Magic Carpet. The year 2015 marks 60 years since the debut of the trendsetting Citroën DS, a car that still looked modern when it was replaced 30 years later.
Much has been made of the DeLorean DMC 12’s starring role in Back To The Future that celebrates its 30th anniversary in 2015, but there is another significant car in the films: the Citroën DS, which glides past as 1985’s idea of a futuristic hover car when the action moves forwards to 2015.
The DS was itself launched in 1955, the year to which the film time travels and so celebrates its 60th birthday this year. Citroën today may be a shadow of its former self but the DS was truly revolutionary when it was unveiled: to put it in perspective, the Austin Westminster in this issue of Drive-MY was launched just the year before, but still featured a cart-sprung ‘live’ rear axle, front kingpins, unassisted steering and non-servo drums.
Early cars featured single lamps – the famous swivelling lights would be introduced in 1967.
The DS by contrast, with its hydraulically-powered suspension, steering, clutch and brakes, was futuristic in the extreme, yet in its homeland was considered a relatively commonplace, if upmarket, family car.
Development of the DS – as most readers will no doubt be aware, the French pronunciation of the letters equates to Déesse, the word for Goddess – originally began shortly after the launch of the similarly revolutionary Traction range in 1934. The Traction range originally aimed at the top end of the market and so the brief was originally to create a mid-market car with a more modern style, but WW2 intervened.
Despite management and occupying forces ordering the suspension of future model development during the conflict, work carried on in secret, but with the priorities now somewhat changed.
As the conflict wore on, it became obvious that when peace returned, the road system would be devastated and fuel would be in short supply, meaning that a new model would need supple suspension and a modest powerplant – clearly the proposed V8 version of the Traction was out. The new car was given the title of Voiture Grand Diffusion, essentially a mid-range volume seller.
By this time, the development of the 2CV was already under way and prototypes were tried with the 2CV setup. The system that worked well on the lighter, smaller 2CV proved to permit excessive body roll on a larger car and so an alternative was required.
Meanwhile, a production engineer named Paul Magès who had joined Citroën back in the mid-1920s, had been tasked by new managing director Pierre Boulanger, to transfer to the R&D department to study future suspension systems for the 2CV.
Magès initially began his research around the idea of liquid/gas systems and when results looked promising, Boulanger suggested he apply the research to a larger vehicle – the proposed VGD.
The big issue in getting Magès’ ideas from concept to reality was the fine tolerances involved in manufacturing the componentry, but with these overcome the system proved workable and with the necessary high-pressure pipework in place it was relatively straightforward to extend the system to operate the braking system, too.
By then Mages had become an enthusiastic exponent of hydraulic control and subsequently designed a hydraulic clutch actuation and steering system.
Meanwhile, the bodywork of the new car had been progressing under the direction of the man regarded as the project’s father, André Lefebvre. The construction of the VGD would prove to be as radical as the Traction was conventional, with a layout that mirrored the much later Rover P6. A central steel monocoque frame – the caisson – was envisaged, to which lightweight alloy panels could be attached. In the late ’40s, the Traction range was beginning to look increasingly outdated and it was accepted that a new look was needed, but early prototypes were a long way from the glamorous production car: indeed, at least one of them was nicknamed L’Hippototame or Hippopotamus.
When Boulanger was killed in 1950 while testing an experimental Traction, new MD Pierre Bercot, appointed by Citroën’s owners Michelin, agreed to restart the project and it was here that the development of the DS really gained impetus.
Citroën stylist Flaminio Bertoni had already been working in secret on improving those ‘Hippo’ prototypes and was gradually working towards the distinctive shape, although the final shape would be finalised only six months before the eventual launch.
One of the reasons for the delay in freezing the body style was the question over the car’s powertrain. The design team had initially envisaged using a flat-six engine, but the all-alloy air-cooled unit proved expensive to manufacture and its power output of 64 bhp from 1806cc was considered too low for the mid-sized VGD. Citroën lacked the resources to design an all-new unit from scratch and so the decision was taken to go with the conventional OHV engine from the Traction car, designed by Georges Sainturat. The problem though was that the six-cylinder version simply wouldn’t fit in the new car and so the 1911cc four-pot version was chosen. With a new cylinder head and other revisions, Sainturat extracted 75 bhp from the engine that was installed with the transaxle ahead of it, an arrangement that saw the powerplant intruding into the passenger compartment slightly.
Attempts were made to incorporate the gearbox and differential into the sump in the BMC style, but finances dictated that this would be a dead end and so the DS effectively became a mid/front-engined car. Elsewhere, the new car used disc brakes mounted inboard in the 2CV style and plastic – the new wonder material of the 1950s – was used extensively. The translucent roof panel was GRP while the dashboard was plastic, as were many of the interior fittings and the engine cooling fan.
The DS proved handy in rallying, especially (right) with V6.
