Got dragged to the beach yesterday with the family but back on it now!!!!!
Thanks for all the replies, much to think on.
I think my rear sprocket is aluminium. Looking at the flange on the tyre side of the sprocket, that is a little dirty so whilst the belt is close to that side it is not really hitting that flange, leaving the dirt in situ. There are wear marks on the teeth but interstingly not equal wear marks along the length of the each tooth. There is more wear on the outer end of the tooth than the inner end of the tooth. Can only think this means more belt pressure on the outer end of the tooth.
The hub (or what I think you mean as the hub) looks silver to me so fits in with my car being a 2012 car. Yes it has a minilite type wheel and yes there is black dust a plenty.
On the BB sprocket, having jacked the car up a bit higher, there does not seem to be any belt wander but in fact the belt looks to be very tight up to the outside edge flange as the inner face of that flange is highly polished by belt contact. At this end the belt is not wandering at all imho as the dirt build up on the BB sprocket is too much to indicate belt wander.
I ran a straight edge between the sprockets as best I could and the contact points all seemed to make contact equally. If out of alignment I would have expected an air gap between the straight edge and the sprocket at one contact point.
So from your comments and observation today, I think the uneven wear on the rear sprocket teeth says that there has been some alignment at the rear to try and make the belt wander at the BB sprocket away from its outside flange. But it is now not sufficeint, if it ever was.
So it seems I need to consider a steel rear sprocket upgrade and to look at the mounts on the BB if I wish to get a realiable and quiet running belt alignment. Not comfortable with playing with swing arm adjustment on a DIY basis yet. Guess I will need to live with this squeal a while longer until I can sort the items needed.
