Daimler-Benz Aktiengesellschaft, Untertürkheim, Stuttgart
In 1883 Karl Benz founded the Benz & Co Rheinishe Gasmotoren Fabrik in Mannheim and three years later the
first Benz cars were seen on the roads. Gottlieb Daimler had built engines since 1882 and
1890 he and Max von Duttenhofer founded Daimler-Motoren-Gesellschaft to deliver car engines to Panhard
et Levassor and Peugeot. Both companies grew and were among the earliest competitors in car racing.
The Austrian businessman Emil Jellinek became interested and ordered two cars from Daimler.
Soon Jellinek became the prime reseller of Daimler cars. When Daimler died in 1900 von Duttenhofer
continued leading the company with the brilliant Wilhelm Maybach as technical director. The same
year there was a catastrophe when their test driver Wilhelm Bauer had a fatal crash in a race at Nice
with a car ordered by Jellinek. |
The car had been too short and high and Jellinek ordered a new lower, stronger and more stable car to be constructed according to his specifications. He ordered 36 cars with two reservations, he wanted the sole right to sell Daimler cars in certain countries and he wanted the cars to be named after his daughter Mercédès. The new car made its debut in 1901 and was such a revolutionary design that it can be considered the first modern car. Soon all Daimler built cars were called Mercedes. In 1903 the factory was moved to Untertürkheim where it has been since. That same year came the first major race victory when the Belgian Camille Jenazy won the Gordon Bennett race in Ireland. But it was almost a non-event for the team as a factory fire had destroyed the race cars and new cars had to be borrowed from private owners in the last moment. Mercedes followed up their reputation as a force to be reckoned with by winning the 1908 French GP with Christian Lautenschlager behind the wheel, its main rival being a Benz driven by Victor Hémery.
Benz had as early as in 1901 announced that he would not produce cars for racing, thus creating a conflict between him and co-owner Julius Ganss that ended in Benz resigning in 1903. Ganss had a racing car built and raced without greater success. In 1904 Benz returned to the company. Then there was no race action seen by Benz until 1907.
Mercedes cars had also been used for attempts on the land speed record with William K. Vanderbilt, Pierre de Caters and Herbert Bowden being succesful. In 1909 Benz produced the 21.5 litre 200 bhp "Blitzen Benz", the fastest man made vehicle of the pre-war era. Driven by Hémery, Barney Oldfield and Robert Burman it shattered the land speed record. In 1914 Lautenschlager again proved victorious, leading the Mercedes team to a triple victory in the French GP in what has been called the race of the century.
With the French GP closed to the German factories after the war Mercedes moved their interest to other kinds of racing as Indianapolis and Targa Florio. And Benz built the sensational rear engined streamlined "Tropfen Wagen" in 1923. That same year Ferdinand Porsche was employed by Mercedes. But Porsche's Grand Prix project, the first Mercedes with an 8 cylinder engine, produced a car with dangerous handling as proved by Count Zborowski's fatal accident at the 1924 Italian GP.
Things were changing. On 1 July 1926 the integration between Daimler and Benz became a fact creating Daimler-Benz AG. Mercedes junior driver Rudolf Caracciola was turning into a top driver, being the surprise winner of the 1926 German GP while former driver Alfred Neubauer found it more interesting to organize than to drive and debuted as team manager for Mercedes at the 1926 Solitude GP.
There was no interest in building GP cars in the new company and the racing department had to do with sports cars of the S, SS and SSK type. Bad world economy led to that Mercedes-Benz retired from racing in 1931, the factory continuing to support Caracciola as semi-privateer with a SSKL car. With that car Caracciola became the first non Italian to win the Mille Miglia, a performance that only Stirling Moss has been able to repeat. The next year even that support had to be stopped, Caracciola moving on to Alfa Romeo with a promise to return when times got better.
In 1934 Mercedes returned to GP racing creating a sensation with their streamliner with independent suspension. With the exception of the 1936 season Mercedes-Benz dominated GP racing for the rest of the pre-war era. With the factory destroyed during the Second World War it was not until the 50s that Mercedes could think about racing again. Starting off with the 300SL sports cars the team was back at Formula 1 racing at the 1954 French GP, Juan Manuel Fangio taking both the 1954 and 1955 titles for the team. But after that the decision was taken to retire from both sports car and GP racing, a decision probably prompted by the infamous Le Mans catastrophe where Pierre "Levegh"s Mercedes 300SLR crashed into the grand stand with 80+ casualties. It would take 34 years until the Silver Arrows returned.
