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PostPosted: Fri Aug 14, 2020 10:26 am 
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Joined: Sun Jan 23, 2011 4:54 am
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Gents,
my kids use a a 0-25/30psi gauge for kart tires- usually we run 10-15psi, and a 1/2lb makes a difference on these guys..

Last weekend my gauge got dropped and when I picked it up, the needle was sitting on 5psi. dammit!
Just to get through the day, I thumped around on the side of the head until my gauge agreed with one borrowed from a friend. (It's already in the trash!)

Before I invest in another gauge, I'm curious if the digital ones are less susceptible to damage from dropping. my car gauge stays in/near the trailer at the track and isn't really subjected to the beatings, but our kart gauge gets drug all over the place into and out of hot pits 10 times a day.. no matter how careful you are, things are gonna happen with that much travel.

So my question: Are the decent digital gauges (Longacre or equal) better at taking small drops and whatnot than the analog gauges? would an oil filled analog gauge also help, or is that a moot point when its being banged around?

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PostPosted: Fri Aug 14, 2020 11:33 am 
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I would expect digital gauges to be more shock resistant. And I can relate from sad personal experience that when I dropped my friend's expensive oil filled gauge that it was ruined. :oops:

Short of being dropped I'd expect a mechanical gauge to last longer and of course it can't run out of battery!

PS - I'm the kind of person that likes to annoy others by using a pencil type mechanical gauge at the track. Resolution is poor but most of them (mine anyway) are quite accurate and don't seem to mind being dropped. Resolution not good enough for 10psi kart tires!


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PostPosted: Fri Aug 14, 2020 1:09 pm 
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I keep one of those pencil gauges in the truck as a backup for checking trailer tires, but that's about it. I collected a bunch of them several years ago and tried them all out at one time.. there was at least a 20psi variance in them!! I guess if you get a decent one, they might be OK.. but I just couldn't trust anything in my pile of them when one had air leaking out of it, another read 20psi low, etc.

I certainly don't expect bulletproof reliability out of any gauge after you give it a beating, but my current one was dropped less than 6" and moved 5psi. dang. guess it's time was up.

So my asusmption is that the digital gauges have a pressure transducer in them and they are more reliable after impact than the 100yr old bent tube with a gear on it.

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PostPosted: Sat Aug 15, 2020 5:22 pm 
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Location: MILWAUKEE
I dropped my analog gauge and it was stuck at 5 psi. Too cheap to buy a new one; I opened it up ( that was the hard part) and tweaked the pressure tube to get the reading to be correct.
Worked fine until a crewman left it on the ground in from of a tire and you guessed it "crunch".

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PostPosted: Sun Aug 16, 2020 3:36 am 
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Found that the non-liquid gauges didn't hold accuracy despite not being damaged or dropped so we switched to the Longacre liquid units and they hold up well. We do carry the pencil gauges but you have to keep them lubricated or they won't last or stay accurate. Must be why they made 3-in-one oil.

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PostPosted: Sun Aug 16, 2020 7:42 am 
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Matt93SE wrote:
I keep one of those pencil gauges in the truck as a backup for checking trailer tires, but that's about it. I collected a bunch of them several years ago and tried them all out at one time.. there was at least a 20psi variance in them!! I guess if you get a decent one, they might be OK.. but I just couldn't trust anything in my pile of them when one had air leaking out of it, another read 20psi low, etc.

I certainly don't expect bulletproof reliability out of any gauge after you give it a beating, but my current one was dropped less than 6" and moved 5psi. dang. guess it's time was up.

So my asusmption is that the digital gauges have a pressure transducer in them and they are more reliable after impact than the 100yr old bent tube with a gear on it.


The digital gauges have a solid state transducer which itself is pretty bulletproof. If they get a bad connection etc they would just typically die. So a cheapy one is probably much more likely to "just die" than to have a calibration issue. I say this with very little direct experience with digital hand held tire pressure gauges but a fair bit of experience with sensors generally.

The Bourdon Tube analog gauges are shock sensitive, IMO, because of the tiny gears and linkages required to amplify the small motion of the tube to the large motion of the indicator.

Many, maybe most, of the pencil gauges are garbage. But they are so simple that there isn't much to go wrong or go out of calibration. I got a bunch of US made 0-50 psi ones years ago from the defunct Trak Auto and they are amazingly accurate and durable. I tested my collection a few years ago against a Longacre analog gauge and threw away the ones that weren't within ~1psi in the 25-30 psi range. Resolution is poor, would not use for a kart or formula car. Plus the funny looks at the track are worth something. :)


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PostPosted: Mon Aug 17, 2020 4:48 am 
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Thanks, Al. I had envisioned similar with the digital gagues, which is why I think they'd stay a little better on cal vs. an analog one. I used to "calibrate" load cells w/strain gauge tension mooring monitoring systems for ships. While these were looking at 100-200 tons of tension, they were all solid state stuff inside, and they either worked or they didn't. We had to pull the load cells from the fixing and then tested them against a reference using a 250T hydraulic ram (hand pumped of course!). If they were within tolerance, they were reinstalled. If they were off, it was significant and obvious due to the low reading and the fluctuating numbers as the strain gauge was breaking down inside the unit at full load. So the were simply replaced instead of calibrated.

I suspect a digital pressure gauge would have a similar solid state transducer of some sort inside that either works or it doesn't but doesn't drift based on a small impact.

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PostPosted: Mon Aug 17, 2020 12:15 pm 
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I think you are correct.


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PostPosted: Tue Aug 18, 2020 6:48 am 
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Joined: Fri Mar 28, 2014 11:26 am
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Location: Jackson, MS
To protect the gauge we took a beer can huggy (the thick foam rubber kind) and put a hole in the side of it so the hose could be run through it. The gauge lays in the bottom of the huggy. Very protected. I have a gauge I have have had for over 30+ years and it is still accurate within 2 lbs. It just works. :shock:


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PostPosted: Tue Aug 18, 2020 10:37 am 
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Dragonfly wrote:
To protect the gauge we took a beer can huggy (the thick foam rubber kind) and put a hole in the side of it so the hose could be run through it. The gauge lays in the bottom of the huggy. Very protected. I have a gauge I have have had for over 30+ years and it is still accurate within 2 lbs. It just works. :shock:

Built back when people gave a damn, and likely not in CHI-NA. ;)

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