The new car was launched at the 1955 Paris Motor Show and wowed the crowds with its futuristic looks. Its name had by now changed from VGD, to Projet D, to the official launch name of DS19 and within minutes of the unveiling, a fleet of cars swept out of the Citroën gates and into the Paris rush hour. After early ‘scoop’ reports in the press, Citroën had imposed strict secrecy and so the new car would have been a stunning sight. That first day, some 12,000 orders were taken for the new car, allowing Citroën and its owner Michelin to heave a sigh of relief. After all, the car had been some 18 years in the making and the firm really needed something fresh and modern.
As detailed in our side panel, the DS would run for 20 years until being replaced by the CX that, although looking similarly revolutionary was in fact slightly more conventional, lacking the hydraulic gearchange and caisson body structure. Driving the DS today is a fascinating experience, even if you’re used to classic Citroëns and by the standards of its ’50s contemporaries, is in a different league.
Open the surprisingly hefty door, settle into the massively padded seats and you could well be in a Landcrab or a Mercedes-Benz saloon, an impression that endures when you nudge the gearlever to the left and trigger the starter. What happens next though is a world away from anything with a BMC heritage, as the car’s hydraulics come up to pressure, marked by the back gently rising, shortly followed by the front. On early DS’s there’s no clutch pedal and moving off is accomplished by selecting first, then taking your foot off the brake. At this point, the engine revs raise sufficiently to engage the clutch and the car creeps forwards like a conventional automatic. Squeeze the pedal and the car starts to move away, with the next gear engaged by simply easing off the gas and moving the lever.
On the majority of cars in the UK, there’s a rather more conventional clutch pedal and getting underway is a more familiar process.
Whatever transmission is fitted though, you’ll come up against another DS quirk when you get to the first junction and find yourself hanging on the belts as you try the brakes for the first time. I’ve driven countless old Citroëns and covered thousands of miles in the DS’s successor the CX, but every time I drive a DS or ID, I still get caught out by the brakes initially. The foot pedal is little more than a switch, with just a brush with the toe needed to unleash the full 12,000 psi of hydraulic stopping power.
It only takes a few minutes to get used to though and once up to speed you can appreciate the DS’s legendary ride. Our frost-addled roads today are probably little better than the Routes Nationales of the ’50s that inspired the DS and it does a wonderful job of gliding over the potholes and speed bumps. The self-levelling characteristics of the system stop the rear end from sagging even with a full load of people and luggage and although it does roll more than the average modern saloon it’s ultimately pretty tenacious. Citroën itself, conscious of the power deficit of the early cars against the competition, claimed that its supple suspension meant it could achieve faster average speeds on rough roads than many more powerful cars that simply had to slow down and that holds true today.
The later cars did benefit from increased power and ultimately electronic fuel injection, with the late model DS23 good for 141 bhp from its enlarged 2347cc engine, but there’s no disguising the age of its basic design: it’s a workmanlike plodder, but does have the advantage of decent torque and to be fair it was still on a par with something like the B-Series for refinement well into the ’70s. All the same, you can’t help wondering what kind of car might have been achieved with the flat-six or even the rotary engine that was later considered by Citroën. There’s also the intriguing fact that the Maserati-powered SM was developed from the DS platform and early prototypes were essentially two-door DS’s with the Maserati V6, one of them being rallied successfully by Bjorn Waldegaard.
At cruising speed though, the engine note is subdued and the car’s general refinement is well above anything from the mid ’50s including some much more expensive cars. By contrast, the MkI Jaguar saloon feels very old-fashioned with its thick pillars and ’40s-style detailing, while even the MkII, although it’s from the same era feels like a car of the old-school compared with the Citroën.
Of course its futuristic style was probably its undoing in the UK market, where the cars never sold in massive numbers despite being built here at Citroën’s Slough factory for a while. The reluctance of the average back street garage to get involved the hydraulics was probably one reason, while the outlandish styling no doubt scared people off.
All of which explains why the DS was a popular sight in France well into the ’80s, the car accepted in its homeland simply as a very good family car, but a rare sight over here in conservative Britain. Ironically, the Hydrolastic ad Hydragas systems that featured in our own homegrown products are no less complex in their basic concepts.
The DS left a lasting legacy on Citroën and even today its name is being used as a style-heavy sub-brand, even if the firm’s cars have abandoned the hydraulic suspension. Its successor, the CX, used a similarly striking body, but retained the older car’s hydraulic suspension, brakes and steering, while even the Traction-era engines were carried over until the ’80s.
The CX’s successor, the XM, was perhaps slightly more conventional in appearance but still employed the hydraulics, with the suspension gaining electronic control to give it an ‘active’ ride and prevent it leaning in corners. Surprisingly, the XM became a relatively familiar sight in the UK, especially in well regarded diesel form and the estate version was truly enormous in carrying capacity. The XM was in turn replaced by the C5 of 2001 that was a relatively mainstream car and became a common sight on UK roads thanks mainly to extraordinarily aggressive pricing by Citroën. From 2005 it was joined by by the C6, which was the last of the big Citroëns and the last of the firm’s cars to offer the hydraulic suspension.
Despite being a refreshingly different alternative to the usual German-made executive cars, the C6 ended production in 2012 and has yet to be replaced. Indeed, if it does, it will likely be the DS name that returns.
