Help: Schwinn Stem Pinch Bolt SIZE

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8ball

8ball

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SchwinnStemPinchBolt.JPG


Can anyone tell me the size/pitch of a Schwinn Stem Pinch Bolt? My guess is 10mm x 1.25 pitch... that I'm hoping to buy at the hardware store wall-o-drawers (didn't see 1.25, just 1.50 @ #1 visit there, B4 posting 2U all)... but could it be a special "Schwinn only" part that I'll need to buy (eBay $5 plus $4 ship, ouch) online?

Thanks
 
take it to a place like Ace Hardware where they have those sizing things where you can screw the bolt into the different sizes until you find one that fits. Don't be too surprised if it turns out to be some odd size and pitch that they don't carry, and is not on the sizing thingy. LBS is the next step. If it is SAE consider yourself very lucky. Ummm, what's wrong with that one! :D
 
They did have a proclivity towards uncommon thread count, but I think I have found that size in the past. Ace, or maybe Pep boys, Home Depot fasteners are crap in terms of material.
 
Age?... I've got a few stems that I've pulled the same bolt out of - oldest was an Excelsior and newest was a 60's Breeze. Bolts from both stems were the same, would screw into each others stems. I've got other similar stems without bolts, so I need replacements, the two bolts I have will also fit into those other stems.

Agreed, would have to be SAE from Chicage right?... yet my metric thread gauge fits nicely into their threads at 1.25. I'm think'n Ace and HD are longshots for such a part. No Pep Boys here.

I may need to by a vintage bolt(s) yet figured it wouldn't be this mysterious. Maybe its like their old wheels/tires... only a Schwinn pinch bolt will fit a Schwinn stem.

New listing on eBay* : $14 = 1 bolt. Their description says "not available in hardware stores". The $5+$4ship mentioned earlier** is starting to seem like a deal.

* http://cgi.ebay.com/SCHWINN-BICYCLE-STE ... ltDomain_0
** http://cgi.ebay.com/Schwinn-Stem-Pinch- ... ltDomain_0
New for $16!! http://cgi.ebay.com/SCHWINN-BICYCLE-STE ... 2201499630
 
measure the diameter of the threaded section with a caliper, then count how many threads are in an inch, thats what your looking for :) in SAE

but go to the hardware store first, if they cant match it at least they can measure it and tell you what size your looking for. unless you want a used one, then just pm me your address if you dont mind a scavenged bolt :wink:
 
CCR said:
measure the diameter of the threaded section with a caliper, then count how many threads are in an inch, thats what your looking for :) in SAE

but go to the hardware store first, if they cant match it at least they can measure it and tell you what size your looking for. unless you want a used one, then just pm me your address if you dont mind a scavenged bolt :wink:
Click to expand...

I went to the hardware store to start, thinking the bolt had to be there. Went through many drawers. When asked them to measure, they said thread gauges are "misleading"... not a good sign as to their knowledge. I think they rather sell a lawn chair or gallon of paint than track down an odd bolt.

To be honest, I'd rather go with an original part, it just the prices seemed high. So I'm sending you a PM CCR. Thanks
 
Seeing this post made me wonder exactly what thread convention is this bolt? It's not metric that is for sure. It's not 3/8" - 16 UNC or 3/8" - 24 UNF either. When I measured off 1/2" and counted the threads I counted 10, making the pitch 20. 3/8" - 20 is BSF or British Standard Fine.

I found a supplier for them: British Tools and Fasteners. 3/8 - 20 x 1 LG. is 60 cents.

http://www.britishfasteners.com/index.p ... how_detail
 
Ancient thread, never answered here. I'm looking for the same info, a 10 mm 1.25 nut seems to fit the bolt but a little loose. I believe it is a actually a 3/8-20 tip bolt, which is hard as heck to find? 3/8-20 works out extremely close to M10-1.25, maybe 0.3 mm off on thread pitch over the length of an inch, and a fraction of a mm smaller diameter. I finally found some 3/8-20 BSF (Britsh Standard Fine) bolts on a site for vintage British cars. I'm hoping the threads are not too "fine" in terms of depth and they will work. I'm wondering if I could carefully tap the stem to M10-1.25 without weakening the threads too much.
 
