My Car Quest

February 26, 2024

Citroën SM – Comment

Text and photos by Optimader –

This is an extended Comment from the recent I Want A New Drug post.

Citroen SM

Citroen SM

Citroen SM

Citroen SM

Citroen SM

Nervous 1973 liter Automatique engine donor car with just a few of the spares. Very complete rust free car but had a tough life apparently.

The spare fenders are the Italian delivery with the quarter size round side marker lights. A low production valuable spare.

I will break this car up for spares as I am disinterested in a heroic restoration. Interestingly, the automatic transmission as a part is valuable (to owners with auto. trans. cars) as 1973 is the year they corrected the gearing & put in the 3.0L engine.

This is a challenging car to retrofit to a manual, consequently the Automatiqes should be optimized as what they are.

Citroen created the upgraded performance 3.0L engine to bring up the performance inadequacy of the 2.7L engine matched with the automatic transimission (an exclusive creature for the US market).

600 SMs (of 12,920 total produced) with the 3.0L/5speed combination were built for the European market. Due to the desirability of this combination, matching number OCDing takes backseat to this upgraded engine/trans arrangement. I will save the original engine and trans of course, but I have also elected to put in the aforementioned rerated transaxle with the Quife LSD and upgraded clutch. The original transaxle is perfectly adequate, but why not…

Citroen SM

Very nervous at this point…you will note that the US cars had the crappy sealed beam headlight arrangement. Presently a Euro nose cost north of ~$10K if you can find one. A consideration when valuing these cars. Figure a Euro car should always have a $10-15K premium over similar condition US destination car.

Citroen SM

Donor engine removed like it’s the back streets of Brazil.

Citroen SM

Engine is very good condition actually (57K miles). As long as it’s apart re-sleeving and forged pistons, overhauled heads of course.

Citroen SM

A looksee inside…freshly overhauled of course, sodium exhaust valves removed.

Citroen SM

Freshly re-sleeved (wet sleeve).

Citroen SM

Crank, yet to be cleaned up.

Citroen SM

Engine bay arrangement, central green sphere is the high pressure hydraulic pump at 5:00 is a pressure accumulator and the left and right are the olio-gas suspension damper spheres. One side is the modulating hydraulic fluid, split line is a diaphragm which isolates top that is charged with N2.

Those spheres are at all four corners and the hydraulic fluid circulated back to a large reservoir (ATM pressure) located at the firewall corner on drivers side–you can see the hoses. To the left of the pump is, obviously enough, a rotary AC compressor. This is a required upgrade from the original York Piston compressors. This retrofit is a good visual que when looking in the engine bay of an allegedly “restored car”

Citroen SM

Harry Martens is the go-to guy for the quaife LSD equipped transaxle.

Let us know what you think in the Comments.



Citroën DS logo

Citroën SM - Comment
Article Name
Citroën SM - Comment
Interesting comments about the Citroën SM by someone who knows.



  2. Philip Sarris says

    I’ve always wanted to drive one, they just look so cool. Also, they are well regarded by many as unequaled in overall drivability.

    SKIP: there is one for sale on BaT and this is a comment that gives some insight as to why they have a following.

    Mr.Mitch, one of my daily drivers is a ’65 Citroen DS19 with Citromatic shift. I grew up with these cars – what is it you want to learn about them? The DS was recognized in 1999 around the world as one of the top 5 most significant cars in the first 100 yrs of the auto industry – it came in 3rd in the world – behind the first place Model T Ford, and the Mini as no. 2. Not to shabby for a French Space Alien – a body more aerodynamic than a Porsche 911 – I saw the study at NWestern U. back in the ’60s. Better ergonomics than most other cars ever designed. Most comfortable, capable suspension ever designed, and the SM incorporates all that and much more – capable of cruising solid as a rock at 140 mph, able to win the Paris-Dakar road rally on rock roads, best brakes, steering, good fuel economy for such a high speed tourer, and best lighting ever engineered – see Automotive Engineering magazine from back around 2002 – both the DS and SM with their steering headlights made the cover of the best automotive industry mag in publication.
    Another example of the quality of engineering in all Citroens: No other car in the world uses tapered rollerbearings instead of supercheap rubber bushings on ALL suspension arms – they never vary or get sloppy after yrs of use and are entirely lubed for life – never requiring maintenance.
    When I worked with a GM exec engineer in the ’80s, he told me he and another exec engineer brought a ’57 DS19 into their dept to tear down, study & cost analyze. This again is in 1957. Their guys came back, told the execs that for GM to build a DS19 would COST GM $10,000. Not to sell but just to MANUFACTURE. The technology in the hydraulics, suspension, braking, steering & comfort could not be equalled by anyone else.
    PLUS – the SM was the only car ever to offer carbon fiber WHEELS as an option. They cut wheel wt in half or more. Until you’ve seen & studied a list of the design genius within any Citroen you just won’t comprehend them. Ask Jay – watch his video.

  3. Optimader says

    Skip , I always appreciate your insights, as well in this case your concerns of regarding how I allocate my time. Worry not, I think my inclinations have worked out for me pretty well so far!

    As a sidebar, I will say There’s something very distinctive about you posts, i just havent put my finger on it yet?

    Anyhoo, the Citroen SM can be very polarizing to some, but that is consistent with the response to other objets d’art and advanced engineering solutions

    I am an engineer by education and inclination so when I look at an SM I see automotive engineering jewlery, it is so beautifully thought out and executed. No less, all designed more than a decade before the vestigial introduction of CAD/CAM to the automotive design/ construction scene.
    To my eye, what I see is not weird, rather alloy castings that are works of art, a beautiful huge weight saving hood that is the largest single piece automotive aluminum stamping produced until recently, heck I can pick it up by myself!

    The front suspension is composed of beautiful forgings and precision machined componets, as Philip alludes to, not just roller beatings, tapered roller bearings ( look that up) designed to accommodate both radial and thrust loads, the suspension design remains unmatched still ~50 years on, the arrangement is front mid-engine meaning all drive train components are behind the plane of the front wheel axis.
    The rare Michelin RR composite wheels are a derivitive from a NASA patent weighing in at 4kg and change, Massive inboard disc brakes in the front with the consequent elimination of unsprung weight, these with the DRAVI self centering steering will pull the SM down from high speed with little or no driver steering input.

    I am 6-2 and the interior just ergonomically sucks you in, literally a car one wants to sit in. The DRAVI self centering steering and the breakpedal mushroom, again features that remain unmatched in the industry are fantastic.

    The unique driving experience, big range on a full tank, performance with the evolved fixes to nuisance issues make these cars one the ultimate long haul GT cars to experience—- IMO

  4. Joel Siegel says

    how are you going – is it done? I am just starting to restore my 71 SM that I purchased in 72 and blew engine in 83. I really enjoyed driving this GREAT car. and hope to do soon (I am 79). Found Excelsior Motors recently where I will getting new parts. If you want to check him out –

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