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I'm sure you all know this... but check those torque wrenches!

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I finally got around to calibrating my torque wrenches today after four years of use. I'm ashamed to admit that they were way off! One was reading 20% high, the other 25% (meaning when I dial in 50 ftlbs, it's clicking at 40). Not good. Fortunately, adjusting them was easy. Don't be dumb like me... calibrate frequently, or have it done by a professional. Now time to recheck all my lug nuts!

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Honestly it seems weird to me that a relatively new unit would be that far off. I guess I should test mine, but they're 20 years old and I would be shocked if they were very far off.

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2 hours ago, robertcope said:

Honestly it seems weird to me that a relatively new unit would be that far off. I guess I should test mine, but they're 20 years old and I would be shocked if they were very far off.

Robert, I think part of the reason mine were this far off was that when I first purchased them, I did not yet know the "rules" for how to properly use torque wrenches. I used them to loosen bolts that were beyond their range. I also occasionally forgot to zero them for a day or two after use. Those two mistakes can have detrimental impact on a click-style torque wrench's accuracy. Rule of thumb is still to calibrate every year if you use it often. Based on my frequency of use, every few years is appropriate I think.

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In the USAF our torque wrenches had to be calibrated on a schedule - I think it was quarterly.

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We calibrate annually for everything at work.  I should do my personal ones though.

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I had this old school Craftsman torque wrench that was not a clicker, rather it had an indicator that flexed on a scale.  It got out of zero after about a year, but I adjusted based on the new "zero".  Not sure if that was accurate haha but was kind of nice to see what it was doing vs a magical clicker 😄

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Good reminder. I got a fixed torque wrench at 100lbs that never moves. Makes it easy to dedicate to just my wheels for track days and hopefully calibration is less of a concern. I just got it this year, but I intend to check it at the start of each season at least

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On 8/19/2019 at 8:36 AM, KevinDB said:

I had this old school Craftsman torque wrench that was not a clicker, rather it had an indicator that flexed on a scale.  It got out of zero after about a year, but I adjusted based on the new "zero".  Not sure if that was accurate haha but was kind of nice to see what it was doing vs a magical clicker 😄

Those guys are considered more repeatable and accurate than the clicky type, because the flex rate of the steel is a constant (within the temp range humans can survivably work in anyway).  so if they drift from zero, you just bend it back until it re-zeros and you move on.  easy to 'calibrate' and the only drift is the zero point.

 

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A few years ago, a good autocross friend and I bought exactly the same torque wrench and air pressure gauges.

At one event he mentioned that his lugs seemed to loosen some at every event.  He said they felt tight with a breaker bar, but the wrench clicked with little effort

We did the simple thing of using both wrenches on my car.  Very different clicking points on the same lug.

Obviously we had them both recalibrated, and we continue to do the simple both wrenches on one lug to see if there is an obvious problem

We do the same with the air gauges.  At one point we found that there was a 5 psi difference between them,  So we compared to other gauges at the event to see which one had apparently died.

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My torque wrenches are not fancy enough to have factory calibration as an option. One is a kobalt from Lowe’s, the other is a harbor freight special. I’ve heard you can get a snapon guy to do it if you find them at a local auto repair shop. But that would’ve probably cost as much as the torque wrench itself did. 

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On 8/22/2019 at 7:08 AM, nealb said:

We do the same with the air gauges.  At one point we found that there was a 5 psi difference between them,  So we compared to other gauges at the event to see which one had apparently died.

Before I was into road racing I did offroading/Jeeps and prior to that, drag racing. I did not have fancy gages...they were pocket pop-up style gages but with individually graduated marks...I always used the same one - as long as it was xx pressure for me, I knew I was where I needed to be. I need to see if my "fancy" Longacre digital gages are close to each other - even buying a "correct" gage these days can be a hassle....find your needed range, let's say it's 30 psi for your street car, you want a gage that reads to 60 psi. For my race cars we start at 16-18 psi cold, so ideally you'd want a 40 psi gage...crazy, eh?

I'm sure Matt will be along shortly to give the "enginerd" answer.... 😂

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