Why So Much Disdain For Using Torque Tools

[Trav]

Those figures seem to be somewhat inaccurate.

http://www.lifetime-reliability.com/free...ty_You_Want.pdf

Quote:
It is impossible to guarantee accuracy when tightening fasteners by muscular feel. Using a process that ranges ± 35% to get within ± 10% of a required value is playing a game of chance. Every fastener in the world tightened by ‗Feel‘ is at risk.

 

[Shannow]

I see no reason for using a torque wrench on a gasketted spark plugs, when they are designed for snug plus 1/4 turn, by feel is just as good. Same for sump plugs diff and gearbox fill plugs, shock bolts etc. etc. etc.

As per JOD, the torque wrench tells you next to nothing about the strain imparted on the fastener, and thus the clamping force, and where in the fastner's safe stress range you are...a rough dry fastener, and the joint could be dangerously loose.

Most of my industrial tightening experience for the last 10 years has been "snug" (200ftlb), then angle tightened to the desired strain, or hydraulically tensioned, and then locked with the nut.

Only by having strain incorporated can a fastener be really installed correctly.

 

[punisher]

Kind of split on this. After you turn wrenches for awhile, you learn the "feel" of fasteners and tools. There are certain critical applications that always get a torque wrench (or a stretch gauge Shannow), like internal engine fasteners, transmission valve bodies etc (essentially any component you have to worry about deformation due to improper clamp loads).

The reality is most of my "final torque" was determined by feel, or the sound of my impact or air ratchet. Like most things, there is a certain amount of common sense, and experience, involved. I think a torque wrench is almost mandatory for a newb who has no/little experience, likewise, if you have been turning wrenches for 15 years, I am OK with you going by feel on non critical components.

All I can say is, in my case, I never had any recheck due to improper fastener torque.

 

[Bluestream]

Originally Posted By: punisher
Kind of split on this. After you turn wrenches for awhile, you learn the "feel" of fasteners and tools. There are certain critical applications that always get a torque wrench (or a stretch gauge Shannow), like internal engine fasteners, transmission valve bodies etc (essentially any component you have to worry about deformation due to improper clamp loads).

The reality is most of my "final torque" was determined by feel, or the sound of my impact or air ratchet. Like most things, there is a certain amount of common sense, and experience, involved. I think a torque wrench is almost mandatory for a newb who has no/little experience, likewise, if you have been turning wrenches for 15 years, I am OK with you going by feel on non critical components.

All I can say is, in my case, I never had any recheck due to improper fastener torque.


I agree with punisher. In fact he took the words right out of my mouth, but I was too lazy to type it all out.

 

[Trav]

Quote:
I see no reason for using a torque wrench on a gasketted spark plugs


Nor do i, but sump plugs in aluminum pans or engine cases or tapered seat plugs in aluminum is another story.
I did a lot of bike engine work for many years and some of the sump plugs had high torque values e.g 19mm thread plug 55nm, 46mm fine thread top tub nuts at 60nm.
These values were beyond my feel with a 1/2 drive ratchet, problem is if you bugger it it could be a engine case or fork tube.

I don't use a torque wrench much for most external fasteners other than manifolds and heads but 100% when its internal on the engine or trans or brake parts.

Working with small diameter bolts and large fasteners with odd torque all in aluminum made me a little paranoid i guess.
I can honestly say using the torque tools on these all aluminum parts i never stripped or damaged a bolt but i know a lot of guys who were grand masters at fitting heli coils.

From experience if the threads are dirty then throw the torque wrench in the bin because its useless. I always use a thread chaser internal and clean the bolt threads or replace them if TTY.
I have a 2003 Honda manual with a * for some bolts, it said torque value = clean threads, never seize applied. So they took lubed threads into account in the torque spec.

 

[bigmike]

Maybe I've just had bad tools or bad specs (both have been true at times), but I've only broken bolts when using a torque wrench. When I do it by feel, I've never broken anything.

I have no problem using one when its calibrated and the spec is correct. I wouldn't bother unless it is a critical component.

 

[hattaresguy]

I use a torque wrench when its needed, but for a drain plug? Seriously?

OTOH the Jiffy Lube guys probably should they seem to have no feel.

 

[GeneralEclectic]

Originally Posted By: Pablo
That must be a new thing. The attitude on BITOG used to be that your torque wrenches should be used for all threaded fasteners, calibrated at least annually, preferably every six months, traceable to NIST and that you certainly could not trust a torque tool in the as purchased conditions.


