Yanmar 2gm lost drive

[Saddletramp]

On my Yanmar 2gm there is a what looks like a nut on the end of the splined shaft that holds the flange on.

I have not been able to get the flexible coupling out yet as I can not move the plates far enough apart ( shaft anode hitting p bracket)

The nut looks like it needs a special tool to do up. A peg spanner, of some sort.

My question is why did it come undone? Anyone any advice on the tool required, is it left hand thread etc. /forums/images/graemlins/confused.gif

 

[earlybird]

It is a L/H nut IIRC, with a recess to clear an o-ring. You should be able to get a hexagon socket on it. It may have loosened through not being tightened enough in the first place. You could try Loctite Nutlock for re-assembly but the threads will need to be thoroughly cleaned.
Add, further thoughts!!, for locking, is part of the nut punched into a recess at the end of the shaft? no need for Loctite in that case.