Targa Florio Mercedes

A Description of the 1924 2-litre Racing Car Painstakingly Restored in Recent Times by G. M. Palmer

Vintage racing cars, especially those in near-original condition, are not particularly numerous, so I was delighted when, last year, Mr. G. M. Palmer, better known to me as the designer of the Jowett Javelin, the prototype twin-cam M.G. engine and the M.G. Magnette, and now an engineer with Vauxhall Motors Ltd., produced his beautifully rebuilt 1924 2-litre Targa Florio Mercedes and rated it at a V.S.C.C. Silverstone Meeting, proving that, apart from being a talented automobile engineer, he also ranks high as an enthusiast for vintage cars.

When this splendid white racing Mercedes came out again this year for the V.S.C.C. Pomeroy Memorial Trophy Competition, I decided that it was time I discovered something about it. So one Sunday I found myself on the way to a village near Oxford, in another excellent twin-cam motor car, the Fiat 524 Sport coupé, to lunch with Mr. Palmer and inspect the result of some five years of painstaking spare-time work. The notes that follow are the outcome of this most interesting visit, during which Mr. Palmer generously placed at my disposal all the data in his possession and took me out in his historic and inspiring motor car.

The Targa Florio Mercedes of 1924 was a development of the car designed and built by Paul Daimler to compete in the 1923 Indianapolis 500-Mile Race. Three of these cars were entered, and were driven by Werner, Lautenschlager and Sailer. They qualified at about 98 m.p.h. and in the race Werner held third place at half-distance at a speed of about 91 m.p.h., but they were dogged by minor mechanical troubles, and finished eighth (Sailer at 80.68 m.p.h.) and 11th (Werner at 74.65 m.p.h.). Lautenschlager hit the wall early in the race and retired. His car was sold in the U.S.A., ran in the 1924 race as a Schmidt Special, and is almost certainly the car restored by Joseph Reutershan, now owned by Henry Austen Clarke, Jnr., of New York.

The design was modified in detail during the winter of 1923 by Dr. Ferdinand Porsche, who had just joined Daimler as Chief Engineer, and three cars were entered for the Targa Florio in May 1924. A road-racing two-seater body with rear-mounted twin spare wheels replaced the taper-tailed Indianapolis body, while the supercharger was almost doubled in size, and carburetter and internal engine changes were made.

Three cars were entered, and were driven by Werner, Lautenschlager and Neubauer. Werner won the Targa Florio at 41.02 m.p.h., and the Coppa Florio, on the way, with Lautenschlager 10th and Neubauer 15th. It was Lautenschlager’s last drive for Mercedes, and it was the second major race to be won by a supercharged car. During the summer of 1924 these cars were outclassed by the new six- and eight-cylinder Grand Prix cars, so were only used for European hill-climbs; they won the Klausen (driven by Werner) and the Semmering (driven by Merz). They were used as practice cars for the Italian Grand Prix at Monza in September 1924, when Mercedes entered their straight-eight 2-litre cars, which proved dangerous to handle, Zborowski being killed in one at Monza.

So far as is known, Mr. Palmer’s car and that in the Daimler-Benz Museum at Stuttgart are the only survivors of these four-cylinder Targa Florio Mercedes.

The 2-litre four-cylinder engine has a bore of 70 mm. and a stroke of 129 mm. The single-piece combined cylinder head and block is of welded construction, each cylinder barrel and combustion chamber being machined from separate forgings, the four being united by sheet metal water jackets and base-plate, a form of construction pioneered by Mercedes and used for their victorious 1914 4½-litre G.P. cars. This is bolted to an aluminium crankcase with a cast ribbed oil sump housing the three-bearing built-up type counterbalanced crankshaft. Bearings were originally of the roller-type, lubricated by intermittent oil jets collected by circular troughs on the shaft. The fully-machined steel connecting rods also had roller-type big-end bearings.

