Bosch Classic

Mille Miglia endurance test

Bosch Classic develops starters for pre-war Mercedes vehicles

Bosch also continuously invests in reverse engineering of spare parts for classic vehicles. By doing so, the company manages a balancing act between the past and the present.

Hurry up: Mille Miglia is no sightseeing ride!


1 000 miles or 1 609 kilometers from Brescia to Rome – across Italian landscaped – and back again. The journey passes serpentines, demanding mountain sections, picturesque villages and follows precipices and canyons. But it’s all about time and points, no matter if there is sunshine, rain, wind or fog. Mille Miglia pushes men and materials to their limits.

This was as true back in the 1930s as it is today. These days, it’s 1927 to 1957 models participating at the “Mille” – cars that already participated back then. Among the participants of this historic race: a bright red 1930 Mercedes SS and a white 1928 SSK.

If they are to cope with the stresses and strains of Mille Miglia, they need to be equipped with robust technologies. This includes the starter of the large seven-liter engine. But spares for this wearing part have become rare by now. Whenever spare parts are no longer available, the Bosch Classic product marketing team assumes the challenge. This business division of the automotive supplier specialized on resupplying parts for old and very old vehicles wherever economically possible.

But how about a starter for a pre-war race car? Even for Michael Plag’s – very special – request, Bosch Classic found a suitable solution. Obviously the project manager of Mercedes-Benz Classic Service and Parts in Fellbach close to Stuttgart did not only look for a new starter for the bright red Mercedes SS. He is well aware that other pre-war Mercedes models face the same issue: In order to keep the aged engines running, matching starters are spare parts desperately searched for. The vehicles affected are often rare and of high value.

This marked the birth of a special starter project. For this purpose, Uwe Schmitt, product manager at Bosch Classic gathered an expert team consisting of associates from different development departments and countries – e.g. from the Indian location in Bangalore or the German locations in Göttingen and Schwieberdingen.

“Since a product as sophisticated as a starter consists of different individual components, it is almost impossible to rebuild it without a drawing;” Schmitt explained. Accordingly, Bosch started searching for constructional drawings. Despite the tedious search, only part of them were available. Another possibility to rebuild the starter would have been dismantling an original one, analyzing each and every part of it and making a new drawing based on the results. Unsurprisingly, the owners of the few genuine starter still available were not willing to hand them in it for such a purpose. In fact, the time frame would have been to short anyways. After all, the project was to be finished before the next Mille Miglia.

An alternative was required. The team took a starter out of the current series and adapted it to meet the constructional requirements of the vehicle. At vehicles this rare, modifications right on the vehicle are not an option. Whereas back in the days, so-called saddle fixations with metal strips were used, flange fixtures are used nowadays.


A challenge

But the developers had a brilliant idea: They developed a mounting bell around the starter befitting the vehicle-specific installation conditions. This allowed fixing the starter into the engine compartment by means of the original metal strips. The team invested numerous extra hours into the development of this starter. “Only people who like dealing with such things and with a certain passion for it assume such an extra task,” Schmitt said. "As is the case with new developments at the automotive industry, this case also required stress tests and test runs to get the vehicle manufacturer’s approval.”

They were performed at the laboratory and at tests right on the vehicle. In this case this meant: „Mille Miglia“ – as if the race itself was not stressful enough the 86-year old Mercedes race car. The “Mille” is not short on challenges. Throughout the first two days, it was pouring buckets of rain – quite a tough challenge since Mercedes SS doesn’t know protection against the rain, wiper blades, power steering nor even brake booster. “For the tests, a certain and well-defined number of cold and warm engine start-up was to be performed with the car,” Schmitt explained. Long before the drivers, he, Michael Plag and the other Mercedes-Benz pre-war service teams were already up early in the mornings and back on the car.

The new “old” starter passed all tests and can now be installed as official Mercedes part. Michael Plug and his colleagues at the Classic Center in Fellbach close to Stuttgart did not only equip the Mercedes SS with it, but also the white SSK participating at the Mille Miglia for many years already. The starters are installed, maintained and prepared for their duty at the workshop – which actually reminds rather of a wonderfully bright artist’s studio than a workshop.