Mercedes-Benz SSK / SSKL
The "24/100/140" was the prestige "flagship" of the newly joint Daimler-Benz AG company. Constructed by Ferdinand Porsche the car with its 375 cm wheelbase first appeared in 1925. The 6 cyl 6.3L engine (94 x 150 mm = 6242cc), cast as one piece in an aluminium-silicon alloy with a cast iron top, delivered 100 bhp. When the gas pedal was pressed to the bottom it temporarily engaged the 1.41 Ata supercharger giving a total of 140 bhp/3100 rpm. For 1926 an upgraded variant appeared and also a shorter sporty variant called "K" (Kurz) with a 340 cm wheelbase. The improved engine gave 160 bhp (with supercharger).
Not able to build a real Grand Prix car the factory decided to derive the 24/100/140K into a sports car. Appearing in 1927 the "S" (Sport) had a new lower body, a completely revised chassis, improved brakes, and the engine had been moved 30 cm backwards to improve the weight distribution. The engine was enlarged to 6,7 L (98 x 150mm = 6789cc), had dual carburettors and a 1.5 Ata compressor giving 180 bhp/3000 rpm in normal circumstances and 220 bhp in works specification with higher compression rates and special fuel.
In 1928 a two seater touring variant appeared,. Called "SS" (Super Sport) it had a higher engine hood than the "S" and the engine was further enlarged to 7.1 L (100 x 150mm = 7069cc). Giving 200 bhp normally with a special race camshaft and a 1.69 Ata compressor it delivered up to 275 bhp/3300 rpm in race conditions. Factory race cars even used a 1.83 Ata "elephant" blower.
A shortened model for mountain climbs, the "SSK" (Super Sport Kurz), appeared in 1929 with a 295 cm wheelbase. The engine was improved during 1929-30 to finally give 310 bhp/3300 rpm with 1.83 Ata compressor.
Altogether 149 type S, 114 type SS and 31 or 32 type SSK were built. (Actually 155 + 102 + 37, but five S and seven SSK cars were modified to SS spec and one S car to SSK spec). The SSK chassis numbers were: 35986-35990, 36047-36056, 36083, 36241-36260 and 36393.
As Mercedes-Benz retired from racing in 1931, the factory continued to support their drivers as semi-privateers with special "SSKL" (Super Sport Kurz Leicht) cars. By using thinner steel for the frames and by drilling a multitude of holes in the chassis the cars were made some 120 kg lighter than ordinary SSKs.
Five of the SSKs were converted in 1931 by the factory to type SSKL The very first SSKL was raced by Caracciola/Sebastian at the 1931 Mille Miglia, which they won. With the car Caracciola also proved victorious in the 1931 German GP and Stuck became hillclimb champion in 1932. Two of the cars were rebuilt as streamliners, the one von Brauchitsch took to victory in the 1932 Avusrennen and the one Otto Merz had his fatal accident with at practicing for the 1933 Avusrennen.
Additionally to the early factory modifications of 1931, five customer SSKs were changed in 1932 and one each in 1933 and 1934 to SSK "L" making a total of 12 (according to Tragatsch). The engines of these later models were probably not changed to the desired 310 bhp.
The Mercedes W25 was a combination of traditional and revolutionary thinking. After having considered but rejected a rear engined design Mercedes followed a scheme used in their type 380 passenger car.
The chassis was of a traditional box section type, pierced to save weight. The engine was also of traditional type, a 3.4 litre straight-eight with forged steel cylinders in two 4 cylinder blocks with welded on water jackets and with double overhead camshafts. The one piece crankshaft had 5 bearings. A vertical Roots supercharger was placed at the front end, working at double engine speed and supplying a pressure of 1.66 atmospheres. The supercharger pushed the air into two double choke carburettors, a relief valve venting out the surplus pressure in the air when the driver lifted the gas, creating the famous high pitched Mercedes-Benz scream.
The aluminium gearbox was revolutionary, placed in unit with the rear axle with the ratios working indirect. The input shaft was below the output shaft lowering the propeller shaft and thus the driver seat. To be able to transmit the available horsepower through the wheels independent suspension was used throughout with swing axles rear and wishbones in front. The front wishbones were connected to coil springs carried inside a cross tube.
The car had a streamlined body work of hand-beaten aluminium alloy painted in white. The Lockheed hydraulic brakes had aluminium drums 50 mm wide with a diameter of 400 mm.