Double overhead camshafts are used, directly operating four valves per cylinder set at an included angle of 50º. The valves have 12 mm. dia. stems with screwed adjusting pads at the cam end, as on Hispano-Suiza o.h.c. engines, and the exhaust valves are mercury-filled for cooling probably the first time such valves were used in a racing-car engine. The camshafts are driven by spur and bevel gears with a vertical shaft at the flywheel end. A cross-shaft drives the magneto and water pump.

A Roots-type supercharger mounted vertically at the front of the engine is driven by a multi-disc clutch, at 1.78 times crankshaft speed, by bevel gears, is engaged on kick-down of the throttle pedal, and blows air into a 1¾-in. dia. double venturi updraught carburetter, as on other supercharged Mercedes cars at this period of history.

Power output of the original engine was claimed to be 68 b.h.p. unblown and 120 b.h.p. blown, both at 4,500 r.p.m.

The clutch is a double cone type, of 240 mm. dia. It drives a separately-mounted four-speed gearbox with a right-hand lever mounted just inside the frame. The ratios are 1, 1.22, 1.60 and 2.42 to 1.

At the rear of the gearbox is the universal joint and spherical bearing of the torque-tube-type rear axle. This is typically Mercedes, with a crown-wheel integral with each half-shaft, the differential gears being between the two pinions. The axle ratio is 3.93 to 1.

Springing is by normal half-elliptics, shock-absorbers being Mercedes lever-type with bronze/steel friction faces, the load on which is augmented by cam action either side of the laden position.

The brake pedal operates one set of shoes, through rods, in the 320 mm. dia. rear brakes, and the same size front brakes through cables. The steel brake drums are integral with the R.W. hubs. The external handbrake operates a second set of rear shoes.

The wheelbase is 107½ in. and the track 55¾ in. Original tyres were 29 x 4 straight-sided but the car is now shod with 5.50 in. x 20 in. Dunlop covers. The gearing gives 105 m.p.h. at 4,500 r.p.m. As used at Monza the cars must have been higher geared, as they were said to do 115 m.p.h.

The body on the present car is a replica of the original.

After its competition career on the Continent was over this Mercedes was shipped to England and was used for sprint racing here by E. A. Mayner, who was apparently Works Manager of British Mercedes, then at premises in Camberwell (but David Scott-Moncrieff says he was on the Sales staff, at Long Acre). At the time it was reputed to be the actual car with which Werner had won the Coppa and Targa Florio but today Daimler-Benz make the same claim for the sister car in their Museum at Stuttgart. Some sources said that it had an engine out of one of the four 1923 Indianapolis Mercedes, which engine Werner had personally taken back to Germany after the American race, either the one from Werner’s own car or that from the Lautenschlager/Sailer crashed car. In view of the subsequent redesign of these engines this theory must be accepted with reservation but it seems likely that Wemer’s mechanic delivered the Targa Florio car in person to Mr. Mayner.

This gentleman made good use of the car, which had been registered XY 4876 on May 11th 1925, the engine No. being 1275X2 and the chassis No. 23012. At the end of that month he made second fastest time of the day at the Shelsley Walsh hill-climb, being 0.4 sec. slower than Major Segrave who was driving a supercharged 2-litre G.P. Sunbeam. The following month Mayner ran the Mercedes at the Skegness speed trials and made f.t.d., Malcolm Campbell’s 350-h.p. V12 Sunbeam doing 33.4 sec., the Mercedes 33.0 sec. A week later the Mercedes won its class at the speed trials on Pendine sands, where it was third fastest, and then, on the promenade at Herne Bay, Mayner netted another f.t.d. of his own, clocking 23.2 sec., or 1/5 sec. faster than Capt. Frazer-Nash’s Frazer Nash.

Before the 1925 season was over he had been placed second in the Stalybridge hill-climb, and he tidied up these performances by making second-f.t.d. over the flying kilo. on Southport sands in 24.2 sec., being beaten only by Segrave and the supercharged Sunbeam, which was 1.4 sec. faster, and by being placed second in the mile race, third in another of these races, although failing to finish in the 10-mile race.