That suspension
The heart of the Citroën system is a highpressure hydraulic pump, driven by a belt from the engine like a conventional power steering pump. The pump produces a constant pressure of LHM (liquide hydraulique minérale) fluid and is engaged and disengaged by a solenoid-operated clutch. Hydraulic fluid under pressure is stored in an accumulator sphere, from where it can be drawn off as required from a kind of hydraulic ring main running round the car.
Each suspension arm is attached to a pushrod with a sphere on one end and a piston on the other end moving in a cylinder. Fluid can pass from the sphere into the cylinder according to the position of a height control device, while pressurised nitrogen gas in one half of the sphere provides the springing effect. A shock absorber effect is achieved by using a restriction between the cylinder and the sphere.
The clever bit is the height control and it’s very simple: it’s essentially a valve attached to the anti-roll bar, one at the front and one at the rear. As the suspension drops, the valve allows more hydraulic fluid into that end in order to raise the suspension and when it reaches the correct point then the valve closes. Similarly, if the suspension is too high, the valve releases pressure back to the reservoir. A dashboard lever allows the position of the valves to be manually adjusted in order to raise and lower the car.
The brakes work from the same hydraulic system and are equally simple: essentially, the brake pedal is in fact a valve which allows high-pressure hydraulic fluid into the callipers and forces the pads against the disc in order to stop the car. Because of the colossal pressure inside the system, the pressure is reduced for the braking system in order to give the driver some hope of modulating the pressure without locking up the wheels. In an elegant twist, the Citroen designers even arranged for the rear suspension to drop slightly under braking to counteract the natural nosediving effect.
As for the steering, that’s as simple as the brakes. Essentially when you turn the wheel, you’re opening a valve which allows fluid to enter one side or the other side of the rack and provide power assistance in whichever direction the wheel is being turned. Let go of the wheel and the system returns to the centre point where both valves are closed, another Citroen quirk.
Various refinements were introduced with Citroen’s CX, GS, Xantia and XM, but the greatest advance came with the Xantia Activa in 1993, where the hydropneumatic system was turned into a true active ride system. Body position sensors were used to determine the amount of roll and supply hydraulic fluid to the relevant side of the car in order to keep it level.
Evolution of the Goddess
1955 The DS is launched in Paris.
1958 The cheaper ID is launched, using hydraulics only for the suspension. The name is another play on words, the letters ‘ID’ being pronounced Idée, the French word for idea.
1959 The eight-seater Safari estate is launched, initially as the more basic ID.
1962 The front end styling gets tidied up, allowing for a 5 mph improvement in top speed. The convertible Décapotable is launched, built for Citroën by coachbuilder Henri Chapron.
1964 The super luxury Pallas trim is added, alongside a new DS21 model with a 2175cc engine.
1966 The fluid in the suspension is replaced by LHM mineral oil, instead of the previous vegetable oil.
1967 The car receives a facelift that gives it four lamps behind the glass fairing. The famous directional headlamps are added, the inner pair turning with the steering, while the outer pair are linked to the suspension to give a level beam while accelerating or braking. Contrary to urban myth, it’s achieved by a mechanical linkage, not hydraulics.
1968 The ID models are renamed DS, becoming the D Super with the new DS20 engine, or D Spécial with the older unit. All cars gain a restyled dashboard.
1969 Bosch electronic fuel injection is offered as an option on the DS21, with the ID19 Spécial added as a entry-level model. The millionth DS is built this year.
1970 A five-speed gearbox is offered on the DS21. The ID19 is rebadged as D Spécial and D Super.
1972 D Super gains a 2175cc engine and the DS23 replaces the DS21, with a new 2347cc engine offering 124 bhp on twin carbs, or 140 bhp with Bosch injection.
1973 The DS20 is discontinued.
1975 DS production is discontinued in readiness for the new CX. A total of 1,455,746 were produced.
Pierre Magès
Citroën engineer André Lefèbvre is often regarded as the father of the DS, but engineer Pierre Magès bears equal credit for his vision that produced the hydraulic system.
Magès joined Citroën in 1925, initially as a production engineer and found favour with André Citroën himself after reorganising one of the firm’s engine factories, before the firm’s MD Pierre Boulanger asked him to join the R&D department to investigate future suspension systems for the 2CV. He began working on gas/liquid systems and developed a prototype set-up fitted to a 2CV and using a gas reservoir at each wheel, separated from the liquid by cork. The cork proved unsuitable for the high pressures involved and what we know as the suspension sphere was then developed.
Boulanger asked Magès to develop the system for the proposed VGD. In 1942 he extended the high-pressure hydraulics to the brake system and varied the front-rear bias according to vehicle load, using a mechanical balancing linkage.
In 1949, the system proved itself in extreme weather testing in Norway and Algeria, after which it was decided to add the manual height control, to allow the car to pass over packed snow and rough terrain. In 1952, the hydraulically operated gearchange was added and in 1953 the systems were judged sufficiently developed to proceed to production in the DS.
The Break estate was available as a seven or nine-seater, plus the Commerciale van.
