From the archives

ONE-SEASON WONDER

Smarting from defeat by Auto Union, the Daimler-Benz board invested in an all-new design 

Eighty years ago – in the early-summer of 1937 – the single-season racing car design that for 45 years would hold the record as being the world’s most powerful Grand Prix car was beginning to make its mark.

Today almost all racing fans with any sense of history whatsoever will be familiar with the car. It was the Mercedes-Benz W125 – the rakishly-bodied, three-holes-up-front, single-seat ‘Silver Arrow’ with which the Daimler-Benz AG’s works racing team was intent upon recovering the lost prestige of having been beaten to the previous year’s European Championship by the rival rear-engined Auto Union equipe. Indeed, it’s generally overlooked these days, but Mercedes-Benz was not just beaten by Auto Union in 1936 – once they realised they had a terrible problem with the revised W25 they were effectively dumped out of Grand Prix racing entirely for some months.

For 1937 they then built the W125 to the contemporary 750kg maximum-weight Grand Prix formula, which had initially been applied for the seasons of 1934-36 inclusive. That formula had itself been dreamed up by the administrators to counteract the free-formula racing years of the early 1930s, when the world had been hamstrung commercially by the Great Depression, and race organisers in both Europe and the USA were simply thrilled skinny to hear from anyone willing to build and race single-seat, open-wheeler cars.

Through 1932-33 such ‘freak’ Grand Prix cars as the U16-engined Bugattis, the twin-six Alfa Romeo Tipo A and the stupendous coupled-crankshaft Sedici Cilindri (16-cylinder) Maserati V4 and V5 designs had been the machines that set new performance standards. So the rule makers of the time equated complexity, and weight, with unruly power. Against that background, therefore, the fix seemed simple. Limit weight, and engine capacity, complexity and power and speed would all be reined in at a stroke.

So governing body the AIACR – forerunner of the FIA – devised its 750kg Formula and applied it from 1934-36 inclusive. However, the gamekeepers of the AIACR were trying to control the collective ingenuity, brainpower, funding and political intent of Hitler’s ‘New Germany’, and of its massively capable – and determined – motor industry giants.

They were, of course, Daimler-Benz AG with its Mercedes-Benz brand – and the go-ahead and ambitious new Auto Union combine.These two new powers waded into the Grand Prix racing scene in 1934 like riot police abseiling into a school-kids’ graduation bash. Their stun grenades simply embodied the startling specifications of their brand-new 750kg Formula racing car designs – straight-eights for Mercedes-Benz and rear-engined V16s – all supercharged – devised by the Porsche Büro for Auto Union. They deployed German industry frontier technologies in the latest light alloys, all-independent suspensions and hydraulic brake systems. And both produced large-capacity high-powered GP cars which still slipped in – just – beneath that 750kg weight ceiling.

In effect the poachers’ new ploy defeated the gamekeepers’ new fence almost from the outset in 1934. Once the German newbies – described by an understandably grudging Enzo Ferrari as those ‘TransAlpini’ – achieved reliability their full superiority would dominate.

Within two years an alternative Grand Prix formula was being actively canvassed by the French-led AIACR for 1937-39 and maybe 1940 too. Any complacency about a maximum-weight formula limiting power and performance had long since been replaced by plans for sliding-scale engine capacity limitations, accompanied by minimum weight limits. But by the time new measures achieved consensus support – slashing supercharged engine capacity to 3000cc and unsupercharged capacity to 4.5 litres, with weight having to be above a minimum 800kg – it was too late for the contenders to comply for 1937.

For this reason the 750kg Formula was given a single-season extension instead. And it was for that single season, now 80 years ago, that the epochal Mercedes-Benz W125 Grand Prix Rennwagen emerged.

It was on May 9, 1937, that Mercedes-Benz promptly celebrated the new model’s racing debut with immediate victory in the Tripoli Grand Prix, in what was then Italian-ruled Libya. Following this opening triumph, the new 5.66-litre supercharged straight-eight machines went on to dominate the entire season. 

The Mercedes-Benz drivers won four of the five Grand Prix races that counted towards that year’s European Championship – effectively the World Championship equivalent of the period. This included two 1-2-3 finishes and two 1-2s. And at the end of the season the team’s senior driver, Rudolf Caracciola, was crowned European champion for the second time. 

 The goal had been an extremely ambitious one: to produce a brand-new Mercedes-Benz racing car within the space of just a few months in time for that 1937 season. The short-wheelbase 1936 car had proved desperately difficult to drive and was even considered unacceptably dangerous by its drivers. Newly appointed young development engineer Rudolf Uhlenhaut put many miles on one of the cars at the Nürburgring to assess its challenge himself. It had certainly proved unable to compete with its Auto Union rivals – and they, with their long rear-mounted engines and swing-axle rear suspension, were considered almost impossibly demanding to drive – unless your name was Bernd Rosemeyer, who won the championship that year. Uhlenhaut concluded that what Mercedes-Benz needed for 1937 was a more rigid chassis frame, revised suspension front and rear, and considerably more horsepower.

