Mercedes-Benz W123 E-Book

James Taylor

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch

Seitenzahl: 302

Veröffentlichungsjahr: 2019

Beschreibung

The Mercedes-Benz W123 was launched in 1976 and sales quickly surpassed those of its predecessor, the W114. The W123 went on to become the most successful Mercedes, selling 2.7 million cars. Mercedes-Benz W123 - The Complete Story explores the life of this highly regarded executive car from its initial evolution, development and production to the creation of new models and its success in motorsport. The book features the styling, engineering and technical advances introduced over the lifetime of the three series; full technical specifications together with customer options, equipment and interior trim for each model; production numbers and vehicle number sequences and finally there is a section on the little-known details of the manufacture of the car in China.It is superbly illustrated with 240 colour and black & white photographs. James Taylor is a professional motoring writer with over thirty years' experience and Mercedes-Benz is one of his favourite car manufacturers.

Leseprobe

Mercedes-Benz W123

THE COMPLETE STORY

OTHER TITLES IN THE CROWOOD AUTOCLASSICS SERIES

ALFA ROMEO 916 GTV AND SPIDER Robert Foskett

ALFA ROMEO SPIDER John Tipler

ASTON MARTIN DB4, DB5 & DB6 Jonathan Wood

ASTON MARTIN DB7 Andrew Noakes

ASTON MARTIN V8 William Presland

AUDI QUATTRO Laurence Meredith

AUSTIN HEALEY Graham Robson

BMW M3 James Taylor

BMW M5 James Taylor

BMW CLASSIC COUPÉS 1965-1989 James Taylor

CITROEN DS SERIES John Pressnell

CLASSIC MINI SPECIALS AND MOKE Keith Mainland

CLASSIC JAGUAR XK – THE SIX-CYLINDER CARS Brian Laban

FERRARI 308, 328 & 348 Robert Foskett

FORD CONSUL, ZEPHYR & ZODIAC Graham Robson

FROGEYE SPRITE John Baggott

JAGUAR E-TYPE Jonathan Wood

JAGUAR MK 1 AND 2, S-TYPE AND 420 James Taylor

JAGUAR XJ-S James Taylor

JAGUAR XK8 Graham Robson

JENSEN V8 Mark Dollery

JOWETT JAVELIN AND JUPITER Geoff McAuley & Edmund Nankivell

LAMBORGHINI COUNTACH Peter Dron

LAND ROVER DEFENDER James Taylor

LAND ROVER FREELANDER James Taylor

LOTUS ELAN Matthew Vale

MGA David G. Styles

MGB Brian Laban

MGF AND TF David Knowles

MG T-SERIES Graham Robson

MAZDA MX-5 Antony Ingram

MERCEDES-BENZ CARS OF THE 1990S James Taylor

MERCEDES-BENZ ‘FINTAIL’ MODELS Brian Long

MERCEDES-BENZ SL & SLC 107 SERIES Andrew Noakes

MERCEDES-BENZ S-CLASS James Taylor

MERCEDES-BENZ W124 James Taylor

MERCEDES-BENZ W126 S-CLASS 1979–1991 Nik Greene

MERCEDES SL SERIES Andrew Noakes

MERCEDES-BENZ W113 Myles Kornblatt

MORGAN 4/4 Michael Palmer

PEUGEOT 205 Adam Sloman

PORSCHE 924/928/944/968 Glen Smale

PORSCHE CARRERA – THE AIR-COOLED ERA Johnny Tipler

PORSCHE CARRERA – THE WATER-COOLED ERA Johnny Tipler

RELIANT THREE-WHEELERS John Wilson-Hall

RILEY:THE LEGENDARY RMS John Price-Williams

ROVER 75 AND MG ZT James Taylor

RANGE ROVER – THE FIRST GENERATION James Taylor

RANGE ROVER – THE SECOND GENERATION James Taylor

ROVER P4 James Taylor

ROVER P5 & P5B James Taylor

ROVER 800 James Taylor

ROVER SD1 James Taylor

SAAB 99 & 900 Lance Cole

SHELBY AND AC COBRA Brian Laban

SUBARU IMPREZA WRX AND WRX STI James Taylor

SUNBEAM ALPINE AND TIGER Graham Robson

TOYOTA MR2 Nigel Burton

TRIUMPH SPITFIRE & GT6 Richard Dredge

TRIUMPH TR7 David Knowles

VOLKSWAGEN GOLF GTI James Richardson

VOLVO AMAZON Richard Dredge

VOLVO 1800 David G. Styles

Mercedes-Benz W123

THE COMPLETE STORY

JAMES TAYLOR

First published in 2019 byThe Crowood Press LtdRamsbury, MarlboroughWiltshire SN8 2HR