Winner, Best Laugh of the Week.

Sadly to say, there are way way too many "professionals" that think their personal calibration (including the number of hammer impacts their air wrench makes, probably) is good enough. I won't set foot in ANY tire store any more because of this. I've taken off one too many lug nut that was "torqued" to 250 lb-ft where it should have been 80. The only places that touch my wheels and tires now are the two highly-trusted and conscientious shops that do other mechanical work on my cars.

 

[Trav]

Not in a steel pan. Aluminum cases always, there are too many horror stories, cracked cases, stripped threads, stripped aluminum plugs, etc not to use one.

Mind you these sometimes have higher torque values not just snug then a little pressure and in many cases over torque will result in very expensive repair if you strip them or god forbid crack them.
Many of these are going in vertical, it sort of disturbs the "feel" working at that angle.

+1 on the Jiffy Lube

 

[JOD]

Originally Posted By: Trav
Those figures seem to be somewhat inaccurate.

http://www.lifetime-reliability.com/free...ty_You_Want.pdf

Quote:
It is impossible to guarantee accuracy when tightening fasteners by muscular feel. Using a process that ranges ± 35% to get within ± 10% of a required value is playing a game of chance. Every fastener in the world tightened by ‗Feel‘ is at risk.




I'd urge to read Bickford's book, the methodology behind his tests, and then the Ajax Handbook--then make your determining as to which set of data are more accurate. I have, and in my opinion it's not even close. No one is infallible, but Bickford really is the most godfather of research into bolted joints. Yes, K can be a better proxy than operator feel, under very specific circumstances (as he mentions). Clicker-type torque wrenches as they're typically used by experienced operators do not fall into that category.

My own experience is that I've tightened many, many more fasteners without a torque wrench than with, and yet nearly all of the failed joints I've had are while using a torque wrench. This experience is what led me to start researching this in detail in the first place.

I'm not trying to convince you to do otherwise, but I do want to make it clear that some people are "against" torque wrenches because the best published research on the subject suggests that their use is redundant or counterproductive, not because of some misplaced sense of superiority. And those who opt to not use a torque wrench (for whatever reasons) are just as likely to get it right as those who don't. If you want to keep using one, by all means keep using it; but understand its limitations, and understand why a joint may fail even though you're using one--and realize that you are not 'more accurate', or 'more professional' than those who don't.

 

[Trav]

Sorry i totally disagree with you. This guy maybe the be all and end all as you say but every automobile, motorcycle and aircraft manufacturer or anyone who publishes a torque spec would disagree.

The next time i fly i wouldn't feel to comfortable if the guy repairing the aircraft just went by close enough "feel" tightening the bolts, would you? Honestly.

 

[JOD]

Originally Posted By: Trav
Sorry i totally disagree with you. This guy maybe the be all and end all as you say but every automobile, motorcycle and aircraft manufacturer or anyone who publishes a torque spec would disagree.


I've published torque specs for fasteners which have much smaller margins to the yield point; the guy who's blog I've linked works in the aerospace industry, and his entire job is in researching and providing torque recommendations for aerospace fasteners, so you comment above is clearly incorrect.

Originally Posted By: Trav
The next time i fly i wouldn't feel to comfortable if the guy repairing the aircraft just went by close enough "feel" tightening the bolts, would you? Honestly.



I'd trust them just about as much with 'operator feel' as with a clicker-type torque wrench--which is to say I wouldn't trust it very much! This is the point you seem to be missing, or ignoring. It's not any more accurate with a torque wrench, whether you see a number on the dial or not. And this is why I don't like torque wrenches.

If the joint tension is an aerospace fastener is really critical, the joint tension isn't measured with a clicker torque wrench, because there are much more accurate methods available.

 

[demarpaint]

JOD- Help me understand this. If two novice mechanics were installing main bearing caps with torque specs and no way of measuring them what would happen? Now lets say one guy is 6'5" and 300 lbs, the other is 5'5" `130 lbs. Do you think the bigger guy might just make them tighter than the smaller guy? Who would do a better job with no way of measuring?

 

[Trav]

You keep harping on torque wrenches.
Read the title of the thread.

Quote:
Why So Much Disdain For Using Torque Tools

Which includes more than just wrenches.
FWIW i use an angle gauge on most critical bolts.

