360 engine vibration
Well, after another 4 hours of theory, what if's, measurement, head scratching etc I think Ive found the cause of the damper wobble and it turns out we are all correct.
Yes it didnt ring 100% correct when the damper was run up in the lathe and was true that the damper was at fault. However I believe it is the damper at fault. But not for the reason of a loose or misaligned outer ring due to rubber deteration.
Its late again and I need to get to bed, I'll post a video and reasoning tomorrow but the summary is I believe the damper has had a defect when it was manufactured. Where the hole and rear face have been machined parallel to each other but slightly wonky and hence causing the wobble when mounted on the crank. But when gripped on the outer of the shaft where the oil seal runs the damper runs true. For the damper to be made it must be machined one one side then taken out of the lathe and then turned around, if misaligned and we only need a 5 thou misalignment here it will cause the 40 thou wobble on the outer edge. Photos and video to follow tomorrow.