Proper Torque Wrench Usage

[TheMadMech]

I've always been told that you aren't supposed to use a torque wrench like a ratchet even though it's got the ratcheting feature. You are supposed to tighten the fitting with a wrench/ratchet then torque with the torque wrench.

Why?

It's a rule I've mostly followed but it just makes no sense to me what-so-ever. Why would they make it with the ratcheting feature if you can't use it?

Anyhow, It'd be great to hear what everyone's thoughts are on this as I'm looking to get some torque wrenches for myself.

 

[Wes J]

That's not a rule. That's just something someone told you.

Don't use them to break loose a fastener. Keep you hand square to the handle. Slow steady pressure. It's only really accurate when the nut or bolt is turning. Back off the spring pressure when you are done.

That's it.

 

[Bagherra]

I personally don't see a problem with using the ratching feature...I would never use it to break torque though...

btw...taught "front load" for beginner helicopter mechanics coming in the Army including the proper use of torque wrenches and that was instilled on the students from Day 1...

 

[pi_guy]

I use it to break fasteners if I need to know were they at proper torque. Example would be wheel bearing nuts, torqued to 160. But when it clicks and does not move I go for the breaker bar or impact gun.
I use my 1/4 15 in lbs TW to do pre load on gearboxes and it used right and left.
And some gear boxes have both right and left handed nuts. But in all the gear changes I have done it is done with a big breaker bar.
I know a car that the wheel nuts are torqued in the 200 ft/lbs range and they have a 600 ft/lbs wrench and they need the TW to get the wheel nuts off

 

[Wamsutta]

The two general rules are don't use it as a breaker bar and always store it on zero.

 

[Dr. Jekyll]

The two general rules are don't use it as a breaker bar and always store it on zero.

This is exactly what I learned growing up as well!

 

[Jim Diesel]

If it has a ratchet head, use it.

 

[Fcvapor05]

I use it to break fasteners if I need to know were they at proper torque. Example would be wheel bearing nuts, torqued to 160. But when it clicks and does not move I go for the breaker bar or impact gun.
I use my 1/4 15 in lbs TW to do pre load on gearboxes and it used right and left.
And some gear boxes have both right and left handed nuts. But in all the gear changes I have done it is done with a big breaker bar.
I know a car that the wheel nuts are torqued in the 200 ft/lbs range and they have a 600 ft/lbs wrench and they need the TW to get the wheel nuts off

The torque needed to remove a fastener is not the same as the torque needed to correctly install one. Breaking fasteners free with a torque wrench tells you nothing.

 

[mr.speaker]

The torque needed to remove a fastener is not the same as the torque needed to correctly install one. Breaking fasteners free with a torque wrench tells you nothing.

This is so true.

But it's weird if you read his first sentence and then his very last sentence , he seems to realize this since he says "I know a car that the wheel nuts are torqued in the 200 ft/lbs range and they have a 600 ft/lbs wrench and they need the TW to get the wheel nuts off"

Another good rule is to have the clicker tq wrench calibrated regularly .. I get mine done dirt cheap at a local college once a year

 

[gigamel]

Sure you can use the torque wrench like a ratchet - Just make sure the bolt is turning when the torque wrench clicks - Otherwise back off the bolt a little and re-tighten.

 

[gdocktor3]

Although you could use a torque wrench as a ratchet, I wouldn't. They are pretty sensitive as is so why risk knocking it out of calibration using it like that? The torque wrench ratchet heads have a lot of small, intricate parts and springs. Totally different from a normal ratchet. I think that's asking for trouble. Here's a link showing you how to repair and calibrate it yourself. http://www.instructables.com/id/Fixing-and-Calibrating-a-Clicky-style-Torque-Wrenc/?ALLSTEPS

 

[sberry]

How much off are the wrenches that are calibrated all the time. I would think it it wasn't staying in it isn't much good.

 

[Ghost11]

You can definitely ratchet with it, but i wouldnt use it to tighten a bolt all the way down like you would a regular ratchet. Get the bolt, or whatever, as close as you can, then tighten with TW. Go slow and steady, reset the TW to zero, and keep it in its case.

