top of page

Safety and Crashworthiness


SM Crash Test in support of USA certification?

Notice USA side marker light on rear fender




US Federal Motor Vehicle Safety Standard (FMVSS) No. 215 titled, "Exterior Protection," applied to 1973 model year cars. This safety standard mandated that no damage should occur to safety-related components (such as headlights) when the vehicle was subjected to crash tests at 5 miles-per-hour (8 km/h) for the front bumper and 2.5 MPH (4 km/h) for the rear bumper. 


This requirement forced a number of changes to the front bumper of 1973 SM's bound for the USA and Canada. The parts book shows that most of these changes were implemented in 7/72, which might include a few very late 1972 cars. 


We will take these design changes one at a time; (A), (B), (C), and (D) below: 


The parts books show that the stainless steel front bumper halves were reinforced with added steel on 1973 USA/CAN cars. The part numbers are as follows:

Screen Shot 2020-10-27 at 7.49.25 AM.png



The parts book also shows an added structural member behind the front bumper that was unique for front crash protection on 1973 USA and Canadian SM's. See item 15 from the parts book snippet (P/N 5427371). This strengthening member caused a change to the bumper brackets as well (items 4 & 5 from the parts book snippet). 

bumper parts.png

The parts book shows an extra front bumper component for 1973 USA/Canadian SM's only

A reader of this website snapped a photo of this structural member (below).

processed 2.jpeg

Strengthening member behind the front bumper on 1973 US/Canada SM's (item 15 from the parts book)


There was a change to North American 1973 SM's that we think is part of the 5 mph front end crash requirement of FMVSS #215. The aft corners of the front fenders had an extra threaded fastener to help restrain the aft edges of the front fenders in the event of a front accident. See photos below. 

fender bolt.jpeg


Another change that is likely associated with FMVSS #215 is the rubber strip on the front bumper. The parts book shows that 1973 USA/Canadian SM's have a different rubber strip on the leading edge of the front bumper. The part number for the Euro strip is 5407567. The part number of the strip used on 1973 USA/Canadian cars is 5427994. 

Intuitively, it would seem that the thicker rubber strip would be on the USA cars, but oddly it seems to be the reverse. Euro SM's (and USA SM's in 1971 and 1972) have the thicker strip. USA/Canadian SM's in 1973 have the thinner strip.


Thick rubber strip on Euro cars and 1971/1972 USA/Canadian cars


Thin rubber strip on 1973 USA/Canadian cars

The rear bumper apparently did not require changes to comply with FMVSS #215 as all of the main components are identical to Euro models. 

It is interesting to note that the Wikipedia entry for automotive bumpers identifies a requirement for bumper heights and specifically lists this as a reason for halting the importation of the SM into the USA.

This photo appears to be the result of the 5 mph crash test on USA front end components




The parts book shows some differences with side view mirrors on US and Canadian cars (flat glass vs. convex glass). French cars were equipped a left side mirror with convex glass (no right side mirror). US and Canadian cars all had the same left side mirror, but with flat glass (also no right side mirror). 


But every-now-and-then an SM shows up with a matching right side mirror. An example is on the car in the photo below. A reader contacted us and indicated right side mirrors were an aftermarket item offered by an SM club in Europe. Notice the chrome stem is longer to improve the visual line of sight to the mirror from the driver's seat. 

side mirror right.png

Example of an SM with the OEM mirror on the driver's side and an aftermarket right side mirror



All USA and Canadian SM’s received hydraulic components called leak finders (two per car) that were not installed on French cars. Leak finders were small hydraulic components that were located in the tubing leading to the front and rear brakes. If there was a hydraulic leak somewhere downstream in the brake system, the leak finders would shut off flow to the affected brakes, thus retaining the hydraulic system integrity for the remaining brakes, as well as for other hydraulic systems on the car. If a leak finder detected a leak and shut off flow, a switch at the end of the leak finder would be actuated to illuminate the red STOP warning light on the dashboard. According to the parts books, leak finders were also installed on Norwegian and some Swiss SM’s. 


