Originally Posted by
purevl
The spacers between cogs on most freewheels are plastic, if you use the torch you'll melt them for sure. The cogs are also likely hardened. If anything, you might try "freezing" the body with CO2 or an air duster, but I wouldn't use anything harsher than a blow-dryer for heating. Even if you have new spacers, the burnt-on grease and plastic will be a real beast to clean off.
Have you considered just rebuilding the freewheel? If the cogs aren't worn then the bearing surfaces likely aren't either, mostly they just get really dirty. Of course that's only an option if your smallest cog is big enough for you to disassemble the body without removing it.
I can't see anything but metal between the cogs. If there's plastic there, would it be visible?
I've already flushed out the freewheel with mineral spirits and relubricated it with a 1:1 mixture of chainsaw bar oil. That helped some, but the freewheel still is really noisy. It sometimes makes a loud "clank" while under load, and on hills it vibrates the whole drivetrain enough for me to feel it in my feet. The problem is that the bearing surfaces have worn to the point that no matter how much I tighten the ring above the top set of bearings, the center of the freewheel still "wobbles." I can put my fingers inside the hole in the center of the freewheel body and wiggle it back and forth, and see the crack around the ring narrow and widen as the center moves. There also is some forward-and-back movement as well as side-to-side.
I've had some trouble with the vibration causing the ring to loosen and start unscrewing while I'm riding. It gets REALLY loud then and the ring gets loose enough to turn with just my fingers. The last time it happened I screwed it down so hard that I thought I was going to break the pins off my pin spanner, and it doesn't seem to have loosened again, but there's still considerable sideplay in the center of the freewheel body. The NOS body I have is the same model, and it doesn't wobble like that, so that much freeplay apparently isn't normal.
I'm starting to think I ought to just replace the whole freewheel, but since it's a vintage bike, I'm trying to keep it as "original" as possible, or at least use NOS replacements of the same type. But this problem has kept me from riding more than two or three times in the last three weeks, and I'm getting tired of spending more time working on the bike than riding it.