 

[Evilunclegrimace]

Maybe that rule was for when torque wrenches didn't have the ratcheting feature, although when I was young I would use a ratcheting adapter on a beam wrench. They used to have different accuracy standards for right or left hand use. Torque is a range, and seldom in automotive work, if ever, does the value have to be an exact amount. It is more important that headbolts, etc. are torqued evenly than exactly to a specific value.

I would have to disagree and say that Torque is twisting effort not a range. The torque Specification is a range and it is very important to fall with in the specs. There is usually a percentage of error that is allowed(let's use 5%) and that is taken in to account in the engineering of the bolt. If the bolt is not torqued with in the specified it is not stretched to allow maximum clamping force, so even if the bolts were all equally torqued and they did not reach the proper torque spec then they would not be providing the proper clamping force.

There are a two things to keep in mind about torqueing a bolt,90% of the force of the wrench is used to over come friction between the threads in the block and on fastener and between the under side of the bolt head and its mating surface. The other 10% is used to stretch the bolt to the proper length to allow the bolt to keep clamping force applied to the mating surfaces.

 

[winlinmac]

Some of these micro-click torque wrenches only work "properly" in one direction in-spite of a direction lever being included (cosmetic purposes, perhaps?). Reduces cost in production and sold cheap to the customer.

 

[gdocktor3]

Some of these micro-click torque wrenches only work "properly" in one direction in-spite of a direction lever being included (cosmetic purposes, perhaps?). Reduces cost in production and sold cheap to the customer.

Where do you get that idea? There are a lot of left hand thread applications out there.

 

[Rossco]

Breaker bar, pry bar, snipe. Whatever it takes to get the 35 million dollar shovel back into the face.

Depending on manufacture. They should be stored @ 25% rated scale.

 

[pi_guy]

The torque needed to remove a fastener is not the same as the torque needed to correctly install one. Breaking fasteners free with a torque wrench tells you nothing.

It tells you if it is loose or never got to proper torque range in first place.

 

[pi_guy]

This is so true.

But it's weird if you read his first sentence and then his very last sentence , he seems to realize this since he says "I know a car that the wheel nuts are torqued in the 200 ft/lbs range and they have a 600 ft/lbs wrench and they need the TW to get the wheel nuts off"

The point being is they had no other manner to break wheels free, they were forced to use TW.
So one sub point being for every "this is the proper way" there is always a case where it does not fit.

 

[Tinner]

They should be stored @ 25% rated scale.

No, they should be stored with the spring unloaded. That would be at zero.

 

[Rossco]

No, they should be stored with the spring unloaded. That would be at zero.

No is such an Absolute.

Just experience. When I worked for CAT, depending on what part of the world, I would be issued with torque wrenches. Either ****-on, Proto or Norbar.

Each wrench would come with a Certifcation card. Date and serial numbers, calibration time, location and a guarantee of accuracy if stored at 25% rated.

Email 'Caterpillar Mining' and tell them they are wrong.

 

[flat tire]

do you loose the torque value by using an extension ?

 

[MShaw]

No, an extension will not affect torque. A universal or offset adapter will.

As for frequent calibration, I have a Snap on 3/8" dial torque wrench that is over 40 years old and when I was sent back to snap on recently they said it was not in need of recalibration. It was always used with a ratchet adapter to tighten bolts in increments from snug to the full required torque.

 

[Fcvapor05]

if ever, does the value have to be an exact amount. It is more important that headbolts, etc. are torqued evenly than exactly to a specific value.

This is most definitely not the case. Torque values are specified for a reason.

It tells you if it is loose or never got to proper torque range in first place.

No, it doesn't. Applied torque and backdown torque are not related in a simple way, at all. It is entirely possible to torque a nut to ** ft-lbs and then to not need **- ft-lbs to remove it, or to need greater than ** ft-lbs. Much depends on materials in the fasteners, materials being fastened, thread coatings, thread lubrication, and on and on and on.

