Originally Posted by
stronglight
I was told the failure points were not at the clamp areas (which is where I would have expected) but rather at the rear of the stem - just fore of the expander bolt and quill column.
I've yet to see an AVA cracked at that juncture, and I will not believe it until I see one.
Originally Posted by
stronglight
[CENTER]
Is it not ironic that this example on sheldon Brown's website
shows no signs of any weakness or potential failure? 
The only thing remotely likely to crack on that example is the expander area, just above the slot. AVA slotted the stem
twice, as opposed to once, allowing someone to conceivably flare the bottom of the stem out enough to start a crack. The square cut at the end (as opposed to a round hole) doesn't particularly help. This is an early-mid '70s stem:
She's already cracked:
Double slotting (also seen on Sheldon's stem). Get a load of the angle that the cracked portion is sticking forward:
...which can result in this:
I've always thought that the clamp mechanism on these were prone to failure as well though - the thin design of the example I show above pinches and deforms the bar clamp more then it assists. Sheldon's stem (a much older stem, probably from the early '60s) doesn't even come close as a candidate for it. I also have a later '80s AVA stem that appears to rectify the beefiness of the clamp:
...and the slot, which is now a single opening at the rear with a triangular taper at the top - supposedly for strength, but those sharp edges are still stress risers:
-Kurt