Automotive Archaeology

Peeling away the layers to discover the history of a unique car

By Michael Kunz, The Classic Center

Photographs by Dieter Rebmann and the Classic Center

Restoring any classic car has its challenges, but what do you do when restoring the only surviving example of a car of which fewer than a dozen were originally built and documentation is sketchy to nonexistent? You do what any archaeologist would do when reconstructing a found artifact: seek what information is available, peel off the layers of history one at a time, and let the car tell its own story.

The truth is, the Classic Center didn't intend to restore the 1934 150 Sports Roadster that Mercedes-Benz has owned since 1951. Because it was completely intact, and we knew from a previous experiment that the engine would start and run, we only intended to clean it up and recondition the mechanicals so that it could be driven as part of a three-car press event to showcase Mercedes-Benz's early innovations in mid-engined and rear-engined automobiles (see The Star, Jul-Aug 2010, p. 18).

To accomplish this, we dropped the drivetrain out of the 150 roadster, disassembled the engine and transmission, and cleaned, checked, and reassembled everything. The engine was in such good condition that we never even pulled the head, choosing instead to use the pistons, rings, bearings, and crankshaft that had been in the engine. Of course, we didn't have much choice, because this engine is the only one like it in existence, so a rebuilld would have been difficult at best.

Then, with less than three weeks to go before the first journalists would arrive in Irvine, we ran into a problem. With the drivetrain out of the car, we could inspect the wiring and cable linkages that ran down the spine of the frame. What we discovered was that the nearly 60 years the car had sat unused had taken their toll. The wiring was so brittle it fell to pieces when we touched it, and the cables were equally useless. To refurbish the controls would require taking the body off the frame, and if we were going to do that, we might as well restore the entire chassis. So that's what we determined to do.

Any restoration starts with basic research to learn as much about the car being restored as possible. When we're working on a 300SL, or a 220SE, that's not too difficult; factory records are complete, and we have a wealth of experience from previous restorations on which to draw.

However, no one has ever restored a 150 before, for the simple reason that only one exists, the one sitting in front of us.

Here's what we did know: Mercedes-Benz had entered six specially built rear-engined coupes in the 1934 2,000km German Rally. The following year, the chassis of a mid-engined car, consistent with the chassis of our car, was exhibited in the Berlin Automobile Show. A brochure was produced, with several artist renderings of a mid-engined roadster that are almost identical with our car, suggesting there was an intention to sell the car to customers, perhaps if enough interest was shown at the Berlin show.

Subsequent to the show, records indicate that five 150 Special Roadsters were built, and apparently all of them were then sold. There is no further record of the earlier coupes, and none is known to exist.

Our next information is that in 1951 Daimler-Benz had the opportunity to buy a 150 Special Roadster from an individual who had been driving it but needed to a four-passenger car and couldn't afford to own two cars. A written purchase evaluation was prepared, the company bought the car, and it was placed in storage in Stuttgart.

According to the evaluation, the car was painted a light metallic blue with black interior trim, and was in good running order. In fact, the seller had commented on how the car always attracted positive comments at motorsports gatherings.

Regardless, little is known of the car from 1951 until 1985, when it was put on display in the Mercedes-Benz Museum. However, by that time - perhaps to make it more attractive as a display - the car had been painted red, and its wheels painted a distinctly unoriginal silver.

When the new museum opened in 2003, the roadster was no longer needed for display, so it was later shipped to us in California as one of the first cars for the U.S. Classic Center display of historical Mercedes-Benz automobiles. We were proud to display it, but restoration to running order was never contemplated until this year.

Because these roadsters had not been put into production, there are no other records beyond the few pictures from the 1935 auto show. For details on how to restore the car, we were on our own, having to trust that we could get enough information from the car itself if we were careful when we disassembled it.

Therein lies the second precept of good restoration: The process of disassembly is at least as important as the repair of parts and the reassembly of a car. As each part was removed, our staff members made careful notes and took detailed photographs. By the time we were done, we had more than 1200 images of the car in the files. These photographs and our notes would function as our workshop manual when we began to reassemble the car.

We were fortunate that because of this car's history, it was incredibly complete. We can guess that because of its unusual nature, this car must have been hidden during World War II. Otherwise it might have been canniblized for parts like many other cars in war-torn Germany. It reappeared sometime after the war, and then was used for transportation and, we assume, to attend an occasional motorsports weekend until 1951. Then, again because of its historical value, it was tucked away in the Daimler-Benz collection and eventually put on museum display.

In the process of literally peeling off the layers of dirt, grease, and paint, we made some interesting discoveries. First, the car has enormous integrity. Nearly every major part was stamped with the chassis number, or a part serial number, and often the date that the part had been manufactured. For example, the clutch plate is stamped 11.34 for its month and year of manufacture.

As another example, when removing a manifold, we discovered one small patch of untouched light-blue paint. That gave us the paint shade with which to paint the engine. Our most interesting discovery was that this car was apparently originally one of the coupes. Not only does the serial number indicate the car was built as a coupe, but the outriggers show evidence of having been cut, and some welds were redone on the motor mounts, all consistent with converting one of the original coupes to the mid-engined roadster configuration. We can hypothesize that there may never have been 11 150s. Instead, there may have been just the six 1934 coupes, which were converted to the five roadsters and one display chassis in 1935. There's probably no way we'll ever know.

Parts we did need to replace, such as seals and bearings, were often common with those on Mercedes-Benz cars built immediately after the war. In addition, parts like the rusty shock absorbers could be rebuilt by craftsmen we use for work on similar components of other prewar cars. We were even lucky with the unusual forced-air radiator; a readily available core for another radiator would fit.

The only place we really stumbled for a while was with the carburetor. Though it was a Solex, it was made of pot metal and crumbled in our hands as it was being disassembled. With some research, we discovered that this particular carburetor had been used on Alfa 2300 Berlinettas and a French dump truck. That's where networks come in. One vendor with whom we had worked previously had the 75-year-old Alfa version of the carburetor, which could be adapted to our engine, in stock.

Though we know the show car had been a light color when displayed in Berlin, possibly the same light-blue as our car when bought in 1951, we did make one exception from our normal standards of originality. Millions of peoples had seen and remembered this car in red with silver wheels when it was on display in the museum in Stuttgart, and there is even a 1:43 scale model of it in those colors, so we decided to preserve that aspect of its personality.

Aside from the problems with completing a three-month project in three weeks, we were incredibly fortunate that so much of the car had been intact, but we still believe that the work could not have been done to the museum standards that we felt were essential had we not followed our normal practices: research, document, carefully disassemble, use period practices when possible, and be fortunate enough to have a strong network of resources on which to rely.