If your 2CV travels involve driving on the wrong side of the road on the continent you will know that you have to change the pattern of the head lamp dipped beam. This is a legal requirement in France.

At one time you could get kits of triangular sticky patches which, when stuck on the lens, blank out the high part of the beam. These have been replaced with stick-on clear covers which incorporate a lens to divert the beam and are available from the usual motorists' shops. Some lamp units have an adjuster on the back of the reflector to switch between driving on the left and driving on the right.

If your lamp doesn't have the adjuster there's a fairly simple DIY modification which, if you know how to change a bulb, you can make quite easily.
The dip filament of the head lamp bulb is shielded so that its light is directed to the upper part of the reflector which in turn directs the light downwards to the road (rather than straight ahead).

On RHD cars the shield directs the beam slightly to the right of vertical (when viewed from behind the lamp). This results in the beam in front of the car being higher on the left. So to reverse this situation you need to rotate the bulb (looking from the back of the unit) slightly anti clockwise. In order to achieve the asymmetrical beam the bulbs have to be fitted in a precise position so there is a lug on the bulb which locates in a slot in the reflector. The ring carrying the springs which hold the bulb in place has a tab on it which locates in the same slot in the reflector.

Carefully lift and remove the ring from the reflector. Now you need to cut a new slot. With the existing slot towards you measure 4mm to the right (anti-clockwise) of the existing slot (see photo) and using a hacksaw or small file make a new slot the same size as the original (red in the photo below). Replace the ring with its tab in the new slot, refit the bulb with its lug also in the new slot for driving on the right and you're finished. To check the result aim your dipped beam at a garage door or wall at a distance of about 10ft. The result should be as shown in the diagrams below. (It's a simple matter to switch back by removing the bulb, lifting the ring and relocating the tab in the old slot and refitting the bulb).
ADJUSTING 2CV HEADLAMP BEAM
Beams should be parallel to each other and they should also be parallel to the ground. Set the headlights to the highest position (I.e. set for minimum load in the car) by turning the big rubber knob under the right hand side of the parcel shelf (on RHD cars) clockwise.

a). Park the car on level ground facing your garage door or a wall. Carefully measure from the top of each headlamp to the ground and the distance between the centres of the lamps. Now put marks on the door or wall directly infront of the lamps, the same height as the top of the lamps and the same distance apart. Check by eye that, from above, each headlamp rim appears exactly parallel with the headlamp bar (i.e. each headlamp is facing straight ahead).

b) Turn on main beam. The top of the beams should be on the marks and the centres of the beams should be directly below the marks. If not, carefully adjust each headlamp by loosening the large nut under the appropriate lamp and swivel the lamp on the lamp bar until the correct aim is achieved then tighten the nut.

c) As a final check, dip the lights, and the flat 'cut-off' section of each dip beam should appear of equal height and very similar shape (remember that individual bulbs can vary slightly). See diagrams on this page.

d) Consider marking the main beam centres and the upper edge of the dip beam on the wall/door ('magic marker') and the exact position of the cars wheels on the floor (paint/duck tape). This will simplify resetting in the future, if required.
and adapting for driving on the right
a = height from top of lamp to ground
b = distance between lamp centres
THE WESSEX DUCKS
THE WESSEX DUCKS
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