One of the five silver race cars which made history in the 1940 Mille Miglia, the BMW 328 Kamm Coupé was named after German aerodynamics pioneer Wunibald Kamm. The last known model vanished back in 1953, but now, thanks to BMW Classic, the famous race car has been recreated to celebrate both an important milestone in the group's motor racing history, and the development of vehicle aerodynamics.
"We are very proud to be able to bring this car back into the public spotlight," said Karl Baumer, Director of BMW Group Classic."We’ve come up against some major technical challenges, had many discussions and racked up countless hours of research, but when you see the car for the first time you can sense the passion and expertise invested in the project by everyone involved – all those years ago and today."
As WWII took hold in Germany, BMW moved its precious race cars to a rural location, far away from the potential destruction they may have faced in Munich. Surviving the war unscathed, the cars were soon scooped up by Allied soldiers with three Mille Miglia Roadsters resurfacing years later in America, England and Russia. The winning Touring Coupé, after initially being seized by the Americans, was quickly secured by a senior BMW employee, this car too finding its way across the Atlantic when the employee decided to emigrate.
The Kamm Coupé was the only one of the five to remain on German soil, with former BMW Director of Racing Ernst Loof acquiring the car for his own personal use. Unfortunately after facing financial trouble, this car too was sold, and subsequently sent to the scrap yard after an accident in the early 1950s.
In the mid-1990s, BMW founded BMW Mobile Tradition, and plans for a reproduction of the famous Kamm Coupé were set in place. But the task proved to be a difficult one with all the car's original plans and photographs vanishing with history. It was only through the hands-on assistance of a private collector in Munich that the BMW team were able to collect enough photographs to show the car on a variety of angles to form a computer generated likeness, design specialists scanning the images to create a 3D blueprint.
A few reliable constants, such as the wheel rim diameters, wheel offset, headlight size, door handles, wing nuts, indicators and BMW logos, were added until they appeared in the same position in every projection. Each image offered a new series of datum points for wheel arches, windows and other body parts, each linked to the fixed constants.
Piece by piece the information collected until finally enough data was accumulated to construct a virtual solid model. Once it was determined that the car looked right from every possible angle, a computer controlled five-axis milling machine was used to sculpt a life-size model from a block of highly compacted foam.
From here, a restorer was commissioned to stretch an original BMW chassis by 200mm and construct a steel space frame according to the templates provided by the original photographs. The project was suspended shortly after the job was begun.
Sometime later, as part of the concept design process for the new BMW museum, an idea was born to rebuild an intricate Elektron space frame of the Kamm Coupé as a showpiece for the “Lightweight design” area of the museum. An exact copy of the original space frame was duly produced with the help of a specialist based near Munich.
Aluminium was selected as the material in place of the original Elektron, and the frame’s weight duly came very close to that of the original. Although this display frame was never intended to be used in an actual car, the Kamm Coupé idea remained on the table. In the end, it was a project initiated by the Meisterschule für Karosserie- und Fahrzeugbau Leipzig-Leisnig-Erlbach (master craftsmen’s college for body and vehicle construction serving Leipzig, Leisnig and Erlbach) in partnership with the BMW plant in Leipzig that got the ball rolling.
The original plan was to cover the existing steel space frame with aluminium body panels to replicate the external appearance of the car at least. The Meisterschule produced moulds of the foam model in which the panels of the outer skin could be shaped. The finished body has since been on display at the Leipzig plant.
With the 70th anniversary of the Mille Miglia victory fast approaching, BMW Classic was determined to bring its plan to recreate the Kamm Coupé to fruition. However, highly skilled specialists were required to turn the collection of individual parts into a car that could actually be driven. With his excellent BMW 328 Touring Coupé and Mille Miglia Roadster restorations for the new BMW Museum still fresh in the mind, it was clear that René Große – based in Wusterwitz in the state of Brandenburg – would be the right man for the job.
Große used the foam model as the basis for a glass fibre-reinforced plastic mould. This was then shaped (with the help of additional wooden elements) into a strong casing which was split down the middle into two parts. The 25mm-diameter tubes for the space frame – made from an aluminium alloy that allowed work-hardening – were then fitted into these two half-shells. Extreme precision was the order of the day here, as no corrections could subsequently be made to the outer skin.
All this endeavour was aimed at ensuring that the frame would get close to the 30kg weight of the original. For the outer skin, the team used pure aluminium body panels from a second set supplied by the Meisterschule. The newly made panels for the inside – for the inner front wings, bulkhead, double floor section of the body, dashboard and fuel tank, for example – then had to be integrated into the mould.
The body experts in René Große’s team called on all their skill and experience to fit the body to the space frame. An interesting detail of the construction were the 40mm-wide aluminium strips which were welded to the frame at the outer edges of the metal skin. The outer skin was then edged inwards around these strips to a width of a few millimetres to achieve the visually intricate edges on the bonnet, windows, doors and wheel arches.
This detail, like the design of the bonnet hinge and door hinges, had been patented by BMW. And that meant there were sketches available which enabled the team to render the new parts as close as possible to their original templates.
Other challenges included the technical tweaks which set the Kamm Coupé apart from its series-produced siblings, such as the set-back radiator, engine and transmission, modified rear axle and a host of other alterations requiring meticulous detailing.
The BMW 328 Kamm Coupé was finally handed over to BMW Classic in a brief ceremony last month. That left only a short amount of time to prepare the newly created racing car for its big day at the 2010 Mille Miglia – 70 years after its last, memorable appearance in the race.
(With BMW Australia)