Posts Tagged ‘Rudy Uhlenhaut’

moss 1

(Bert Hardy)

Stirling Moss sets off on his first test laps of an ‘orrible looking Mercedes Benz W196, Hockenheim 4 December 1954…

Stirling Moss started the 1954 Grand Prix season, the first year of the 2.5 litre formula with a customer Maserati 250F acquired with family resources and some trade support. By seasons end he was Officine Maserati’s ‘team leader’ albeit unsigned by them for 1955 which rather created an opportunity for others.

Mercedes re-entered Grand Prix racing from the ’54 French Grand Prix and quickly, again, became the dominant force. The idea for this article was finding some Bert Hardy ‘Picture Post’ images of Stirling Moss’ first test of the W196 at Hockenheim on 4 December 1954, the precursor to him joining the great marque for 1955.

Some quick research uncovered an article written by Mattijs Diepraam and Felix Muelas on 8w.forix.com, a great website if you haven’t tripped over it by the way.

It’s a ripper article the contents of which they sourced from Ken Gregory’s and Stirling Moss’ books. Rather than re-invent the wheel I have truncated their article a smidge without taking away their interesting, nitty-gritty of circumstances around Stirling and Alfred Moss, and Moss’ Manager, Ken Gregory’s deliberations and negotiations about ‘the boy’s 1955 contractual commitments.

‘The Hockenheimring, was still raced anti-clockwise like they do at Indianapolis when Stirling Moss flew in to test the car that was the class of the field from the word go at the 1954 French GP.

After a few laps he knew. And then there was that handsome offer made to Ken Gregory. Mercedes simply wanted Moss and the effort to get him was meticulously planned. It left Gregory gaping at the negotation table – as he readily admits in his highly entertaining 1960 book ‘Behind the scenes of Motor Racing.’

‘And still it almost went wrong – although knowing Neubauer cum suis a plan B and even plan C would have been rushed out of the Untertürkheim premises forthwith. The first thing Moss and Gregory noticed of Mercedes-Benz interest was a brief and factual telegram by Daimler-Benz AG enquiring about the availability of Stirling Moss for 1955.’

“CABLE WHETHER STIRLING MOSS BOUND FOR 1955 STOP. OUR INQUIRY WITHOUT COMMITMENT – DAIMLER-BENZ.”

‘Stirling’s gut reaction was no. He had a signed contract with Shell-Mex and BP for 1954 and 1955 and was sure of a sponsorship clash with Mercedes suppliers, Castrol. Beside that, the contract was a done deal and he would not think of dissolving it so shortly after he had given his word – of which, in Stirling’s view, the contract was merely a written confirmation. He didn’t have time to think about it anyway, as he was due to leave for the US, to race in the so-called Mountain Rally.’

moss 3

Moss relays to Rudy Uhlenhaut left and Karl Kling what its like out there, car far less forgiving than the 250F Moss raced in 1954. Stirling has done plenty of laps by the look of his face (Bert Hardy)

‘Gregory thought otherwise, and after consulting Alfred Moss, decided to go Stuttgart himself. On the advice of Stirling’s dad, Ken armed himself with monstrous demands, to act like a tough British cookie and see what happens. It was a total shock to Gregory to find that Herr Neubauer, the long-time Mercedes boss, was infinitely better prepared for the meeting. Not only did the overbearing team manager come up with the most remarkable details of Stirling’s career – he also came up with a figure that would amount to Moss’ salary, a number that froze Gregory to the ground and left him gasping for air until he got on the flight back to England.’

‘Before leaving he convinced Alfred Neubauer to pair Moss with Fangio in the new 300 SLR sportscar, and of giving Stirling a test before anything was signed. The rest of the deal was ironed out on the spot. The Shell and BP matter was conveniently postponed until after Stirling’s arrival.’

‘On his return Gregory phoned Stirling in the States, having tracked him down in the Rootes building in New York. Initially an irritated Stirling reiterated his view on the contract with Shell and BP but then Ken told him about the contract terms – the sportscar pairing with Fangio, the permission to race his 250F in non-championship events – and, of course, the money involved. An honourable human being he may be, Stirling is only human as well. This was too good to be true.’