This e-book first published in 2019

www.crowood.com

© James Taylor 2019

All rights reserved. This e-book is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorised distribution or use of this text may be a direct infringement of the author’s and publisher’s rights, and those responsible may be liable in law accordingly.

British Library Cataloguing-in-Publication DataA catalogue record for this book is available from the British Library.

ISBN 978 1 78500 606 7

CONTENTS

Introduction

Acknowledgements

Timeline

CHAPTER 1

DESIGN AND DEVELOPMENT

CHAPTER 2

FIRST-SERIES SALOONS, 1976–1979

CHAPTER 3

THE LATER SALOONS, 1979–1985

CHAPTER 4

THE COUPÉS, 1977–1985

CHAPTER 5

THE T-SERIES ESTATES, 1978–1985

CHAPTER 6

LWB SALOONS AND ‘PLATFORMS’

CHAPTER 7

THE 123 SERIES IN NORTH AMERICA

CHAPTER 8

THE 123 SERIES IN MOTORSPORT

CHAPTER 9

THE AFTERMARKET

CHAPTER 10

BUYING AND OWNING A 123-SERIES MERCEDES

APPENDIX I

PRODUCTION STATISTICS

APPENDIX II

VEHICLE NUMBER SEQUENCES

APPENDIX III

THE MERCEDES 123 IN CHINA

Index

INTRODUCTION

The Mercedes-Benz 123-series cars seemed like a pinnacle of the automotive world when they were new, and were certainly seen as the benchmark by which other mediumsized saloons could be judged. In Britain at a time when even the flagship products of British Leyland were built to very variable standards and suffered from poor reliability, the Mercedes stood out like a beacon.

In many ways, it still does, and the old saying that ‘they don’t make ’em like that any more’ certainly holds true in this case. Even Mercedes no longer makes ’em like it used to: it probably could not afford to, and, even if it could, no one would be able to afford to buy them. Such high standards of engineering and construction came at a price in the late 1970s and 1980s, too, and (as Chapter 10 explains) trying to replicate them in a restoration can be very expensive indeed.

I feel respect, then, for those who try; and am envious of those who have been lucky enough to find a 123-series car in really good condition and are able to enjoy it just as its first owner did all those years ago. On a personal note, I have always liked these cars very much indeed, and so I was delighted to have the opportunity to further my interest by writing this book about them.

ACKNOWLEDGEMENTS

I must acknowledge the help of Mercedes-Benz Classic and the Daimler-Benz Media site, both for information and for the majority of the illustrations. Thanks, too, go to Mercedes-Benz UK, whose press office provided a great deal of information about changes in the line-up when the cars were new. I have absorbed a lot of information from members of the Mercedes-Benz Club in the UK and from its excellent publication, the Gazette, and I have made full use of such material as is available about the 123 range in German. Finally, special thanks go to the many photographers who have made their work available for use through WikiMedia Commons, and to Magic Car Pics, who were also able to supply several excellent pictures.

TIMELINE

1976, March

123-series Mercedes launched at Geneva Show as a nine-model range of petrol and diesel saloons

1976, July

First long-wheelbase ‘platforms’ built

1976, December

123 series introduced to the USA

1977, March

Coupé variants introduced at Geneva Show

1977, September

Long-wheelbase limousine variants introduced

1978, April

Estate variants enter production at Bremen plant

1979, October

Second-series models introduced; introduction of new M102 engines for 200 and 230E models; 300TD Turbodiesel announced for Germany

1980, autumn

ABS option introduced; several minor revisions; 300TD Turbodiesel introduced to the USA

