situated forward of the wheel centre-line, so that the connecting-shafts run constantly out of line. At the rear the drums are slightly smaller and are mounted on each side of the differential. In addition to the turbo-fins for cooling, the rear brakes have air ducted to them from a scoop in front of the windscreen, as well as receiving air from an opening under the driver’s seat, while the front ones rely solely on the air passing through the radiator, which is mounted on the foremost part of the chassis frame, with an oil radiator on the left of it.
The front suspension is by double wishbones, of unequal length, with a torsion bar connected to the lower one. This torsion bar runs forward and is enclosed in a tube, which is itself a torsion bar, so that, with a length of 12 in, the effect of 24 in. is obtained, as on the pre-war Vauxhall cars. All the steering parts are highly polished or chromium plated, as in fact are all the detail parts of the car. The finish is truly “Motor Show,” as on the pre-war Grand Prix Mercédès-Benz, and makes contemporary Grand Prix cars look rather “home-made.”
The rear suspension is a new departure for Grand Prix cars, for it is a reversion to swing axle, but not of the normal type. Each wheel is carried at the extremity of an arm that runs down wards and inwards to a point directly below the differential housing, where it is pivoted, thus giving a long radius to the arc of the wheel movement and also, and more important, lowering the roll-centre. To each of these arms is connected, by a link, a long, thin torsion bar that runs forward into cockpit, being located beside the driver’s seat, while the telescopic shock absorber is also connected to this swinging arm. The hub carrier is an elliptical plate located to the chassis by a Watts link mechanism, the bottom link running forward and the top one backward, while the transmission shaft runs through the hub plate. A Mercédès-Benz universal is used at the hub end of each transmission shaft, while a sliding universal encased in a rubber telescopic sleeve is mounted at the differential end of each shaft.
The swinging arm members of this rear suspension are typical of the workmanship of the whole car, for they are 2 1/2-in. tubes at the hub end and taper into an H-section bar at the pivot end. This principle of swing axle is similar to that used on the new 220 model Mercédès-Benz touring car. All wheels are of the wire-spoked type and 16 in. diameter, those at the front having larger hub centres than the rear, enforced by the large universal required for the brake shaft to pass through the steering pivot. In order to avoid any errors the front hub caps are three-eared and the rear two-eared, both being normal knock-off type. The dry-weight of the complete car is 13 3/4 cwt.
The fully enveloping body is of elektron sheet and only 0.028 in. thick and welded or riveted as occasion demands. In order to cool the rear tyres large swoops are cut in the front of the wheel humps and cowled exits are riveted onto the inside of the humps behind the wheels. A headrest is faired into the body behind the driver’s seat and in this is the filler cap for the fuel tank which is a single one, mounted above the differential and gearbox and holding 42 gallons. The oil tank for the dry-sump lubrication is mounted on the left of the car, behind the front wheel, with an air-exit from the radiator passing alongside it. The driving position is somewhat reclining and the driver has his feet very wide apart, there being a footrest beside the clutch pedal, while the steering wheel, identical to pre-war Grand Prix Mercédès-Benz, has four spokes and is quickly detachable.
The eight exhaust ports merge into two short pipes which eject from the off side of the car, just in front of the cockpit, while a detachable panel allows access to most of the sparking plugs; the remainder, the front four or five, are accessible only when the off-side front wheel is removed. This at first seemed most unreasonable, but a little thought showed that there was reason behind it. At the pace at which modern Grand Prix races are run there is no time for pit stops for fuel, let alone sparking plugs, and clearly Mercédès-Benz have complete confidence in Bosch plugs. If an engine starts to misfire it is due to some derangement in the internals which has affected the plugs, so that a change of plugs is only going to delay the inevitable and the chances are that after the first misfire the race has been lost anyway.
Nowadays any plug specialist will agree that fouling in a racing engine is only due to the engine not being 100 per cent. or the wrong plug being used, and Mercédès-Benz engineers obviously believe in this, having no intention of running an engine that is not 100 per cent. on the fits and clearances of pistons, rings, valves, guides, etc. This is, of course, the advantage unlimited resources have over a private owner who has only one engine which has to be kept as near 100 per cent, as is possible, but which is usually only achieved in its first race.
To complete this story of the scientific approach to Grand Prix racing, as distinct from the sporting approach, the detail work on the question of jacking the cars for wheel removal is one little instance. A complete undershield is fitted, with only the air aperture under the driver’s seat and the ribs of the gearbox breaking the smooth flow, consequently it normal type of jack is useless. At the front and rear of the car, runners are fixed to the undershield and the quick-lift jacks have ball-races on the two vertical posts and these roll along the aforementioned runners as the jack is slid under the nose or tail of the car.
Just in front of the rear wheels, on each side of the car, the frame has a tube into which a solid bar can be inserted and a single jack levered on this bar raises the complete side of the car.
For transport of the team Mercédès-Benz diesel lorries are used and each one is built to hold two cars, one above the other, while aluminium covers lined with felt fit over the wheel humps, which are the highest points of the cars, to prevent any possible damage. Another lorry carries all the spares and equipment and in addition there is a fully-equipped workshop lorry, and it is obvious that Mercédès-Benz have come back into Grand Prix racing not only to stay, but also to win.
Many readers have already complained that Motor Sport is too pro-German and doubtless the same people will not agree that Mercédès-Benz justify such a complete description, but personally I feel that July 4th witnessed the beginning of a new era in Grand Prix racing, similar to that witnessed in 1934 at Montlhèry, when from the point of view of technical interest the current Alfa-Romeos and Maseratis were made to look obsolete. The peak of Grand Prix racing ceased to be a sport almost from its inception, for the aim has always been to achieve more speed and/or power than your rivals, and that is a science. The drivers supply the sport by using the scientific instruments given them by the engineers to do battle against one another.
Until the fall of the flag, Grand Prix racing, and any racing for that matter, must be approached by the designer, engineer, mechanic or team manager as a pure science, where the brain comes first and foremost; even though the drivers may supply the sport, they must always be controlled by the science of motor racing, especially if It is a matter of teams racing against teams. That a science is a serious matter is accepted, and therefore the science of Grand Prix racing needs t o be taken equally seriously and it is the Mercédès-Benz organisation’s ability to provide this serious approach to Grand Prix racing that has always appealed to me and always will, nationalities, politics, or personalities being of no importance.
As a mechanical instrument, the 1954 Grand Prix Mercédès-Benz sets a new standard, but in fairness I would say that I saw a similar standard, for its time, in 1949, when I first had a private look at the B.R.M. Then I witnessed a new conception for the current Formula I with the same mechanical appreciation that I viewed the new Mercédès-Benz. Unfortunately, it was obvious that the conception was beyond the capabilities of those concerned, as has subsequently been proved, but it was just as much a landmark in the development of the racing car. After the result of the first race of the Mercédès-Benz it would seem that this landmark is going to stay, unlike that of 1949, but as these words are being written before the British Grand Prix I may have to eat this page of Motor Sport. — D. S. J.