‘According to Gregory his stance immediately made an about-turn. And this is where Stirling’s own account of things takes off in his 1957 book In Track of Speed… “I was to receive the sensational and most encouraging news that the German Mercedes firm was ready and anxious to sign me as one of their official Grand Prix team for 1955. It is not easy, now, properly to analyse my feelings when the news reached America. I had gone over there to compete in the Mountain Rally, and had driven a Sunbeam in a trio of cars which won the team prize. When I heard of the Mercedes offer, I was a little awed, a little bewildered, and very pleased. With all my experience, I had not done a lot of real racing in the Grand Prix series on cars which stood a real chance. True, I had led the Maserati team for the latter half of the year, but to have a place in that all-conquering team – and I felt in my bones that it would all-conquering – was to give me a unique personal opportunity.”

And this is the November 22 entry for Stirling’s diary: “Up early, called on Jaguars, then to Rootes, where Ken called and told me of the fantastic Merc offer. Wow!”

Enough said.

moss 2

Neubauer projects and Moss listens and talks to Uhlenhaut (Bert Hardy)

Hockenheim Test and Build-up…

‘Between November 22 and December 3 lay a couple of weeks that became a string of field days for the press. The latter date would be the day of Moss’ return flight to London where he would meet up with his father and manager, the three of them flying straight through to Frankfurt for the planned test on December 4. In the meantime, Jerry Ames of Downtons, the British publicity agent for Mercedes-Benz did everything to alert his Fleet Street colleagues on the arrival of the important test, and this caused a flurry of reports on the Moss-Mercedes case. Did he have a verbal agreement with Maserati? What about the Shell/BP deal? How much would Neubauer be willing to fork out? And where were the principles of a man that had stated that he wanted to win the World Championship in a British car?’

‘All of it was fairly benign, though. From the US, Stirling had already released a carefully worded statement about his ambition to win the Championship in a British car but that there was very little hope in doing so the following year, and that as a professional racer he really had no other option than to accept the offer. These words were generally accepted as sincere. On the day of the test, however, the press were dealt a red herring by a wicked Neubauer. Although the news of the test was carefully leaked by Ames, leading to Picture Post magazine sending their feature writer Trevor Philpots and star photographer Bert Hardy on a plane to Frankfurt the very same day, the two Brits were picked up by a Mercedes-Benz driver pretending to have no knowledge of English and driven off in the wrong direction. It left Neubauer in the safe knowledge that Moss would say yes to them first before the British press could get hold of a possible no. The Picture Post duo were only allowed onto the Hockenheim grounds by the time the serious business was long underway.’

‘And so Stirling arrived at Hockenheim undisturbed to find everything thoroughly prepared for his test. And that’s understating things- to Moss and his party thoroughness was redefined. Mercedes chief engineer Rudolf Uhlenhaut had seen to it that the car had every aspect modified to Stirling’s build and style. So that was one excuse out of the way. Then there was Mercedes regular Karl Kling to set a yardstick – one that was set at 200kph just days before by the same Kling. But there had been a recent rainstorm, so that when Stirling did his reconnaissance laps on a 220A saloon, then switching to the 300SL gullwing sportscar, the track was still wet. These first laps soon created a dry-ish line on which Moss got his first hand on the W196.’

‘He thought it (the W196) was uncompromising, as any Mercedes driver would reveal. He admitted as such to a watchful Ken Gregory. “Stirling was not immediately at home with the Merc, and while Kling was circulating he told me he thought it was a very difficult car to drive; it was ‘fighty’, inclined to oversteer, and much more sensitive to handle than the Maserati, though the power, he said, was ‘fantastic’.” Despite being confused by the peculiar transmission at first he felt confident that he could master the car. He got down to a 2.15 – comparing to an average of 201kph – a time that was later equalled by Kling on a track still drier. A previously nervous Uhlenhaut was by now beaming with pleasure. A short discussion followed with Alfred Moss and Gregory, after which Stirling concluded that he should take Mercedes up on their offer, assuming that the sponsorship clash between the oil companies could be solved – and indeed it was solved in a most gracious way, with Bryan Turdle, competitions manager of Shell-Mex and BP, not hesitating to release Stirling from his 1955 Shell commitments.’

