Strain on valve stems with air pressure monitors [message #342416] |
Wed, 10 April 2019 06:30 |
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RF_Burns
Messages: 2277 Registered: June 2008 Location: S. Ontario, Canada
Karma: 3
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So I installed air pressure monitors on my tires last year. TST unit with 6 monitors included for $199 which seemed to be a good deal. So far has worked excellent.
Then I read the monitors should be installed on all steel valve stems. Mine are rubber with a metal sleeve which seem to be rated for our use up to 80psi (I believe). So I Googled a site with a centrifugal force calculator to measure this. The sensor weights 0.77 oz according to the TST site and the distance from the center of the wheel to the center of the sensor is 6.5". So at 700rpm (approx for 65MPH on my LT225/75R16 tires) the calculator indicates 4.4Lb-force.
That seems like alot! maybe I'm using the calculator wrong, but I then tried several others with the same result. It works out to be a 100 times increase in weight force.
Has anyone had issues with the sensors causing issues? Have you changed to all metal valve stems?
Thanks,
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC. 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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Re: Strain on valve stems with air pressure monitors [message #342420 is a reply to message #342416] |
Wed, 10 April 2019 08:23 |
JohnL455
Messages: 4447 Registered: October 2006 Location: Woodstock, IL
Karma: 12
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Are these the add on screw on type? Realize that those have the schraeder depressed so it can't do it's job and you are relying on the threads and the seal there to retain air. Not a fan of add on's that can cause faults.
John Lebetski
Woodstock, IL
77 Eleganza II
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Re: Strain on valve stems with air pressure monitors [message #342421 is a reply to message #342416] |
Wed, 10 April 2019 08:55 |
rjw
Messages: 697 Registered: September 2005
Karma: 4
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Senior Member |
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RF_Burns wrote on Wed, 10 April 2019 07:30So I installed air pressure monitors on my tires last year. TST unit with 6 monitors included for $199 which seemed to be a good deal. So far has worked excellent.
Then I read the monitors should be installed on all steel valve stems. Mine are rubber with a metal sleeve which seem to be rated for our use up to 80psi (I believe). So I Googled a site with a centrifugal force calculator to measure this. The sensor weights 0.77 oz according to the TST site and the distance from the center of the wheel to the center of the sensor is 6.5". So at 700rpm (approx for 65MPH on my LT225/75R16 tires) the calculator indicates 4.4Lb-force.
That seems like alot! maybe I'm using the calculator wrong, but I then tried several others with the same result. It works out to be a 100 times increase in weight force.
Has anyone had issues with the sensors causing issues? Have you changed to all metal valve stems?
Thanks,
I have a TST TPMS with flow through monitors (sensors). I have Alcoa wheels and metal valve stems. The sensors are a fairly tight fit in the wheels which probably help to keep them from moving around.
I installed them in July 2013. It's been over 40,000 miles and almost 6 years and the only issue I had was at random intervals, some of the sensors would drop off and not display. The solution was to add a repeater. That fixed the problem and I have no issues.
The system works great. I would not want to be without TPMS.
Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com
Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.
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Re: Strain on valve stems with air pressure monitors [message #342526 is a reply to message #342416] |
Mon, 15 April 2019 08:03 |
jhbridges
Messages: 8412 Registered: May 2011 Location: Braselton ga
Karma: -74
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Senior Member |
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Bruce, the tire doesn't start and stop each rotation - it rotates at a constant speed. The motion of any spot on the tire accelerates and decelerates >relative to the ground<. Thus at the top of the spot's rotation it is traveling faster than the coach while at the bottom it is traveling slower than the coach >relative to the coach<. Its rotational speed is unchanged. It will induce a bit of a Doppler shift in the signal transmitted by pressure sensor relative to the receiving antenna on the coach. So far, I've not seen this to be a problem.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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