[SOLVED] Does anyone know what thread size a tire valve stem and the Schrader valve are? Solved

replying to Wally, Verlyn Foster wrote: You can obtain a T handle valve stem tool at any auto parts store. These have the capability of internal and external thread repair as well as an easy out for broken valve cores.

I finally bought 4 and put them everywhere so I could always find one of the damned things.

I think the outer thread is nominally 0.303" or 7.7mm by 32 TPI. A

Mike, in Nottingham UK

replying to Wally, Jim B. wrote: By my measurements it is 19/64 (7.54 mm) x 32 threads per inch. I am also seeking a tap & die for such an animal. Jim B.

replying to Wally, Jim B. wrote: By my measurements it is 19/64 (7.54 mm) x 32 threads per inch. I am also seeking a tap & die for such an animal. Jim B.

Metal valve extenders are a cheap source of the male and female threads if you have the tools to adapt them. Otherwise 5/16-32 UNEF does fit, though loosely.

This explains Schrader and Presta valves.

It gives 6 atmospheres as the maximum pressure for Schrader and 15 for Presta, and 0.302"-32TPI as the Schrader thread.

This shows which bicycle thead standards are metric and which are inch.

-jsw

replying to Larry Jaques, Ted Crum wrote: The thread specification for the Schrader valve has almost been lost to history by now. Of course, it is not a metric specification, 32 TPI is not metric. The actual thread is 5/16-32 NEF, with a 80% thread height. Wait, you say, the major diameter isn't 5/16. NO screw has a major diameter equal to it's nominal size - look at a bolt with an unthreaded shank; the threaded part is always smaller than the shank. I bought a 5/16-32 die a while ago and used it to cut Schrader-compatible threads on a .305" rod, and it worked perfectly. There are a lot of bad-fitting parts on the market now, made by offshore firms without the institutional knowledge of archeological bent to get this right.

replying to Larry Jaques, Ted Crum wrote: The thread specification for the Schrader valve has almost been lost to history by now. Of course, it is not a metric specification, 32 TPI is not metric. The actual thread is 5/16-32 NEF, with a 80% thread height. Wait, you say, the major diameter isn't 5/16. NO screw has a major diameter equal to it's nominal size - look at a bolt with an unthreaded shank; the threaded part is always smaller than the shank. I bought a 5/16-32 die a while ago and used it to cut Schrader-compatible threads on a .305" rod, and it worked perfectly. There are a lot of bad-fitting parts on the market now, made by offshore firms without the institutional knowledge of archeological bent to get this right.