1981, July

Carburettor 280 models end production; five-speed manual gearbox available for some models

1981, autumn

Energy Concept announced, with far-reaching effects on 123-series cars; LPG dualfuel 200 introduced; all-diesel 123 range introduced to the USA

1982, autumn

Third series of 123 models introduced at Frankfurt Show; all cars now with rectangular headlamps

1984, autumn

All diesel models fitted with particulate filters as standard; new 230E KAT model for Germany; replacement 124-series range announced

1985, August

Final coupés built at Sindelfingen

1985, November

Final saloons built at Sindelfingen

1985, December

Final ‘platform’ variants and final long-wheelbase limousines built

1986, January

Final estates built at Bremen

       CHAPTER ONE       

DESIGN AND DEVELOPMENT

In 1968, just a year after the M114 six-cylinder and M115 four-cylinder models had been introduced to the showrooms, Mercedes-Benz designers at the company’s Stuttgart headquarters began thinking about the medium-sized saloon that would replace them. This was not in any sense considered to be premature. There are always ideas left over from the design of a new car that are worth retaining for its successor, and in any case an early start to the design of such an important model – the medium-sized saloons were Mercedes’ strongest sellers – was no bad thing.

Responsibility for the engineering of the 123-series cars fell to Hans Scherenberg, Mercedes’ long-serving technical chief.

At that stage, the key figures in the Mercedes-Benz passenger car division were the engineering director Hans Scherenberg and the chief designer Friedrich Geiger. Between them, these two were to be responsible for the design of the next generation of medium-sized saloons. One early decision they took was to develop the new cars with a common design that would suit both four-cylinder and six-cylinder variants. Instead of two different but related projects, as there had been for the W114 and W115 models, there would be a single project. It would be coded W123.

Friedrich Geiger was in charge of the Mercedes styling department in the late 1960s and early 1970s, and oversaw the development of the 123-series shape.

To the uninitiated, W123 sounds like a random alphanumeric group, but, as with all Mercedes-Benz matters at the time, it was underpinned by logic. The initial ‘W’ stood for Wagen (German for ‘car’) and ‘123’ was part of a numeric sequence. That sequence had begun in the 1930s and by the late 1960s had gone way past 100 (the number allocated to the big Mercedes 600 limousine announced in 1963). Numbers 114 and 115 had been allocated to the New Generation saloons released in 1968, and 116 represented the forthcoming new flagship model that would be released in 1972 as the S Class. Although none of the numbers between 117 and 122 was associated with a production model, they were probably all used at Stuttgart; indeed, details of abortive projects numbered 118, 119 and 122 have leaked out over the years, so there were undoubtedly others along the way.

As work began on the new W123 models, a new look for Mercedes-Benz cars was already in preparation within Friedrich Geiger’s styling department. It would not become public knowledge until 1971, when the new R107 SL sports cars (the ‘R’ standing for ‘roadster’) were announced. Crucial to the new look were simple, elegant lines that helped make the cars look low and purposeful, while at the front a shallower version of the traditional Mercedes-Benz grille was flanked by horizontal headlamp assemblies. These features represented a radical departure from the vertically stacked light units that had characterized the cars of the 1960s, and they were to be matched at the rear by large, horizontal light units with distinctive ribbed lenses. The design was meant to reduce any build-up of road dirt that might obscure the light. Unsurprisingly, the intention was for the new W123 cars to follow this new design direction too.

The assembly lines at Sindelfingen in the late 1960s, with examples of the 114 and 115 saloons alongside the 113 ‘Pagoda’ two-seaters and, under shrouds on the extreme left, the big W108 coupés.

A new Mercedes family style was emerging as the 1970s opened; the R107 roadster that replaced the W113 pagoda-roof cars was the first model with it.

Meanwhile, the guidance given to Hans Scherenberg’s engineers was also very much forward-looking. The new W123 models were to be safer than their predecessors, not least because they would have to satisfy and stay ahead of new legislation affecting motor vehicles that was being introduced all round the world by the late 1960s. They were to incorporate whatever technical advances would be ready in time for their launch, which at this stage was tentatively proposed for 1974, and there were also to be general improvements in refinement. Another element of the engineers’ brief was that the W123s should be easier to repair and service than their predecessors. This was a particularly interesting idea that arose from a clear appreciation that modern cars were becoming more and more complex – and that a new Mercedes-Benz still had to be simple enough to be maintained and repaired by mechanics in what were then called Third World countries.

