The W125 was powered by a superchargeddouble overhead camshaft5,663cc (345.6cuin) capacity 94mm ×102mm (3.70in ×4.02in)inline 8 which produced 595hp (444kW) in race trim. Its highest test bed power measured was 637bhp (646PS) at 5,800 rpm, with 245bhp (248PS) and 643lb⋅ft (872N⋅m) of torque developed at a mere 2,000 rpm. In 1938, the engine capacity of supercharged Grand Prix cars was limited to 3000cc, and the W125 was replaced by the Mercedes-Benz W154.
The W125 was considered the most powerful road racing car ever for three decades until large capacity American-built V8 engines in CanAm sports cars reached similar power in the late 1960s. In Grand Prix racing itself, the figure was not exceeded until the early 1980s (when Grand Prix racing had become known as Formula One), with the appearance of turbo-charged engines.[2]
The W125 reached race speeds of well over 300km/h (190mph) in 1937, especially on the AVUS in Berlin, equipped with a streamlined body.
In land speed record runs, a Mercedes-Benz W125 Rekordwagen was clocked at 432.7km/h (268.9mph) over a mile and a kilometre. This car was fitted with a DAB V12 engine (82 x 88mm) of 5,576.75 cc (5.6L, 340.31 CID) with a power of 726hp (736 PS) at 5,800 rpm. The weight of this engine caused the car to weigh over the 750kg maximum limit, so it never appeared in Grand Prix.
Concept
Due to the uncompetitiveness of their W25 car, Mercedes pulled out of the 1936 Grand Prix Season midway through the year in order to concentrate on designing a car that would see them return to the top of the rankings. A new racing department ('Rennabteilung') was set up within Mercedes-Benz in order to work on the car. Rudolf Uhlenhaut, previously a production car engineer for the company, was selected to lead the design team in late 1936. Uhlenhaut had not previously designed a racing car, but had significant experience testing road cars on the Nürburgring race track, experience which allowed him to adapt his knowledge relatively easily to racing cars.[citation needed]
When testing the old W25 car, Uhlenhaut remarked that the suspension was too stiff, preventing the wheels from following the road. During the test session, a wheel came off the car, yet Uhlenhaut continued to drive the car as if nothing had happened.[3] This stiffness caused the chassis to flex and the rear axle to bend by up to 7–10cm (2.8–3.9in) under braking. The brief for the new car included a stiffer chassis and more travel on the suspension to avoid the problems experienced in the 1936 car.[citation needed]
The W125 had a much stiffer tubular frame construction compared to the previous W25 model. This was achieved using oval tubes made of nickel-chrome molybdenum steel which flexed considerably less than the frame used in the W25.[citation needed]
The bodywork of the W125 was aluminium, which like its predecessor was left unpainted in its bare silver colour. This brought Mercedes' cars during this period (and rivals Auto Union, whose cars were the same colour) the nickname of Silver Arrows, the racing colours of Germany being silver (German racing colours were white but stripped paint to the aluminium for weight savings).[citation needed]
Engine and transmission
In the absence of any limitation on engine size (and only a 750kg (1,650lb) total car weight limit to work against), Mercedes designed a superchargeddouble overhead camshaft 5.7 litre inline 8 engine for the W125. Bore & stroke were 94mm ×102mm (3.70in ×4.02in) and actual displacement was 5,662.85cc (345.57cuin). Utilizing a Roots type blower the M125 produced 632lb⋅ft (857N⋅m) of torque at the start of the season. The engines built varied in power, attaining an output between 560 and 595 horse power (418-444kW) at 5800 rpm- an incredible figure for the time. Fuel used was a custom mix of 40% methyl alcohol, 32% benzene, 24% ethyl alcohol and 4% gasoline light.[4] The engine weighed 222kg (489lb) - approximately 30% of the total weight of the car, and was mounted in the front of the car. The engine ran rough, but if it started running smooth, the crankshaft would begin to crack.[5]
Like its W25 predecessor, the W125 used a 4-speed manual transmission. The gearbox design was changed to a constant mesh type, which provided better reliability compared to the sliding mesh transmission of the M25. In a constant mesh gearbox, the transmission gears are always in mesh and rotating, but the gears are not rigidly connected to the shafts on which they rotate. Instead, the gears can freely rotate or be locked to the shaft on which they are carried. The previous sliding mesh transmission required the gears to be spinning at roughly the same speed when engaged; otherwise, the teeth would refuse to mesh.[citation needed]