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Neubauer and a thoughtful Moss, the most recent of so many stars the German worked with (Bert Hardy)

Maserati Intervention…

Then came another thing to be solved. During the test a telegram arrived for Neubauer. It came from Commendatore Orsi of Maserati, claiming he had a contract with Moss and that Mercedes should back off. The claim was understandable as Moss had quickly become the lead Maserati driver since his display at the 1954 Italian GP and Orsi wasn’t particularly keen to see the second best driver of the world go off and team up with Fangio, doubling Maserati’s task. But Moss Sr and Gregory were able to convince the Germans that Stirling had in fact not agreed to anything, not even verbally. And so Stirling Moss was announced as the number two Mercedes-Benz driver for 1955 shortly after.’

‘For Moss the choice of Mercedes was obvious…The British manufacturers were a long way from threatening the establishment, and the new Climax engine was still not ready. Mercedes-Benz by all means were. And they showed it at that December 4 test. It had been a test with a thoroughness previously unseen by British drivers. But also one with immaculate attention for the human being inside the driver. That was Mercedes-Benz too. This is Stirling’s own recollection of the comfort he was supplied with as soon as he got back to the pits: “What really impressed me was that as I clambered out of the car, rummaging in my pockets for a handkerchief or rag to wipe my face, a mechanic suddenly appeared, bearing hot water, soap, a flannel and a towel! Out there in the middle of the desolate Hockenheimring this was forethought I could hardly credit. I thought then that to be associated with such an organization could not be bad…”

 Checkout my article on the Mercedes W196…

https://primotipo.com/2015/10/09/mercedes-benz-w196-french-gp-1954/

Photo Credits…

Bert Hardy

Bibliography…

8w.forix.com article ‘How Stirling Got His Mercedes Breakthrough’ by Mattijs Diepraam and Felix Muelas

Tailpiece…

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Neubauer, Alfred and Stirling Moss toast 1955 success, a year of bitter sweet for the great marque, Le Mans not in their wildest, worst dreams (Bert Hardy)

 

merc staub

(Max Staub)

Mercedes Benz returned to Grand Prix racing with a vengeance at Reims in 1954, here Fangio leads Karl Kling in the W196 Streamliners…

Mercedes had a habit of re-entering racing in the French Grand Prix every 20 odd years, when doing so bringing new standards of engineering excellence with them.

In 1914 the 4 cylinder SOHC 4483cc engined Mercedes 18/100 of Sailer, Lautenschlager, Salzer, Pilette, and Wagner crushed the opposition at Lyon just before The Great War. The course was 37.6 Km long, 20 laps of it took the winner Christian Lautenschlager 7 hours 8 minutes!

1914

Three of the 1914 French GP winning Mercedes team cars at Unterturkheim post event. L>R #28 Lautenschlager 1st, #39 Salzer 3rd, #40 Wagner 2nd. (unattributed)

In 1934 Auto Union and Mercedes came to Monthlery with cars which would largely sweep the board until War again intervened.

Although on that day an Alfa Romeo triumphed. Louis Chiron won in a Scuderia Ferrari Alfa P3 from Achille Varzi similarly mounted, the three 2.9 litre supercharged straight-8 Mercedes W25 of Rudi Caracciola, Manfred von Brauchitsch and Luigi Fagioli retiring with a variety of maladies.

1934

1934 French GP, Montlhery. Rudy Caracciola Mercedes W25 DNF, from Avhille Varzi Alfa P3/Tipo B, 2nd. (unattributed)

And so it was that Mercedes returned to racing after a break of 15 years at Reims on the weekend of July 4th 1954, 40 years after Lyon and 20 after Monthlery…

fangio reims

JM Fangio, Mercedes Benz W196, Reims victor 1954. (Jesse Alexander Archive)

cutaway 1

The W196 was a triumph of complex engineering, the 2.5 litre straight eight cylinder car had the following new features; Direct injection of fuel into the cylinders for more precise ignition of the incoming fuel charge, the engine lying on its side only 20 degrees from the horizontal to allow a lower bonnet line and the driveshaft to pass beside the driver rather than him sitting on it.

Desmodromic or mechanical operation of the valves allowed higher rpm than the valve springs of the day could handle, 4 wheel independent suspension using a new type of swing axle at the rear, inboard brakes front and rear to lower unsprung weight and a streamlined all enveloping body helped the car to quicker thru ze air.