Above all, these were to be very rational cars, in the way that was characteristic of Mercedes-Benz at the time. Every little detail was to be thought through carefully, and engineering would take precedence over appearance in every case – although appearance was by no means low down on the list of design priorities. Nor would the engineers allow themselves to be rushed by sales teams anxious to get the new car into the showrooms: throughout the design and development stages of the 123 series, it seems to have been understood that this car would be released when it was ready, and not a moment earlier.

ACHIEVING A STYLE

These days, car designers prefer not to use the word ‘style’ to describe what they do, arguing that it diminishes the value of their contribution to the completed car. Nevertheless, the word was current to describe the visual design of cars in the 1960s, and Friedrich Geiger’s team would have seen themselves as ‘stylists’.

They started in the traditional way, sketching out proposals on paper. The most promising of these were then turned into three-dimensional scale models, and then a further selection was made, with the preferred designs being created as full-size models, using clay on a wooden armature. Friedrich Geiger would no doubt have been encouraging the younger men in his team as they worked towards successful solutions; it was his job, too, to maintain a continuity with existing Mercedes styling traditions so that the new cars were recognizably products of the Stuttgart manufacturer. It looks as if he may have deliberately provoked them with some radical ideas as well: for some years he had been keen on extended rooflines that finished in a cowl over a reverse-rake rear window. Some designs with this quite un-Mercedes-like feature persisted in the mix until quite late in the styling process.

Some of the full-size clays that existed by summer 1970 were clearly identifiable as ancestors of the production car, although the final details of such features as lights had not been settled by this stage. In profile, the new W123 saloon was surprisingly similar to the W114 and W115 models it was to replace, but more rounded, softer lines and modern details such as single-piece front-door glasses without a quarter-light disguised the similarities very effectively. The bonnet shape was simpler, too, with flatter sides that met the wings in a gentle curve, whereas the older cars had a raised section to blend with their vertical light stacks. Less visibly, an extra 45mm (just over 1¾in) in the wheelbase gave more room in the passenger compartment. Inevitably, some themes were carried over from the 107 roadster models and the 116 S Class; not only had such themes proved themselves to be successful, but they would also give the family resemblance that was traditional to the Mercedes-Benz passenger car range.

The second new model with the new Mercedes style was the W116 S Class saloon, which arrived in 1972. It was inevitable that the styling solutions chosen for these cars would have an impact on the new W123 models.

The W123 design did not immediately take on the latest styling elements. This early full-size mock-up, dated January 1971, is really a cautious progression from the existing 114 and 115 style, with more rounding in the body and an interesting take on headlight design.

Styling development progressed through 1/5th scale models like the one seen here with a cutaway scale model designed to show the volumes devoted to each element of the car. The scale model shows a dipped waistline that did not make it into production. It also has US-style impact bumpers with a design that was not adopted.

In August 1971, the Mercedes-Benz Board of Management visited the styling studios for an update on progress. Geiger’s team arranged for the three most promising full-size clay models to be viewed amid a selection of older Mercedes models and rival saloons in the same market sector. The board selected its preferred option: a scaled-down and lighter-looking derivative of the 116 S Class design, with a more pronounced rake from front to rear. That was then worked up in more detail, with the final design being signed off in summer 1973.

Bruno Sacco took over from Friedrich Geiger when the latter retired in 1973, but the shape of the 123 series had already been signed off for production.

The final stages of W123 styling development were overseen by Bruno Sacco, who took over as head of Mercedes-Benz passenger car styling when Freidrich Geiger retired in December 1973. However, he made no attempt to alter the design language of the cars, which had been entirely created by Geiger. Sacco’s take on Mercedes-Benz styling would not become apparent until the introduction of the W126 S Class saloons in 1979, and would steer the company’s cars in a distinctively different direction.

