Bicycle Mechanics - damaged threads on freewheel hub

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ellens.joshu
05-12-09, 11:48 PM
i was reinstalling the freewheel on my rear hub today after replacing a spoke. It became cross-threaded and did some slight damage to the threads on the hub. i've been tryin to re-thread it on correctly but am having trouble as now it keeps wanting to cross-thread because of the damaged threads.
anyone have any advice on how to get this threaded correctly? can i repair the thread anyway?
this is an original shimano hub from my all original 1975 Sekine SHT so i really really really don't want to have to scrap it.
thanks
mrrabbit
05-13-09, 12:38 AM
I sometimes use a box knife...starting in and working out...usually able to fix threads until the last one on the very outside of the hub. It is always difficult to salvage the STARTING thread. That's the critical one.
It would be cool if you could find or make a tool that is a snap ring consisting of inner threads that are the correct pitch for chasing outwards. I bet someone already has one - much like the inner snap-in thread chaser for crank arms.
=8-)
If you really, really don't want to scrap it, then you will have spend a really, really long and tedious time with with a tiny jewelers file to clean up the threads well enough to get a FW started on it.
The real key to this will be carefully threading on the freewheel so that it catches the original threads and not the newer "threads" the cross-threading created. A FW ittself is pretty unwieldy for this, and you can't really see in there to see what is happening. So, instead do it with an old BB lockring. Same size and threads, and they are small enough that you can see and feel exactly what is happening.
File is up as best as you can. Then carefully chase on the BB ring a few times and then take it off. Then carefully thread on the FW. This is a doable task if you have the desire to save the hub.
jim
JohnDThompson
05-13-09, 11:58 AM
i was reinstalling the freewheel on my rear hub today after replacing a spoke. It became cross-threaded and did some slight damage to the threads on the hub. i've been tryin to re-thread it on correctly but am having trouble as now it keeps wanting to cross-thread because of the damaged threads.
anyone have any advice on how to get this threaded correctly? can i repair the thread anyway?
this is an original shimano hub from my all original 1975 Sekine SHT so i really really really don't want to have to scrap it.
thanks
A "thread file" ought to clean it up quickly:
http://www.cicle.org/wordpress/wp-content/files2.jpg
operator
05-13-09, 07:04 PM
i was reinstalling the freewheel on my rear hub today after replacing a spoke. It became cross-threaded and did some slight damage to the threads on the hub. i've been tryin to re-thread it on correctly but am having trouble as now it keeps wanting to cross-thread because of the damaged threads.
anyone have any advice on how to get this threaded correctly? can i repair the thread anyway?
this is an original shimano hub from my all original 1975 Sekine SHT so i really really really don't want to have to scrap it.
thanks
Who cares.
Think about it this way. Freewheel rear, shimano hub modern double walled rims can be had for less than $50 USD MSRP. If you can't spend a little bit of time trying to thread it on correctly just buy a new wheel. Time is something you'll never ****ing get back.
Sometimes people can have pretty good reasons for investing a little time in a part or two.
j
Who cares.
Think about it this way. Freewheel rear, shimano hub modern double walled rims can be had for less than $50 USD MSRP. If you can't spend a little bit of time trying to thread it on correctly just buy a new wheel. Time is something you'll never ****ing get back.
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