Work started in March 1933 and the new car was ready for testing in February 1934. Von Brauchitsch had a crash at Monza due to tyre failure and the next month Henne had a crash in the second car at Nürburgring after having problems with the differential. The new cars were entered at the Avusrennen but withdrawn after practice because of carburettor problems. Instead they made their debut at the Eifelrennen. Legend says they failed the 750 kg limit at the weight-in by 1 kg and that during the night the white paint and filler was removed and replaced by a thin coat of aluminium color. The next day the cars then passed the weight check and went on to win their first race. However late research has shown that the 1934 Eifelrennen was run to a free formula with no weight limits so there is something fishy with the story. Anyway, whatever the reason, from that race onwards the cars featured in the silver color that had already been adopted by Auto Union.
To answer the challenge from Auto Union the engine was replaced by the interim M25AB and then the M25B type adding 70 bhp at a cost of 4 kg more engine weight. The M25 B engine was also used during the 1934 speed record attempt, the engine giving 430 bhp with a special fuel mixture.
There was a bad crash during practice for the German GP where von Brauchitsch fractured his skull but otherwise the season was quite successful with four GP victories and one hillclimb victory. However there were things that could be improved for 1935. Especially the gearbox had proved to be difficult during downshifts. For the 1935 season four new chassis were built and the old cars were rebuilt. The M25B engine was used with the smaller M25AB supercharger while the M25A engines were used by the junior drivers and as spares. A new fuel formula for the season increased the engine power. The new cars featured improved brake cooling, a redesigned more user friendly gearbox and 65 mm rear brakes. A ZF self-locking differential and an air cleaner for the supercharger were introduced during the season. Late in the season the 4.3 litre high torque M25C engine was introduced. A streamlined variant with closed cockpit was used by Geier at Avusrennen and Caracciola and Fagioli used cars with small radiator cowls in that same race.
1935 proved to be the best season ever for Mercedes with 9 major victories including a 1-2-3 at the Spanish GP and with Caracciola becoming the European Champion. However, Geier destroyed one car in a serious crash at the Swiss GP.
In 1936 the W25 cars had an oil cooler added and were used mainly as spares. Fagioli and von Brauchitsch raced them at the Monaco GP and von Brauchitsch prefered the old car at the Eifelrennen where Lang probably also raced the old car.
1934 1935 cars had different mirror
Avus 1935 (Geier)
Monaco 1936 (Fagioli, v Brauchitsch) Eifelrennen 1936 (v Brauchitsch, Lang)
Early testing 1934 Speed record
Monaco 1935 Tripoli 1935 Avus 1935 (Caracciola, Fagioli)
French GP 1935 Monza test Monaco 1936 onwards? 1936 (Fagioli, v Brauchitsch) Eifelrennen 1936 (v Brauchitsch, Lang)
Mercedes-Benz W25 (36 or "kurz")
To face the challenge from the new cars of Auto Union and Alfa Romeo the Mercedes factory decided to construct a new 600 bhp 5.6 litre V12 for the 1936 season. This D type engine became known as the DAB as it had the same bore and stroke as the AB engine. When the first engine was assembled during the summer of 1935, it proved to be seriously overweight (295 kg against 185 kg for the old engine).
To fit this heavy engine into the cars under the 750 kg limit demanded considerable changes to be done to the 1936 cars to save 110 kg of weight. Mercedes-Benz made the radical decision to cut off 25 cm from the wheel base of their GP car. Other news in the car included a transverse gearbox and a de Dion rear axle. (It has often been said that the Mercedes W125 was the car that re-introduced the de Dion axle, but the 1936 Mercedes was in fact the first.) The new car was in fact so small that the tall von Brauchitsch could not fit properly into it. The exhaust system was also new with the pipe much lower to the ground. Somehow the engineers managed to squeeze the engine in under the weight limit only to find that the weight distribution was such that the car was totally undriveable.
Instead a 4.7 litre 450 bhp variant of the straight 8 engine known as the ME25 had to be built in a hurry and put into the new cars. But that was to demand too much of the old engine block. During the season the cars suffered from numerous engine failures. The car had also bad road holding, it was oversteering and the steering wheel gave a heavy kickback to the drivers. The chassis wasn't rigid enough for the suspension to work in a proper way. To cure the problems Mercedes held an extensive test session at Nürburgring in August 1936 testing 48 chassis changes. After a new failure at the Swiss GP the Mercedes-Benz team withdrew from racing to reorganize itself for 1937.
The car and the DAB engine were later developed into streamlined record breakers where the cars behavour in curves was a minor consideration.
