Yep... that was exactly what I was going to do next. There is an excellent engineering firm nearby that I have used for many things and they will be my first port of call. Plus I've being thinking it may not be a case of simply one bent leg but the perhaps the whole caboodle might actually be twisted somewhat. And, as you say, it's not summat to be resolved at home in a garage. See above - & besides I'm not entirely sure Brancato engineering is still going.
Now I've calmed down a little I revisited this measurement and it is still out but nowhere near as bad as I first thought - 1mm tops. Not sure if you are aware but the swingarm pivot is mounted in a pair of eccentric casting that are themselves fitted into the frame. Rotating these castings moves the pivot backwards/forwards & therefore the complete swingarm to allow for adjustment of the chain tension. Initially I was measuring from the split in the casting up to the mount hole but this time I measured from the bottom side of the actual pivot up to the bottom side of a bolt in the mount hole. And using a much better stick it has to be said...
I've now got the straightened swingarm back from Maidstone Motoliner so yes it was bent. I've just rough fitted it along with the shocks and the LHS is still short of it's top mount but by the small amount I remembered it always was. This is quite manageable and most probably down to manufacturing tolerances... ho hum. Difficult to get comparable photos - first is when it was bent and the second as it is now.
One thing I noticed when re-assembling is the underside of the swingarm showed chain wear witness marks and I'm not quite sure why as I haven't seen that before. Perhaps the chain was running slack, although I'm always checking it's tension, or, as I'm now thinking, it was the result of the pothole that bent the swingarm i.e. the shocks go to full compression and the bottom chain run angle becomes much tighter. I can't remember at what point it happen but I also recall the chain itself requiring a large adjustment and then more frequently as is the case when a chain has reached it's end of life.
So reassembly all went well although I have done a couple of things differently. I fitted a brand new chain and for the initial slack adjustment have tried the 'all three axes in a line' theory i.e. shock top bolts not in place and have the rear axle, swingarm pivot & output shaft all in a line. Secondly all the shock mounting bolts, apart from the left hand top one, weren't threaded all the way through their mounts. I'm not sure whether they should be but have decided to use longer bolts to allow a locking nut on the other side. Additionally, the bottom bolts are M10 1.5 pitch but the top ones are M10 1.25 fine pitch... who knows why