In industrial and aviation circles, this type of device is called a volumetric hydraulic fuse, since it passes a specific volume of fluid before it “fuses” and shuts off flow. The fluid volume needed to “set” the fuse is designed to be somewhat more than the normal volume of fluid needed to apply the brakes. In this manner, the fuse will never “set” with normal braking activity, but will “set” if an abnormally high volume of fluid passes out to a set of brakes. Leak finders made bleeding the brakes a bit of a chore since the leak finders interpreted brake bleeding as a leak and therefore shut off flow to that set of brakes. (The key to bleeding the brakes is to press on the pedal exceedingly lightly, which allows a very small flow around the outside diameter of the leak finder piston, which prevents the leak finder from closing off flow.) 


Leak finders were installed in the driver’s footwell area, directly on the brake valve. 

SM Leak finders as installed on a USA/Canadian brake pedal unit – the long leak finder is for front brakes, shorter for rear brakes

leak finder.jpg
leak finder2.jpg

Disassembled leak finder

Screen Shot 2020-11-03 at 2.17.30 PM.png

Leak finder location in a brake schematic

Why were the leak finders added to the SM brake system? It stems from a 1968 safety requirement imposed by the USA; Federal Motor Vehicle Safety Standard FMVSS No. 105. Among other things, this safety standard imposed a dual-circuit brake master cylinder (the standard incorrectly assumed that all cars had conventional master cylinders). One circuit of the dual master cylinder was for the front brakes and a second circuit was for the rear brakes. Citroën's leak finders somewhat mimicked the behavior of a dual-circuit master cylinder on a conventional brake system since a leak in one circuit (front or rear) would not affect the other.


Even though these regulations kicked-in in 1968, somehow Citroën avoided having to make design changes to the DS to meet these regulations until April of 1971, at which time the leak finders and other strange things started to happen to the brake system. You can read about these changes to the DS brake system HERE. All SM's in North America received these parts. 

Certain hydraulic tubes associated with the brakes on USA/Canadian cars were coated with nylon (Rilsan) for additional corrosion protection. We believe this was part of a deal Citroën struck with USA regulators, along with the leak finders, to meet the “dualized” brake master cylinder requirements of the era. 

But it seems that the leak finders and Rilsan covered tubes only temporarily satisfied the US regulators. We found a 1974 exchange between the National Highway Traffic Safety Administration (NHTSA) and Citroën where the NHTSA was pushing Citroën to prove that their centralized brake system (with leak finders and Rilsan covered tubes) was as safe as a dual-circuit master cylinder. You can read this some of this exchange between Citroën and the NHTSA HERE and HERE. 


The NHSTA even requested Citroën to provide a cost estimate to convert their centralized brake system to that of a conventional dual-circuit master cylinder type system. Since this correspondence is from 1974, it post-dates the era of the DS and SM. However, does this mean that brake system architecture was yet another reason why Citroën gave up importing cars to the USA? Sounds like it might be. 

In addition to the above changes, the parts books show that USA/Canadian cars had a different pressure switch on the brake pedal unit to warn of low incoming pressure at the brake valve. 



ALL USA/Canadian cars had interior door handles and door latches that allowed the doors to be locked from the inside. The locking action was to push the door handle tongue forward. On some Euro models, the doors could not be locked from the inside. See video demonstration.


We believe that the ability to lock the doors from the inside was a USA safety requirement, starting in the late 60’s. Note that USA-bound DS’s had a design change to accommodate this requirement in 1969. 

USA / Canada front door lock



All USA/Canadian cars have a data plate riveted in left door jam (A-pillar) indicating that the car conformed to USA safety standards for that year. The data plate was yellow on cars manufactured in 1971 and turned to orange on cars manufactured in 1972 and 1973. This is one of those places where it is important to understand the difference between manufacturing date and model year. A 1972 car manufactured in late 1971 had the yellow plate and a 1972 car manufactured in 1972 received the orange plate. 


The orange plate included the Gross Vehicle Weight Rating (GVWR), a USA requirement of the era. The GVWR is the maximum weight rating of the car, including fluids, passengers, and cargo. DS’s of the era had nearly identical safety data plates, also installed in the left door jam.