The very experienced pre-war engineering team of Dr Fritz Nallinger and Rudy Uhlenhaut were in control of the conception, design, development and testing of the new car.

french paddock

Reims 1954 paddock shot. #18 Fangio and #22 Hans Hermann Mercedes W196 Streamliners being prepared for the race. Open bodies used from Nurburgring 1954 onwards, Streamliner body about 60 pounds heavier than the ‘Nurburg’ slipper/open wheeler bodies. (unattributed)

The purpose of this article is not to write in detail about a car which has had everything written about it, rather the words are a support to the wonderful painting and cutaways originally published in that splendid annual, Automobile Year, in this case the 1955 edition.

cutway 2

(Automobile Year)

In his Automobile Year technical review of the 1954 season noted journalist/Le Mans Winner/GP driver Paul Frere explains in great detail the technical advances of the car but also makes clear all of the Benz victories in ’54 were scored by Fangio, saying that the cars speed was partially a factor of Fangio’s dominance as a driver rather than it being a function of the cars speed itself. He and Alberto Ascari were the standout drivers at the time.

The W196 won four of five 1954 races entered, impressive with a new car; Frere also makes clear that the development potential of the car was obvious and subsequently reinforced in their 1955 season!

french start

French GP Start; #18 Fangio, #20 Kling Benz W196, #10 Alberto Ascari Maser 250F #2 Gonzalez Ferrari 553, #12 Marimon Maser 250F, #46 Prince Bira Maser 250F, #22 Hans Hermann Benz W196, #6 Hawthorn Ferrari 553, #4 Maurice Trintignant Ferrari 625, #34 Robert Manzon Ferrari 625, #14 Luigi Villoresi Maser 250F. (unattributed)

At Reims Fangio was on pole with his young German teammate Karl Kling alongside and Alberto Ascari in a factory Maserati 250F. Alberto and Onofre Marimon were ‘loaned’ to Maserati by Gianni Lancia given his new D50 GP car was still not raceworthy and the drivers otherwise unemployed for the weekend.

Ascari’s race was over on lap 1 due to either gearbox or engine failure depending upon the report you read, this left Fangio and Kling to run away with the race.

Hawthorn and Marimon scrapped for 3rd before the Argentinian stopped for a plug change and dropped to the back of the field.

start 2

Fangio left, and Kling Mercedes W196 well clear of Ascari’s Maser 250F shortly after the start. (unattributed)

Pre-war Thai driver Prince Bira drove a great race in a customer 250F dropping to 4th having run out of fuel and losing time switching to his auxiliary tank, and his 3rd place, so Robert Manzon was 3rd in a Ferrari 625.

Hans Herrman in the other W196 took fastest lap early in the race before over-revving the engine leaving its telltale at 9100rpm!

So, a dominant Mercedes start to a run which sadly only lasted until the end of the 1955 season before their modern era return and the dominance of 2014/5…

fangio thillois

Fangio, Thillois Hairpin, Reims 1954. MB W196. (unattributed)

Etcetera…

grid shot

Front row pre start. Fangio, Kling and Ascari. Hawthorn fiddling with his goggles on row 3. (unattributed)

cutaway 3

(Automobile Year)

merc w 196

Nice section of the W196 cylinder head and operation of its desmodromic valve gear. (Automobile Year)

Race Footage…

Credits…

Max Staub, Automobile Year, Jesse Alexander Archive

monaco

Manfred von Brauchitsch,winner, Rudy Caracciola 2nd 1937 Monaco GP, held that year on 8 August. Loews Hairpin. These 2 were 2 laps in front of 3rd placed Christian Kautz in another Mercedes W125. (unattributed)

Mercedes Benz’ 1937 Grand Prix car was famously the most powerful racing car until the 7-8 litre Can Am aluminium Chev V8’s deployed in the early 1970’s finally exceeded its output of circa 645 bhp. It took the 1.5 litre turbo-cars of the late 1970’s for a Grand Prix car to best those numbers of 1937…

The 750 Kg formula of 1934 to 1937 created an ‘unlimited formula’ of the type only replicated by the Can Am Series of the mid-sixties to mid-seventies. The class was minimum weight based which meant the German teams of Auto Union and Mercedes Benz, bouyed by Government subsidies and rapidly advancing military technology were able to build very light and powerful cars…far more powerful than the regulators had imagined or intended!

