So I've finished mounting a filter under the swingarm and thought I'd post back pics for the next person who has such wanton desires, as I couldn’t find any on the forum. it was very fiddly, especially getting the oil pipes connected, but at least i still have the full toolbox for much needed tools! below some pics
1. the bracket i made from some 50x3 bar. note the weird angles to get the filter mounted so the filter in & out pipes clear the frame, and sloping back a bit for more tyre clearance. i tapped threads into the bracket to ease mounting.
2. the bracket and filter head, mounted on what I assume are spare mudguard mounts on the frame - this 61 super rocket has a shorter mudguard and those mounting points were doing nothing else. note there's a good 8mm below the swingarm and the filter sits just above the stop point for the centre stand and can be easily changed with the wheel on.
3. the mounted filter with the wheel back on. has good clearance.
4. the plumbing. i cut the return line and it was plenty long enough for both new sections. for the filter out rubber pipes turned too tightly and risked crimping, so i used a fancy 120 degree speedflow bend, but I'm not too happy with this as I mutilated it a bit to fit. so one day I may redo it with a piece of copper tube (shaped a bit like the wire in the last pic below). the problem is protrusions on the gearbox which forces the pipe to veer inward (to the centre line) then turn tightly up to face the oil tank return
5. top view of the plumbing. its tight. if my gearbox adjust further back i hope it still all fits.
6. if you really want to make a similar bracket, a plan. don't drill the holes until you make sure it fits your bike as there is little room for error. and make sure you have a plan for the plumbing - that bent wire is the starting shape for some tubing from the filter out (3/8 od) to the tank return.
if you think i've done something likely to me cause trouble please let me know!!