Correct torqueing procedures?

[monkey spanners]

I'm sure we all torque our nuts on a regular basis but a doubt has been put in my mind to this practice after reading some comments on a tool forum.

Basically it was claimed that using an extension between the torque wrench and socket will lower the applied torque to the fastener, the longer the extension the worse it gets. Do you wise chaps think this correct?

I can see how if you were using an impact driver that the extensions would act a bit like a spring and absorb some of the energy but with a hand held torque wrench it would be a constant twisting action so i can't see where the twisting energy goes if indeed it doesn't appear at the socket end to turn the nut.

A recent experience that i'm now wondering about,

I replaced a discharge valve gasket on a large copeland comp in a air drier and the only way i could get enough swing on the torque wrench was with about 5ft of extensions so i could stand outside the machine! At least either way it was tightened evenly which i thing is also important with gaskets.

[Tayters]

Hi Jon,

I've always known this to be the case but as to how much difference it will make I've always thought to be debatable when the other variables are considered such as the friction on the thread itself. This will change on a longer or shorter thread, if there is oil on it or not and how much friction there is at the head where it meets the casing when tightened down (washer type, flat or cone surface, etc). Add to that the inaccuracy of the torque wrench so who is to say what figure you are left with.

Most I've ever used is a 2' extension and so far not had anything too loose/tight.

[Grizzly]

As my uncle said to 40yrs ago (He was an ace mechanic!) when I complained that whilst rebuilding my Triumph 5TA.
That "I could not torque up the big end shells as I did not have a torque wrench"?
He replied "That what do you think they used before torque wrenches?"

True but not really applicable nowadays, because if you rebuild something and the nuts or studs have not been torqued. Then most will not honour their warranties.

Personally I think the first question any self respecting Engineer should ask is. "What are the torque settings"!
I think what is being said about applied vertical torque is Bo**ocks!

Nowadays you may have to torque to a specified setting and then using a annular gauge move to so many degrees forward.
Ask any modern car mechanic.
The only time I have seen problems is when someone has not applied the torque settings.
But in fairness a cast or malleable iron fitting ain't going to be bothered about the amount of torque applied.
But con rod or other items made of alloys do!

Only my opinion, but it is based on years of training and experience!
Grizzly

[nike123]

http://www.freeinfostuff.com/TorqueExtension/TorqueExtension.htm

[Grizzly]

SPOT ON NIKE!

Sadly I cannot give you a rep point as we musty of agreed on something else recently!!!
Grizzly

[charlie patt]

i had a issue when doing tk heads and big comps dont like takeing my snap on stuff in the rain but cheaper extension bars do twist so i cured the issue by useing my good kit also the twisting effect tends to push the torque wrench one way and twists the socket the most even torque you will get is a t torque wrench the shortest extension you can and square sided sockets ie 6 spline not 12 spline

[Rob White]

SPOT ON NIKE!

Sadly I cannot give you a rep point as we musty of agreed on something else recently!!!
Grizzly


I can't give you rep points but I can NIKE, so I've repped him for you :D

Rob

.

[nike123]

We call that a "cession"!:D

[monkey spanners]

Thanks everyone!

[glenn1340]

10958Here`s what we used to use on diesel loco cylinder heads. I can`t remember what the initial torgue setting was 750 ft/lbs maybe but then it was finished off with a torgue multilpiler moving five notches on the socket over a mark made on the head on 0 finnishing on 5 alternating between the multiplier heads. Definitely a job for the apprentice. It didn`t stop the studs from shearing off though.

[PaulZ]

Hi Nike
Good link, I have saved for future reference.
Have added to your rep.
Paul

[monkey spanners]

10958Here`s what we used to use on diesel loco cylinder heads. I can`t remember what the initial torgue setting was 750 ft/lbs maybe but then it was finished off with a torgue multilpiler moving five notches on the socket over a mark made on the head on 0 finnishing on 5 alternating between the multiplier heads. Definitely a job for the apprentice. It didn`t stop the studs from shearing off though.

Wow looks like that would keep you fit!

[FreezerGeezer]

Regarding a 'normal' extension, I've wondered in the past about the effect it may have as I often find that there's enough slop in the system that the torque wrench ends up not at 90* to the fixing. If you hold the extension to keep things lined up properly, that surely interferes with the accuracy?

[glenn1340]

....and that was only one bank, there`s another bank of six cylinders on the other side.

[FreezerGeezer]

I discovered that Norbar have some useful info on the subject, and apps for iPhone & Android.

http://www.norbar.com

http://www.norbar.com/calculators/torque-wrench-extension-calculator.aspx

Hope they help someone. I have no relationship with Norbar, by the way.

[monkey spanners]

I discovered that Norbar have some useful info on the subject, and apps for iPhone & Android.

http://www.norbar.com

http://www.norbar.com/calculators/torque-wrench-extension-calculator.aspx

Hope they help someone. I have no relationship with Norbar, by the way.

Thanks! More apps for the phone!