The W125 made its first competitive outing in May at the 1937 Tripoli Grand Prix with Mercedes-Benz entering four cars. German Hermann Lang won his first Grand Prix motor race to give the W125 a victory on its debut and provide Mercedes with their first victory over rivals Auto Union since May 1936. The next race was held at the AVUS motor-racing circuit in Germany, a 12-mile (19km) long circuit consisting of two long straights of approximately 6 miles (10km) length joined at either end by a curve. As such, it was possible for a car to reach its top speed. Mercedes entered two W125 cars, a streamliner which was modified from the original design to increase its top speed on the straights and a standard car driven by Richard Seaman in case of problems with the streamliner. The streamliner had a top speed 25km/h (16mph) faster than the regular car. On lap three of the race, the streamliner retired while leading due to a gearbox failure. Seaman's regular W125 finished in fifth position.[6]
Hermann Lang demonstrating a Mercedes-Benz W125 at the Nürburgring in 1977. Lang drove a W125 to victory on its debut.
At the Eifelrennen held at the Nürburgring circuit, Mercedes entered five W125's, including one driven by Christian Kautz fitted with the new suction carburettor supercharger system. Kautz finished in ninth, while teammates Rudolf Caracciola and Manfred von Brauchitsch finished in second and third places. For the next race, Mercedes split their entries between two races which occurred within a week of another. Two cars were sent to the US to compete in the Vanderbilt Cup, one of which was fitted with the suction carburettor supercharger used on Kautz's car, and three cars went to Belgium to compete in the first round of the 1937 European Championship. Richard Seaman finished second in the Vanderbilt, and third and fourth place were achieved in the Belgian Grand Prix. Following Seaman's success in the Vanderbilt with the new supercharger system, it was fitted to all of the W125s.[citation needed]
The following two races were also both part of the European Championship. The next round in Germany saw both Mercedes and rivals Auto Union competing on home soil. Mercedes triumphed, as Rudolf Caracciola took his first victory of the year and Manfred von Brauchitsch followed him home in second position. In the next round at Monaco, the positions were reversed as von Brauchitsch won and Caracciola finished in second. A third Mercedes W125, driven by Christian Kautz, took third place.[7]
The non-championship Coppa Acerbo in Italy was the next event the W125 entered. During practice Richard Seaman crashed into a house and destroyed his car. Therefore, only von Brauchitsch and Caracciola started the race. During the race, Seaman took over from Caracciola and despite an engine fire, he finished the race fifth. von Brauchitsch fared better finishing in second position. The Swiss Grand Prix was the penultimate round of the 1937 European Championship. Like in Monaco, Mercedes W125s finished in the top three places, Caracciola taking the win with Hermann Lang in second and von Brauchitsch third. The final round of the championship marked a return to Italy, where at the Livorno Circuit, Caracciola held off teammate Lang to win the race by 0.4 seconds and become European Champion. von Brauchitsch retired from the race and took second place overall in the Championship. Kautz and Lang took third and fourth places meaning Mercedes drivers occupied the top four positions in the championship table.[citation needed]
The W125 entered into two non-championship events before the end of the season. The Masaryk Grand Prix in Czechoslovakia gave the W125 its final victory when Caracciola won the race, von Brauchitsch finished second and Seaman came in third. The race was marred as Hermann Lang had crashed into spectators on lap five, resulting in twelve injuries and two deaths.[citation needed]
The final competitive race Mercedes entered the W125 into was the 1937 Donington Grand Prix. Rosemeyer prevailed, von Brauchitsch finished in second place and Caracciola in third while both of the other W125s failed to finish. The British ERA were outclassed, failing to get classified in their home race.[citation needed]
Retirement from racing
1938 saw changes in the rules, with the maximum limit on weight being replaced with a maximum limit on engine capacity and a minimum weight for the car being introduced; the W125 was no longer eligible for entry without major modification. Instead, Mercedes-Benz developed a new car, the W154, and the W125 was withdrawn from racing.