rudy 1929

Mercedes GP contender in 1929, prior to the ‘serious program’ of the 1930’s. Rudy Caracciola wrestling the big SSK, sports car around Monaco to 3rd place. Race won by the ‘W Williams’ Bugatti T35B. Supercharged SOHC 6.8 litre straight 6, circa 250bhp. (unattributed)

fagioloi

In search of, and finding an apex! Luigi Fagioli in his Mercedes Benz W25 at the Coppa Acerbo, Pescara on 15 August 1934. Nuvolari and Brivio 2nd and 3rd in Maser 8CM and Bugatti T59 respectively. (unattributed)

The mid-engined, radical Auto Union ‘P wagen’ was launched in late 1933 to critical acclaim. Mercedes approach was more conventional, the W25 a front-engined car powered by a DOHC supercharged straight-eight which initially developed circa 315bhp @ 5800rpm. Suspension was all independent by wishbones and coil springs at the front and swing axles and reversed quarter elliptic springs at the rear. Hydraulic drum brakes were used. The cars won 4 Grands’ Prix and 2 Hillclimbs in 1934.

In 1935 the W25 was further developed, Rudy Caracciola won the reinstated European Championship. Tazio Nuvolari’s famous 1935 German GP win aboard his Alfa Romeo P3 the only non-German car to win a Championship GP from 1935 to 1939.

barcelona

Rudy Caracciola in his Mercedes W25B, Montjuic Park, Barcelona on 30 June 1935. Teammate Luigi Fagioli won the Penya Rhin Grand Prix with Rudi 2nd and Tazio Nuvolari 3rd in an Alfa P3. Carac won the European Drivers Title that year. (unattributed)

The capacity of the W25, initially 3.4 litres increased to over 4 litres developing over 400bhp. The M25 straight-8 became unreliable when enlarged to 4.7 litres and 490bhp. A 5.6 litre, 600bhp V12 was tested but the cars, the chassis shortened (becoming so small Caracciola couldn’t fit comfortably in it) and lightened became uncompetitive with reliability, engine and handling dramas, Auto Union winning many races.

german gp

Mercedes team at the foresters lodge ‘ Sankt Hubertus’ prior to the 1936 GP at the Nurburgring. Mercedes W25’s entered for Caracciola, von Brauchitsch,Lang, Fagioli and Louis Chiron. Best placed was the Fagioli/Caracciola car in 5th, Rosemeyer won in an Auto Union. (unattributed)

After the 1936 German Grand Prix, a catastrophic home race for the team, the best placed Mercedes-Benz in 5th position, it was clear that radical changes had to be made to the Mercedes sporting organization.

Management started by looking at the structure of their racing departments, the same issues of lack of nimbleness, communication and decisiveness which have dogged bigger companies such as Ferrari and Renault in recent decades are not new.

The organization used by Mercedes in 1936 had its roots before the First World War. After the death of Hans Nibel in 1934 the central design office was managed by ex-driver Max Sailer. Under him Albert Heess and Otto Schilling were engine design chiefs with Max Wagner the chassis supremo.

Construction, assembly and testing of the cars were handled by the experimental department led by Fritz Nallinger. Jacob Krauss managed chassis construction and Otto Weber engine assembly while George Scheerer, in charge of the dynamometer section, was responsible for engine testing.

Over the years communication between the experimental department and the sporting department led by Alfred Neubauer had begun to fail. ‘Too many cooks’ springs to mind…

bob

Bob Shepherd line drawing of the Mercedes Benz W125. (Australian Motor Sports)

A new technical department between the design office and the racing team was created in 1936. The Rennabteilung (racing department) took over the assembly and testing of the racing cars from the experimental department. In charge of the new department was gifted young engineer, Rudolf Uhlenhaut. He was born in London on 15 July 1906, (died 8 May 1989) his father German, his mother English. He joined Mercedes Benz in 1931 as a Munich University graduate, until 1936 Uhlenhaut had worked on passenger cars not on any of the racers.