“We start the Mille Miglia preparations rather early. Getting the cars ready for the races takes us approximately half a year,” Plug underlined. In a certain manner, old cars are like artworks that need to be repaired. “We often have to perform tedious searching on our archives to repair the cars. Luckily, we have a very good documentation. We sometimes even work with drawing signed by Gottlieb Daimler personally,” he proudly explained. And in some cases, the Bosch Classic experts in Karlsruhe come up with a suitable idea or solution. At Bosch, the automotive supplier founded in 1886, historical know-how is also carefully preserved like a precious treasure. Once one of the company’s products reaches the end of its regular production period, the following questions come up at Bosch Classic: Is the product of relevance for classics? How can we improve it in order to extend its service life? Which stocks need to be built up?


“The way we see it, what really matters is anything keeping the vehicles in operation,” Schmitt explains. Standstills are poison for vehicle technology: After all, it’s all about automobiles and not auto-stationaries. The Bosch Classic range comprises thousands of parts for modern-era classic and classic cars reaching from alternators to wipers. “We want the vehicles to be preserved and we want them to remain mobile and driveable.” This implies a lot of extra efforts for the Bosch Classic team.

Several parts are rather rarely needed. This requires proper storage capacities and sometimes even different storage conditions. In addition, these products require a lot of extra work the customers are often not aware of: To ensure the specific storage period of each product, certain test measures need to be performed at specified intervals. This reaches from lubrication to energizing electronic components.

Due to the quantities needed, the production of certain parts is even more economical than keeping them on stock. All in all, several thousand products for classic cars of different ages are still produced by Bosch and at different locations. For the reproduction of various products, Bosch Classic took over the respective machines of different Bosch plants. In this regard, knowledge transfer is of major importance.

“The know-how about these machines and parts is documented at the different plants. The employees know exactly what to do in order to ensure the desired production quality. They pass on their know-how to the younger generations,” Schmitt explained.

Bosch also continuously invests in reverse engineering of spare parts for classic vehicles. By doing so, the company manages a balancing act between the past and the present.

We want to contribute to maintaining just this joy for as long as possible. That’s what our product marketing team stands for.

Uwe Schmitt, project manager of Mercedes-Benz Classic Service and Parts

Actually, the originality of the respective products shall be maintained. But wherever possible, modern technology is used – for various different reasons. Due to current environmental regulations, the use of some materials is now longer allowed by now. Furthermore, today’s electronics and technological know-how often help improving mechanically delicate solutions used in the past. In this manner, the reliability of the respective parts can be improved.

“We want our customers to be satisfied and happy using our products,” Schmitt said. The “black battery” is a good example hereof. It was a huge desire of the classic-car community and was thus relaunched. It looks like the 1950s and 1960s model but is equipped with state-of-the-art technology. Often, reproduction is not possible due to the low quantities required. In many cases, however, the parts can be reconditioned or remanufactured, e.g. cleaning their housings and replacing wearing parts. This is the case, for instance, with starters and alternators, fuel distributors or ignition distributors. All of them are given a second chance, a second live.

And yet, not only wickedly expensive vehicles are seldom enough to be granted permission to take part in the Mille Miglia. More and more people develop a passion for the technologies of the good old days. In Germany alone, 388 000 vehicles are registered as historic vehicles and their number is still growing. Owning and restoring a classic car is more than just a hobby. These vehicles tell stories, they enchant their owners and spectators alike and they make people smile. Classic cars make people happy.

“We want to contribute to maintaining just this joy for as long as possible. That’s what our product marketing team stands for“, Uwe Schmitt emphasized. He agrees with the advice of numerous classic-car experts: “If you’re interested in classic cars, you should consult an expert under any circumstances. In most cases, he will be able to estimate the price and the required restoration efforts more in detail. After all, classic cars shall be a very special joy for their owners for as long as possible.”

Do you have any questions? Just contact the Bosch Classic hotline.

Monday to Friday 8 a.m. to 5 p.m.