Visit to a Mercedes
In MOTOR SPORT last November I described how Lt.-Col. Gallop made the re-acquaintance of the 16-valve Aston-Martin be drove in the 1922 French Grand Prix at Strasbourg. This day in Gallop's company proved so interesting, and threw so much light on matters relating to Ellis' car which hitherto had been obscure, that I was delighted to arrange for him to visit another historic car with which he was closely associated some twenty-four years ago.
The car in question was the 1924 2-litre, straight-eight Mercedes, now owned by J. A. Peck, of Staines. It was so technically advanced in its day that it deserves more attention than has been paid to it by authoritative writers of our time.
For Clive Gallop visiting this car brought sad memories, for it was while driving one of the team at Monza in 1924 that his close friend Count Louis Zborowski, for whom he was acting as manager, was killed.
As early as 1922, when Zborowski went to the Mercedes works at Stuttgart after the Strasbourg Grand Prix, he and Gallop were shown a single cylinder test rig of what was to become the straight-eight engine used in the G.P. cars two years hence. At that time Mercedes had evolved supercharged, 4-cylinder, twin o.h.c., 1½-litre racing engines of 65 by 113 mm., and two cars so endowed ran in the Targa Florio.
In 1923 Mercedes had a crack at Indianapolis and I am able to reproduce a rare photograph of the team at that race, a picture which Gallop, who went out with Zborowski and his team of Bugatti cars, brought back with him from America and has very kindly loaned to me. These cars were 4-cylinder 2-litres, of 70 by 129 mm., based largely on the Targa Florio Mercedes. Similar cars ran in the 1924 Targa Florio and with one of them Werner won both Targa and Coppa Florio.
Meanwhile, Zborowski had been invited to drive officially for Mercedes, as his father had done before him. He was invited to handle one of the new 2-litre straight-eight cars in the Italian Grand Prix at Monza. He was naturally elated and went out with Gallop, taking Len Martin, his usual riding mechanic, with him. The Germans were very courteous, but not particularly communicative about the cars, which were making their first appearance, being brought from Stuttgart by train. They were obviously very fast, and of advanced design. They gave their drivers a hard ride, and the peculiar exhaust system in which air was allowed to enter the open swaged entry in the tail pipe thus eliminating the need for an expansion joint and acting as an "extractor," emitted such a harsh crackle that one German mechanic could stand it no longer and threw a fit during a practice run. Incidentally, while at Monza Zborowski was loaned a Lancia "Lambda" tourer, a car with which he was well acquainted, as he kept one at Canterbury for the Countess. to use.
The Mercedes engines, of 61.7 by 82.8 mm. (1,980 c.c.), were roller-bearing units throughout, with the exception of the little-ends, and had a very rigid crankcase. The nine roller bearing crankshaft was supported in a form of steel "cradle," which gave it great stiffness: The cylinder "block" was formed by welding the water jackets round the separate steel cylinders, and as the cylinder flange holding-down bolts were prolonged to run through the cradle and bearing caps the whole construction was very well tied up. The crankshaft itself was not especially robust, but experienced its two main periods below the normal r.p.m. range. The Roots supercharger was at the rear of the engine, with the magneto above it, and it sucked from a variable-choke carburetter, known as the automat. This is interesting, as Mercedes were pioneering blowing air through the carburetter on their production cars at this time. Fuel was carried in a central chassis-tank forming part of the undershield. The twin o.h. camshafts actuated four sodium-cooled valves per cylinder. The dry-sump lubrication system embraced a deep sump and an oil tank, the filler of which protruded from the front near side of the bonnet. The engine was designed by Dr. Porsche and is believed to have been stressed to run up to 8,000 r.p.m.
This remarkably advanced engine gains a new significance when it is remarked that the 3-litre Mercedes-Benz racing cars introduced in 1934 for the new Formula had virtually the same power unit, except for a more robust crankshaft and different supercharger layout, and sans the cantilever crankcase bracing. In the 1924 car the engine was installed behind a small, slightly-vee radiator far back in a conventional chassis. This frame had notably long front dumbirons, which were boxed-in from the radiator cross-member to a point exactly above the front axle. The large-diameter, cable-operated brakes had detachable covers on the back-plates, from behind which the steering arms protruded. Castor-action was attained in the true sense, the stub axles "trailing" in rear of the axis of the king pins of the I-section axle, which was flat-set on ½-elliptic springs damped by rather primitive friction shock-absorbers.
The steering column was on the off side of the narrow 2-seater body, and the drag-link was bent up at the front to clear the axle, meeting its steering arm ahead of the axle when the wheels were straight ahead. An external hand-brake lever with no ratchet was used and a central lever controlled the 3-speed gearbox. The clutch was a small multiplate and final drive was by torque-tube.
