Widsith

(I meant to post this in the Bicycle Mechanics forum, but put it here by mistake instead, so I've reposted it there. However, this is an old freewheel on a vintage Univega, so I'd still appreciate any thoughts you folks have on it too.)

I've been trying for several days to get the small cog off my Suntour Pro-Compe freewheel without any luck. I tried a freewheel vise and chainwhip, but couldn't budge it. All I was accomplishing was dragging my workbench around the garage. So I took it to the LBS and they couldn't get it off either. They're usually pretty good at getting stuck components loose, but this time it was no dice. One of the mechanics told me he tried so hard he was afraid he was going to break his tools before he gave up. I brought it home, left it soaking in a bowl of Liquid Wrench overnight and still ended up dragging the workbench around the garage again. So I've had it soaking in the Liquid Wrench for a few more days, and tonight I'm going to pick up some PB Blaster on the way home from work and see if that does any better. I've also bought one of those little pencil-thin butane torches to see if heat will help break it loose.

Any advice on how to proceed? I don't want to damage the cogs, because they're in great shape and the whole point of this exercise is to remove them from the worn-out freewheel body and put them on the NOS body I bought to replace it. Should the torch be applied to the cog, to the freewheel body, or both? How hot should it be? (The torch is supposed to reach 1500° F.) Do I need to try to remove it while it's still hot, or after it cools? Should I use the PB Blaster on it before or after heating it? (I assume that stuff is flammable, and don't want to start a fire!)

Any advice will be appreciated.

bikemore 

That is more then I have ever done. Have you tried with an extended lever?
I have a Park Chain whip (the type with the round handle) and then I have
a pair of gas pipe nipples. One 1 1/4 inch the other three quarter (not positive
on size) connected together. Makes about an 18-24" extension. Put the larger
pipe around the handle. Works wonders in a lot of cases. Not sure about yours.

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.

Widsith

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.

evwxxx

Suntour freewheels are not uncommon, or expensive. Just get a new one!

Widsith

My chain whip is the Parks type with the flat handle, but I think I'll try to find a piece of pipe I can fit over it and give it a try.

Widsith

That's sounding more and more like the best option all around.

purevl

Most of the time the plastic spacers are a dark grey which can look deceptively like metal especially if dirty. It's a possibility, of course, that you don't have any plastic spacers, but most every freewheel I've ever taken apart has had them.

I don't understand how the body could be in such bad shape if the cogs are still good, those bearings are only in use while you coast, after all. Perhaps the cogs have already been replaced at some point or the body has been rebuilt incorrectly or something.

There's on other option to try but it will require some ingenuity. You can put the wheel on the bike, shift into the lowest gear, secure a chainwhip or length of chain on the small cog and use leg power to break it loose. It's something I would do with the bike mounted on a trainer or with an assistant or two, but you should be able to generate plenty of torque in that fashion. It's actually an old touring trick from back in the days when one might need to replace a spoke on a freewheel-equipped rear wheel with a minimum of tools. A length of cable and a short piece of chain can fit handily in a tool kit and when affixed to the frame permit you to remove the freewheel cogs without removing the body.

Good luck!

Widsith

I've wondered the same thing. I bought the bike used, and it clearly has seen a lot of hard use, but when I overhauled the hubs, BB, etc. they were in excellent shape and obviously had been well-maintained. The chain has no wear that I can detect with a Park chain wear indicator, so it likely was replaced not too long before I bought the bike. I suppose the cogs might have been replaced, too, but they look like they've been on there for a very long time. I was surprised at how little wear there was on the teeth.

I may try lashing a chainwhip to the bike and get my sons to help me try your suggestion.

Seasnarf

Under the ring ( bearing race ) that you tightened with your pin spanner there are usually several shims of varying thickness. These are how the original bearing clearance is set. I have had good luck by just removing the thinnest shim. Alternately, you might try rebuilding with the guts of your replacement freewheel. I love keeping old stuff working.

T-Mar

+1 on the longer lever. Also, sometimes it is easier to tighten a cog than loosen it. Tightening it may break the friction, allowing you to loosen it.

Widsith

Nope, no shims under there. If there ever were any, they've already been removed.

jgedwa

Let it soak in penetrating oil for a while. Maybe a week. Bang on it with a hammer firmly a few times every now and again. Soak again. Try to remove it with a long extension. And repeat.

Or just buy an NOS one for $20. I am stubborn, so I would go the above route.

jim

Seasnarf

Wow. I'm surprised there are no shims. If it had shims originaly and they've been removed, tightening the bearing race should lock the unit up. They can be hard to see. I'd be surprised if the manufacturing tolerances would allow it to be assembled with random parts right out of the bin. I applaud your effort.