Since the yellow plate and orange plate were of slightly different size, they were riveted on different faces of the left front door pillar. The orange plate that is used on the later cars is very difficult to read due to its location. 

72 door jam plate.png

Yellow plate used on cars manufactured in 1971

72 safety data plate.jpg

Orange plate used on cars manufactured in 1972/1973


Lets take a closer look at the wording on the orange safety data plate. Huh? Is that a typo? Yes it is! Somehow this escaped being noticed by Citroën. It also escaped our notice, until a reader saw the mistake! This same mistake is also on late '72 DS's. 




Canadian SM’s received a Transport Canada sticker in the left door jam identifying that the car complied with Canada Motor Vehicle Safety Standards (CMVSS) of the era. After digging through Canadian government paperwork available on-line, we found a reference in a document that suggests this sticker was required for model year 1972 cars.  The '892' number on the sticker is a unique number assigned to the car manufacturer, in this case, Citroën


A reader provided a photo of a CMVSS sticker on a Canadian 1972 SM. 

Canadian CMVSS sticker 


Charles Morse



Delivered with every American market SM were a series of pages that contained vehicle performance data; tire load margins, passing capability (acceleration), and stopping distance. It is stated that this data was required by a government regulation called, Regulation 375. We were able to find a 1970's copy and it was a regulation associated with consumer protection. Sure enough, the regulation required that the above information be provided:

"...At the time a motor vehicle is delivered to the first purchaser for purposes other than resale, the manufacturer of that vehicle shall provide to that purchaser, In writing and in the English language, the information specified in Subpart B of thls part that is applicable to that vehicle...."

"...Subpart B - Consumer Information Items - Sec. 

375.101 Vehicle stopping distance.

375.102 Tire reserve load.

375.106 Acceleration and passing ability..."

These pages were sometimes loosely inserted into the owners manuals and so they were often lost with time. At this point, it is quite rare to find a copy. But site contributor Greg Long had one. Click HERE to see these pages.


Vehicle performance data



Per the parts book, there are a variety of differences on USA/Canadian cars associated with the steering wheel, ignition switch, and the anti-theft steering wheel lock. We have been unable to ascertain all of the specific differences, but one likely change is that the USA door buzzer function requires a special electrical input from the ignition switch, thus requiring a unique switch part number. Also, on 1973 models, the turn signals were required to be self-cancelling on USA models, thus driving more changes in the steering column area. 



The US regulators starting thinking about side impact resistance for car doors in the mid-1960's. Details of the requirements were debated for several years but eventually the Feds settled on their first requirements which were published in Federal Motor Vehicle Safety Standard (FMVSS) #214. The requirement consisted of a series of forces to be applied horizontally to the door with resulting crush depth limits. These requirements were first imposed on all cars sold in the USA with manufacturing dates after 01 January 1973. If any readers want to read through a history of early side impact requirements, do an internet search for this old document published by the National Highway Traffic Safety Administration (NHTSA) in 1982: DOT HS 806 314.

Most auto manufacturers (including Citroën with the SM) complied with the new rule by adding a horizontal steel beam inside the door. The SM parts book is not completely clear when door beams were implemented, but the parts book shows a series of door changes made in 11/72. This is a reasonable date to comply with FMVSS #214 which would have kicked in a month or two later. Below are photos of an SM door with the door beams. These photos were provided to us by a reader. 

Screen Shot 2020-11-30 at 8.07.21 AM.png
side impactR.jpeg
side impactF.jpeg
Screen Shot 2020-11-30 at 8.07.21 AM.png

Door beam as seen on a left door of a 1973 US model SM



The parts book show that the sheet metal side members (sills) that run down each side of the interior of the car were different for 1971 US models (just for US, not Canadian cars). For 1972 and 1973 models, the parts were standardized for all cars globally.


It is unclear what is different about the US side members, but seat belt attachment point changes are a viable theory. It worth remembering that very few 1971 SM's were imported to the US. 

The parts book shows that side member (item 1) is unique for US cars

bottom of page