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TPMS - lock nuts on caps?

maillemaker
Explorer
Explorer
I purchased a TPMS system for my RV.

The sensors are screw-on caps. Not flow-through. When you install them, they come with a lock nut you are to tighten up against the sensor cap.

The problem here is on my dualies I cannot get a wrench in there to secure the lock nut. The other problem is you can't add air while the cap is in place, so it would be impossible to remove the inner dually sensors to ever add air if needed.

Is the lock nut really needed? Is this an anti-theft mechanism or is there an actual danger of the cap unscrewing?

Worst case is I guess you lose a cap, or it loosens and you slowly leak air (which you would then detect).
1990 Winnebago Warrior. "She may not look like much but she's got it where it counts!"

10 REPLIES 10

maillemaker
Explorer
Explorer
I don't want to fool around with extension tubes.

I was able to reach in through the gaps in my hubs to attach the sensor caps without the jam nuts.
1990 Winnebago Warrior. "She may not look like much but she's got it where it counts!"

StirCrazy
Nomad III
Nomad III
you can buy extension tubes for your inner duals that put the cap in a better place for adding air. thoes might be what you are looking for .

Steve
2014 F350 6.7 Platinum
2016 Cougar 330RBK
1991 Slumberqueen WS100

maillemaker
Explorer
Explorer
This is the unit:

https://smile.amazon.com/gp/product/B07QNV8T31

You will have to watch their little video to see the nuts (more properly "jam nuts"). It's at the 4:38 mark.

Basically, you thread a small nut onto the valve stem, then screw on the sensor cap, then use a wrench to back off the jam nut until it binds against the bottom of the sensor cap. This locks the nut and sensor to the stem. In order to remove the sensor cap, you must first loosen the jam nut with a wrench.

On my rear dualies, it's impossible to get a wrench (or your hand) through the wheel cutout to work a wrench against the jam nut.

I thought about going to a tire shop and having them unmount the outside wheel and install the sensor on the inside and then put it all back together, but then if I ever need to add air I can't as I can't remove the sensor.

Based on what I'm reading here the jam nut is just anti-theft so today I'm going to install the caps with no jam nuts.

https://en.wikipedia.org/wiki/Jam_nut
1990 Winnebago Warrior. "She may not look like much but she's got it where it counts!"

Lynnmor
Explorer
Explorer
maillemaker wrote:
The entire unit with 6 sensors only cost about $120 or so.


Could you tell us the brand and model of the system? I have no clue what you mean by "locknuts." TST systems have a cap that just slips, reducing theft by slipping without the special tool. Maybe you are calling a cap a locknut.

maillemaker
Explorer
Explorer
OK the consensus seems to be these are just anti-theft to make them difficult to remove without a tool. I'm going to ditch the lock nuts.

I don't think these things are high-theft. The entire unit with 6 sensors only cost about $120 or so.
1990 Winnebago Warrior. "She may not look like much but she's got it where it counts!"

wa8yxm
Explorer III
Explorer III
The Lock nut is normally an anti-theft device.
The Sensors are usless without the matching receiver..
In theory a low theft item.
Especially on dual tires where they can not even be seen
HOWEVER. that said.. You have different sensors than I had.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times

scbwr
Explorer II
Explorer II
I found the locking nuts to be a pain, so I took them off. It makes it so much easier when you are checking/adjusting tire pressure, and I monitor tire pressure frequently, especially before hitting the road after the MH has been stored for awhile.
2012 Newmar Bay Star 3302
Blue Ox Avail
BrakeBuddy Advantage
2015 Malibu

"Get busy living, or get busy dying."
Andy Dufresne, The Shawshank Redemption

Garry_Gayle
Explorer
Explorer
I use a crowsfoot with an 6" extension to tighten my inner locknuts. Get your inner valve stems changed so they angle thru the hole correctly

naturist
Nomad
Nomad
They are only anti theft. Leave the locknuts off.

2oldman
Explorer
Explorer
maillemaker wrote:
Is the lock nut really needed? Is this an anti-theft mechanism or is there an actual danger of the cap unscrewing?
I believe it's anti theft, but it was such a pain when airing up I took them all off. I seriously doubt they are a hot item in the pawn shop.
"If I'm wearing long pants, I'm too far north" - 2oldman