Your hub broke due to the very common issue of hub to support interference.
Notice the shiny area just above the break.
Can you elaborate on this at all? Any specific cause, or just something to keep an eye out for? I imagine a thicker fiber washers would help push the hub back.
Edit - incorrect or broken #1 or 2 thrust, or mismatched parts.
Notice the earlier picture of a truly broken hub, it has a rough appearance. The second image is a smooth break, like it was machined in a lathe.
When first building the unit, place the empty support on the input assembly and see if there is interference.
