Fork crown spindle rotates when tightening nut

[DerekAJS30]

Trying to reasemble the front forks, when tightening the fork crown centre nut (bottom one) the entire centre spindle rotates and the nut will not do up. It was tight but I assumed the spindle was welded in so could not rotate. Looking at the parts manual it seems this is more than one part, with a circlip. So now i'm confused. I have several concerns:
Why is it turning?#
Is it safe if i can do the nut up
and how do I stop it turning so as to be able to undo/tighten and adjust the ball races.

I cant find anything in the workshop manual. Any help and experience greatly appreciated.

[clive]

That spindle is an interference fit in the bottom yolk with a circlip to stop it slipping out. I assume your 57 bike has 11/4 stanchions. My guess is the bottom nut is binding on the end of the thread. Happened on one of my bikes and I had a large washer made to fit under the nut. Truth is it did not really solve things as i think the reason it was bottoming out was that the frame cups that hold the steering bearings had fretted and worn in the past. Although i was able to tighten up the bearings it did not stop the steering being a bit vague.. i. Would suggest you need to see why that spindle is turning and if the nut was bottoming out, why? If it is loose bearing cups others have i think used JB weld to settle them.

[DerekAJS30]

Thanks Clive. It turns out the new stainless nut is binding up very badly despite heavy lubrication. I ran it up and down to check before assembly and it was fine - now its not !! The old nut has no issues. I will purchase a normal nut. I'm having second thoughts about stainless, particularly where it impacts on older parts. Looks good and doesn't rust but if there is a critical thread involved i'm not sure about any benefit.