Putting it back together it goes bearing, external truarc, at least two shim washers, internal truarc.
Manuals are here...
http://projectmopedmanual.info/Manual_HTML/motobecane.html
specifically this one, look see page 37-39 for pictures and description...
http://projectmopedmanual.info/Manuals/Motobecane/Motobecane-repair-manual.pdf