Dating suntour parts
Dating suntour parts
Perfects usually have a bronze or gold finish on the sprockets; Pro Compe, a silver finish, but the sprockets otherwise are interchangeable. The New Winner used the same threaded sprockets as the Perfect and Pro Compe, except for the outermost one or two sprockets, which attached at a new and different, smaller threading.In the wide 6-speed version and the 7-speed version, the outermost sprocket was threaded to the next sprocket, rather than to the body.
It was possible (and not unheard-of) to assemble Sun Tour freewheels with some of the sprockets backwards, markedly degrading shifting performance.[Bruce Dance reports: All Sun Tour freewheels are date-coded using the two-digit date code system as described on the Trek vintage and velobase sites.The oldest 'Perfect' I have is a 'Q' so probably 1974; it is also marked '8.8.8' and 'Maeda Industries' but not marked 'Sun Tour'.] First Sun Tour freewheel to hit the US market was was the "Perfect", mainly a 5-speed system, though 6-speed versions are not rare.Sun Tour was the world's leading innovator in bicycle componentry in the 1970s and brought real respect to Japan, but was eclipsed by Shimano in the late 1980s.This article describes some of Sun Tour's technical advances, and offers information on maintenance of some Sun Tour components.The result was a much lower incidence of damaging tools or freewheels.
Sun Tour also popularized the use of splined sprockets.
I used to regularly modify Regina and Atom freewheels by re-grinding the teeth of the sprockets so that they somewhat resembled those of Sun Tour or Shimano sprockets...a treatment later known as "Sheldo-Glide." [And I found that this modification only worsened the tendency of a 7- or 8-speed chain without protruding rivets to slide along.
This is now the widely available chain that engages well with the sprockets of these freewheels.
Using an indexed shifter avoids this problem; modern 5- and 6-speed index shifters are still compatible with old wide-spaced freewheels, or you could use an alternate cable routing or JTek adapter with a different indexed shifter-- John Allen.] Another advance pioneered by Sun Tour was in freewheel removal.
Sun Tour still stuck with the traditional two-prong remover design, but provided much deeper notches and a matching tool with a considerably better fit.
The splined sprockets for the New Winner had shallower splines than those for the Pro Compe and Perfect, and were not available in the largest sizes -- but it was easily possible to adapt Pro Compe and Perfect sprockets by filing or grinding the splines.