Extra Long Valve Core

Who knew... the other day I pre tripped a tractor that had a cold flat tire, and wasn't sure why, so I checked the valve core and this long thing was in there. It wasn't actually the problem, but I'm not sure if I could have replaced it with a standard length one, is the whole valve designed for a short or long core? Seems like it would have to be...

They don't even seem to be widely available, and I'm not sure if there's a size range for particular tires. Anyone else using them? Guess I'll ask someone in the parts department if they know anything about those.

Otherwise, I have a tubeless tire valve remover/installer that might allow me to switch out the whole unit with a standard core included, if it ever comes up that a long core is bad and the standard one won't work (at least I can get valves for sure). Just depends if I can reach it with that tool on a truck (and have nothing better to do at the time).

This time I used my bead blaster air tank to make the tire inflatable, and that pinpointed the puncture. Sometimes the bead unseats from a leaking valve too, which would make it field repairable, except now I'm finding nonstandard equipment in there.

 

Oh, I guess looking inside a valve stem would answer my question, for the most part. There's nothing in there for the core to actuate, just a hollow tube. Most likely the long and short cores are interchangeable then. None of the Chinese sites that list the long cores give much of description as for why they exist. Just that they can be brass or stainless steel.

I was thinking more of a valve extension, where the long core depressor makes contact, and that is what's being extended in the opposite direction (like there's an inner and outer core working in series). Here, it just seems to be flow related as for why they get extended on the other end (some of those say they are filters). Could be for a TPMS somehow, I doubt they plug into anything on the other end though, or at least air is going to flow in and out from the base of that extension, not through it (so the valve itself should function the same either way). Best guess anyhow, I couldn't look inside the particular stem I pulled that one out of.

Actually, now that I've compared notes, I think the solid kind are designed for valve extensions only, and this one just happened to find its way inside a valve stem instead... That's probably why the extended cores are only available on the wholesale end, to be included in valve extensions which are sold retail (someone must have parted one out and reused the core there).

 

Looks like they're using the type with a spring in the installation video (where they remove the core and inject beads through the stem). Then a document for those says "in order to reduce the possibility of valve leaks, the use of a long valve core or valve core filter and a metal valve cap is recommended". I'd guess a longer core prevents beads from clumping inside the valve stem. Not sure why they are said to reduce leaks though (I doubt the beads are small enough to get stuck in the core).

Actually, it looks like a FAQ for dyna beads says "the purpose of the filtered valve core is to prevent a bead from getting caught in the valve core mechanism. So if your valve stems can accommodate the filtered valve cores, then by all means go ahead and use them".

Maybe the end of that type of core is V-shaped to catch beads, and the spring action deflects them back into the tire. I think they recommend caps also because the longer one might lose torque with an unbalanced design and unscrew when the wheel is rolling (the shortest cores are said to be for high performance applications, like race cars, with wheels spinning fastest).

The spring action/filter types are sold as parts retail, so those would be the bead deflectors, and the solid kind I suppose for valve extensions (or the extra long one pictured to the left is both). I had the valve extension type in there with no spring, but it could have been used as a bead blocker too. None of them seem to be described anywhere they're sold (besides that they are long, well duh, but for no apparent reason). That's kind of a trend with tools and such, I guess they figure more people buy something if there are imaginary uses for it (I don't know, that could work either way too).

Okay, I kind of made this up, because now I find that the old Schrader valve had an external spring, and the newer short type has an internal one. Oddly enough, it looks like those would deflect (or at least block) balance beads too, so maybe that's why the long design is still around and recommended there. Ahead of its time?






See, I thought the visible spring was in addition to the concealed one, for some kind of double action (it's possible, yet the spring pictured up top is more bare bones, so I guess that says it all).



Personally, I'm going to stick with the short cores as needed, because valve caps get in the way, and don't prevent leakage when a core is bad or loose, or it's that the caps wear out too, I've found (except the flow through extension caps I'll leave on there). At least the concealed spring cores are considered higher performance, and are less likely to rattle loose. I don't think a balance bead can unseat the cup in that direction, maybe checking pressure could suck one into it, but that would be audible, and could be plunged with the gauge chuck, or blown out with inflation. Numerous reviews are saying those long cores are leaking with beads in there (some comments here too).