Alternator tensioning rod "lock nut"

[awolff280sl]

Does anyone know the size and thread pitch of the lock nut labelled "1" in this photo? Thanks.

[waqas]

Hi Andy,

I can get you the dimensions tomorrow.

However, this so-called locking nut it is not really needed. The nut "2" rotates around the long bolt, but inside the cinch clamp. This cinch clamp is attached to, and is tightened by, bolt "3". I found out the hard way that the correct procedure for adjusting the belt tension is to first loosen the cinch bolt "3" before making any adjustments on the nut "2". (and then re-tightening bolt "3" to lock the adjustment)

[awolff280sl]

Hey Waqas, thanks but don't trouble yourself now. I was contacted off the forum by a kind and knowlegable soul who provided the information: M10 x 1.5 - 17mm hex.
From an intuitive standpoint, I have also assumed that the lock nut was unecessary, for the reasons you cited. Part of this assumption was no doubt also related to my prior difficulty tightening the alternator belt in the face of the rotary compressor. But now that I'm using a longer belt and thus have relatively easy access, belt tightening was no problem. So I've decided to ditch my assumption that the lock nut is MB redundancy. I've been wrong about that sort of thing in the past.
Also, in addition to loosening bolt "3", I loosen bolt "7" prior to adjusting my belt.