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In 1970, Citroën launched two new models - the SM and what was probably the most technically dense car within its market sector, the GS which beat the SM to the Car Of The Year Award that year.
While
the GS was a technological tour de force since it introduced self
levelling suspension and powered disc brakes to the mainstream, the SM
was Citroën's long awaited flagship, intended for a wealthy, discerning
elite.
The SM was the product of over half a decade of development work
and its technical solutions to the problems of powerful front wheel
drive cars included DIRAVI - DIRection A Rappel AsserVI or VARIPOWER as
it is known in Anglophone markets. This was a fully powered steering
system which provided maximum power at low speeds with the power being
reduced as velocity increased. This was coupled withpowered centering
and only two turns from lock to lock. Centre point steering (where the
pivot point passes through the centre of the tyre tread contact point
was possible thanks to the front brakes being mounted inboard on either
side of the differential.
Hydropneumatic, self levelling suspension
was carried over from the DS although the mounting points for the
suspension arms were in front of the wheels rather than behind them as
in the DS.
The SM was launched at the Geneva Salon in the spring of 1970.
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Technical specification 1971
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Number of cylinders
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V 6
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Cubic capacity
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2 670 cm3
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Bore and stroke
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87 x 75 mm
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Fiscal power rating
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15 CV
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Fuel system
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Three Weber carburettors
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Maximum power output in brake horse power
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180 SAE @ 6 250 rpm
170 DIN @ 5 500 rpm
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Valve gear
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4 overhead camshafts, 2 overhead valves per cylinder
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Transmission
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Front wheel drive via 5 speed manual gearbox
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Brakes
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Fully powered discs, front brakes mounted inboard, parking brake operates on front brakes
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Suspension
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Self levelling, fully independent, variable ride height, hydropneumatic with anti dive, anti squat geometry
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Steering
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Rack and pinion, DIRAVI/Varipower
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Dimensions
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Length
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4,890 m
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Width
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1,840 m
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Height
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1,320 m
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Wheelbase
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2,950 m
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Front track
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1,530 m
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Rear track
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1,330 m
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Weight
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1 450 kg
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Maximum speed
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220 kph
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Above - suspension layout
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The SM , despite being longer than the DS, was a 2 + 2 Grand Tourer.
The body was styled by Robert Opron who was also responsible for the GS and CX .
The
glass front housed no less than six headlamps, all of which were
connected to the suspension to maintain a constant beam height whether
accelerating or braking while the inner pair were connected to the
steering. American customers had to put up with four fixed round lamps with no glass nacelle.
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In
1973, power output was increased to 188 bhp SAE @ 6 250 rpm/178 bhp DIN
@ 5 500 rpm thanks to the fitting of electronic fuel injection. Top
speed increased to 228 kph.
In 1974, the SM Automatique was launched, fitted with a 2 965 cm3
engine developing 190 bhp SAE @ 6 500 rpm/180 bhp DIN @ 5 500 rpm, fed
by three Weber carburettors and a three speed Borg Warner automatic
gearbox offering a top speed of 205 kph.
Escalating fuel prices in 1975 coupled with the unimaginative dead hand of Peugeot killed the SM off.
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Click on the two engine cutaways to see large version (will open in new window)
Below the fuel injected engine
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Above and below in its first outing, the gruelling Rallye du Maroc, the SM came first in Group 4
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Above, below and below left - Henri Chapron built two four door drophead SMs for the Elysée
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