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:confused:

If I am re torqueing head bolts with a 6” extension at 110 ft/lbs how much torque am I loosing?
Or what should I set my wrench at to achieve 110 ft/lbs with the extension?
 

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An extension (in the regular sense of the word) doesn't change the torque wrench setting.
 

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Originally posted by Mike_C:
An extension (in the regular sense of the word) doesn't change the torque wrench setting.
as long as you keep it perpendicular
 

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Precisely Perpendicular, which I find VERY difficult and have found my torques off as much as 6-8 lbs using extensions. Brian
 

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It will change the amount of torque applied. How much is another question. Not enough that I would worry about it though. If it bothers you just add three or four pounds to the setting on the wrench to make up for it.
 

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I agree w/Mongol. I wouldn't use an exstension on a head bolt but other "Non Essential" bolts I would just add 3-4 lbs. Brian
 

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It sure does make a difference, have you ever heard of torque sticks? There will be a difference between Snap-On & craftsman extensions.
 

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Yes it does make a difference. That is what sway bars or torsion bar does. Twist. Way back when I was an engine machinist there was a formula for the distance but I don't recall it. Never the less never use an extension on head or main/rod cap bolts. If you try to guess you might stretch them. FAILURE!
 

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Use the shortest largest diameter extension you have as well as a good 6 point socket (a deep well socket can shorten the extension needed) . As stated above keep everything perpendicular follow the torque sequence and you should be OK with a short large diameter extension.
HTH
CB
 

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An extension used perpendicular with the bolt will not change the torque applied no matter how long it is. If you put a load cell that is used to calibrate torque wrenches at the end of a 6", 9" or even 12" extension and used a flex beam or breaker bar torque wrench you would react the same torque at the load cell no matter which extension you used or even if you put them end to end. This is only true for a 'static' load. Where it does make a difference is with an impact wrench.

As for torque sticks they are specifically designed for use with impact wrenches and do not actually limit torque but allow a designed amount of flex (twist) that effectively limits the torque applied to the bolt by reducing the effective rotation of the impact hammer blow.

As a foot note using a crows foot with a torque wrench does require a torque correction.
 

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That just means you have to turn the wrench a bit further before it clicks off. The torque applied to the bolt will still be within specifications.
 

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Mongol
Adding three or four pounds is EXACTLY wrong. When the extension is not perpendicular your are increasing the length of the lever which in turn would give you an artificially high reading. Best bet as Cone Basher said,"shortest extension...six point..". I might add a six point deep socket may give you the clearance required with a minimum amount of distorted readings. And for the purists, torque wrenches should be calibrated every six months.
Bill
 

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OK, there is alot of fuss on here about twist and so forth. From experience I have had with load cells, the biggest error you can make is with technique. A person who torques quickly will get a huge error compared to a slow and deliberate pull. I have seen errors up to 20% and accuracy well within 3%, just by how a person wrenches. The procedures where I work require that bolts are torqued in 4 steps, each time using the correct pattern. After the final torque, it is a good idea to go back and "ring" the pattern again. This is because of what is known as gasket creep. I'm involved in training maintenance workers. We have a $40,000 torque training mock-up with strain gauges on each stud. When you torque a fastener, you would be surprised to know that the strain on the opposite fastener will go up and those adjacent will go down. This can be explained as the part pivots on the gasket, if you will. Think of it as a tetter totter. one goes down, the other (opposite) goes or at least trys to go up. Also, getting back to creep. It depends on the gasket material, but I have seen the strain gages loose tension for up to 15-20 minutes after initial torque. So it makes little sense to me to argue about an insignificant amount of twist in a 6" extension when there are what I believe to be bigger issues. Also, stay away from the bottom and top 10% of the torque wrench span. I detest those specs of lets say 6-8 ft lbs. I can't even read that on my ft lb wrench. Instead, convert it to "lbs by multiplying the mean by 12. 84"lbs is well within the range of my "lb wrench.

Also, people always argue about where you have to have your hand on a torque wrench. I know that snap-on and others will have a line for where to pull, but we have proven on our calibration machine that it dosn't matter unless of course you are dealing with a beam type. With the beam type, of course you need to pull evenly on the pivoting handle. Both the click type and dial type were quite accurate no matter where we pulled. We don't calibrate them willy nilly like this, but when we put it to the test, it didn't seem to matter.

Anyways, thats my 2 cents, (or should I say $40,000) on this.

Jerry
 

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The amount of tq applied to the bolt will not change as long as like mention proper tech. is used. You may have to rotate the tq wrench slightly further in comparison to not useing an extension since in theory the extension twist but as long as it does'nt bend or break and wrench is tq'ed far enough to reach it setting the bolt will be tq'ed to that value. If useing an extension did change the value it would be same as useing deep socket compare to short socket. I do find it easyer to use the tq. wrench with the short's length needed but only because it makes it easyer to keep wrench straight and not come in at an angle to the bolt.
The example of compareing a suspensions sway bar is not totally the same as extension on wrench. The sway bar/torsion will transfer tq. "if" added motion/rotation is applied from the source. Sooner or later if enough force is used to over come,use up the twist of the bar,it will no longer twist and transfer the force thru it.Or break. :confused:
 

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Nice post Jerry.

People tend to oversimplify torquing bolts, and it is far from being simple. I know this will start another debate but; there is only one sure fire way to set the proper pre-load in a fastener and that is to measure bolt stretch. All other methods are influenced by a multitude of factors that require assumptions that may or may not be correct for any given bolt installation.
 

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Originally posted by Mike-Noyes:
An extension used perpendicular with the bolt will not change the torque applied no matter how long it is.

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If the head bolts are in New York and the torque wrench is in LA, using a 3000 mile extension. You will lose some torque, but you'll gain 3 hours.
 

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ffr1668, your killing me here. Its like a race to see who can get more technical. Don't use the ext. if at all possiable but if you have to, keep it as straight as you can and don't worry about it. It will not make that big of a difference. mong
 
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