One of the parts most often screwed up on dumpster bikes are the freewheels. And, older 5-speed units are difficult to find, and not getting any easier as time goes on. So, I've been collecting any 5 and 6-speed clusters I find, rebuilding them, and keeping them in a box. You never know when you'll need one of those vintage things. And when you do, having it cleaned, greased, and ready to go saves alot of time.
Recently, my search has yielded a pair of rare finds - two straight-block, 5-speed clusters (I guess everyone else calls them "corncobs"). You don't come across these everyday. They would be perfect for an older racer (with 120mm spacing) that has a shot cluster. Or, a single speed conversion that would allow fine tuning of the gear ratio.
On the left is an Atom, 14-15-16-18-21 The right is a SunTour Pro-Compe. 14-15-16-17-18
It takes a little bit of work to disassemble, clean, lube, and get back together. But I think they are worth it. And, when work is slow, it keeps me occupied!
I hate to ask but how do you take one apart. I have done a lot of wrenching but I have never disassembled a freewheel. I have always flushed good with solvent and flooding with oil. It has always worked for me.
You unwind the cap that's got the two holes and the manufacturer's stamp.
Open 'er up and begin the fun.
I've ended up removing broken pawls and springs on ones I've done.
They usually only work for a short while on a reduced number of pawls.
Long story short, you insert the proper freewheel remover tool from the back (the tool being held in a vise), and tap off the lock rings. All freewheels I've taken apart are reverse thread on the lock ring. Tap it clockwise until you can spin it off with your fingers. Once you've got the lock ring loosened, take the freewheel and hold it over a plate or dish to catch all the ball bearings as they fall out. The unit then comes apart. It's sort of tedious till you get the hang of it. After that, rebuilding clusters becomes routine. I've even made new springs when the originals were just shot - the Atom in the picture has two home-made springs.
With the SunTour, it uses the 2-notch removal tool. And that tool doesn't fit from the back. So I had to make a "holder tool" so I could loosen it's lock ring. Took a little effort, but got it.