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Schwinn experts: 83 Shifter boss screw size

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Schwinn experts: 83 Shifter boss screw size

Old 07-17-17, 08:03 AM
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howellhandmade
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Schwinn experts: 83 Shifter boss screw size

The project is restoring a trashed 1983 Voyageur (non-SP) for my wife. The DT shifters were so corroded and wrecked that it seemed a good opportunity to change to bar ends. I modified the Shimano cable stops to fit the unusual (to me) bosses, and now find that the screws that fixed the shifters are also unusual. M5 is too big, as is 10-32. M4 is much too small. Anybody know what size these screws are? I could just tap out to M5 but thought I should ask here before doing something irreversible.

IMG_1463.JPG

Last edited by howellhandmade; 07-17-17 at 08:17 AM.
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Old 07-17-17, 08:21 AM
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brian3069 
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The oddball Shimano shifter bosses use a 4.5m screw. Tapping it out to 5m is probable your best option.
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Old 07-17-17, 08:34 AM
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howellhandmade
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Thanks, that's easy enough. Certainly easier than making a 4.5 screw.
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Old 07-17-17, 05:45 PM
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I had the same issue on a 1985 Centurion Ironman bicycle... I had the bike shop tap it for the more common 5.0m metric threads used on later model Shimano (and others) shifters. Easy peazy. It's a shade tree mechanic's level job, but I didn't know anyone who had taps for metric threaded holes.
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Old 07-17-17, 08:58 PM
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These are 4.5mm x 0.75mm thread. This is, in fact, a standard metric thread type. If your hardware store can't get them, try McMaster-Carr.


Source: Sutherland's 4th Edition
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Old 08-23-17, 03:10 PM
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What is the "A" dimension (stub diameter) of the Simplex bosses?
The Campagnolo and early 80s Shimano A type is 9mm.
Measuring it off a pic on the internet I get 3/8" for the Simplex?

Last edited by avhed; 08-23-17 at 03:19 PM.
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