Multiple considerations affected the final styling that was signed off for production. Among them was the need to sell the cars in the USA, where the requirement for side marker lights had led to some rather ugly solutions on the 114 and 115 models. For the 123 series, Geiger’s team fell back on the wraparound front lights they had designed for the 107 and 116 cars, which made the turn signals more easily visible from the side and could also be used to house marker lights when these were needed. It was an elegant solution that also simplified manufacturing by using a single lens design to cover all requirements. The rear light units wrapped around the sides of the car for the same reason, and of course the lenses of both front turn signals and rear light units had the same ribbed design as on the 107 roadsters and the 116 S Class: Mercedes insisted that this prevented the entire lens from becoming obscured by dirt.

However, the 123s could not be made to look too much like the more expensive S Class cars, for fear of upsetting the owners of these top-model Mercedes. As a result, although both cars were made to look longer and lower by horizontal lines running along their flanks, the rubbing-strip on the 123s was mounted much higher up than its equivalent on the 116, and was matched by a discreet styling crease at bumper height. The radiator grille was much lower on the 123 than on the 114 and 115 models and very similar in overall appearance to that on the 116 type. Where the grille of the S Class had plastic vanes in a cheese-cutter design, the 123 had simpler horizontal slats. For further distinction, the 123s all had single bumpers, while the 116s had a distinctive two-tier design.

The designers had also been required to address the issue of how to distinguish the more expensive 123 variants from the entry-level cars. The company director paying a 30 per cent premium for one of the most expensive six-cylinder saloons would certainly expect it to be readily distinguishable from the four-cylinder diesel taxi variant. The styling department’s answer was to incorporate a number of subtle differences – some of them perhaps a little too subtle to be appreciated by anyone who was not a Mercedes-Benz aficionado!

The most obvious difference was at the front, where the less expensive models were given paired round lamps while the top models had rectangular units. Much less readily visible were the chromed air vents at the back of the bonnet on the six-cylinders, where the lesser models had black vents. At the tail of the car, twin exhaust outlets distinguished the sixes, together with extra chrome below the rear light units. Beyond that, the clearest distinction was the model badge in its traditional place on the boot lid – when one was fitted, of course.

THE NEW GENERATION SALOONS

The existing Mercedes saloons were the W114 and W115 models, still attractive by the mid-1970s but with quite geometric lines that were beginning to look outdated.

In Britain and the USA, the new Mercedes saloons introduced in 1968 were always known as ‘New Generation’ types, but in their native Germany they were called ‘Strich Acht’ (or ‘/8’, meaning ‘Stroke 8’), because they were introduced in 1968. Their model designations were largely similar to those of the previous generation of Mercedes-Benz saloons, so, to distinguish one from the other, unofficial designations such as ‘200/8’ became common for a while. The four-cylinder cars (and the five-cylinder diesel models) were known to Stuttgart as W115 types, while the six-cylinder models were W114 types.

There were both petrol and diesel engines in the New Generation saloons, giving a range that consisted of eleven models. The seven petrol variants were the four-cylinder 200, 220, and 230/4, and the six-cylinder 230/6, 250, 280 and 280E. The four diesels were called 200D, 220D, 240D and 240D 3.0, the first three having four-cylinder engines and the last one a unique five-cylinder type.

There were also two-door coupés, all with six-cylinder petrol engines. Over the years, these models were called the 250C, 250CE, 280C and 280CE. Mercedes-Benz built no estate models themselves, although there were some aftermarket conversions. Long-wheelbase multi-passenger models were based on the 230/6 petrol and 220D and 240D diesel models.

The saloons and coupés shared an overall length of 4,680mm and a width of 1,770mm. Both had the same 2,750mm wheelbase, but the saloons were 1,440mm tall while the coupés had a lower roofline and were 1,395mm tall. Long-wheelbase models had an overall length of 5,335mm and a wheelbase of 3,400mm. They also had 15in wheels instead of the 14in size that was standard on saloons and coupés.

Approximately 1.9 million vehicles of the 114 and 115 ranges were built between 1968 and 1976.

