I took apart the stem of my Motobecan Nomade and now I can't get it back together correctly. The wedge is in its proper place and the stem goes in as far as it needs to, but the fork doesn't turn with the stem. Looking down the stem tube, I don't see anywhere the teeth on the front of the wedge would catch. Could it be possible something else fell out that was needed for the wedge teeth to catch on the fork, or am I just missing something extremely obvious?
Unless you tighten the bolt on the top of the stem to drive the wedge up and sideways into the smooth inside of the steerer tube it won't grab. There is no place for the teeth to grab until you tighten the bolt. It grabs wherever you tighten it. High, low, right, left, whatever.
There should be a little grease on the wedge and the stem itself. It may stay in one place for a long time and not come apart years later. Just a thin coating here and there, not a lot of grease. It may be too slipery the first time you put the greased parts in to hold the stem in place. Don't try to super tighten the stem nut if the stem slips when you put it back in. Take the stem out and wipe some of the grease off. It is possible with enough force to dent the tube that the wedge and stem grab. I take the wedge off the bolt and put a little grease on the threads of the bolt too.