75th anniversary of the Mercedes Benz W125 Silver Arrow - 595 bhp and 750 kg in 1937
By Mike Hanlon
March 18, 2012
Before the "space race" became a metaphor for national technological capability, the Grand Prix motor race was regarded, at least by Hitler and Mussolini, as the most readily available way of displaying its world-leading technological prowess. In 1930s Europe, the exploits of Mercedes Benz and Auto Union for Germany, and Alfa Romeo and Maserati for Italy, were powerful tools key to the national interests of their home countries.
Hence the first outing of Mercedes Benz new 1937 Grand Prix car was not in Europe, but in the vitally important Gran Premio di Tripoli.
The Gran Premio di Tripoli was first held in 1925 in the capital of what was then an Italian colony in North Africa named Tripolitania - part of Italian leader Mussolini's dream of recreating the glory of the Roman Empire. Tripolitania was later unified as Italian Libya, then after WWII, it became Libya.
In the mid-thirties, the Grand Prix of Tripoli became Mussolini's showcase of the empire he was creating, and the Grand Prix of Tripoli became a powerful propaganda tool as he sought to invigorate the local economy with tourism.
In the twenties and thirties, North Africa became motor racing's bold new frontier. The fly-away rounds to warmer climates that now mark the beginning of the Formula One season, were once the sail-away non-championship Grands Prix in North Africa.
In addition to the Tripoli Grand Prix, the Tunis Grand Prix regularly ran either the week before or after the Tripoli Grand Prix, held in one of the world's great cities - Carthage (Tunis). As you might expect, intrigue surrounded both events.
To pay for it all, a national Italian lottery was created, with vast fortunes to be made for those who won, and the cost of a ticket within reach of the common man at just 11 lire. Tripoli, the Tripoli Grand Prix and the lottery were a huge national event.
Lotteries have been a popular fund raising exercise throughout history with the Great Wall of China having been funded with a lottery and Roman Emperor Augustus Caesar had raised funds for repairs to the City of Rome with the sale of lottery tickets, so Mussolini decided a lottery would finance his Grand Prix in Tripoli.
To win the lottery, you had to be one of the 30 tickets chosen to be represented by a driver in the Tripoli Grand Prix, and then ... your driver had to win. The tickets for the first lottery were drawn a week prior to the 1933 event, which proved to be a very bad idea. It lead to what is widely believed to have been the only "fixed" Grand Prix in history (more at the bottom of this article).
The funding for the Mellaha Lake racing circuit ensured it was every bit as grand in its day as any on the Grand Prix circuit today. It had a grandstand as big as any at a motor racing circuit in the world at the time, and was the first in the world to use starting lights.
Visiting drivers and teams were treated like royalty and the event quickly became a very important event for numerous reasons, very few of them actually about motor racing.
International racer Richard Seaman described the circuit as "the Ascot of motor racing circuits", likening it to the famous and luxuriously appointed horseracing circuit so close to Buckingham Castle.
Unfortunately for the drivers, while the thoroughly modern pit complex and grand stand had every modern convenience imaginable, it was only modern around the start-finish area.
Although the circuit is now under Mitiga international airport in downtown Tripoli, in 1933 it was countryside and most of the long 13.14 km (8.165 miles) circuit was comprised of country roads in a roughly oval shape. The surface was good, with white lines on either side of the track signifying the racing surface - it was what was just beyond the white lines that presented the dangers.
If you leaf through the gallery for this story and watch the accompanying video, you'll see an era of motor racing where modern concepts of motor racing safety just didn't exist - for the spectator, the officials, the photographers, the drivers. People walk completely unprotected alongside the course, and when you look in detail at some of the hi-res 1930s racing images, you will see astonishing things in every background.
Many of the images in the photo gallery have been added from other major Grand Prix events of the thirties to bear witness to a time when motor racing was naive and unvarnished. Our thanks to Mercedes Benz for enabling us to use its extraordinary historical library.
The Mellaha Lake racetrack used public roads with all the same buildings, trees, walls, crumbling edges and other obstacles - in most cases completely unshielded, with not a single bale of hay to be seen guarding a tree or lamppost - that was a safety innovation long into the future. This was in the period where the occasional death at a race meeting was accepted as inevitable.
When nationalism began to take hold in Europe in the early thirties, and race teams had funds swelled from state coffers, the technology progressed rapidly.
When the cars first started using the Mellaha Lake circuit in 1933, the average speed of Achille Varzi's winning Bugatti T51 was 105.086 mph.
When the Mercedes team rolled its new W125 off the boat in Tripoli in early 1937, the 750 kg era of motor racing was about to begin its final year, and the W 125 was developed specifically for that single year.
It was there to win. Mercedes had quit Grand Prix racing in early 1936 in order to build a competitive car for 1937, and the new beast the factory had built represented a quantum leap in race performance.
The W125's supercharged 5.6 liter engine produced 595 bhp (444 kW) and it had somehow been shoehorned into a chassis so light, that it fell under the 750 kg limit by a single kilogram. The engine used desmodromic valve actuation for each of the four valves per cylinder, and the Roots supercharger was located downstream of the twin carburettors.
The engine weighed a full one third of the car's entire dry weight!