uhlenhaut

Rudy Uhlenhaut testing a Mercedes W154 GP car at Monza in early 1938. Uhlenhaut was a race fast, analytical driver. He was entered as potential relief driver in the Le Mans campaign of 1955. W154 in early form, radiator treatment different on the cars as raced and obviously sans bonnet here. 1938 was a 3 litre supercharged/4.5 litre unsupercharged formula. Chassis essentially an SWB version of the W125 frame made possible by the use of the smaller/shorter 3 litre supercharged DOHC, 4 valve V12. Power 425-475bhp. Car dominant in 1938, Caracciola again European Champion. (Mercedes Benz)

On 12th of August 1936 the Rennabteilung tested one rebuilt 1935 car and two 1936 cars at the Nurburgring with Caracciola and Manfred von Brauchitsch the drivers. Tests included different tyres and shock absorbers. A 60kg lead weight was placed over the front suspension in an attempt to get more front grip. After two days the drivers decamped and Uhlenhaut drove the cars himself.

Rudy had never driven a racer before, even though he was used to testing road cars at high speed on the famous circuit. However, he soon settled in and proved to be an exceptionally gifted driver. Famously it has been rumoured that Uhlenhaut once went faster than Fangio at the ‘Ring during a test in the mid 50s. Whatever the case, Rudy was a talented tester and potentially a gifted racer had he the chance to strut his stuff, his wife and corporate commitments barriers to a racing career.

Uhlenhaut concluded as follows in relation to the W25’s he drove; toe-in changes caused by the old steering geometry were too big whilst suspension travel was too little making the springs bottom. The chassis was bending during braking. The experimental department had tried to solve the problems by using both hydraulic and friction dampers and harder and harder springs exacerbating the handling problems and violent kickback to the steering wheel. At the rear the attachment point for the De Dion axle could bend as much as 7-10cm during braking. Because the suspension was so stiff the wheels couldn’t follow the road. Again, famously, once during Uhlenhaut’s tests a wheel came off at high speed yet the car continued on three wheels as if nothing had happened.

After the 1936 Swiss GP ended in emphatic victory for Auto Union Uhlenhaut suggested further racing that year was pointless. So Mercedes retired from the season to focus their efforts on the 1937 car, the W125.

cutaway w125

Tubular frame of chrome molybdenum, double wishbone and coil spring suspension at the front, De-Dion tube and coil springs located by radius rods at the rear. Supercharged 5662cc 645bhp straight 8. 4 speed rear mounted’ box with ZF slippery diff. (Yoshihiro Inomoto)

Uhlenhaut’s assessment of the changes required resulted in a long wheelbase car with reduced polar moment of inertia. The chassis frame was much stiffer. The front suspension was new with greater travel and much softer springs. The car had hydraulic dampers only. The gearbox was changed to a constant mesh type improving reliabilty. During the season a new suction-type supercharger that proved superior to its precursor was also fitted.

The W125 was the first of the MB GP cars to have a tubular frame; of oval section nickel chrome-molybdenum steel of 1.5mm section. 5 cross tubes braced the frame.

The independent front suspension was again by way of unequal length wishbones, 8.45 inches and 10.59 inches in size upper and lower. Coil springs were used. Both hydraulic and friction shocks were used at the front, sometimes hydraulic shocks only.

Rear suspension was De Dion tube, the 2 end halves forged and machined from a single piece of nickel chrome-molybdenum steel. Two channel section radius rods provided fore and aft location with torsion bars, 33.2 inches long and 0.67 inch wide, providing the spring medium.

kautz

This shot of 3rd placed Christian Kautz shows the rear end treatment of the Mercedes W125, Monaco 1937. (unattributed)

Lockheed hydraulic brakes were used, they were of 2 leading shoe type, had Iurid linings with alloy shoes and drums, the latter had steel liners shrunk in.

It is perhaps indicative of preoccupations of the time with engines that about half the ‘Australian Motor Sports’ article which provided the basis of the cars technical specifications, is about the M125 straight-eight engine!

The engine, in typical MB practice was made up of 2 blocks of 4 cylinders, with a bore and stroke of 94x102mm, the engine undersquare, as was the practice of the time, giving a total capacity of 5662cc. The engine developed 645bhp at 5800rpm, the supercharger ran at twice engine speed and was pressurised at 12-14lb per inch.