BS are not the same as UN. BS uses a 55' thread angle, UN is 60'. BS has rounded roots and crests as well.

1.25mm is 20.32 tpi. So, it may start...but it is going to get tighter and tighter the longer the thread engagement length is. Eventually seizing.

You can get taps and dies for 3/8" - 20...but, I don't know where you an get a bolt/screw outside of having a machinist make you one.

I'm stupid busy right now...but, when I get a chance I'll grab one of my schwinn stem bolts and check what it really is.
 
Rusty one... thanks. I just got my shipment of 3/8-20 BSF bolts, they thread into my old Schwinn stems and tighten down like a dream, much better than my last couple of original bolts that have some thread damage.

I can't imagine that tapping the old ones would make them fail, these old stems are pretty bullet proof unless you bend then inside out. I've got one that somebody literally twisted open so that the jaws are open about an inch and a half and the top of the stem is twisted 90 degrees sideways... but it didn't break. And, "over time?" These are 50 and 60 years old already. :)

Anyway - For those looking for an alternative to paying $10 to $20 for a pinch or binder bolt, if you can find someone selling it - these work!

Pros: I bought four 3/8-20 BSF bolts from Moss Motors for $17 shipped. Quick shipping, better price, and they work great.

Cons: They are black coated steel, and the hex heads are slightly wider than original Schwinn bolts, but not as thick. They will not look at all original.

The heads may polish up nice and not look too bad. I'll post pix if I do that.

If you're just fixing up a rider/beater, and the old bolts have crummy threads or rounded off head, these make a great bargain replacement.

There is no mystery. 3/8 inch 20 TPI is the size.
 
A whitworth (BS) bolt into a UN hole will be a bit sloppy. A UN bolt will bind in a whitworth hole.

213.png


The breakage comment was in regards to the broken Schwinn stems I've seen have been broke across the threads. So, I was just theorizing that removing .020"-.030" of material may lead to some higher level of failure than the current rate of failure.

Glad it worked out...but, I don't think it is an optimal solution. Sourcing 3/8" - 20UN bolts would be preferable.
 
I appreciate the advice, but are you sure the stem uses UN rather than BSF? There seems to be no slop, seems to fit perfect. I'm not "disputing" here, I'm asking the sincere question, I'd be fascinated to know if it's UN or BSF. I actually went through charts like you're showing, trying to figure this out, but I don't have the means of checking thread angle. The threads do not seem to have the flats shown in the chart, they seem to have sharp peaks.

My guess was that Schwinn at some early date was following the example of or even using parts from British manufacturers and continued using the BSF up until the 70s as a proprietary decision to maintain continuity. Schwinn always did seem to like to use some proprietary parts you had to get from Schwinn only - like their old 26 inch rims & tires.
 
xray said:
I appreciate the advice, but are you sure the stem uses UN rather than BSF? There seems to be no slop, seems to fit perfect.
Click to expand...
Nope...can't be sure until I check them out myself :grin:. Just following the logic train...sometimes it misses a stop. There are plenty of examples of using oddball tpi on UN threads in the US back in the day (and still today, but oddball UN and metric now)...but, not a lot of examples of the evil Whitworth being used here.
The threads do not seem to have the flats shown in the chart, they seem to have sharp peaks.
Click to expand...
The pics show exaggerated roots and peaks. Your fingers would quickly tell you if the threads actually came to points.
My guess was that Schwinn at some early date was following the example of or even using parts from British manufacturers and continued using the BSF up until the 70s as a proprietary decision to maintain continuity. Schwinn always did seem to like to use some proprietary parts you had to get from Schwinn only - like their old 26 inch rims & tires.
Click to expand...
Possible...I just don't see it as likely. I've seen claims that the pivot bolt on a schwinn springer is whitworth as well...I won't believe untill I see it, however...I could very well be wrong on both parts.
 

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