Monaco GP "Normal"
Swiss GP 1937 Berlin motor show Cars had two mirrors in Tripoli, right side mirror in Hungarian GP, left side mirror in the other GPs.
The Mercedes-Benz W125 was the ultimate pre war Grand Prix car with the stongest engine seen in Grand Prix racing until the turbo era in the 1980s.
Work started in August 1936 under direction of Wagner using ideas developed by Uhlenhaut during testing of the W25. The frame was of an oval tube type with 5 crossmembers strenghtening the chassis considerably. The wheelbase was increased to 280 cm.
The de Dion rear axle was retained but mounted the other way with the center connected to a slot in the gearbox combining sideways rigidity with vertical movability. The springs were replaced by torsion bars. The front suspension was entirely new with long wishbones and an open vertical coil spring offering greater movement to the wheels. The friction dampers were replaced by hydraulic dampers. The new engine, called the F series or the M125, was similar to the earlier straight eights but with a new longer block to accomodate the larger bore. Bearings were later increased from 5 to 9. With a weight of 223 kg the new 5.6 litre engine was only 20 kg heavier than the original 3.4 litre A type. The old gearbox was replaced by a constant mesh type transverse gearbox. The Lockheed hydraulic brakes now had double shoes and aluminium drums with a diameter of 400 mm and a width of 72 mm. A 240 litre fuel tank in the rear made it possible to run a Grand Prix on a one stop strategy.
The prototype chassis was tested in February 1937 with a ME25 engine. At the Eifelrennen the pressure carburation system was replaced by a suction carburation system on Kautz' car. It was used again at the Vanderbilt cup on Seaman's car with so good results that the new system was adopted to all cars at the next race. The new construction with the supercharger compressing the air/fuel mixture sucked in from the carburettors increased the engine power with as much as 30 % at low revs and 11% at full speed. It also ended the typical Mercedes engine scream.
By June 1937 the car had become 8 kg overweight and had to be slimmed down. Chassis stiffening was reduced and lighter constructions were adopted for dampers, brakes and seat.
With 6 victories, 9 second places and 5 third places the W125 dominated the 1937 season bringing a new championship for Caracciola.
Here is a sample of the multitude of different car variants during the 1937 season:
"Normal" Belgian GP Monaco GP (Lang)
Coppa Acerbo Coppa Acerbo Swiss GP (von Brauchitsch) (Caracciola) (von Brauchitsch)
Swiss GP (Caracciola) Italian GP At the Masaryk GP the cars Donington GP (Seaman) were color coded
Chassis Log W125:
For the 1937 Avusrennen Mercedes-Benz developed some new car constructions. The 1936 GP chassis with the DAB engine that had been used for record breaking got a new streamlined body to be raced by von Brauchitsch. A second 1936 chassis was lenghtened and equipped with the M125 engine for Lang while a third streamlined body was put upon a 1937 GP chassis for Caracciola. Seaman raced a normal 1937 GP car while Zehender had a 1936 chassis with a DAB engine. The streamliners were equipped with internal jacks.
Mercedes-Benz entries at the 1937 Avusrennen: # Driver Chassis Wheelbase Engine Type 35 Caracciola W125 long M125 5.6L streamliner 36 von Brauchitsch W25 short DAB 5.6L streamliner 37 Lang W25 long M125 5.6L streamliner 38 Seaman W125 long M125 5.6L GP 39 Zehender W25 short DAB 5.6L GP
The new formula meant a 46 % reduction of engine volume for Mercedes. After considering both rear and front engined cars with straight 8s, V12 and unsupercharged V24s the factory finally decided on a front engined car with a supercharged V12.
The chassis and suspension followed closely the W125. The hydraulic rear dampers could be controlled from the cockpit during the race.
The V12 engine with its double overhead camshafts was prepared for fuel injection but at the end carburettors were used. The double carburettors incorporated all the experience gained by the DAB engine during record attempts. They featured the most advanced prewar GP system with automatic venturi valves and an "extra" carburettor (known as the Zusatzvergaser) coming on in at high RPMs. Early tests showed that at 8000 rpm the cylinders had a tendency to hit the valves. The team had to use another camshaft during the first races of the season, sacrifying horsepower (425 bhp at 7800 rpm), until the problem was cured. Lang's engine at the French GP gave 474 bhp at 8000 rpm. Later in the season engine power was dropped back to some 435-445 bhp for reliability reasons.
The engine was placed offset in an angle so that the propeller shaft passed to the left of the driver seat, making it possible to build the car very low. The new gearbox had 5 gears, the first gear being protected by a latch from being engaged by mistake.
