Agentnelson,

That's the right size allen wrench, the deal is that you need 2 of them, one on each side of the spindle shaft. The screws in the shaft may have been Locited (kinda like glued) to the spindle. Don't be afraid to twist really hard to break it loose. It's already broke.
Last resort, dremel tool and cutting wheel.

Dave / Choppersrule