Serious design for 1937 actually commenced in August 1936. By September 9, 1936, engineer Josef Müller’s chassis-concept team had decided to extend wheelbase from 2505 to 2798 millimetres. A new frame structure comprising oval-section tubes as twin longitudinal members interlinked by circular-section cross-members improved the frame’s torsional stiffness compared with the preceding W25 by a claimed factor of 2.65.

 Uhlenhaut led the charge in having the suspension feature long-travel, soft springing with improved damping to keep the wheels in better contact with planet earth. What is today regarded as conventional double-wishbone and coil spring independent front suspension and a de Dion rear suspension system with low roll-centre were adopted. Front and rear spring travel was increased by 50mm at the front to 140mm. Wind tunnel testing of the new body design saw the Cd – coefficient of drag – figure fall from 0.620 to 0.589.

 The fact that the Daimler-Benz board cleared investment in an expensive engine revision for just this one final 750kg Formula season marked how much the defeat by upstart Auto Union had stung them. 

Engine designer Georg Scheerer produced the M125 power unit for the W125 car – an eight-cylinder in-line supercharged engine, its pistons displacing 5660 cubic centimetres. Through that 1937 season the W125 cars would reach speeds in excess of 300kph – 186mph – with the enlarged new engine pounding out from 556-585bhp. Running in the most favourable conditions – on a Stuttgart dyno – an M125 engine’s output was even higher at a maximum 646bhp.

Here was the power standard – not to be matched by another Grand Prix car until the 1.5-litre turbocharged era gained pace through 1981-82, 45 years later. The first of 11 W125 works cars built was finished in February 1937.

It would be Hermann Lang – the team’s former engine specialist mechanic – who would win upon the car’s debut at the Tripoli Grand Prix on May 9. It was his first ever Grand Prix victory – like Valtteri Bottas 80 years later at Sochi – and he achieved it at an average speed of 131.75mph. Yes, 80 years ago those guys were not kidding around… 

FIELD ‘PHONE OF DREAMS

Thoughts on a bygone fragment from the Le Mans 24 Hours

As we run up towards this year’s Le Mans 24 Hours, a little piece of Sarthe circuit history passed into the Revs Institute/Collier Collection museum in Florida a few weeks ago. It’s not a super-significant piece of sporting memorabilia, but it’s truly engaging nonetheless. It could be described as ‘start-straight pits to Mulsanne Corner signalling pits field telephone No9’, and it was removed from the old garage wall on the Monday morning after the 1990 Grand Prix d’Endurance. 

The story of telephone ‘numéro neuf’ is that remote pit-signalling had been considered prudent at Le Mans following the terrible disaster on the start/finish straight in 1955. The slowest point on the entire circuit was the right-angled Mulsanne Corner at the end of the eponymous back straight, so immediately after its apex a rudimentary row of shelters was set up on the infield verge, protected by an earth and wattle bank and connected to the main service pits by a wind-up field telephone system. 

Renowned designer/stylist/aerodynamicist Peter Stevens was the man who walked off with the telephone in question, with – I would emphasise – the owner’s approval. He was a prominent member of the Richard Lloyd Racing Team that in 1990 ran two Porsche 962s in the pink and white livery of Japanese sports clothing company Italya. The cars were No43, driven by Manuel Reuter, J J Lehto, and James Weaver, and No44 for John Watson, Bruno Giacomelli and Allen Berg.

Peter recalls: “The telephones were installed on the Wednesday morning just before first practice. The signal crew would be given a number relating to a phone socket that was connected to the team pit by permanently laid wires. There was often a struggle to get the phones working properly before practice began. By the 1980s many teams had been experimenting with their own radio systems but reception was notoriously poor there. 

“The old pit complex was due to be demolished on the Wednesday after that year’s race and, over the years we had been going there I had taken a bit of a shine to those pit-wall telephones. We had become firm friends with Alain Bertault, the former journalist and driver who had for many years been vice-president of the Automobile Club de l’Ouest, the Le Mans organiser. He’d been really good to us in the past and, when I asked what was to happen to the pit telephones once the demolition crew moved in, he said, ‘They’ll just be scrapped. Take one if you like – and don’t forget to take the screws!’ So I did.” 

After sitting for years in Peter’s home office, he decided earlier this year that the phone would make an ideal item for Miles Collier’s stupendous museum in Naples, Florida. And when we arrived there for this year’s Connoisseurship Symposium, Pete duly made the presentation (left, Peter in stripes). Miles Collier is a quiet man at the best of times. If I was a medical man, I might describe him on this occasion as “Speechless – but conscious, ambulatory – and smiling.” He was extremely chuffed at Pete’s generous thought. 

Bertault – who drove small-engined CD aerodynes at Le Mans from 1962-67, usually paired with André Guilhaudin – sadly died in 2016, but telephone No9 lives on…