SOMETHING OLD, SOMETHING NEW

It had been Mercedes-Benz policy for some time not to introduce a new model and a range of new engines all at the same time. Typically, a model range was given a mid-life facelift, which would involve some visual and equipment changes as well as the introduction of some new engines. These new engines would then become the engines for the next generation of cars; they would in turn serve until those cars were facelifted, when they would be replaced by more new engines – and so the cycle would continue.

This would prove to be the case for the new 123-series cars. Most of their engines would be further-developed versions of those that had been introduced for the W114 and W115 models at the mid-point of their life cycle, although the mix would be leavened by a single new one when the cars were launched and by several more new ones when it was the 123s’ turn for a mid-life facelift.

A total of eight engines were carried over from the old models. Two of them were four-cylinder OM615 diesels, with 2.0-litre and 2.2-litre capacities, and one was an OM616 four-cylinder diesel of 2.4 litres. The fourth engine was the OM617 3.0-litre five-cylinder diesel. There were two sizes of M115 four-cylinder petrol engine, one of 2.0 litres and one of 2.3 litres, and the last two were M110 six-cylinders with twin overhead camshafts and a 2.8-litre capacity, one with carburettors and the other with fuel injection.

Other major units were also carried over from the previous generation of medium-sized saloons. As a result, the four-speed manual gearboxes, of Mercedes’ own design, found a new home in the 123-series cars, as did the fourspeed automatic gearbox, again a Mercedes design, although this would not be made available on all models.

As far as engines were concerned, there would be just one new one for the 123-series cars at launch. This was developed specially for the range in the first half of the 1970s, and was intended to meet anticipated customer demand for a six-cylinder car that did not have the high cost of the planned top models, with their 2.8-litre engines. To give it a clear place in the 123-series hierarchy, it was drawn up with a 2.5-litre swept volume – larger than the biggest 2.3-litre four-cylinder but smaller than the 2.8-litre six-cylinder. A smaller-capacity version of the existing M110 2.8-litre was not considered the right solution, probably because its twin-overhead camshaft configuration would have made it too expensive. Instead, a completely new six-cylinder type, appropriately known as the M123, was drawn up, with a simpler single overhead camshaft configuration.

Suspension design became a mixture of old and new. The W114 and W115 saloons had depended on sub-frames, but for the 123-series cars the suspension would follow the lead of the W116 S Class and would be bolted directly to the bodyshell. The wheel tracks would also be a few millimetres wider than in the 114 and 115 cars, to improve handling. The front suspension layout was essentially the same as in the W116, with both anti-dive characteristics and zero-offset steering geometry, to give greater stability. One of its unusual characteristics was the high-mounted anti-roll bar, which located the upper suspension control arms. At the rear, the semi-trailing arm independent suspension had only detail changes from its W114,W115 and W116 versions; Mercedes even declined to change its traditional description of it as a diagonal swing-axle type!

The front suspension of the W123 featured coil springs, a high-mounted anti-roll bar, and anti-dive control.

Zero-offset steering geometry ensured that each front wheel retained maximum contact with the road at all times.

There were novelties in the braking system, however. Where the W114 and W115 models had disc brakes at the front with drum brakes at the rear, the 123-series cars switched to an all-disc system, with servo assistance as standard. A split hydraulic circuit was also standard, and so was the ‘stepped’ master cylinder arrangement that Mercedes had pioneered on the 450 SEL 6.9 that was the flagship of the W116 S Class range. This featured twin brake master cylinders with different bore sizes, which ensured that, if the front braking circuit failed, the different bore diameter of the master cylinder linked to the rear brakes would automatically compensate by increasing braking effort to the rear wheels.

The layout of the trailing-arm rear suspension was very similar to that on the 114 and 115 models, and, as far as Stuttgart was concerned, was still a version of their long-standing diagonal swing-axle design.

The rear suspension: the 123-series cars were designed with disc brakes all round, not just on the front axle like their predecessors.

INSTRUMENTS

The drive towards logical, functional but also attractive design had already delivered a highly acclaimed instrument panel layout for the R107 roadster and W116 S Class saloons, and this was carried over for the 123 range. Beautifully clear, it consisted of three circular instruments, the precise details of which could be varied to suit the version of the car and/or its intended market.

