rsg

What is the thread size of the Schwinn rear Japan Model J cog/hub from a 1970's Junior Varsity, 24" wheel 5-speed??

Just got a NOS replacement hub for the bike but the threads on the new hub are slightly damaged at the lead threads & they need to be re-tapped so I don't strip the cog or hub? Anyone that knows this answer please reply here. Thank you.

T-Mar

I'm not into Schwinns but it's hard to imagine them using anything other than English (1.37o" x 24TPI). VAR and some other companies did make them, so you may be able to find one at an older, larger, LBS. Buyer one would be very expensive. However, provided the first couple of threads are OK, you may be able to clean them up with an English bottom bracket lockring, as both use the same thread.

rsg

Is there any tap/die sets that I can use to fix the hub??Who makes them??

zukahn1 

+ Nearly all Schwinns from this era are threaded standard English /Schwinn. You should take a little time to see if you can actually get a something with English threading to screw on there otherwise yes a better established shop should be able to rechase the thead. Also as a last option these hubs are pretty common and easy cheap to get if your up for relacing a wheel.

T-Mar

Also, since it is a male thread, the other option is to buy a 24 TPI thread file. Some of the better retail chains do carry them but they usually carry sets, which are quite expensive. An industrial supply house should have individual thread files, which are fairly reasonable at about $15. If you have to, you can order one through Sears. They're much cheaper than the dies.

jacksbike

I have never heard of the possibility of rethreading a rear freewheel hub and have never ever seen a tool made for it. Headsets, bottom brackets, pedals, dropouts , yes, but rear hub, no. Anyhoo, agreed that it is standard british threading.

T-Mar

Dies are avaialble for rethreading English and Itlalian theaded freewheel hub shells and bottom brackets but they're hard to find and often expensive.

One alternative for odd size male threads are thread files. You just buy the approximate pitch (TPI) and can use it to clean up any diameter male thread with that pitch. Thread files look like a file with rows of thread sections (i.e if you could unwrap a short section of a tap and lay it out flat, you would have a thread file). You mate the file into a clean section of the thread you want to repair and advance the file into the damaged section with short strokes like a normal file.

Another alternative are the NES thread repair tools which look like a pipe cutter with two adjstable cutting jaws. They're more versatile in that they adjust to fit any pitch within a specific range but they also work over only a specific diameter range. They're also not good for very short thread lengths, like freewheel threads on hub shells. They're about twice the price of a thread file. Both tools have their advantages and disadvantages, depending on the particular application.

rsg

Are you sure the Model J freewheel thread is 24 TPI?

Scooper

Couldn't you verify by using a ruler and counting the number of threads? Even if you've only got, say, a half an inch of threads, if there are 12 threads over a half inch that's 24 TPI.

T-Mar

If you want to be sure, buy a thread pitch gauge set. They're typically under $10. I think I've even seen them for sale at Walmart.