It won in Tripoli in front of a brace of Auto Union C machines - Bernd Rosemeyer in second, Ernst von Delius third, Hans Stuck fourth, and Luigi Fagioli in fifth, with the W125s of Caracciola and Seaman sixth and seventh.
Just four years after Varzi's Bugatti had average 105 mph to win, the average speed of Herman Lang's winning Mercedes-Benz W125 in 1937 was 132.440 mph (213.14 km/h) - around an identical circuit.
Speeds had increased 27 mph and indications suggest the real limits on the cars' lap times by then was really how much risk the driver was prepared to face. The image below is of Richard Seaman's Mercedes Benz two years later. He was leading a Grand Prix by 20 plus seconds when he slid off the racetrack in the rain and hit a tree.
Prominent driver deaths sometimes provoked safety concerns and the fatality of the incredibly popular British driver helped create a new law for Grand Prix racing - compulsory helmets.
After it won its initial race in Tripoli, the W 125 wrote its way into the record books, winning the Grand Prix of Germany (Nürburgring), Grand Prix of Switzerland (Bremgarten), Grand Prix of Monaco and Grand Prix of Italy (Livorno), with W125 drivers finishing first, second, third and fourth in the European title.
In Formula One racing itself, the W125's horsepower figure was not equaled for nearly half a century, when turbo-charged engines reappeared during the eighties.
It wasn't just about the engine though.
In order to build a chassis capable of handling the horsepower of the massive motor, newly appointed chief engineer Rudolf Uhlenhaut used a frame of nickel-chrome molybdenum steel, with four crossbars. The picture below shows Uhlenhaut with a post-WWII frame and engine.
The previous race car had used a box section frame but Uhlenhaut used an elliptical cross-section tubing which increased the torsional stiffness of the vehicle, without its engine, to three times the amount of its predecessor, the W25.
Mercedes Benz description of the W125 is taken from the company archives: "The front wheels were steered by double wishbones with helical springs, as in the celebrated 500 K and 540 K production models. The wheels at the rear were mounted on a De-Dion double-jointed drive shaft providing constant camber adjustment, with longitudinal torsion bar springs and hydraulic lever-type shock absorbers. Shear and braking torque was transferred to the chassis by lateral links.
Uhlenhaut went on to become the technical brains behind many of Mercedes greatest designs. In the image below, he is pictured second from left with Mercedes Team Manager Alfred Neubauer at left, plus British journalist Dennis Jenkinson who had just witnessed Sterling Moss' legendary 100 mph Mille Miglia victory from the passenger seat.
"After extensive test drives on the Nürburgring circuit, Uhlenhaut opted for a revolutionary chassis design. He made the bold and visionary decision to replace the customary principle of hard springs and minimum damping with the exact opposite. The W 125 featured soft-sprung suspension and exceptionally long spring travel, with a high level of damping, setting the pattern for today’s Mercedes-Benz sports cars. "
The W 125 competed in Grand Prix races for just one year. In 1938, Mercedes-Benz replaced it with the W 154 to comply with the new 3000-cc formula for Grand Prix cars, though it must be said that the W125's frame was replicated in the W154 grand prix car of 1938.
The record breakers
During the mid-thirties, Mercedes began experimenting with aerodynamically optimised vehicles with a view to breaking speed records. In January 1938, Rudolf Caracciola achieved the fasted speed ever recorded on a public road (on the Frankfurt–Darmstadt autobahn) in an aerodynamically optimised rekordwagen version of the W 125.
The eight cylinder engine was replaced for the attempt with a 736 bhp (541 kW) V12 engine, and the vehicle achieved 432.7 km/h over a kilometer and 432.4 km/h over a mile.
That's a shade quicker than the 2012 Bugatti Veyron Super Sport's 431 km/h.
It's also a lot quicker than was achieved by a recent model Formula One car which was taken to Bonneville Salt flats.
The Fixed Race
The initial Tripoli Grand Prix at the new Mellaha Lake circuit, the 1933 race, is the only motor race of note that has ever been regarded as "fixed" - the laws of human nature have seen baseball, cricket, basketball and football fixed, but this is the only motor race I'm aware of where drivers of different teams conspired to influence the outcome of a race.
Unfortunately, there appears no definitive version as to what happened behind the scenes with the 1933 race, but the short story is that the ticket holders from the grand lottery knew which drivers would represent them a week before the race. The drivers were still in Italy (where the 30 ticket holders were) and there were both written and verbal agreements made that may not have, (and almost certainly didn't), contribute to a fair result.
There are varying opinions as to what really happened, with Mercedes Team Manager Alfred Neubauer controversially recounting the incident in his 1957 book - Speed was My Life. Neubauer indicated Varzi, Nuvolari and Borzacchini were the main culprits, with Campari and Chiron as strong suspects. These were five of the biggest names of the sport of motor racing at the time. In the end, nothing happened. The race results stood, no-one was fined or had their license revoked and like so many of the scandals faced by powerful interests, it simply dropped off the news agenda. Clearly administrative governance, the willingness of the media to acquiesce, and public safety, have all come a long way since then.
Neubauer's version is contested and the "fixing" may indeed have been only slightly more serious than the current "team orders" issues.