Does it Damage Click Stop Torque Wrenches to Loosen Nuts

[Trav]

I agree with not using it to loosen fasteners, but I’m curious as to what gets damaged and why. For example, torque is set for 100 lb-ft and the breaking torque on a fastener is 75 lb-ft. What exactly is causing the damage?

Fasteners are sometimes much tighter to remove that the original torque setting eg lug nuts and bolts, suspension fasteners. It is common to properly tighten a bolt to spec say 100 lb.ft then later come to remove it and you need a long breaker bar or big impact gun.

 

[demarpaint]

Fasteners are sometimes much tighter to remove that the original torque setting eg lug nuts and bolts, suspension fasteners. It is common to properly tighten a bolt to spec say 100 lb.ft then later come to remove it and you need a long breaker bar or big impact gun.

Exactly, and why I'd use an impact gun, breaker bar, or wrench to loosen them, not my torque wrenches.

 

[vwmaniaman]

So I would guess the loaner tools at parts stores aren't worth using.

 

[LDB]

They can be used to loosen. They can be used to hammer. They can be used as a lever to lift. They can be used as a doorstopper. They can be used as a wheel chock.

It is for proper torque when tightening a fastener. Nothing else. Just because it can does not mean it should.

 

[Chris142]

So I would guess the loaner tools at parts stores aren't worth using.

Pretty much. I let a guy in the shop next door use my Snap On tq wrench. A few minutes later I had to go there anyway and I saw him using it as a breaker bar with a pipe on it.

 

[NYEngineer]

Pretty much. I let a guy in the shop next door use my Snap On tq wrench. A few minutes later I had to go there anyway and I saw him using it as a breaker bar with a pipe on it.

There are a very select few I will loan a precision tool to. My T&D pinion depth checking tool is at the top of the list. Torque wrenches as well.

 

[Nessism1]

I damaged a Snap-On dial type torque wrench (made by Precision Instruments), when checking torque on a motorcycle cylinder head.

When checking/torquing fasteners like this, I get the fastener moving by first cracking it loose, then I quickly reverse direction and tighten to spec. The nut in question made a loud snap sound when it was first broken loose, and the shock of that event sheared off a screw inside the mechanism.

Precision fixed and calibrated the wrench for $75, so no major harm done. And I learned a valuable lesson about care for torque wrenches.

Oh, and some torque wrenches only operate in the tightening direction. Such wrenches might be okay for loosening, but I'd check the data sheet instead of assuming.

 

[JohnnyG]

This is the reason for my post SEVERAL months ago about how a torque wrench works. If you look at the internals of the most common design, and likely inexpensive wrenches, the mechanism works identically regardless of the direction your turning the bolt. I can't see any way that loosening will change anything.
BUT, if the manufacturer specically says not to, then I wouldn't. After all, there is such a thing as left hand threaded bolts. Therefore you won't be going out to but a specific torque wrench for those.

https://www.motor1.com/news/739023/torque-wrench-explained/

 

[The Critic]

This is the reason for my post SEVERAL months ago about how a torque wrench works. If you look at the internals of the most common design, and likely inexpensive wrenches, the mechanism works identically regardless of the direction your turning the bolt. I can't see any way that loosening will change anything.
BUT, if the manufacturer specically says not to, then I wouldn't. After all, there is such a thing as left hand threaded bolts. Therefore you won't be going out to but a specific torque wrench for those.

https://www.motor1.com/news/739023/torque-wrench-explained/

Theoretically correct, however, "breaking loose" a fastener often requires 2-3x (or more) torque than the specified value. This often exceeds the allowable range of the wrench and thus, damages the torque wrench.

 

[JohnnyG]

Theoretically correct, however, "breaking loose" a fastener often requires 2-3x (or more) torque than the specified value. This often exceeds the allowable range of the wrench and thus, damages the torque wrench.

Agree. That's a whole different situation though. I wouldn't expect someone to exceed the full setting of the wrench in any situation. There's a tool for that for sure.

 

[Jetronic]

Click stop style torque wrenches, does it hurt them to loosen nuts and bolts with them?

Not if the torque wrench was used -correctly- to do them up last time.

 

[vavavroom]

Ever notice how newer torque wrenches only have a one direction head?

My loose screw requires reverse tightening.

 

[D60]

Not if the torque wrench was used -correctly- to do them up last time.

Nah, as stated previously breaking a fastener free may require much more than initial torque to tighten to, say, 100 ft lbs

Beyond that people are confusing torquing a LH fastener with using a TW as a breaker bar on a RH fastener. Quite often only the better TWs are accurate or meant to be used in reverse. If they are, of course torquing in reverse is acceptable.

All I can tell you is LONG LONG ago when I was more broke and even dumber than I am today I had a Craftsman DigiTork (tiny numbers in a window) and I used it as a breaker bar to remove u-bolts on a truck 8.8. That wrench was FUBAR after that and I personally learned to not use a TW as a breaker bar. One of those touch-the-stove-to-learn-that-it's-hot moments

 

[Kira]

And every manual for the five I own says not to do that.

He flies jets, mods fora AND reads manuals! Astro's my hero!

 

[Jetronic]

Nah, as stated previously breaking a fastener free may require much more than initial torque to tighten to, say, 100 ft lbs

Beyond that people are confusing torquing a LH fastener with using a TW as a breaker bar on a RH fastener. Quite often only the better TWs are accurate or meant to be used in reverse. If they are, of course torquing in reverse is acceptable.

All I can tell you is LONG LONG ago when I was more broke and even dumber than I am today I had a Craftsman DigiTork (tiny numbers in a window) and I used it as a breaker bar to remove u-bolts on a truck 8.8. That wrench was FUBAR after that and I personally learned to not use a TW as a breaker bar. One of those touch-the-stove-to-learn-that-it's-hot moments

I use anti-seize, they don"t get tight like that. My beta torque wrench does both btw.

 

[JRay’07]

Both my 1/4" and 3/8" drive CDI torque wrenches are equipped with reversing heads. It seems silly that the manufacturer would give you the option of destroying your tool with the mere flip of a switch. That being said, I only use them within their preset limits in the righty tighty direction.

 

[rijndael]

Not if the torque wrench was used -correctly- to do them up last time.

Rust, Loctite, Galvanic Corrosion, and Grit all have a say too.

 

[Torrid]

I don't use my torque wrenches to loosen bolts because I've heard it does damage or make them less accurate. I do have straight breaker bars for bolt removal and I'll switch to a standard ratchet if I want that capability while backing out bolts. Then again I have 25 years of tools collected from the time I worked in a shop in my younger years. I've only added to it after time.

 

[JRay’07]

Here is one of my calibration certificates. Notice how these measured values are given in both the clockwise and counterclockwise directions. As long as the wrench is operated within the set range it should not cause damage.

 

[Oliveoil2]

Yes. That’s what breaker bars are for.