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Manfred Von Brauchitsch in his Mercedes W125 during the 1937 Coppa Acerbo, Pescara. He was 2nd, the race won by Bernd Rosemeyer’s Auto Union Type C. (unattributed)

In terms of the cars detailed engine design and construction;

The blocks comprised steel forged cylinders with water jackets and ports welded thereto in sheet steel. The cylinders were spigotted into the alloy, barrell shaped crankcase. The crank ran in 9 main bearings of split roller type made by SKF. Big ends were also of this type.

Pistons were provided by Mahle, conrods fully machined ‘H section’ made of nickel-chrome steel and had plain bronze bush gudgeon pins. Lubrication was by way of dry sump with a battery of gear type oil pumps and a front mounted oil radiator.

rudy 14

Lovely profile shot of Caracciola and the W125. Swiss GP, Bremgarten in August 1937. Rudy won the race from Herman Lang and Von Brauchitsch, also W125 mounted. (Mercedes Benz)

The cylinder head featured hemispherical combustion chambers with 2 inlet and 2 exhaust valves per cylinder at an included angle of 60 degrees. The exhaust valves were mercury filled for cooling. Two gear driven overhead camshafts were used, 1 plug per cylinder was fired by magneto. The heads were not detachable.

A Roots type supercharger originally blew air, in established Mercedes fashion into the carburettor but later in 1937, the blower was reconfigured to deliver the mixture in the more usual way. A twin-choke carb was used, the fuel mix a heady brew of 86% methyl alcohol, 4.4% nitro-benzol, 8.8% acetone and 0.8% sulphuric ether…who said fuel alchemy started in the 1980’s!?

A single plate dry clutch was mounted to the engine flywheel, the 4 speed gearbox, with ZF ‘slippery diff’ and final drive unit mounted to the rear crossmember.

The cars wheelbase was 9ft 2 ins and track 4ft 10ins, the W125 weighed 16.4 cwt.

benz

1937 Donington GP. Manfred von Brauchitsch from Rudy Caracciola, Mercedes W125. Rosemeyer won in his Auto Union from Manfred and Rudy. (unattributed)

The W125 proved a winner, Caracciola victorious at the German, Swiss, Italian and Hungarian Grands’ Prix giving him his second European Championship whilst Herman Lang won at Tripoli and von Brauchitsch at Monaco. The W125 was put to one side at the end of 1937, in an attempt to slow the cars down, there is nothing new in this!, the authorities mandated a 3 litre supercharged/4.5 litre unsupercharged formula for 1938/9. The chassis of the W125 evolved into that of the 1938 season W154, that car powered by a 3 litre supercharged V12 and similarly dominant.

A story for another time…

swiss

Start of the Swiss GP at Bremgarten in 1937. #14 and winner Caracciola W125 with #10 and #8 Hans Stuck and Bernd Rosemeyer both Auto Union Type C mounted. (unattributed)

Etcetera…

monaco

Mercedes team lineup of W125’s at Monaco 1937. #8 Caracciola 2nd, #10 Von Brauchitsch 1st, #12 Christian Kautz 3rd and #14 Goffredo Zehender 5th. Rosemeyer, the best placed Auto Union was 3 laps behind Von Brauchitsch! (unattributed)

avus

Streamliners at Avus in 1937. #35 Caracciola Benz W125 overtakes # 31 Rosemeyer Auto Union Type C in the Nordcurve. Rudy won the first race, Von Brauchitsch the second in another W125. (Mercedes Benz)

dick

Dick Seaman in his Mercedes W125 during the Masaryk Grand Prix, Brno September 1937. He was 4th. Caracciola won from Von Brauchitsch in another W125 and Herman Muller in a Auto Union Type C. (unattributed)

outline

Mercedes Benz W125 drawing. (unattributed)

rudy

Rudy Uhlenhaut in 1955 at a Hockenheim test session beside the ‘Blue Wonder’ Mercedes high speed transporter with a W154 GP car on ze back. (unattributed)

SLR

A truly wild road car for any era; Uhlenhaut and his road legal Mercedes 300SLR racer. (Mercedes Benz)

Bibliography and Credits…

‘Australian Motor Sports’ March 1952 article by Bob Shepherd

forix.com article on Rudy Uhlenhaut by Leif Snellman, Mercedes Benz

Finito…