 

[winlinmac]

It was mentioned in one of the detailed Tekton torque wrench reviews on Amazon. http://www.amazon.com/dp/B00C5ZL0RU/?tag=atomicindus08-20

I think that reviewer was somehow trying to draw a point, but couldn't figure something out. I was a prospective buyer of Tekton's torque wrenches, but that review left a lot to be desired.

Where do you get that idea? There are a lot of left hand thread applications out there.

 

[wafrederick]

I was told to set it to the lowest torque spec reading when not in use.I see this on the how to shows jerking on the torque wrench after hearing the clicking noise.This is a no no,you get a false torque reading if you do this.Basically stop when it clicks.Read the torque specs correctly.It was shown on Gas Monkey Garage,an employee broke an oil pan bolt on a LS3 because he torqued down the pan bolt in foot pounds and it was in inch pounds.

 

[snakeeyes]

The torque needed to remove a fastener is not the same as the torque needed to correctly install one. Breaking fasteners free with a torque wrench tells you nothing.

I beg to differ we used breakaway torque on fasteners when testing prototypes at Cummins. Thermal expansion, weather conditions, and lots of shaking can loosen fasteners or cause them to seize. Knowing what you have after so many cycles can help determine if you have the right fastener for the expected life of the part. We used old dial torque wrenches that would push a needle until the bolt broke free.

Breakaway torque has a very specific place where it is needed, but the average user does not need that info typically.

 

[gdocktor3]

It was mentioned in one of the detailed Tekton torque wrench reviews on Amazon.

Enough said....

 

[gdocktor3]

Found this online - When a torque wrench is in regular use it does not need to be wound back. However, when storing a torque wrench for an extended period of time, users should always wind it down to the minimum scale setting and never to zero.

A fully loaded torque wrench, left in storage for a long period, can cause a ‘set’ in the spring, causing it to weaken over time. On the other end of the scale, by completely off-loading the spring, other components within the wrench may move fractionally relative to each other. When you reapply spring compression the orientation of these components can change, therefore affecting accuracy. All in all, it is better to leave a bit of compression in the spring while in storage.

 

[Tinner]

No, they should be stored with the spring unloaded. That would be at zero.

OK, that was poorly worded. It should be at it it's lowest setting, where there will be little or no pressure on the spring. They shouldn't be set below that. Sorry for the confusion.

 

[Evilunclegrimace]

Evilunclegrimace, it is obvious that your experience is limited. No bolt size has an exact torque specification. Torque is always suggested as a range. It is important to be within that range, but not necessarily to torque to a very specific number, which is vitiated anyway by the accuracy range of the wrench itself. Also, it is usually specified that the bolt or nut either have or not have a lubricant applied to the threads before torqueing, and the nature of that lubricant if so specified. Some torque specifications, such as Caterpillar, don't even give a final torque value, but require a torque-to-spec and then 60 degree, 45 degree, or other additional turn on the bolt.

Perhaps you need to reread my post.

 

[Evilunclegrimace]

Rick Joe, I would suggest that your experience is what is limited. EVERY bolt has an EXACT torque spec. Period! That spec is dependent on the strength rating of the bolt( grade 1,grade 5, grade 8 etc.)It is also dependent on the thread pitch either USS( coarse) or SAE (fine). I will agree that the final assembly spec is subject to the accuracy of the torque wrench being used and I alluded to that in my original post using a 5% error of accuracy. The type of lubrication of the bolt is specified by the manufacturer be it motor oil, Moly lube or even pipe thread sealant to name a few possibilities.

As far as Cat not giving a final torque spec they actually do give a final torque spec but they also specify that the bolt be turned an additional 45-60-90 degrees to properly stretch to bolt to achieve its proper clamping force. I will stand by my statement that torque in this instance is a specification not a range.

 

[Rossco]

OK, that was poorly worded. It should be at it it's lowest setting, where there will be little or no pressure on the spring. They shouldn't be set below that. Sorry for the confusion.

No worries. Just because CAT says 25% doesn't mean it should be. It's just how I do it. Maybe I should have said : It's recomended by CAT to store @ 25%.