These successes in British speed events, which were well attended and reported in the motoring Press of the day, were no doubt regarded as useful in publicising contemporary Mercedes models, which were rather stolid and Teutonic but immaculately made, and as a means of establishing the effectiveness of the Mercedes system of supercharging, which could be brought in when required and which if, as claimed, doubled the power of the engine, was a very effective “extra gear” or acceleration booster; it was exploited very effectively on the subsequent production 33/180, 36/220 and 38/250 Mercedes-Benz cars.

Anyway, Mayner was out again with the Targa Florio car in 1926, making f.t.d. on the first day of the Skegness speed trials in June, which involved a f.t.d. kilo. in 33.8 sec., and later coming in second in the kilometre race. Then Kindell, who was as far as I can ascertain works tester in those days for British Mercedes, is said to have won the 2-litre class of the mile and 10-mile races at Southport, and the Mercedes was second to Davenport’s G.N. in another short race on those sands. But when Mayner sought to close the season by competing at Shelsley Walsh he failed to complete the course due to misfiring. Nevertheless, these performances with the old Mercedes racer, which must have been put on the drawing-board in 1921/22, were sufficient for Mr. Frank Sedden, Managing Director of British Mercedes-Benz, to sign up Raymond Mays to drive the car during the 1927 season. Mays’ great runs at Shelsley Walsh, where he had held the record in his Bugatti days, must have convinced Mercedes that this would pay dividends. In his enthralling book “Split Seconds” (Foulis) Mays has told how he took over the car and what he did to it, before running it to 6,000 rpm on occasions, in some events with the supercharger permanently engaged (he prepared it at Eastgate House, Bourne, which in many ways was reminiscent of Higham, near Canterbury, half-a-decade earlier). He tied with Davenport’s G.N. “Spider” at the Blackpool speed trials, for f.t.d., in 27 sec. for the half-mile, won the mile race at Southport very easily, crossing the line at 118 mph, was second to Eyston’s Bugatti at Skegness, beaten by 1/5 of a sec., was vanquished at Shelsley Walsh by Davenport, who was 0.4 sec. quicker, but turned the tables on the G.N. at Colwyn Bay. He had also managed second-f.t.d. at the Amateur Shelsley Walsh hill-climb.

Incidentally, in those days racing cars were frequently driven to and from these meetings and it was presumably for this reason that the Targa Florio car had been registered. However, when it was being driven by Mays a 33/140 Mercedes-Benz chassis was turned into a transporter to take it about the country.

Towards the end of the 1927 season Mays was offered a seemingly more attractive proposition by Mercedes, one of their 1924 straight-eight G.P. cars, but it proved so unsuitable for Shelsley Walsh that he substituted the four-cylinder car. According to his book, Mays had sufficiently impressed Mercedes-Benz in Stuttgart to be offered a place in their official racing team (then of sports cars), as Zborowski had been before him and Seaman was to be subsequently, but this he declined. . . .

After Mays had finished with the two 1924 Mercedes the dangerous eight-cylinder was sold to the Hon. Dorothy Paget and converted into a road car, and the Targa Florio car was, it seems, also given a dynamo, starter and lamps for the same purpose. It appears that Lord Tollemache bought the Targa Florio car and there is a story that it was fitted with a closed body, which sounds improbable. Later it is said that a rod came through the side of the crankcase.

I have remarked previously that this is so far as is known the only surviving 1924 Targa Florio Mercedes outside the Mercedes Museum. Indeed, it is unlikely that any more of these cars or any of the Indianapolis cars came to this country, but this is another tangled story, which I propose to evade at present. Even that noted, historian T.A.S.O. Mathieson is convinced that Capt. J. C. Davis had one of the Indianapolis Mercedes and ran it at Brooklands, but I think he may be confusing this with Peter Hampton’s rebuilt 1922 Targa Floria Corsica-bodied and pansified car, which was extensively described in Motor Sport in 1937, because the cars which Davis ran at Brooklands in 1931-32, with dismal results, had 2.4-litre and 2.6-litre engines.

