Schwinn Springer Fork Help - What size it this!?!?

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Section 8

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My son bought a 1948 Schwinn B6.
There is no nut on the pivot bolt in the fork.

We went to Ace hardware and tried every nut of every pitch including metric and had no luck.

The bolt threads into the fork arm so just using a different bolt isn't an option.


Does anyone know what weird size or thread pitch this is?

046.jpg
 
I took some measurements.
It seems to be 13/32 with a 20 thread pitch.

When I googled 13/32 nuts, I get Sturmey Archer axle nuts.
Does that sound right?
 
I tried a Sturmey Archer axle nut- seems to be the right size but the thread picth is way off.
 
I would take the bolt with me and go to the hardware store. They probably won't have it, but will know where to steer you to find one.
 
Wildcat said:
I would take the bolt with me and go to the hardware store. They probably won't have it, but will know where to steer you to find one.
Click to expand...

We went to Ace hardware and tried every nut, of every pitch, and every possible size including metric and had no luck.
 
MagicRat said:
Replace the pivot bolt with a standard size.
Click to expand...

The bolt threads into the fork arm so just using a different bolt isn't an option. Don't really want to drill it out and rethread it.
 
I can supply you with the telephone numbers of a couple of guys that have the stuff new and probably used for very reasonable prices, not the highest price ever sold on eBay......PM
 
Hardware stores usually only carry thread sizes that are common in household use, primarily all UNC stuff. It could be that you're dealing with something UNF. Visit a place like Fastenal. If nothing else, the folks there should be able to identify the thread.
 
Please pardon my language...

Mr. Schwinn used "jerked-off" sizes to keep you buying HIS parts.

He was a marketing genieus!
 
Schwinn isnt the only company to use 'proprietary' threading, Raleigh, various gunscrews, even gas line fittings, to name a few, are also non-hardware threads. Im sure he(they) could had given you a good, rational reason for it, but it is aggravating and your 'follow the money' idea may be spot on.
If you want to get overwhelmed by threads, just look through The Machinery Handbook, the machinists reference.
 
You could take it to a local machine shop and see if they can duplicate it. At the very least they should have a thread pitch gauge (you can buy them cheap online as well, from places like Enco) and should be able to tell you what size it is. Many times, stuff like this is a finer pitch (more threads per inch) of a common thread size. I have a Sears bike with some wacky hardware on it. Ended up at a giant Ace hardware in the next town over and they had what I needed. I don't know if this helps you any, but it can get you started...
 
It's not fine, it's not coarse.
It's not metric and it's not British Standard.

No luck at Ace, True Value, Home Depot, Lowes or any of the old school local bike shops

I walked into Fastenal and presented them the bolt. I informed them they could not find a nut for it.
They proudly told me they had, or could get EVERYTHING.

They took measurements and 2 days later, called and informed me I that I was right. No dice.
 
You need to have a machinist check it with a thread pitch gauge and mic the major dia.; while you are at it ask what he suggests and/or how much to make you one.
Some of the 'odd' propretary threads are VERY close to an existing something so once you know what it is you can see if it might be feasible to tap the fork to an available bolt without too much change to the existing thead. Buying the tap might cost as much as having a new nut made, so work with your machinist on what he has on hand.
BTW, local 'tech' schools often have machinist classes and an instructor that might be VERY helpful; and a lot of auto repair/hotrod/motorcycle speed shop guys are skilled in this stuff too.
 
My father in law is a retired machinist form the Navy and later GE. That was his suggestion too.
It seems to be a 25/64 with a 20 thread pitch. Not only is that a weird size, it's half way between coarse and fine thread.

Someone on eBay seems to have them- They won't say what it is other than "it's the right one" and they want about $30 for one nut.
 
Arggggg
I hate it when that happens.
If you arent doing a 'restore' bear in mind that the crossbolt screws into the fork and is locked down with the nut, so what you 'need' is a lock down, safety retainer for the bolt. A soft steel (hardware store grade) that just fits over it, or one you drill out the threads a bit to be a snug fit, and drilled tapped on a side (or two) for small set screws might work. I would want corresponding set points drilled into the bolt threads for the set screws to seat into a tad when you have the bolt tensioned up where you want it for free action.. All this can be done at home, with a hand pwr drill and a vise, but a drill press is nice (beg, borrow, or beer one). The nice thing about this approach is that if/when a nut turns up you are set to go with no damage done.
 
Section 8 said:
My father in law is a retired machinist form the Navy and later GE. That was his suggestion too.
It seems to be a 25/64 with a 20 thread pitch. Not only is that a weird size, it's half way between coarse and fine thread.

Someone on eBay seems to have them- They won't say what it is other than "it's the right one" and they want about $30 for one nut.
Click to expand...

That is a weird size. The $30 for one nut may seem a little high, but if you look at the fact that most machine shops charge $75+ per hour and anytime they make anything, there is set up and programming (if they are using a cnc) period where they aren't making parts, but still need to pay overhead, it makes sense. This is especially true for small run jobs. If they only sell a small amount per year, then they justify the cost by charging more. I only point this out because I work in a machine shop and people come in every day with some small project and then get angry when we tell them how much it will be. They almost always respond with "But, it's so simple, all you have to do is..." :roll:

Anyway, not to be a discouragement, but you would be hard pressed to have someone make you one nut for less than $30 unless you find a trade school or hobby machinist willing to give it a shot for learning/fun. If they agree, have them make a dozen and sell em on eBay for $20 each, lol.
 

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