First attempt at pattern Dow dampers was that the valve did not quite reach the oil. Used more oil but still not happy.
Second attempt was an auto jumble purchase of a complete kit - yoke, extended bushes, complete dampers etc. No longer have either but memory is that the second set had longer rods. Worked fine on compression but stll had the clang on extension, tried more oil, thicker oil but it still happened and I thought that perhaps what was happening was that on extension, oil was being drawn through the 2 drillings in the fork shafts from the space between the bushes.........
Anyway I really wanted them to work but could not get them to work as I wanted so first my local motorbike enthusiast engineer converted the A10 fork bottoms to accept A65 damper rod internals, this worked fine but splitting mudguard and some corrosion to studs resulted in me transplanting a complete set of damper rod forks from a 1968 Lightning which was a lot more expensive unfortunately.
Has anyone sen or used the Webco dampers in second photo. Sorry about the quality. Looks like they screw in to replace the bottom bush retaining nut. Seen in the 1961 Webco catalogue.