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Let's talk a little torque tech?????????????/

Posted By: 65racer

Let's talk a little torque tech?????????????/ - 12/28/11 04:07 AM

Was wondering how many of you guy's figure
out the torque of a bolt, or stud,when you are using
an extension on your torque wrenches?

I am in the process of freshening my engine,
and ready to torque the heads, and was figuring
out the torque when using an extension on the
wrench the studs call for 80 lbs, but when you
figure it out with an extemsion on the tw the
torque valus is quite a bit less, I am figuring
it this way

length of torque wrench multiplied by the stated
torque of stud

20" x 80 lbs

Now add a 4" extension on for clearance over the
rocker stands, add the 4" to the length of the
torque wrench

20" + 4"

Now take the totals of the 2 and divide them,

20x80= 1600
20+4= 24 devide the 24 into the 1600

Now you have 67lbs average for the torque of
the studs this seems like it is low to me, am
I over thinking this or not, I have had a problem
for the last few seasons with head gaskets showing
leaks when the engine comes down for the winter
freshening, and was trying to figure out the
root cause of the problem, I feel like they
are not getting torqued enought to seal them.
by the way I am using the steel shim gasket, have
tried every trick I know to tweak them to get a
seal, and have not been successful yet
sooooooooooooo how to you do your torquing, when
you do heads??????

Thanks
Dave
Posted By: Cab_Burge

Re: Let's talk a little torque tedh?????????????/ - 12/28/11 04:16 AM

I was told by a long time Snap On dealer to always add 5 lbs for any extensions(1/2 inch drives), he also said to keep the extensions as short as possible. I try to use deep well sockets now to avoid using extensions
Posted By: ahy

Re: Let's talk a little torque tedh?????????????/ - 12/28/11 04:17 AM

An extension added to the socket will wind up a little but it won't change the torque. Torque is the same at both ends of the extension.

That said, a "click" type wrench does have some dynamics... if you "click it fast" with an extension, torque may be affected - up or down. With a beam style wrench, no impact of the extension at all. For head or other critical fasteners an inherently accurate beam style wrench is better.
Posted By: astjp2

Re: Let's talk a little torque tedh?????????????/ - 12/28/11 04:27 AM

Snap-on has a class on torquing procedures and theory.... Contact your local snap on distributor to find out more about it. Tim
Posted By: MR_P_BODY

Re: Let's talk a little torque tedh?????????????/ - 12/28/11 04:30 AM

Quote:

An extension added to the socket will wind up a little but it won't change the torque. Torque is the same at both ends of the extension.

That said, a "click" type wrench does have some dynamics... if you "click it fast" with an extension, torque may be affected - up or down. With a beam style wrench, no impact of the extension at all. For head or other critical fasteners an inherently accurate beam style wrench is better.



I agree on the extension ... its all under the same load...
I always move things at one rate as to not upset the
torque
Posted By: Evil Spirit

Re: Let's talk a little torque tedh?????????????/ - 12/28/11 04:34 AM

A torque wrench measures the twist sent down into the fastener - the length of the handle only changes the amount of force needed to obtain that twist. So to apply 100FT/LBs of torque (twist) you would need to apply 100LBs at 12", 75LBs at 18" and 50LBs at 24".

As to the extension absorbing torque - that would depend on the length and quality of the extension - a short tool truck (Snap On, Mac, Matco) would deflect less than a longer box store (Home Depot, Ace) extension. I don't know of a formula to figure that out - it would depend as I said on the perticular extension used.
Posted By: jamesc

Re: Let's talk a little torque tech?????????????/ - 12/28/11 05:28 AM

adding an extension should not affect the final torque assuming the fastener is being tightened properly in the first place. the length of a wrench would affect the torque but being you're using a torque wrench that is not a consideration. a threaded fastener is supposed to act like a spring and the goal is to have the proper preload on the spring. most people probably don't understand the mechanics behind a threaded fastener. think of it as an inclined plane (ramp) wrapped around a cylinder. this is why for a given amount of torque a fine thread fastener will apply a greater amount of clamping than a coarse one, it equates to a longer ramp.

imho one of the most important aspects of proper torquing is to make the final tightening in one smooth continuous movement. if you can't do this and stop before the final value then try to hit it again the break away can be greater than the desired value and the fastener will appear to be properly torqued but will actually be below value. it is very critical to make the final pull in one smooth continuous movement. i also think it's important to not have the fastener too tight before the final so you get a nice smooth final pull.

