Safety and Crashworthiness

UPDATED

12/2020

BUMPERS

 

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. The parts book shows that most of these changes were implemented in 7/72, which might include a few very late 1972 cars. In practice however, it seems that these changes were on 1973's only.

 

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

(A) STAINLESS BUMPER BLADES

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:

(B) BUMPER STIFFENER

 

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). 

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).

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

(C) FENDER SECURING BOLT

There was a change to 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. 

(D) FRONT RUBBER STRIP

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. See the Wikipedia entry on automotive bumpers here.

SIDE VIEW MIRRORS

 

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. 

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

BRAKES

 

All USA and Canadian SM’s received hydraulic components called leak finders (two per car). 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 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 “sets” 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. DS models received leak finders mid-year 1971.

 

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

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. Note that the architecture of the Citroën brake system does not easily lend itself to be fully “dualized”.

 

According to the parts books, USA/Canadian cars had a different pressure switch on the brake pedal unit to warn of low incoming pressure at the brake valve. 

Disassembled leak finder

Leak finder location in a brake schematic

DOOR HANDLES AND LOCKS

 

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. 

 

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

SAFETY EQUIPMENT DATA PLATES

 

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 or 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. 

Yellow plate used on cars manufactured in 1971

Orange plate used on cars manufactured in 1972/1973

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 vague reference in a document that suggests this sticker may have been required as of 1971.  A reader provided a photo of a CMVSS sticker on a Canadian 1972 SM. 

Canadian CMVSS sticker 

STEERING WHEEL AND STEERING LOCK

 

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 the specific differences, but one likely change is that the USA door buzzer function requires a special electrical input from the ignition switch. 

DOORS

 

The US regulators starting thinking about side impact resistance for car doors in 1968. 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 only 2 months later. Below are photos of an SM door with the door beams. These photos were provided to us by a reader. 

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

STRUCTURAL

 

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

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