The speedometer was always the largest of the three dials and was always mounted in the centre, although there were different versions of the instrument to suit miles-per-hour and kilometres-per-hour markets. On its left, the dial incorporated three segments, for engine coolant temperature, fuel gauge and oil pressure. The space that had prudently been left for a fourth segment at the bottom was eventually occupied by an additional instrument many years later. The dial on the right was a large clock, although from mid-1980 it could be replaced by a rev counter with a smaller clock set into its face.

All these dials had white markings on black faces, and orange pointers. The result was an instrument layout that has rarely been equalled, let alone bettered.

These instruments were accompanied by a new multifunction stalk on the steering column. Superbly logical and easy to use, this operated the headlights, turn signals, windscreen wipers and horn. Oddly, it did attract unwarranted criticism from some members of the UK motoring press, who felt that too much was being asked of it. At least Mercedes chose to use a separate stalk when they made a cruise control available, and of course the main lighting switch was a rotary type mounted on the dashboard itself.

SAFETY

Mercedes-Benz was at this stage a world leader in automotive safety, categorizing the safety aspects of a car in two groups. In the one group were active safety features, intended to prevent or mitigate accidents, and in the other were passive safety measures, which were designed to reduce the severity of injuries to the occupants of the car in the event of a collision or other accident. As sales literature would rather gauchely explain it, Stuttgart believed that limiting accident damage not only protected the car’s occupants but also made the car cheaper to repair afterwards. Behind the scenes, the car’s designers knew from the start that they had to make the new 123 series safer than the New Generation models in order to keep a step ahead of anticipated legislation around the world.

Central to the improvements in active safety were those made to the steering, suspension and braking systems, which have already been highlighted. However, an enormous amount of design work also went into improving passive safety for the 123 models. Some of it was easy to see, affecting the overall structure of the cars, but this was backed up by small changes that were largely invisible in the finished article. These included the A-pillar trim that was designed to keep dirt off the side windows, and the conventional wipers that replaced the clap-hands type of the 114 and 115 models and covered about 20 per cent more of the screen.

Safety had been a Mercedes preoccupation for many years and the 123-series cars were the first to have a new design of collapsible steering column. The corrugated section ensured that the column would not be pushed back into the passenger cabin under impact.

The front end of the 123-series bodyshell was designed to crumple under impact, absorbing the forces of a collision to minimize their effect on the passenger compartment. The engine mountings were arranged so that the engine would ‘dive’ under the transmission tunnel instead of being forced straight backwards.

The attention to detail was impressive, even by modern standards. For example, Stuttgart’s engineers chose a chain for the parking-brake linkage in place of the rod used on earlier models, because the chain could not be forced into the passenger cabin under impact. They also redesigned a structural flange on the inside of each windscreen pillar, turning it through 90 degrees to point away from the occupants rather than directly towards them, as it had in earlier designs. As a third and very important example, Mercedes-Benz decided that the 123 models should have the first use of the safety steering column invented by safety engineer Béla Barényi and patented in 1963. This had a corrugated section that would buckle under impact, so preventing the column being driven back directly into the driver’s chest. In the event of a diagonal impact – which Stuttgart’s research had demonstrated was far more common than a head-on collision – the column would also deflect sideways.

Much of this passive safety work of course had been done some time earlier, and its results had been incorporated into the design of the R107 roadsters and the W116 S Class. Like the 116 models, the new 123s had a stronger passenger cabin than their predecessors, combined with weaker front and rear crumple zones. A much stronger roof and window pillars helped keep the cabin intact in a roll-over accident, with careful design making those pillars not only stronger but also thinner than before, to improve visibility out of the car. Meanwhile, side-impact protection came from doors that were designed to collapse progressively and also overlapped the sills for additional safety, and there were rigid cross-members mounted under the floor of the passenger compartment.

Several prototypes were destroyed in tests such as this, where a saloon was slammed into a concrete wall to reveal how well the front crumple zone did its job of protecting the passenger compartment.

More crash testing: these are both coupé models, and the numbers painted on their roofs reveal that they were tested in 1978. Both have been subjected to the offset front collision test that Mercedes maintained was most representative of real-life accidents.