At all events, there is no doubt about Mr. Palmer having the ex-Mayner/Mays car. He has the original log book with the same registration number and the aforesaid engine and chassis numbers, which coincide with those stamped on his car. With its papers came a couple of licence discs with a three-letter Hampshire registration on them, which presumably apply to the Mayner car when it was re-registered after the war by Comdr. Foster, R.N., who used it with, I think, a crude slab-tank two-seater body and a production 10/40 engine.

The first thing Gerry Palmer did on purchasing the chassis and box of engine bits was to make a full-size engineering drawing of the engine (which precludes any suggestion that he may have unwittingly built up a 1.5-litre Targa Florio engine!).

Although the engine cylinder block had been sent to Stuttgart by Jeddere-Fisher it had come back to England, legend says in jolly fashion strapped to the carrier of a friend’s 36/220, still minus its con.-rods and parts of the crankshaft assembly. Mr. Palmer decided that to make new roller main and big-end bearings was too formidable so he converted the engine to plain bearings. High Duty Alloys Ltd. made up very light alloy con.-rods, after Morris diesel rods had been tried unsuccessfully, and the late Mr. G. A. Vandervell was most helpful about the thin-shell bearings, which are of sleeve-type instead of the usual split pattern.

The main bearings are adapted Bedford and lubrication is contrived by using a converted Bedford oil pump driven by spur gears from the back of the crankshaft. The biggest task was to machine new spur gears to replace the original, but now useless, spiral bevels. This was done by the Vauxhall Apprentices School, and in spite of the enormous amount of work Mr. Palmer has done himself he was most anxious that credit be paid to the Vauxhall apprentices and engineers and all the other people who did so much to salvage the old engine. The new arrangement was immediately satisfactory, apart from giving 120 lb./sq. in. oil pressure, so that a double relief valve had to be introduced to bring this down to 70 lb./sq. in. The lubricant used is Duckhams 20/50.

The supercharger was found to be in reasonable condition. It blows at about 8 to 9 lb./sq. in Hepworth and Grandage Ltd. of Bradford were another very co-operative company, who made up new Hepolite alloy pistons with pent crowns, giving a c.r. of 6½ to 1 instead of the original c.r. of about 4½ to 1. A set of pistons giving a 5¾-to-1 c.r. is kept in reserve but on modern petrol the higher ratio has proved satisfactory.

The pressurised Mercedes carburetter feeding through an oddly-looped polished brass inlet manifold is retained but the pressurised Autovac was too complicated to reproduce, so it has been replaced by a C.A.V. multi-fuel engine fuel feed pump which gives a higher fuel pressure than the supercharge pressure. Dr. Uhlenhaut was most helpful in sending from Stuttgart drawings of the complicated throttle linkage but Mr. Palmer has to some extent used new linkage of his own design. A by-pass thermostat has been incorporated in the cooling system but the original honeycomb radiator was in good order, even to its Mercedes stars on the casing. Ignition is now by a Bosch sleeve-inductor magneto to single plugs per cylinder in the centre of the heads. This magneto was generously supplied by Bosch of Stuttgart after Mr. Palmer had happened to mention his problems in the sparks department; it is probably a mid-1930s instrument.

The Mercedes chassis was in very reasonable condition and has needed comparatively little restoration. A previous owner had changed the brake cable run, from one along each side of the frame, to a single cable on the o/s, with a cross-over to a transverse cable running out to the front brakes. Mr. Palmer tidied up the change-over box. These are typical Mercedes brakes of the period, with neat convex back-plates and gear compensators at the ends of the cable runs, the cables looking astonishingly thin. The original shock-absorbers, similar to those used on the 1914 G.P. Mercedes, are retained.