The body was low and streamlined and the radiator compensated the loss of height by being wider than on earlier cars. The new engine proved to be extremely heavy on both fuel and oil. A hatch for adding oil during the pitstop had to be added and as fuel was used to cool the high reving engine the fuel consumption went up to 1.2 - 1.5 litre/km (1.6 - 2.0 mpg). That meant that special consideration had to be made about the tank location. A 142 litre saddle tank over the driver's legs plus a 242 litre rear tank gave a total of 340 litres which was enough to make a GP with one stop. The saddle tank was first filled with the overflow going to the rear tank. Chassis 1 and 14 were later rebuilt with a new tank combination with a 227 litre saddle tank and a 170 litre rear tank and raced by Caracciola in the Coppa Ciano. Later several chassis (possibly #6, 7 and 12) were rebuilt. Caracciola and Lang used the large saddle tank cars at the Swiss GP where Caracciola's and Seaman's cars featured improved 470 mm rear brakes. Caracciola's car had an unique appearance with two notable air scoops and a new radiator design. At Monza Caracciola and Seaman had large saddle tanks and large brake drums and von Brauchitsch a large saddle tank with only Lang prefering an original car.
The W154 proved to be a successful car with good handling. There was a problem with poor oil economy that was solved during the season with new pistons and additional oil scavenge pumps. The engine also proved fragtile if pushed over its limit. A cronical problem was that the engine was hard to restart after pitstops. After a troublesome Pau the W154 was to dominate the 1938 season with 6 victories, 6 second positions and 5 third positions from 9 starts and Caracciola claimed his third European Championship. For those 9 races 14 cars and 19 engines were produced, which shows that Mercedes-Benz saved no efforts to achieve success.
Chassis log: See "Mercedes-Benz W154 (1939 body)" below
French GP Onwards
Large Saddle Tank Type
Mercedes-Benz W154 (1939 body)
Incorrectly known as the W163 in most motor books, the 1939 cars featured a new body on the old chassis. The saddle tank now had a volume of 185 litres and the rear tank 235 litres giving a total of 420 litres! Seaman's fatal accident at Spa proved the risk in running with such a fuel load. The outer edges of the brake drums were redesigned so that they worked like fans blowing cool air through the brakes. The radiator was of a new design, giving the car a smaller front area. During the season multi-stage supercharging was introduced with the larger primary blower situated to the right and the smaller secondary blower to the left, both running at a speed of 1.25 of the crankshaft. A new constuction enabled the carburettor to be programmable with extra jets being opened at chosen throttle settings.
The two stage supercharger was used by Lang at the Eifelrennen and proved victorious first time out. For the Belgium GP the new system was found on Caracciola's, Lang's and Seaman's cars. During the middle of the season there were a series of engine failures, before the problem was located. It turned out that the Zusatzvergaser could stuck in an open position. That drenched the plugs and cylinders with fuel destroying the piston rings and making the engine to fail.
For the season a new engine was built. Featuring the same volume as the M154 the M163 was a more strong design that solved M154s heavy oil consumption. The compression was higher and the fuel injection features were missing. The M163 engine was used by von Brauchitsch at Eifelrennen and the Belgian and Swiss GPs, by Brendel in the German GP and by Lang at the Swiss GP and at Beograd.
The car was victorious in 5 out of 7 races only failing at Reims and Beograd.
Chassis log W154:
Following the announcement that the 1939 Tripoli GP would be run as a Voiturette race Mercedes-Benz could not resist the temptation to build three 1.5 litre cars for the race, especially as it looked like that the 1.5 litre class would be the next GP formula. The decision was taken on 15 September 1938 with the race being held on 7 May 1939. Only a company like Mercedes would have the abiltiy to build a new car from scratch in such a short time. In fact only two cars were ready on time, the second car being put together on the ship during the trip to Tripoli.
As much as possible from the W154 was used on the new car, the W165 being more or less a miniature of the GP car. The V12 engine was built similar to the 3 litre engine but with a single large supercharger for all cylinders. The chassis and suspension was a copy with only minor differences. The wheels were 17" with 360 mm brake drums. The propeller axle was as usual to the left of the driver forcing the driver to sit on the right of the center line in this smaller car The first car was tested at Hockenheim in April 1939. After Tripoli there were much rumours about their next appearence but in fact the cars were never to be raced again.
According to papers from 1946 found by Doug Nye four cars had been built: chassis 449546/1, 449547/2, 449548/3 & 439806/4.
Back to Contents