G1nko

I rescued an '87 Trek 330 from the trash bin. I've spent the last 4 weeks derusting and rebuilding everything on this bike and hoped to get it on the road today, but found the chain skips under modest load in the two smallest sprockets on the freewheel; the four lower gears are all fine.

The bike is equipped with Suntour shifters which can be either indexed or friction; currently they're indexed. It has a Suntour Alpha four notch 6-speed freewheel. The dropout spacing is 130mm.

Visual inspection doesn't reveal much. The sprockets look a little worn, but not badly. There are no broken teeth. The pulleys on the Alpha 5000 derailleur are worn, but again, not particularly badly.

NOS 6-speed Alpha freewheels on eBay are over $100; crazy money as far as I'm concerned. 7-speed Alpha freewheels seem to be readily available.

So here's the question: what's the best way to deal with this?

Can I disassemble the freewheel and flip the sprockets around? I've never done this but read it's one possibility.

Can I use a different brand of 6-speed freewheel? It just needs to screw on there, right? The notches are only for removal so a Shimano 6-speed should work fine.

Or should I consider a 7-speed Alpha? I'd lose the indexed mode, but it should work fine as a friction shift, right?

fietsbob

current F/W have adopted the hyperglide like tooth profile and sell for pretty cheap.

If you own 2 chain-whips , most freewheels are held together by the high gear cogs screwing on
and the last few on splines . so you can take the cogs off if you wish.

hold whip on a splined cog and unscrew the smaller ones , with the other.

new ones are cheap enough , It would be for recreation, this project, a money loser, time wise.

FBinNY 

Sun Tour freewheel sprockets are not flippable. The splined ones have beveled tops and sides and won'r work right when flipped, and the threaded ones simply cannot be flipped.

Your best bet is to remove the freewheel, soak it in a bucket of mineral spirits or other petroleum solvent, taking it out nd spinning once in a while to work all dirt and dried grease out. Then drain and oil with a clingy oil like Chain-L or Phil's. Some ST freewheels have an oil hole drilled in the inner body and exiting at the threads, or you can simply add from the tip, and rotate to work it in until it drains out the bottom. Allow to complete draining and it'll be good until your next major overhaul.

Otherwise, any 6s frewwheel of the right gear range will work.

Pibber

yup, Suntour freewheels are pricey.

Are you using a new chain? Did you properly size the chain? You may need to check your RD's high/low lockouts for proper positioning. Check shift cable tension, the like.....

Some Shimano freewheels of that time have the screw tooth design which will require a different chain if you're using a chain that came with the original Suntour drivetrain.

I can't speak to the reversal of the cogs on the freewheel; i haven't attempted anything like that, yet. Switching to 7 on friction shouldn't pose any problems with Suntour DT shifters. Mine seem to have pretty wide gearing options.

If you've got a co-op near you, you might be able to source a chain or freewheel there that would be appropriate.

G1nko

I already removed the freewheel and cleaned it so its nice and shiny, so that's not the issue.

I put a new SRAM PC830 chain on it, so that's not it, either.

Looks like its either going to be 7-speed Alpha or Shimano 6-speed.

As far as it being a money loser, so far I'm in about $50 for bar tape, a chain, two derailleur cables, brake pads, and some blood, sweat, and tears.