Although Jeddere-Fisher was in process of making a body for the car, Mr. Palmer scrapped this and made a very fine replica of the Targa Florio body, even to mudguards and undertray. The angle-iron framework was made up by a local blacksmith and covered with alloy panelling in the home garage. The white paint was renewed, and it is interesting that when the chassis was scraped-down traces of red paint were found. When Mercedes went to Sicily for the Targa and Coppa Florio races they feared that if the cars were raced in their National colour so soon after the war they would be stoned by patriotic peasants. So they were painted red, like the Alfa Romeos they vanquished. But later, certainly by the time one of them came to England in 1925, they were white. So either this is some of the original red paint or a subsequent owner, perhaps tickled by the legend, reverted to the red colour. A fine three-trumpet bulb horn was a prominent feature of the cars in 1924, so it was poetic justice that, while looking at antique furniture in Dunstable, Mr. Palmer should come upon a brass four-trumpet horn, which is very appropriate to his Mercedes. A Lucas starter motor, a generator hidden up under the scuttle, and sidelamps out of sight under the front mudguards, were fitted and this historic motor car was ready for the road again.

As Mr. Palmer is a fully qualified automobile engineer, I asked him if he had any comments to make, adverse or otherwise, about the racing engine Mercedes had designed more than 46 years ago. He said he was astonished that they were content to use a three-bearing crankshaft when they had used a five-bearing shaft for the 1914 G.P. engine, and that he had been surprised that there was only one universal joint between the separately mounted engine and gearbox, this being behind the clutch and so about a foot aft of the rear main bearing. Any misalignment of the two units or flexure of the frame thus applied load to the rear main. The original roller bearing might well have been able to cope with this but he was doubtful about the ability of a plain bearing to do so. So a degree of flexibility was introduced by driving the clutch by six studs fixed in the flywheel with nylon bushes in the clutch. These lasted only about 150 miles, were replaced by bronze bushes which lasted 80 miles, which in turn were replaced by bonded rubber brushes which lasted about 40 miles and caused retirement from the recent V.S.C.C. Pomeroy Trophy. Nylon bushes of a different design have now been fitted.

After our photographer had taken some colour photographs and departed Londonwards in his Morris 1100 we set about going for a ride in the Mercedes. Pressure is pumped up in the typically Mercedes tail tank, a few pumps are given with the Ki-gass, and the starter button pressed. Starting is rendered a bit reluctant because the supercharger clutch tends to drag from cold, so the car’s owner prefers to use the electric starter, saying that the way the mechanics used to hand-crank these engines is just another thing he admires about the racing personnel of contemporary times. At present the starter is all too eager to jam, for no apparent reason, and is to be replaced by a pre-engagement starter. It jammed on this occasion but Mr. Palmer quickly had the undertray and the starter off, working like a surgeon who is thoroughly conversant with his patient.

Then the engine broke into life, was allowed to warm up, and we were away. The sense of power puts this Mercedes definitely in the vintage racer as distinct from fast vintage sports-car category, and above the howl of the wintery wind round my tight-strapped flying helmet (there is not even an aero-screen on the passenger’s side) and the noise of the indirect gears, the scream of the blower could just be defined as the accelerator was pressed to the floor. Mr. Palmer estimates the present maximum in road trim as about 95 m.p.h. I do not know what we did during this brief spin but it was sheer joy to feel the white car accelerate, to rush past modern saloons, brake securely for the roundabouts on the Cowley ring-road, weaving a little under the strong retardation, and corner firmly on stiff half-elliptic springs. It was all much as they must have found it during that long-ago Targa Florio, similar to the view Lautenschlager had of that Lyons road in 1914 when he was in pursuit of Boillot’s blue Peugeot. . . .

The present owner says he finds the gear-change tricky; if it is any consolation I believe that Mays broke the gearbox on two occasions and that the selectors were altered at his request to make gear-changing less difficult. What Werner and his team-mates thought of it I do not know.

Mr. Palmer is to be warmly congratulated on so splendidly restoring a very historic vintage racing car. He is a pretty versatile motorist, too, for apart from the faithful Vauxhall Velox estate-car that accompanies the Mercedes to race meetings, he is rebuilding a Type 44 Bugatti and owns an Alfa Romeo Giulia. But I am sure pride of place goes to the 1924 Targa Florio Mercedes.—W. B.