well you at least need a bit of thread poking out of the nyloc, otherwise it'll come off. Later model tie bars had a hole for a split pin to stop the nut from coming off
I reckon the design is for the outer washer to go over the thread, and then when the nut is tightened it should be hard up against the stepped shoulder on the bar. However, the nut is the only caster adjustment, so the wheel alignment bloke usually adjusts the squish on the rubber to even them up and take up any bend on the bar etc.
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did I tell you that I won a
trophy?