I'm a reasonably good bike mechanic. But so far, I've never had a freewheel apart to the level of cogs and spacers, though I've removed cogsets from bodies to clean and lubicate pawls and bearings.
I've been wanting a particular ultra-six freewheel setup for one of my bikes, but wide-range ultras are rare and very expensive. Corncobs, on the other hand, seem to be a lot easier to find. Would it be practical to buy a narrow-range ultra--say a 13-14-15-16-17-19--take the cogset apart and reassemble it with the cogs I want, taken from a couple of 5-speed Suntour freewheels? My understanding, quite possibly wrong, is that 5 and 6 speed New Winners, both ultra and regular, use the same cogs and bodies--that the only difference is the spacers. Also, that cogs from 5-speed Perfect or Pro-Compe freewheels can be installed on a New Winner body with ultra spacers.

Am I right or wrong about that? What kinds of frustrating problems am I letting myself in for?

Well, for one, in several threads discussing Ultra 6 freewheels, some people have mentioned some difficultly shifting accurately a wide ratio Ultra 6, i.e. when attempting to shift only one cog it skips to the next one. My Ultra 6 is a corncob like your example and it shifts pretty well, though the 16T cog can be a little elusive sometimes.

I've not had any trouble with the shifting on my three ultra spaced Suntour freewheels. All of mine have a low cog of 32 teeth, and a high of 13 teeth, so a very wide range. I have two six speed setups, one with a Sachs-Huret Eco Duopar and down tube friction shifters, and the other with a Campy Rally (2nd Gen) and Suntour barend shifters. My final ultra is a seven speed, I shift it with 7 speed Shimano Sora STI brake lever shifters.

If I miss a cog with the downtube or barend shifters on the six speed setups, it is user error, or I hit a frost heave or crack in the road while shifting! The seven speed index shifting is basically flawless.

Jon,

You are on the right path about changing the spacing on Winner and New Winner bodies. The spacers are the key. The bodies can even handle seven speed set ups with the correct end cog.

In my experience, however, some cogs like to be removed from some Winner bodies, and others do not. I'm not certain why this is the case except to guess that Suntour used some sort of thread lock, and in some cases the application was very generous compared to others. I really don't know.

Unfortunately Perfect and ProComp cogs cannot be installed on a Winner body. However, Perfect and ProComp bodies can be set up with Ultra sized spacers. Thus a more affordable ultra spaced freewheel can be constructed, with the cogs we need to match the hills and climbs of Northern New England. I can help with this if you'd like.

Did you have much frost this morning? We had a few patches.

IIRC, this is an ultra spaced Perfect.

I run a wide range Ultra 7, zero problems other than the big steps. I use a ultra chain.

I think Sheldon put up a detailed article about freewheel building, have you seen that?

I can't say anything about mixing and matching different SunTour freewheel cog styles, but my only experience with a wide-range Ultra was not good. My Trek 610 1984 originally came with a Helicomatic cogset in 14/28, and this was narrow-spaced, and did not shift with any precision. Even allowing for the ancient tooth design (not even a SunTour chamfer much less a smoothly grabby Shimano claw or a key-like Sachs ARIS), it was very poor. I've used the same Shimano 600/6207 derailleur with normally-spaced Reginas (similar ancient tooth), with much better results. YMMV especially with a Suntour tooth.

Another factor may be the use of a narrow chain with the narrow cog pitch. If you can do this with a 9-speed chain rather than a 5/6 speed, that might help you get good operation. With a chain who's gap is wider than the cog, the chain might over-shift just because it isn't narrow enough to sit squarely on the cog. I don't recall testing this before I sold the wheelset, however.

Good luck!

By the way, the Yellow Jersey site used to offer a SunTour freewheel mixing guide, with which one could cook up one's own. If it's still available for download, I bet that would help you.

Let me add, I do run SRAM 8 speed chains on all three of my ultra spaced freewheels. Generally, I find that the more expensive the chain, the better the shifting performance. I also find that a yearly cleaning and use of a quality chain lubricant (I personally like Chain-L), makes a big difference as well.

That looks like a wide six-speed Perfect. Note the extra depth to the body at the small-cog end....

The pastor mentions something which I'd like to expand on. A certain large minority of Suntour freewheels are very difficult to crack the bottom cog/locking-ring. This can be overcome by using TWO of the Pedros cassette lock ring tools, plus oversize PVC cheat bars. Even with the latter tools some freewheels are so stuck that it threatens to blow the Pedros tools -- that's where I stop. Amongst my 50 worst/most-neglected freewheels I had only a 4% failure rate when using the pair of Pedros tools plus 3 foot long cheat bars.

The reason I mention all this if that often it is necessary to pull apart quite a number of freewheels in order to come up with the required rings and spacers to build a custom Ultra-6.

There was only one New Winner body, but the cogs varied by model (5, 6, ultra-6, ultra-7), as well as the spacers.

To do an ultra-7, the cogs would be, in NW parlance, from outer (sm.) to inner (lg.): U-L-T-R-R-A-A (I like that one's sound!)

To do an ultra-6, they would be: S-T-T-R-A-A

To do a normal 6, they would be: E-X-T-R-A-A

For a five-speed, they were: E-T-R-A-A.

To complicate it a bit, a 'P' can substitute for a 'T' cog. There were several different spacers.

Edit: and none of these was designed to index, as the cog spacing can vary by one or more tenths on any given freewheel....

My head hurts.

Exactly. And we haven't even discussed the ramifications of the seven different kinds of spacers (4 ultra, 3 regular) yet.

Which is why they had a cookbook.

Gentlemen-- This is a lot of info. I'm a big fan of suntour drivetrains, but I've never had the courage to crack a freewheel open. I suppose I don't have anything technical to add to the discussion here, but I thought I'd mention that I just finished refreshing an '83 Trek 614 for my wife, and it has the suntour "mighty 6" (14-16-19-23-27-30) freewheel. I live in the mountains of western NC, and I have to say, I think this is a fabulous setup (combined with the "Mighty Tour" 28-45-50 crankset). My wife said she felt like she could ride it up a tree if need be, and the shifting --with the addition of a new SRAM chain-- has been flawless so far. Does the "mighty 6" freewheel use one of the bodies that you guys are discussing here?

Where would one obtain this useful volume?

Yellow Jersey seems to have a 16-page manual available for $3.95 here.

Theirs has to be one of the most confusing websites I've ever visited, but I'm sure that has been mentioned before

As I said in the first place.

As for the site, yes, but ... it's done by bike guys, old ones.
NOT by web guys.

^ Yes, I gather that. Not everyone is a web designer... I know I'm not. Posted mainly to provide a link. I couldn't find one for download, but it could still be there...

Part deux,
The Wrath of Cogs

Sorry, it was just too easy.

Suntour had a shop wall chart for the New Winner freewheels. Easier to visualize the combos stated above. I have a jpeg of it somewhere, will try to find it and post it.

It can be downloaded from here:

https://www.velobase.com/Resource_Too...rNewWinner.zip

That's the brochure not the wall chart/cog rack. But that'll do.

There's also a chart in Sutherland's 6th Edition, pages 4-42 and 4-43

Perhaps this would help:

That's the one! Thanks John.