Thread size of clamp in style valve stems?

[60ch]

My thread pitch gage set has no match for the thread on these valves. Does anyone know what this thread pitch is? The thread Diameter is .469".  This is an Acme TR-40 valve.

Thank you, Terry

Edited August 8, 2023 by 60ch
added Dimensions and valve information (see edit history)

[Frank DuVal]

It is probably metric. The inner threads of a Schrader valve are metric, invented in France, like spark plugs.

[cudaman]

Maybe there will be something useful in this document.

 

 

[Frank DuVal]

Hmm, maybe not metric on these external threads, although 26 TPI is .977 thread pitch in mm. Must be a proprietary thread size, unless it is 12.25 mm with 1.0 thread pitch.😁 

The .406" is 13/32" and the 28 TPI is common here, just not the 13/32" dia. And .406" is 10.3 mm. Although sometimes you see weird stuff, like the Corvair flywheel to crank bolts are 11/32 - 24. Don't look at Lowes.... 🤣 or even McMaster-Carr!😲  

 

The .302" dia is no easy fraction. Not 19/64" or 5/16", somewhere in the middle. 32 TPI. And it is 7.67 mm. This is THE standard Schrader external thread size still in use today, .767 mm x 7.747 mm thread pitch.

 

And the internal, aka Schrader core, size is .209" - 36 TPI, 5.3 mm x .706 mm thread pitch.

Edited August 8, 2023 by Frank DuVal (see edit history)

[viv w]

I was told 26TPI (thread per inch) was used on motorcycles, so maybe this is cycle thread?

[30DodgePanel]

Could it be that the gunk and the damage to the threads is contributing to no match?

 

[Dandy Dave]

You may have to ask to be sure, but these look like they will work to clean up the threads on your tire valves. https://www.ebay.com/itm/184047600698?chn=ps&var=691741210174&_trkparms=ispr%3D1&amdata=enc%3A1yFYYulmQRyiwQDacOTmO4Q2&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=691741210174_184047600698&targetid=1584571731043&device=c&mktype=pla&googleloc=9004833&poi=&campaignid=20394831596&mkgroupid=152460476358&rlsatarget=aud-1314496317827:pla-1584571731043&abcId=9317319&merchantid=115328085&gclid=CjwKCAjw8symBhAqEiwAaTA__OAEAHpTK4Gfn38ols1wMZVXUz7FiEFAVJcjzT6pp6ZNUh2KXufOYRoCjLgQAvD_BwE

[60ch]

Thanks to all that replied to to my question. Each reply added to the final answer. The .469" diameter converted to millimeters is 11.9 mm. I counted the threads on a 1/2" section of the thread and it came out to 13, multiplied by 2 = 26 TPI.

Checking the Ebay auction site showed a 12mm X 26 tap size as one of the 3 taps available for these tire valves.   Thanks again, Frank Duval, Cudaman, viv w, 30DodgePanel and Dandy Dave