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Old 11-26-2019, 05:30 PM   #1
bdubblu
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Default Motorports folks... tell me about VALVE STEMS.

I hate to post this in general, but the motorsports thread has no activity.

I'm seeing that the faster cars are required to have metal valve stems on them. Not sure if this applies only to drag racing, or if there are any circuit regulations that are similar. But I'm going to get them regardless. What I want to know is if there are any types to steer clear of? I see a couple different styles.
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Old 11-26-2019, 05:40 PM   #2
kos
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Required? Depends on the series or discipline of driving.

I haven't bought aftermarket solid stems, the wheels I have purchased came with them (Advan, RAYS, etc)
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Old 11-26-2019, 06:40 PM   #3
willowlee
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Not related, but don't the tpms light up when you used metal stem? Something about the metal ones that only have one port. I was forced to use the rubber ones off my oem wheels when i put my volks wheels on. It came with metal stems, but the tire shop tech say he cannot use the metal ones. Don't know if he's bulll****ting me?
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Old 11-26-2019, 07:43 PM   #4
MedicMoses
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The metal ones on my Sparos were not compatable. Dealer did the swap for me, they showed me that the ones on the Sparcos didn't have the threaded part for the TPMS sensors.
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Old 11-27-2019, 11:46 AM   #5
bdubblu
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Quote:
Originally Posted by kos View Post
Required? Depends on the series or discipline of driving.

I haven't bought aftermarket solid stems, the wheels I have purchased came with them (Advan, RAYS, etc)
I believe most drag strips require them for cars in the 11's. And yes, I agree it might be dependent on the sanctioning body, but that's why I stated all this in my original post.
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Old 11-27-2019, 11:47 AM   #6
bdubblu
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SO... back to my question. Does anyone have any particular reason I should use one style or another for metal valve stems? I just want to stay away from designs that may be flawed.
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Old 12-03-2019, 01:42 PM   #7
jack hidley
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Metal valve stems are not legal for use in any race series that is likely to ever have wheel to wheel contact. If there is ever tire to rim contact, the valve stem either breaks off or gets instantly pulled out of the rim, which results in instant tire deflation.

NHRA requires screw in metal valve stems in cars running 11.99 or quicker, if the car doesn't have a functioning OEM TPMS. There is absolutely nothing wrong with using rubber valve stems at moderately high speeds. The problem here is that most drag racers are really cheap and won't have the valve stems replaced when they replace their tires, so the rubber gets old and cracks, which can then fail.

If your rubber valve stems are replaced at normal intervals (when you install new tires). There is no reason to use metal valve stems.

Most threaded metal valve stems will require the stem hole in the wheel to be drilled out larger. This will keep you from going back to rubber stems in the future.
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Old 12-03-2019, 06:54 PM   #8
Jedi03
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saw the metal ones on trucks when working on them...were pain for the most part but nice for dual axles when they poke through to the outside for checking air...
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Old 12-03-2019, 07:42 PM   #9
WhiteZombie
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What motorsport discipline?

Twisty turny stuff, rubber is just fine and likely the better choice for their flexibility. Rubber on my track car for almost 10 years, no issues. They get replaced with each set of new tires, so 2 seasons with maybe 5-10 events usually.

My buddy did a little blog post on it:
https://nomoneymotorsports.com/2019/...-wrong-choice/


For drag racing I have no clue, so definitely listen to the other guys!
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Old 12-05-2019, 09:15 AM   #10
bdubblu
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Quote:
Originally Posted by jack hidley View Post
Metal valve stems are not legal for use in any race series that is likely to ever have wheel to wheel contact. If there is ever tire to rim contact, the valve stem either breaks off or gets instantly pulled out of the rim, which results in instant tire deflation.



NHRA requires screw in metal valve stems in cars running 11.99 or quicker, if the car doesn't have a functioning OEM TPMS. There is absolutely nothing wrong with using rubber valve stems at moderately high speeds. The problem here is that most drag racers are really cheap and won't have the valve stems replaced when they replace their tires, so the rubber gets old and cracks, which can then fail.



If your rubber valve stems are replaced at normal intervals (when you install new tires). There is no reason to use metal valve stems.



Most threaded metal valve stems will require the stem hole in the wheel to be drilled out larger. This will keep you from going back to rubber stems in the future.


I think the metal stems have more to do with rotation speeds. I was just scanning more and they are required when the tire is tubeless. Sounds like the simple bead of the rubber stem isnít enough to keep it in place... and between the tire pressure and centrifugal force, the stems pop out.

Thatís what I had originally assumed, but was wondering if it was also like an SCCA thing also.
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