The Mercedes R107/C107

FOREWORD

First of all I would like to thank you for having purchased this book. I hope you will enjoy reading it as much as I enjoyed writing it. When the first SL was launched in 1952, nobody envisioned that the name SL would develop into one of the better known household names in the world. The first street-going version of that car, the famous Gullwing, cemented the importance of that name. Today its owners rarely dare to drive them, as their insurance value is too high. They sold in small numbers only to the rich and famous and although marketing and public relation want us to believe otherwise, no modern SL, no matter its technical qualities, will ever be able to compare favorably with that true icon.

Nevertheless they do carry the same name and that implies a certain burden. A burden, the Daimler-Benz engineers have been able to shoulder so far, as every new SL was a car that was able to live in the tradition of a breed that exists, as many journalists and car aficionados see it, in a class of its own.

When the R107 was introduced in 1971, it was supposed to be powered by a rotary piston engine. When this concept flopped, it created a bit of a problem for the engineers. The front and part of the chassis of the car had to be re-designed to accommodate the V8 already known from the W108, W109 and W111 models. It was also heavily debated in the executive board of Daimler-Benz, whether this new SL should be a roadster at all or better a targa coupe in order to fulfill upcoming stricter safety standards. Equally controversial was the idea of head of body design Karl Wilfert to use the R107 platform to launch a W111 coupe successor.

During its production run of a previously unheard of eighteen years, the SL was powered by no less than eight different engines, from a 2.8 L six-cylinder up to the mighty 5.6 L V8.The SLC did not have that kind of stamina. In 1981 it was back to a coupe based on the S-class. And while the SL has for quite some time already a firm place in the heart of every SL aficionado, the SLC starts only now to be seen as part of the proud Mercedes Grand Coupe tradition.

Very few know much about the very short rally career of the 500SL, which was supposed to replace the successful SLC. This book tries to shed some light on little known facts about this interesting car, which has survived till today in private hands.

This book has been revised in December 2016 with the SLC added and updated in March 2018. A comprehensive buyer’s guide can help you to find the model that suits you best. The chassis number and data card are explained in detail and another chapter looks at the price development of both the SL and SLC over the past eight years. It covers both the R107 and C107 from February 2010 to February 2018. All engine options are described, exterior and interior color and fabric choices have been added and the technical specifications include drag times and annual production data for each model. Naturally, this book comes, like all other books by the author, with plenty of recent, non-Daimler AG color photos.

March 2018

Bernd S. Koehling

Developing a trendsetter

On June 18th 1968, some three years prior to the launch of the new SL, the executive board of Daimler-Benz had a long and heated debate about a safety feature of the new SL with the internal code W107. Should the car have a targa bar in order to fulfill future American safety standards, or should it be built with a normal soft top in the tradition of all previous SL models? Most other companies did not see a future in open cars and even Daimler-Benz employees in those days did not fancy the idea of driving an open car as company car.

A targa bar a la Porsche 911 was an option as seen on this conceptual sketch

Hans Scherenberg, board member and head of Passenger Car Development, fought vehemently in favor of the traditional SL roof and luckily his opinion was at the end accepted by his fellow board members. The SL gave me great pleasure, but also caused me great trouble. This was no easy decision for us, he was later quoted.

A fullsized wooden model with different grill proposals

Which roof design to choose?

Friedrich Geiger showed different drawings in Jan. 1967 in order to study the amount of cooling air that passed through the grille

One design even looked at ways to guide the air around the tail, so that it stays clean longer

In another, later meeting it was decided to give all SL roadsters an internal code that should start with an R (for roadster) instead of the traditional W (for Wagen or car). Coupes should start in future with a C. The word roadster should not be mistaken for a sports car though, the R107 was more meant to be a comfortable and fast two-seat Grand Tourer with sufficient space for two passengers and their luggage. In this way the SL roadster differed greatly from the British meaning of a roadster, which was more expressed by cars such as the Jaguar E-Type or even more the Morgan Plus 8.

