The (Citroën) SM Story From an article by Ian Fraser.
Submitted by George Klein Jan/1996
By the conventions of the early 70's the Citroën SM was a weird vehicle, the likes of which never been
seen - and never would again be seen, either. When the SM died 12920 cars and six years later, there
was no replacement. There simply couldn't be for the world that had spawned it now spurned it as too
thirsty, to complex, too eccentric and too expensive. For Citroën, it was the last tango in Paris. The
company has fallen into the hands of steel-eyed businessmen from Peugeot; Maserati, then a Citroën
subsidiary who had supplied the engines for the SM, had been sold off to de Tomaso; and, most
important of all, the engineering hierarchy who had effectively controlled Citroën for years, became
subservient to the bean counters.
Of course, it was not the SM alone that sent Citroën down queer street. There were to many wonderful
new cars in the pipe line for the finances available. The GS, a brilliant all new small car, had been
launched at the same time as the SM; and to further strain the coffers, the CX had been
uncompromisingly developed and tooled as the DS's successor. The money ran out and Citroën
became an arm of Peugeot: that move and the subsequent acquisition of Chrysler's French interest
(re-named Talbot) came close to sinking Peugeot, too.
Although the SM started life in 1970 with three double-choke carburetors, it was eventually converted to
fuel injection instead. Then, to give it enough performance to cope with an automatic transmission, a few
were made with a 3.0 liter (instead of the earlier 2.7 liter) version of V6. The basic body shape remained
the same. One was even covertly converted in Britain to right hand drive in the hope that sales in Britain
could be improved.
When the SM's number came up on the bean counter's wheel of fortune, it just faded from the public eye.
Although never common on the roads, SM's turned from being uncommon to rare to almost extinct.
Inadequately protected against corrosion, the salt and the damp did major damage to body and chassis.
And there was the timing chain wear problem which, if the warnings were unheeded, had catastrophic
effects. In North American cars, the added antipollution device, has made the SM run so hot, that the
exhaust manifold sometimes turned "red hot". Because of this, number of cars were lost to fire. Thus,
rusted and with a blown up engine, many SM's simply sank on its suspension to be abandoned by
owners to destitute to salvage the remains.
But the SM started with high hopes and high ideals. The team that created it was probably the world's
most advanced. It's members saw the SM not only as a high-performance prestige car, but also as the
forerunner of generations of cars in which high pressure hydraulics would revolutionize control systems,
suspension and brakes. And they were not going in blind, either. Working in an austere building on a
bleak hill on the outskirts of Paris, The bureau d' etudes, the team was headed up by design director
Albert Grosseau, with Andre Estagne in charge of engines, Huibert Allera looking after the ergonomics,
Paul Mages the hydraulics and Robert Aupron, the chief philosopher. They firmly believed, for example,
that the benefits of the SM's very high-geared steering easily outweighed the disadvantages of its users
having to acquire new skills to operate it successfully. Even so, the MS's tow turns lock-to-lock was
regarded as a compromise insisted upon, one suspects, by Aupron. Mages was all in favor of just one
turn, which would have made a steering wheel, as such redundant.
Many of the design principles of the beloved DS were incorporated into the SM. Among them were
bolt-on body panels, and, of course, hydra-pneumatic suspension, inboard disc brakes at the front and
front wheel drive. Shovel nose and swivelling head lamps were among the other predictable features.
The DS had already been some way along the path.
The engine was a breakthrough. It was the most exotic power plant Citroën had ever been able to use
and that was only because the French company had bought up Maserati in one of those musical-chair
takeovers that specialist car makers are prone to. It was a light and tiny engine. Just 16 inches long
without ancillaries. Its critics pointed out at the time and ever since, that it should have been a 60 degree
V, not 90 degrees. In effect, it was a V-8 minus two cylinders, the work of Engineer Alfiery, the famed
Maserati designer who held the helm at Lamborghini.
Originally developed as the power plant for the Maserati Merak, itself a lighter, cheaper edition of that old
thunderer, the Bora, the V6 was given a shorter throw crankshaft to bring the capacity down to 2670 cc.
retention of the original stroke would have put the capacity at little over 3000 cc, but the new shorter
throw crank ended up as a massive affair of great strength, running in four main bearings. To keep the
engine short, it was decided to run a jackshaft along the center of the V above and parallel to the
crankshaft, to drive the four overhead camshafts from midway points rather than the end. Thus, the
jackshaft was driven by a single duplex chain from the nose of the crank, while the two pairs of camshafts
were rotated by a chain off the jackshaft. Each of these chains had a manual tensioner, but somewhere
along the line the main chain missed out on any kind of adjustment, an economy measure that has been
a source of costly aggravation for SM owners. Worth remembering is that the primary chain is at the
firewall end of the engine and inaccessible, to say the least.