↑ Walsh, Mick (January 2013). "The Silver Age". Road & Track. 64 (5): 68–73. ISSN0035-7189. On one occasion, I lost a rear wheel at top speed on the straight," Uhlenhaut later recalled, "and the [suspension] was so stiff that nothing happened. It was just like driving a motorcycle [sidecar].
The Automobil-Verkehrs- und Übungsstraße, known as AVUS, is a public road in Berlin, Germany. Opened in 1921, it was also used as a motor racing circuit until 1998. Today, the AVUS forms the northern part of the Bundesautobahn 115.
Silver Arrows is a nickname typically given to silver racing cars with a significant connection to a German car manufacturer. Although the term was coined in 1932, it came into popular usage regarding Germany's dominant Mercedes-Benz and Auto Union Grand Prix motor racing cars between 1934 and 1939. The name was later applied to the Mercedes-Benz Formula One and sports cars in 1954 and 1955, then to the Sauber Group C prototype racing sports cars that raced at Le Mans in the late 1980s as well as the McLaren-Mercedes Formula One cars of the late 1990s and 2000s, and is currently applied to the Mercedes-AMG Petronas F1 cars from 2010 to present.
Otto Wilhelm Rudolf Caracciola was a German racing driver. He won the European Drivers' Championship, the pre-1950 equivalent of the modern Formula One World Championship, an unsurpassed three times. He also won the European Hillclimbing Championship three times – twice in sports cars, and once in Grand Prix cars. Caracciola raced for Mercedes-Benz during their original dominating Silver Arrows period, named after the silver colour of the cars, and set speed records for the firm. He was affectionately dubbed Caratsch by the German public, and was known by the title of Regenmeister, or "Rainmaster", for his prowess in wet conditions.
Alfred Neubauer was the racing manager of the Mercedes-Benz Grand Prix team from 1926 to 1955.
Manfred Georg Rudolf von Brauchitsch was a German auto racing driver who drove for Mercedes-Benz in the famous "Silver Arrows" of Grand Prix motor racing in the 1930s.
The Mercedes-Benz W125 Rekordwagen was an experimental, high-speed automobile produced in the late 1930s. The streamlined car was derived from the 1937 open-wheel race car Mercedes-Benz W125 Formel-Rennwagen, of which also a streamlined version was raced at the non-championship Avusrennen in Berlin.
Richard John Beattie Seaman was a British racing driver. He drove for the Mercedes-Benz team from 1937 to 1939 in the Mercedes-Benz W125 and W154 cars, winning the 1938 German Grand Prix. He died of his injuries after his car overturned at the 1939 Belgian Grand Prix.
The 1937 Donington Grand Prix was a Grand Prix motor race held on 2 October 1937 at the Donington Park circuit.
The 1937 Grand Prix season was the fifth AIACR European Championship season. The championship was won by Rudolf Caracciola, driving for the Mercedes-Benz team. Caracciola won three of the five events that counted towards the championship.
The 1936 Grand Prix season was the third year of the 750 kg Formula. The next iteration of the Mercedes-Benz did not prove successful and the team withdrew during the season to instead prepare for the next one. It therefore fell to the resurgent Auto Union team to dominate the racing. In particular, it was their young, new superstar, Bernd Rosemeyer, who mastered the tricky car and who showed superlative skill in wet conditions. Rosemeyer easily won this season's European Championship by winning three of the four Grands Prix.
