I have used Z bends and clevis's for many years in large gliders and in my powered R/C's. ...never a single problem.

I always anneal the push rod wire with a small torch to soften it before I do the Z bend, thereby avoiding the overstress weakening problem due to too sharp a bend. I believe that the very sharp bend is a critical problem.

Anneal by heating to dull red color, and then using the torch less and less to allow the wire to cool slowly - say, 20 or 30 seconds.

If for some reason you didn't trust the strength of annealed metal, you could reharden it by heating to a dull red color and cooling by dipping in oil. (Hardening has not been necesary for me... execpt when I do landing gears)

Richard Ranney