Check your ESA nut

[norvin998]

Hi Ian.
It was much easier than I had anticipated. I was dreading the operation in case I damaged the brittle mainshaft threads and of course only the broken end is visible.
It came loose with a centrepunch and a few taps of the hammer and I had to use stilsons to wind the remains over the slightly distressed threads on the end of the shaft, sounds more brutal than it was in reality. Once the hex has gone the spring tension is released and the cylindrical part is loose on the shaft.
Good job i hadn't loctited it.
Les.

 

[b'knighted]

Thanks Les,

Does the inner end of the nut lock up against the shouldered end of the splines?
Also does the failure scatter little springs up the road or does the paranoid rider just need to carry normal tools, hammer and centre punch, a new nut and a big elastoplast?

Cheers,

 

[norvin998]

All this happened about 4 1/2 years ago so I can't remember every detail. I can't remember removing lots of chopped spaghetti from the primary drive but I suppose its possible for the springs to escape if the nut loses its hex, then theres nothing holding the washer and ring plate in place. I renewed the primary chain as there was no way of knowing if any debris had got between the sprocket and the chain, I didn't want to risk a future snapped chain.
As far as I can remember, the hex and washer tighten against the cam sleeve. I think the problem happens because there is often an unsupported area of the nut between the end of the shaft and the hex portion of the nut (which bears all the pressure from the ESA springs). If the mainshaft was longer and reached flush with the end of the nut, this probably would not happen. Perhaps later shafts were longer, I don't know.
I think the problem could be metal fatigue, for peace of mind, the answer would be to replace an original nut with a new one.
Oh dear, I normally refrain from mentioning technical things as someone always corrects me. Ok, i've got my tin hat on - fire away.
Les.