I do not propose to deal at length with the specification, as I referred to Peck's car in some detail in MOTOR SPORT for December, 1942. But undoubtedly the design was a most creditable one and the cars were said to be reaching something in the region of 130 m.p.h. at Monza in 1924. I understand that Mercedes intended to make eight of them, as a sort of Targa Florio sports car, but that only five were completed. Peck's car embodies parts of all these cars but its engine number is 1278. Proof that the cars were conceived as a whole and that engine and chassis were not separate entities is nicely portrayed by two small details - a rib on the crankcase to accommodate the chassis-located oil cooler originally fitted, and the clearance gained for the air-pump, which is situated on the rear of the near-side camshaft close to the blower, by casting the supercharger-casing with shorter fins on this side, as distinct from machining them away afterwards.
On the evening before the Italian Grand Prix at Monza, Zborowski was told that his car had developed clutch trouble and would have to be withdrawn. His feelings can be imagined and he insisted that his Mercedes be brought to the starting line. Martin, his mechanic, somehow contrived to push the car in top gear until it fired and the Count got away, realising at last his ambition of driving officially for Mercedes. After a pit-stop to refill the inexhaustible Martin again contrived to push-start the car, unfortunately, as it happened, for otherwise Zborowski's fatal accident would never have happened. As it was, he skidded on an oil-patch coming out of a fast right-hand bend and the Mercedes literally wrapped itself round a tree. The Count was killed instantaneously, but Martin, who was flung out, was able to get back to the pits to report the accident to Gallop and after 48 hours in bed under observation was declared quite fit.
Mercedes held a most thorough and scientific court of enquiry into the cause of the accident and proved to everyone's satisfaction that the off-side front brake did not lock-on and that nothing on the car failed. The oil patch was blamed for Zborowski's death and, although later additional evidence came to light, let us leave it at that.
Thereafter it seems that these cars were withdrawn from long-distance racing, but that the type made f.t.d. in innumerable local hill-climbs against all corners during the next few years. In 1926 these straight-eight cars reappeared, Caracciola winning the German Grand Prix at Avus at 84.4 m.p.h., although another of the team, after making fastest lap, crashed into the timing box, with horrible results.
We encounter Peck's car in this country in 1927, when it was sent over for Raymond Mays to drive at Shelsley Walsh. We are told that even greater secrecy was observed than had been the case at Monza (for did not Gallop photograph the engine in 1924?), the bonnet now being padlocked - the fittings for this are still in place. Mays decided to handle one of the 2-litre, 4-cylinder cars at Shelsley Walsh, as its gear-ratios were more suited to the hill. He tried the straight-eight at Brooklands but found it almost impossible to control unless the springs were almost solid, when the ride was distinctly uncomfortable. However, at the 1927 Autumn Meeting he lapped at 116.91 m.p.h. in finishing second in the 100 m.p.h. Long Handicap. There is no doubt but that the chassis design was inferior to the very high output, short-stroke engine, as is confirmed by close study of the performances of these cars in road-races.
For a long time the car languished at Brooklands, Thomson and Taylor fitting large Hartford shock-absorbers at the front, as well as a steering damper, in an endeavour to improve stability. The Hon. Dorothy Paget then acquired this Mercedes and it was intended that the Hon. Brian Lewis should drive it in the 1928 Ulster T.T., for which it would apparently qualify. To this end, it was proposed to drive a dynamotor from the front of the off-side, or inlet, camshaft and the radiator header tank was cut away to provide clearance. The front three branches of the rather Henri-like four-branch water off-take pipe were also removed and the outlets plugged. There was now only the rear outlet, and a vertical pipe from the front of the block, leading water to the radiator, so that steam pockets formed and to its notorious road-holding the Mercedes added a reputation for overheating.
The T.T. project fell through but one more attempt was made to employ the car. In 1931 Sir Henry Birkin drove it in a Mountain Handicap at Brooklands, his fastest lap being at 64.8 m.p.h. After this it languished until Peck was able to acquire it. It is, fortunately, largely in its original form and the engine is in excellent condition. The gear-ratios are useless and Peck has so far been unable to acquire the alternative sets that exist - it is said that seven axle ratios were available originally. He intends to rebuild the Mercedes, probably using a Lancia "Dilambda gearbox and moving the engine forward in the frame, if more useful Mercedes ratios remain elusive. Gallop was naturally most interested to examine the car - as he said, more thoroughly than he was able to do on any previous occasion! Such things as the original leather-bound steering wheel and the hole in the bonnet, now covered by a "power-bulge," where the oil cooler protruded, brought back thoughts of this car as it was in 1924, when it was certainly one of the fastest ears of its size and amongst the more technically advanced.