Originally Posted by
70sSanO
You can use a UG/HG 7 speed freehub and run a 12t HG and a lockring. You don’t need remove any of the external threads.
The caveats with any Shimano freehub swap are the rear flange thickness, the dust seal diameter, and the obvious one, cones. The RM30 and Dura Ace 74XX are the odd spline/attach ones. And I believe the latest 11 speed.
You can cheat a little if you have a deep recess hub (thick flange) and you install an 8/9 speed thin flange. It won’t reduce it nearly as much as a 7 speed, maybe a couple mm’s, but you’ll need a spacer to make the large cog work.
John
Thank you, yet there are a number of important details which I must learn more about. I just now contacted a dealer selling NOS LX FH-M560 7-speed freehub UG/HG bodies and who claims they fit SOME other Shimano hubs, so I asked if his freehub bodies can fit and work on LX FH-M570 hubs and that question is now pending a reply from the dealer. Apparently UG bodies were threaded with two different threads for lockrings but Shimano parts pages include no information about either of those two threads. Then I have other questions about, as you mentioned, seals, cones and other parts where information about them is often confusing, incomplete, wrong or unavailable. And so, this project could take some while to get to grips with.