Could someone do me a favour and measure how far their bottom ball joint protrudes above the Sierra upright. Oh its a maxi ball joint sorry.

The Sierra upright needs re-drilling to suit the Maxi ball joint (you may know this already).

I do and I have but I've a feeling its not been done proper deep enough. The thread only just comes level with the top of the nut and now putting the wing stay on its not going to be right. Just wondered as the nut seems a right dobber but I think its the right one.

Mine look like this:
i used a tapper reamer from Axminster tools.
HTH

David

Surely ream it untill the top of the taper is nearly level with the top of the hole

Cheers for the photo Dogwood. It appears that the length of the threaded part is equal to the thickness of the upright that it goes through which makes mine some 7.5mm short. That sounds about right. Cheers very much.