The Alfa Romeo P3, P3 monoposto or Tipo B was a classic Grand Prix car designed by Vittorio Jano, one of the Alfa Romeo 8C models. The P3 is considered to be the world's first genuine single-seat Grand Prix racing car and was Alfa Romeo's second monoposto after the Tipo A monoposto (1931). It was based on the earlier successful Alfa Romeo P2. Taking lessons learned from that car, Jano went back to the drawing board to design a car that could last longer race distances.
The 1935 Grand Prix season was the second year of the new 750 kg Formula. The success of the previous year encouraged the AIACR to reinitiate the European Championship. It was composed of the seven national Grands Prix and was won by Rudolf Caracciola, driving for the Mercedes-Benz team. The team dominated the season winning five of those Grand Épreuves, as well as four of the other major races of the season. However, in one of the great motor-races in sporting history, Tazio Nuvolari in a Scuderia Ferrari Alfa Romeo beat the combined numbers of the German teams in their home Grand Prix. The season also saw the arrival on the international stage of the bright young talent Bernd Rosemeyer in the Auto Union team.
Rudolf Uhlenhaut was a British-German engineer, driving engineer for Mercedes-Benz, and the father of Mercedes-Benz 300 SL and 300 SLR. He had a long association with the Mercedes-Benz racing programme of the 1930s and 1950s, and is best known for his road legal Uhlenhaut Coupé version of the 1955 Mercedes-Benz 300SLR race car.
The Mercedes-Benz W154 was a Grand Prix racing car designed by Rudolf Uhlenhaut. The W154 competed in the 1938 and 1939 Grand Prix seasons and was used by Rudolf Caracciola to win the 1938 European Championship.
The Auto Union Grand Prix racing cars types A to D were developed and built by a specialist racing department of Auto Union's Horch works in Zwickau, Germany, between 1933 and 1939, after the company bought a design by Dr. Ferdinand Porsche in 1933. The Auto Union type B streamlined body was designed by Paul Jaray.
The Mercedes-Benz W25 was a Grand Prix racing car designed by Daimler-Benz AG for the 1934 Grand Prix season, in which new rules were introduced, and no championship was held. In 1935, the European Championship was resumed, and it was won by Rudolf Caracciola in a W25. In modified form, the W25 remained in use until 1937, when it was succeeded by the Mercedes-Benz W125.
Otto Merz was a German racing driver, chauffeur and mechanic. He was a driver in the motorcade during the 1914 assassination of Archuduke Franz Ferdinand and later won the second running of the German Grand Prix in 1927. He died in a crash during practice for the 1933 Avusrennen in a modified Mercedes SSK on 18 May 1933.
The Mercedes-Benz Silver Lightning, also called the Silver Arrow, is a concept car built for the 2011 Los Angeles Auto Show Design Challenge, where it won the best animation award for their short film Silver Lightning. It was conceived by the Mercedes-Benz Advanced Design Studio in Carlsbad, California, who also previously created the Mercedes-Benz Biome.
Mercedes-Benz made a series of pre-war supercharged Grand Prix racing engines for their Silver Arrow race cars; between 1934 and 1939. They made two supercharged inline-8 engines; the M25 and M125, and one V12 with two generations; the M154 / M163.
The Mercedes-Benz Stromlinienwagen was a Formula Libre race car designed by Mercedes-Benz for the 1937 AVUS Grand Prix.
References
Dron, Tony (September 2007). "Arrow of Desire: Mercedes-Benz W125". Octane Issue 51. Dennis Publishing. pp.86–90.
Nixon, Chris (2003) [1986]. Racing the Silver Arrows: Mercedes-Benz versus Auto Union 1934-1939 (reviseded.). Isleworth, Middlesex, UK: Transport Bookman Publications. ISBN0851840558.
Sugahara, Louis (2004). Mercedes-Benz Grand Prix Race Cars 1934–1955. Fredericksburg, TX, USA: Mercedes-Benz Classique Car Library. ISBN1933123001.
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