Similar attention to detail ensured that the front structure would collapse in a more controlled way under impact. The Mercedes engineers achieved this by engineering dimples into the inner edge of the main side-members, allowing a progressive deformation of the structure, while also reinforcing the bulkhead area where those side-members met the floor, to limit the extent of impact damage. Even the behaviour of the engine and gearbox in a collision was considered. The engine mountings were designed to shear under impact, directing the whole powertrain assembly downwards via the transmission tunnel rather than directly backwards into the passenger cabin. At the rear, the spare wheel was mounted under the boot floor, again following the lead of the W116 S Class, to help reduce the effects of a rear-end impact.

The inside of the passenger cabin reflected the rational approach so typical of Stuttgart in its heyday, with all of the safety features being subtly integrated into the design. A large amount of interior padding helped protect occupants in the event of an impact and, most noticeably, a flexible bolster at knee height protected those in the front seats. The inboard belt mountings were on the seats themselves, ensuring that the belt was always in the right position across the wearer’s body, regardless of the position of the seat. The same kind of thinking had the return springs for the pedals moved forward of the pedal hangers to keep them as far away as possible from a driver’s legs. Meanwhile, the clear instrumentation was a delight to use, reducing eyestrain and fatigue in the dark or on long journeys, and providing all the information the driver needed at a single glance.

CONTROL CONFLICT

The standard arrangement featured a footoperated parking brake with a release knob on the dashboard.

Right-hand-drive cars had a pull-out handbrake on the dashboard.

Despite Mercedes’ attempts to streamline production by minimizing the amount of variation among the different 123 models, there were several different layouts for some of the major controls.

A foot-operated parking brake was favoured in the USA, where sales were expected to account for a sizeable proportion of 123 production, and this was made standard for most markets. Without a central handbrake on the transmission tunnel, there was room for a large oddments tray, which seemed to be an acceptable trade-off. The handbrake was released by a knob on the dashboard, just outboard of the steering wheel.

However, Britain was another important export market. Not only did it need right-hand-drive, but the Mercedes representation there was also keenly aware that British customers were likely to have an unfavourable reaction to the American-style parking brake. As a result, for British cars, a pull-out handbrake that both engaged and released the parking brake replaced the release lever outboard of the steering wheel. In the interest of simplicity on the assembly lines, Stuttgart decided to make this standard on all right-hand-drive models.

A central gear change mounted on the transmission tunnel was standard on all cars with a manual gearbox, and was replaced by a selector gate on 123 models with an automatic gearbox. However, in some countries the idea of an automatic gearbox selector lever mounted on the steering column had taken a firm hold, so an installation like this became an optional alternative from the start of production – although it disappeared some time before the last of 123-series cars were made.

AMBITIONS

From the start of the 123 programme, Mercedes aimed for a broader model range than the old 114 and 115 series had encompassed. There had been saloons, long-wheelbase saloons, coupés and ‘platforms’ on both short and long wheelbases to suit special commercial and emergencyservice bodywork. But there had been no estate cars. Longtime Mercedes collaborators Binz and Miesen had built such models in limited numbers as aftermarket conversions, but these had been few and far between.

So although the main thrust of development work for the 123 series was always on the saloons, which would be by far the most numerous variants, some thought was also given to later developments. The long-wheelbase variants were fairly straightforward, but the stylists of course had to take their longer roofs and different rear doors into account as the saloon design was being completed, so that the final design did not look like an awkward conversion.

For the coupés, a decision was taken to use a shorter wheelbase than for the saloons, at least partly to avoid the compromises of styling that had been apparent on the saloon-derived 114 coupés. And for the estates, special care had to be taken for very much the same reasons, with Friedrich Geiger’s stylists focusing on a design that flowed neatly from the lines of the saloon without compromising either its looks or its capabilities as a load carrier. In time, it would become clear that they had succeeded only too well in their designs for these two extensions of the 123 range.

However, it seems from an early stage that Mercedes did not have the resources to put all of these variants of the new range into production at once. The saloons would have to take priority, and could be followed within a year or so by the long-wheelbase versions and by the ‘platform’ models on both wheelbases. The coupés would come next, and the estates would follow around two years behind the saloons, not least because of the need to equip a new factory to build them.

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