CAT spec Torque Turns ain't that common. Only ones that come to mind are Dozer croc links and 3500 series head bolts. Vast majority of fasteners have a specific torque for assembly. In reality, 3/8 bolts have a generic torque unless otherwise stated.

 

[Wakefield]

The two general rules are don't use it as a breaker bar and always store it on zero.

I store my 20-150 on 20 not zero

 

[L.Cheapo]

Snap On put a ratcheting head on my Techangle because they expect me to use it. In fact, you can even ratchet while using the torque-to-angle feature.

 

[pi_guy]

I beg to differ we used breakaway torque on fasteners when testing prototypes at Cummins. Thermal expansion, weather conditions, and lots of shaking can loosen fasteners or cause them to seize. Knowing what you have after so many cycles can help determine if you have the right fastener for the expected life of the part. We used old dial torque wrenches that would push a needle until the bolt broke free.

Breakaway torque has a very specific place where it is needed, but the average user does not need that info typically.

I spent about 30 minutes on the phone with a mechanical engineer and one of the subjects we covered was beakaway torque. What I was told it will not be accurate, but that is not my purpose. The purpose is to see large values of difference. Meaning that single nut wheel bearing get torqued to 160 for example and if they had been done to 100 ft/lbs one school of thought. Doing breakaway torque is not going to be near 160 if they had been set low, unless it got damaged by doing so. Which would lead to further inspection.
I remember years ago when FF wheels had 4 lug nuts not one like now, I would check breakaway torque with a beam type wrench and if any were out of line the studs and nuts were further inspected. It really helps to keep the wheels on if you want to finish the race.

 

[Tejaas]

I personally don't see a problem with using the ratching feature...I would never use it to break torque though...



btw...taught "front load" for beginner helicopter mechanics coming in the Army including the proper use of torque wrenches and that was instilled on the students from Day 1...

Oh hell,

We got a former Ft. (Useless) Eustis USAALS schoolhouse instructor on the forum!?!?

(Former 15T/15Y here.)

 

[GirchyGirchy]

As far as Cat not giving a final torque spec they actually do give a final torque spec but they also specify that the bolt be turned an additional 45-60-90 degrees to properly stretch to bolt to achieve its proper clamping force. I will stand by my statement that torque in this instance is a specification not a range.

If it's a torque & angle joint you must use a range for resultant torque.

 

[GirchyGirchy]

I beg to differ we used breakaway torque on fasteners when testing prototypes at Cummins. Thermal expansion, weather conditions, and lots of shaking can loosen fasteners or cause them to seize. Knowing what you have after so many cycles can help determine if you have the right fastener for the expected life of the part. We used old dial torque wrenches that would push a needle until the bolt broke free.

Breakaway torque has a very specific place where it is needed, but the average user does not need that info typically.

Assuming you mean you were using the dial wrench to loosen the capscrew, then you weren't measuring breakaway torque.

 

[Fcvapor05]

....Doing breakaway torque is not going to be near 160 if they had been set low, unless it got damaged by doing so. Which would lead to further inspection.....

Unless they were corroded, or the threads galled, or you blew a seal and sprayed oil all over them, or the studs are nearing their fatigue life and have experienced plastic deformation, or vibration has loosened them, or any of a thousand other scenarios. Once again, in a lab environment where every possible variable is precisely controlled and monitored, backdown torque tells you very little. In the field, where almost nothing is controlled or monitored, it tells you nothing.

If it's a torque & angle joint you must use a range for resultant torque.

You have to remember what your goal is when applying specified torque to a fastener- the actual torque experienced by the bolt means nothing. Torque is an intermediate measurement used to APPROXIMATE preload in the fastener. Preload is what you care about.

Torque-to-yield fasteners exist specifically because using torque to control bolt preload is not extremely consistent. For certain situations, especially high-fatigue installations such as an engine head bolt where stresses are high, materials being clamped can be soft, and clamping force is very critical, properly installed torque-to-yield fasteners provide very accurate preload, every single time.