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Torque wrench question
Post by dxeflyr on May 1, 2006, 9:35am
Here's a noob question for y'all:
When working with a torque wrench and an extension, does the use of the extension mess with the selected torque of the wrench? I may be thinking "fuzzy" physics, but I would imagine that since you're lengthening the arm of the force, you would also alter the amount of work done. Do you have to adjust the wrench when using a long extension on it? Thanks.
Re: Torque wrench question
Post by osut362 on May 1, 2006, 9:58am
won't change the reading unless you make the wrench "longer". if the extension is 90 degrees from the head of the wrench it won't change the readings no matter the length.
Re: Torque wrench question
Post by barrman on May 1, 2006, 10:02am
Al is correct. You only need to think funny when you use a swivel or universal joint style socket on the fastener you are working with. Then only if you are actually utilizing the feature and not 90 degrees to the fastener.
Re: Torque wrench question
Post by dxeflyr on May 1, 2006, 10:12am
Thanks guys... appreciate the help. Thought all of this up working on one of my Broncos the other day, guess I overthought the whole thing, haha.
Re: Torque wrench question
Post by amphi on May 1, 2006, 10:39am
I’ve often wondered the same thing. Some good info found here.
The zone experts here have it right again. Looks like no change if done correctly.
Two extension methods shown below:
From:
http://www.popularmechanics.com/auto...c/1271951.html
http://media.popularmechanics.com/images/tb_1402_1.jpg
From:
http://home.jtan.com/~joe/KIAT/kiat_3.htm
http://home.jtan.com/~joe/KIAT/fig_10c.jpg
Both articles have good info.
Re: Torque wrench question
Post by barrman on May 1, 2006, 12:35pm
Thanks for the articles. I love to collect good technical items to share with my students.
Re: Torque wrench question
Post by 40grit on May 2, 2006, 9:58am
up to a certain point you are correct , but then past a certain ft-lbs, you have to take the rotational deflection of the extension into consideration..there's a chart somewhere with some guidelines...IIRC, it's above like 75ft-lbs that the 1/2" extensions start to deflect a little and give a mis-reading due to rotational torque applied to the extension shaft... the torque wrenches are designed to be used without any extensions, so for some stuff, you need to compensate a little depending on extension length..let me see if i can find the chart..
found this so far...
6. The use of any type of drive end extension on a torque wrench changes the dial reading required to obtain the actual values indicated in the standard torque range tables. When using a drive end extension, the torque wrench reading must be computed by use of the proper formula, which is included in the handbook accompanying the torque wrench.
or from here
http://experts.about.com/q/Eagle-Repair-810/torque.htm
Question
I'm in the prossess of installing a new head. But a friend says that if you use a extension on a torque wrench that it changes the torque. And I
need to know if its true, and if it is is their a formula to figure out how much to conpinsate. I'm using a 6" extension, and a 1/2" to a 3/8" drive adaptor. Please help as soon as possible I realy need the vehical. THANKS!!!!!!!
Answer
I could go ahead and provide a lengthy physics calculation for your question, But I will spare you the deatils.
Your friend is CORRECT.
EXAMPLE: If your torque setting is, Let's say 25 to 30 lbs. Torque it at 35.
In other words just use the HIGH side of the torque spec and add 5 lbs.
NOTE: Just make sure you torque the bolts/nuts in sequence to 15 lbs EACH then go back and retorque them to 35.
Re: Torque wrench question
Post by 40grit on May 2, 2006, 10:01am
plus, adding an extension to the handle doesn't change the torque unless you move your hold point further away from the pivot, then it will still make the same torque for a given degree of rotation, it will just be easier to pull with the added leverage of being further out...100 ft-lbs is still going to be the same amount of rotational change for the torque wrench it self...adding the extension doesn't change the properties of the torque wrench, just changes how easy it is for you to acheive a certain torque...