[Jac Mac]

This diagram explains it for the two types of nut, since the cobra originally came with wire wheels that I assume employed the Rudge ( Female- LHT/RHS ) nut, I could understand why everyone assumes that all centerlocks could be the same, however when you actually check the two principles out the above diagram is correct.

Now to add another curve ball, why do some have more problems than others with knock off's coming loose? I think it has more to do with wheel offset, camber and castor angles, and particularly scrub radius and how the cars weight bears on the center nut. For example-imagine a cobra with some positive camber ( wheel/tire out at top), in this situation the center nut will have more load imposed on it than if the car had 0° or negative camber.

Personally I dont have a horse in this race-yet, but one day before I do I intend to jig up a hub & male nut assy in the lathe so that I can spin it in both directions while changing the effective load inputs from side to side by means of a link to the tool post. Only thing I wont be able to do is simulate the effect that brake heat and different rates of expansion might have on these components . I KNOW that can cause a lot of grief from personal experience. Fat Boy, you should have been around that day- steel centerlock wheels on a male alloy hub with RHT/RHS--LHT/LHS, the self tightening process was definitely in action with that setup-- when the hub assy expanded during the race the center nut ( knockoff ) self tightened, when the hub cooled and shrunk it effectively increased the tightness of the center nut to the point where we had to destroy/cut the nut off by drilling/splitting it off the hub. These wheels were used as a set of wets & had given no problems prior when used as wets, but on this occasion the car had made a pitstop with a puncture during a dry race and as no spare was available the [not] so clever crew fitted the wet type tire/wheel.

BTW, look closely at T. Buttricks pics, both spinner( knock off ) & wheel center spoke are drilled for the safety wire.