Citroën imported the V6s from Maserati works in Modena. Each engine was a small masterpiece.
Die-cast aluminum, it was compact and aesthetically delightful. Furthermore, it weighed only 309
pounds, a sharp contrast to the SM's dry weight of 3197 pounds. With its 9.0 to 1.0 compression ratio
and triple 42mm Weber DCNF2 carburetors, it developed 170bhp at 5,500 rpm with 170 lb.-ft of torque
at 4,000 rpm. Although the power output was relatively low down the rev band, valve bounce occurred at
7,000 rpm; little point in reaching such high revs although the factory's claimed top speed of 137 mph put
the tachometer needle a whisker into the red zone at 6,500 rpm. Drive was take to the front wheels via a
five speed, all-indirect speed gearbox mounted ahead of the front axle line. Suspension, DS derived,
was self levelling and independent all around, and the brakes, a disc at each wheel, were fully powered,
as was the VariPower steering with its self centering and artificial feel.
The SM was a big car. It sat on a wheel base of 116.1 inches (290.2 cm) and was 16 ft (5 meter) long
and 6 ft (2 meter) wide. Its fuel tank was a useful 19.8 gallon (approx. 80 liters) and it ran on 195/70VR15
Michelin XWX tires. Everything was big except the interior: a four seater at the very best with marginal
rear leg room, and not much luggage space. ( The contemporary Mercedes SL carried far less luggage
and was not suitable for even small passengers in comparison.)
The urge for further development was felt at Citroën, and by mid-1973, the SM's V6 was wearing Bosch
fuel injection which boosted output to 178 bhp, again at 5,500 rpm. At the same time, they introduced the
2995 cc version with carburetors, developing 180 bhp, at 5750 rpm but only available when coupled to a
Borg-Warner three speed automatic. It failed to arrest the downward drift in sales. The best year was
1971 when Citroën was able to produce 4988 units, but this number had dropped by 952 the following
year and to an irreversible 2619 by 1973. Only 273 cars came off the line in 1974 and just 115 in the last
year of production. A total of just 12,920 cars were produced in the six years of the SM's existence and
although France was the biggest market, with 5509 units sold, Italy was second with 2070 and the USA
third at 2037. Only 327 SMs were sold in Britain with 134 going to Japan (to close out the lot which were
not allowed into the US after 1974 due to new Department Of Transport regulations.)
When the SM first came onto the US market in 1972, its price tag of $12,000 brought it face to face with
BMW's 3.0CS which, in a CAR Giant Test came out second to the Citroën. Someone shopping in the
same area would probably have looked at the Alfa Montreal, the ISO Rivolta, and the Porsche 911S. A
350SL would have been more costly and the Ferrari Dino 246GT, Jensen Interceptor and Aston Martin
progressively higher. With the benefit of hindsight, it is easy to see which one we should have bought
then and kept until now. Dinos now sell for over $35,000 and are still appreciating. There were not many
options offered with the SM. Virtually all came with leather, air conditioning and radio in the US, while
these were options in most markets.
A heavy car when ready to roll the SM was, nonetheless, quick enough. The little Maserati engine, buried
under the hood beneath innumerable pipes and hoses and airboxes, was willing. When CAR tested the
SM back in 1971, it reached a top speed of 135mph. but the fuel injected SM would come closer to 140
mph, owing to the increase in power and the body's inherent good shape. Reliable Cd (coefficient of
drag) figures are not available, but Citroën's own aerodynamic tests during SM's development suggest
0.35 to 0.37 would not be far from the mark.
Acceleration figures were handicapped by the fact that the SM would not quite reach 60 mph in second
gear unless the tach needle was take into the red. Nonetheless, a carburetor SM would reach 100 mph
in 23 seconds, 80 in 14.3, 60 in 8.2 and 40 in 4.8. Fuel consumption was not good, however,, 13.6 to 16
mph (US) being a normal operating range. First gear would take the Citroën SM to 37 mph, second to
59, third to 90 and fourth to 115. Twenty five years on, all but the fuel consumption figures hold up well.
The rest remains as attractive today as it did at the beginning of the 70s.
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