cush drive hub bearing spacer

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Oct 19, 2005
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I wonder if anyone has any experience of finding different length bearing spacers (part number 062070, item number 23 in the Norton 750 Commando parts book) in the rear cush drive sprocket hub, I have just dismantled one from a 1972 750 and found it to be 32 mm long, whereas I dismantled another of unknown origin and found it to be 36.5 mm long, the difference in length being the spacer part that buts against the bearing in the alloy hub when the two components are mated together. All of the dimensions of various hubs and sprockets I have seem to be the same. Does anyone know if there are different lengths for different years or model changes? Obviously the different lengths would require a different right side axle spacer and would move the rear wheel into a different orientation with regards to the centre position.
Is it the reduced diameter (stepped) section of the spacer that is longer or is the unreduced section longer? From your description I assume it is the reduced diameter section. I have a couple of hub assemblies in the shop, I'll check tonight.
Thanks very much for the reply Ron and the kind offer to check what you have. It is the unreduced section that acts as a spacer between the sprocket hub and the wheel hub. The reduced section that goes into the bearing inner is the same on both. It is such a small amount but 5mm could be the difference between the bike tracking straight or handling like a an early 500 Kawasaki triple with expansion chambers. I have another cush-drive bike which I could also check, but just yesterday I lent it to a fashion shop for a display.
I had two rear hub units in the shop and the bearing spacers in each measure 1.26 inch (32.00 mm). Looks like you need to mill 4.5 mm off the fat end of one.
Thank you Ron for going to all this trouble, this has been a big help. I concur with your findings, yesterday I had a look at another Commando at my friends shop and found that the spacer in there was also 32 mm. I will either machine this long one or get another of the correct length.
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