Quote:
I've published torque specs for fasteners which have much smaller margins to the yield point; the guy who's blog I've linked works in the aerospace industry, and his entire job is in researching and providing torque recommendations for aerospace fasteners, so you comment above is clearly incorrect.



How so, i said..

Quote:
every automobile, motorcycle and aircraft manufacturer or anyone who publishes a torque spec would disagree.



Quote:
I've published torque specs for fasteners which have much smaller margins to the yield point;


Are you sure you are not trying to push your own book?

 

[JOD]

Originally Posted By: Trav
You keep harping on torque wrenches.
Read the title of the thread.

Quote:
Why So Much Disdain For Using Torque Tools

Which includes more than just wrenches.


I realize that--your next sentence though said "torque wrenches", and the overwhelming number of responses in this thread reference torque wrenches. I also made it clear in my first response that I'm strictly talking about friction-type torque wrenches.

Originally Posted By: Trav
FWIW i use an angle gauge on most critical bolts.


As do, I (or sight, depending on the joint), so we're in complete agreement on this. However, as I said most other people on this thread are not referencing angle torque, but K.




Originally Posted By: Trav
Are you sure you are not trying to push your own book?


Yeah, I'm pretty sure. I just trying to help people understand why they can still break stuff (or under-tighten a joint) using a friction-type torque wrench.

 

[Torino]

Gentlemen, this is getting FAR too complicated. Just use the Govt. recommended method--'Tightenthe fastener until it turns loose. Thats it. John--Las Vegas.

 

[JOD]

Originally Posted By: demarpaint
JOD- Help me understand this. If two novice mechanics were installing main bearing caps with torque specs and no way of measuring them what would happen? Now lets say one guy is 6'5" and 300 lbs, the other is 5'5" `130 lbs. Do you think the bigger guy might just make them tighter than the smaller guy? Who would do a better job with no way of measuring?


This exact question is answered by the research on the subject. If you took a random sample of people (experienced and inexperienced) and have them tighten joints to a specific spec based on feel, you'll have a scatter plot of values, and an average and mean differential from the spec. But you'll have this same scatter and deviation (or greater) using a friction-based torque wrench. And the deviation between experienced and inexperienced operators using friction torque is pretty much negligible. Unless the smaller guy is limited by his ability to generate enough force, I can't really see him doing a worse(or better) job tightening the bolt.

 

[1 FMF]

Originally Posted By: Trav

Manufacturers spend time and money putting together torque specs for a reason,

IMHO if I spend good money on quality torque tools I want to use them for what they were intended.


my disdain is towards statements such as that,
not towards torque specs specifically but using the phrase "manufacturers this and that therefore this is why you should or should not whatever". Many times it's pure conjecture when people make statements on behalf of The Manufacturer, and most of the time it's faulty rationalization that the manufacturer did this therefore...
Can you tell me how much time and money they did put towards torque specs?

but regarding torquing fasteners it is my opinion most people who actually come out and say I don't torque this or that and do it by feel actually know what they are doing and perhaps know they don't need to torque such a fastener to a certain value, that tight enough is perfectly fine because that is all it needs. for a drain plug, spark plug, or bolt holding on a cover the only purpose in this case is to make a good seal, and you don't need to torque everything to a specific value in order to prevent it from loosing. It's like you said, you use your quality torque tools for what they were intended- tightening things where you need to elongate a bolt or stud a specific amount like for cylinder heads and rods, or getting an even tightening amount among all the fasteners such as wheel lugnuts so you don't induce runout, not using them for simple things like tightening a drain plug. And if someone needs to use a torque wrence to properly tightening something as simple as a drain plug, then perhaps they are not adept and should consider not performing that kind of work.

And what maybe bothers me the most, especially tv commercials, is the image and perception when a person wearing a white labcoat speaking with a German accent glorifies the trivial. Oh he sounds smart, I better buy that brand of motor oil because I'm just a dumb American what could I possibly know

 

[sandy_d]

Originally Posted By: GeneralEclectic
[

Sadly to say, there are way way too many "professionals" that think their personal calibration (including the number of hammer impacts their air wrench makes, probably) is good enough.


This!

 

[Bamaro]

Its mainly because some things just aren't that important. A drain plug just requires some common sense. Engine work requires a good torque wrench.