1973 Citroen SM from North America - Comments

This Citroen SM sat too long and needed spheres.

Its entire oil cooling system burst and had to be replaced.

Its intricate 3 timing chains needed replacement as well as a total overhaul of the distributor.

Front brakes quite sensitive to wear.

This SM should be kept by true connosieurs of automobiles or mechanics with engineering degrees. It's a marvel when running correctly.

Nothing surpasses this car as a fast, freeway flyer.

Steering fantastic, affording maneuverability of a Mazda Miata.

Fingers always crossed when I am behind the wheel.

Hi Steven.

Great to hear that you also have an SM.

I can imagine that it's hard to find parts in the US.

In Europe (especially in the Netherlands where it seems as

though everybody loves Citroen) many parts can still be obtained.

Your remarks about repairs are indeed correct, to keep the car in shape you need a degree in car mechanics. I do not have such though I am willing to learn and there are many clubs and fanatics who are eager to explain, in detail, how to proceed in repairs.

I don't like the front of the American SM and I don't like automatic transmission in sports cars, but because of the loss of power through the automatic transmissions Citroen delivered the car in the USA with a 3litre engine. As I can see your car is manually shifted which means that somebody did a great job (converted your SM into the most powerful SM possible!!!) Don't worry about the gear box; it was also used by Lotus, even with near to 300HP.

Comment from owner: Thanks for your individual comment. Citroen SM still running as per usual. Should note that ALL 1973/74 SMs built after 01/73 or so came with the 3.0 V6, whether or not a 5 speed or automatic was chosen. This is an original equipment vehicle, fully documented from new. There was no conversion of its transmission.

An automatic transmission actually multiplies torque, so you get more power than a manual. Just a FYI, but a manual is more fun.

To the last comment, yes an automatic has a torque converter, which can at times, depending on engine and transmission speeds act to double or even triple torque, but it does not do this over all driving speeds. A torque converter acts to increase torque under certain conditions. I don't pretend to be an engineer,but the most telling point is that even with a torque converter a small car will always be much more sluggish with an automatic than with a standard. So realized power at the wheels does appear to be less. This may be due to the fact that there is power loss due to the fluid connection in the converter rather than a mechanical one in a clutch, or the lower revving nature of an automatic.

The Citroen SM was originally imported into US as a carbureted 2.7 litre manual. Next a few 2.7 litre automatics were imported (all automatics were carbureted only). Then the automatics went to the 3.0 litre (carbureted) and for the US market the 5 speed manual came with 3 litre carbureted engine for 1973.

Other markets got the 2.7 litre electronic fuel injected engine.

I have had 2 running SMs, both 2.7 litre manual US models. I also had a non-US model with the six headlights under glass just as a parts car as its engine was taken to replace a blown Maserati Merak's engine (so I was told). It had suffered an under-hood fire.

This car is great when in good condition, but requires real dedication to keep it that way, and a lot more to get it that way if you don't start out with an excellent one.

Very expensive to fix if anything is wrong, but not too bad to maintain if it's already in excellent condition.

If you are not so dedicated and technically competent, and don't have a bagful of money to pay one of the very few competent shops in the US to keep it up for you, steer wide of the SM!

The newest of these cars is now over 30 years old, so a lot of stuff is going bad just from age no matter how well the car has been protected from sun and weather.

Watch out for hoses - they deteriorate internally and shed bits of rubber into the engine oil system (the long oil cooler hoses that run from the back of the engine to the cooler beside the radiator) and into the hydraulic system (hoses here, there and everywhere). Hoses may look good, but be disintegrating inside. Diaphragms in the steering regulator, suspension height controls and the accumulators (one on each suspension unit, one on the main regulator and one for the front brakes, hidden under the hydraulic reservoir) gradually dissolve from heat and exposure to the hydraulic fluid, releasing gooey black glop to clog tiny orifices in the system.

Wiring harnesses are likewise old and should be replaced to avoid failures and even fire. New ones have to be made up to order, duplicating the original. Few shops can handle this job.

"Rubber" (actually PVC) gaiters on the steering and the suspension crack with age and heat, allowing dirt to get into precision sliding surfaces and to leak hydraulic fluid onto the suspension bump stops, rotting them.

Plastic gears in the window regulators crack. Metal ones are made for replacement.

Even the cylinder block (aluminum) of the hydraulic pump may crack from age and fatigue. The pump may be rebuilt with a steel block that will never crack.

The engine is very particular, especially in the timing chains and main (rear) tensioner. Only the last revised models should be installed to prevent massive engine damage.

Exhaust valves (sodium cooled) should be replaced with either new sodium cooled ones for the particular and solid ones for the rest of us, as the sodium gradually erodes the hollow valve stems from the inside, which can cause the valve head(s) to fall off into the cylinder(s) and wreck the engine.

Contact the several Citroen SM clubs to learn all that needs to be done to maintain or restore this magnificent machine.

Re. Torque converters: Any gearbox is exactly that, a torque converter. When you're in a low gear, the wheels move a lot more slowly, but with a lot more torque. The extra torque comes from the reactions within the gearbox (manual) or torque converter (auto), and MUST be accompanied by a decrease in wheel speed: thus, the POWER (= torque times rpm) is constant. All of the power comes from the engine: a torque converter can't give you any more power!

In fact, a torque converter usually works on fluid flows within, which have friction losses that you don't get with a conventional gearbox. That's why an automatic sucks power out.

The SM's automatic gearbox (the part that contains the planetary gearsets and clutches) is a Borg-Warner T35 in a special transaxle case. It is notorious for breaking. I have found information that a strengthened main planetary set was available for upgrading the 35 in SAAB 900s. Perhaps one of the SM specialists such as SM World and others can provide more information regarding this possible upgrade if you have an SM automatic that needs to be rebuilt.

One broke in Nashville, Tennessee some years ago. It was being driven at low speed in the city when all of a sudden the engine raced and a grinding noise came from the transaxle. The "park" lock would not hold (the "park" sprag teeth are on one of the planetary cases).

For anyone wishing to convert from an automatic to a 5-speed, the body-frame is the same for both, but many parts are required, so the conversion job is more tedious (to say the least!) than difficult. The best source is an unrestorable, like smashed, rusted out or burned, 5-speed car that is complete (watch out for front end collisions - the steering centering regulator is on the front of the transaxle 5th-gear case; the bellhousing may be distorted if the transaxle has suffered a hard blow). The parts book (relevant pages are essential!!) shows all pieces that have to be changed out, from obvious things like the transaxle and shift lever to engine mounts and exhaust pipes. Some things do not have to be changed, such as the steering unit (the automatic had slightly less steering lock due to spacers in the rack actuating cylinder) but most are have-tos.

The automatic has a number of parts that are "unobtainium." Lower (pinion) shafts and bearings are no longer available new. The diaphragm in the steering centering regulator is no longer available (check with SM clubs for reruns of parts).