As North America was for a car such as the SL a highly important, if not the most important export market, it was no wonder that the R107 was designed with a close eye on what American customers would want to have in their cars. First, the car had to be longer so that an increased passenger compartment could be offered. Additional space was required for the long overdue air-conditioning system. It should not be a dealer installed unit under the dashboard anymore, but a fully integrated system instead. The car needed to be wider too, so that it could accommodate US-required door guard beams as well as larger tires. Although designing cars in Daimler-Benz was mostly a team effort, the person responsible for the final design outcome was Friedrich Geiger, who had already designed not only some versions of the famous pre-war 500K, but also the iconic 300SL gullwing and roadster. One of the main features that was carried over from the pagoda SL was in a slightly altered form the roof design, attributed to Paul Bracq. Friedrich Geiger worked as chief stylist under head of Body Design Karl Wilfert and should succeed him in 1972, when Wilfert would retire after having worked in Daimler-Benz for over forty years.

It was self-understood for a company such as Daimler-Benz that Béla Barényi’s safety concept with front and rear crumple zones and a rigid passenger cell was further developed. The chassis featured a closed transmission tunnel and box-shaped cross and longitudinal members, which offered different sheet metal thicknesses in order to enhance its crumple efficacy. This made the SL one of the safest cars around at its time of introduction.

Now that it had been decided to offer the SL as an open-top car, the only protection in a possible roll-over would be provided by the A-pillars plus windscreen. Consequently the pillars were thoroughly redesigned and had a fifty percent increase in strength over the pagoda SL. And as the windscreen was now bonded into the frame to increase stiffness, the power of resistance in the roof-drop test was remarkable. This way it was possible to license the car for the US without a targa bar.

People, who had seen the big foam-padded dashboard and preferred something similar to the metal dashboard of the W113 SL, did not know of course that the new dashboard had underneath an ingenious sheet-steel design that yielded on impact both in the top section and the knee area. And although the big four-spoke steering wheel was not really everyone's dream, its impact absorbing characteristics, part of which was a wide padded boss, were based on the latest findings of accident research. As an additional safety feature, the fuel tank was moved from the rear end to a safer position above the rear axle. From March 1980 onwards, an electronic anti-lock braking system ABS was offered as a first in a sports car. Almost two years later, in January 1982, also a driver's side airbag and belt tensioner were added.

A number of small but important details underscored the car’s safety aspirations. The seats were available with head restraints, and seat belts were included as standard equipment. The heating system had been completely revised. It was praised for its spontaneous response. Even the doors received air ducts. As head of Daimler-Benz Design Karl Wilfert pointed out, this should enhance both passengers' overall comfort and well-being. Newly developed wind-deflecting moldings on the A-pillars and dirt-repelling covers on the exterior mirrors served to keep the side windows clean. The windscreen wipers swept a respectable seventy percent of the windscreen area and were designed not to lift off even at higher speeds. Some smaller drivers complained though that the wipers would obstruct their forward view, when the wipers were in their rest position.

In addition, an ignition interlock safety system was installed. It was not universally appreciated though, as it ensured that the car's engine could not be started until the driver had fastened the seatbelt. Another safety feature, the large, fluted taillights, were a feature, Karl Wilfert was especially proud of. Even when dirty they would emit enough light, so that other drivers could see the car in inclement weather conditions. A few years back he claimed to have hit another car at night, while it was raining. He was not able to see the smallish taillights in time. These taillights would become a hallmark of all Mercedes passenger cars produced during the 1970s and 1980s.

Paul Bracq (and Bruno Sacco as a matter of fact) had tried for years to convince management plus sales and marketing department to do away with the vertical headlights in favor of horizontal ones. He did not succeed. As already mentioned, the new car did not only feature his idea of a hard top (with the pagoda safety aspect coming from Barenyi), it had also incorporated his headlights. A side effect was the somewhat reduced width of the classical SL face.

Some comments were received in those days that the four-headlamp treatment for the US version was inferior in its looks compared with the flush-mount headlights that were standard for all other markets. These issues did not stop the car though from becoming soon after its launch a big success for Daimler-Benz in almost all markets. It was a high quality open-top sports car (in the US for quite some years the only one), which was regarded with its dominant SL face, the wide-band head- and taillights and its comfortable interior a classic from its day of introduction.

Last tests with a slightly disguised 350SL in 1970 on the Hockenheimring

A rotary piston engine for the new SL

The discussion the executive board had in summer 1968, whether or not to fit the car with a targa roof, was not the only long and sometimes heated exchange of ideas regarding the