use the proper torque specifications, a REAL torque wrench, make sure all threads are in good condition and clean, use the specified lubricant. there's a good bit of difference between using oil and moly. for fasteners such as connecting rods or mains the fastener should be tightened in a manner that duplicates the way they were tightened when the bore was honed.

when it comes to torquing don't just assume that tighter is better. as for steel shim gaskets i'm not sure just what they will withstand. is this an iron head on iron block?

personally i don't think bolts have any place whatsoever in the mains, heads or rocker gear of a high performance engine. studs give more effective clamping and prevent wear on the block and heads. every time you pull up on a bolt it wears the block or heads.
Posted By: MOPARCRAZY

Re: Let's talk a little torque tech?????????????/ - 12/28/11 05:48 AM

The calculation you are discussing is for an extension like a dog bone etc. I assume you are just talking about an extention between the socket and torque wrench, there would be no change. Make sure you have the right lenght bolts in the right positions.
Posted By: Evil Spirit

Re: Let's talk a little torque tech?????????????/ - 12/28/11 06:24 AM

Quote:

adding an extension should not affect the final torque assuming the fastener is being tightened properly in the first place. the length of a wrench would affect the torque but being you're using a torque wrench that is not a consideration.



Again - the length of the wrench does not affect the torque , it only affects the force you have to apply to the wrench to obtain the torque. Torque is being measured at the point of rotation, not where the force is being applied. Take a 2' bar - it does not matter if you apply force at anywhere on the bar or at what angle (3, 6, 9, 12 o'clock) 100FT/LBs of TORQUE is the same, only the force to obtain it changes with distance from pivot point.
Posted By: jamesc

Re: Let's talk a little torque tech?????????????/ - 12/28/11 06:33 AM

Quote:

Again - the length of the wrench does not affect the torque





i was referring to a standard wrench with a given applied force. in this case the length of the wrench DOES matter which was the point i was trying to make. for a given applied force the longer the wrench the greater the applied torque. you put five pounds on the end of a 12" wrench you get five pound feet of torque, you put the same five pounds on the end of a 24" wrench you get 10 pound feet of torque.
Posted By: Evil Spirit

Re: Let's talk a little torque tech?????????????/ - 12/28/11 06:44 AM

Quote:

Quote:

Again - the length of the wrench does not affect the torque





i was referring to a standard wrench with a given applied force. in this case the length of the wrench DOES matter which was the point i was trying to make. for a given applied force the longer the wrench the greater the applied torque. you put five pounds on the end of a 12" wrench you get five pound feet of torque, you put the same five pounds on the end of a 24" wrench you get 10 pound feet of torque.



The bolt really doesn't care where you place your hand to turn it, only how hard you turn it. You don't measure torque at the handle of the wrench, that is applied force . Torque is measured at the socket end, as a measurement of rotational force.
Posted By: MR_P_BODY

Re: Let's talk a little torque tech?????????????/ - 12/28/11 06:46 AM

I have seen some people(not many) that would hold
the extension during the torque process and I told
them not to hold there and explained that they were
changing the value by what ever they were holding
in their hand... hold the wrench at the pivot and the
end... I do like the clicker style.. just makes the
job go quicker....... just make sure they are accurate
Posted By: jamesc

Re: Let's talk a little torque tech?????????????/ - 12/28/11 07:00 AM

Quote:

The bolt really doesn't care where you place your hand to turn it, only how hard you turn it. You don't measure torque at the handle of the wrench, that is applied force . Torque is measured at the socket end, as a measurement of rotational force.




i never said you measured torque at the handle (though in reality you do) but given the amount of applied force and length of the handle you can calculate the amount of torque applied this is why torque is given in POUND FEET a measure of force AND a measure of LENGTH. torque is a measure of a turning force but the value assigned to it is a measure of length and force. my point was that the longer the wrench if you apply the same force the torque will be greater. i was trying to give a little explanation of the law of the lever. i may not be a theoretical physicist but i do have a little smarts you know.
Posted By: Evil Spirit

Re: Let's talk a little torque tech?????????????/ - 12/28/11 07:05 AM

Mr P, lets really confuse them and toss using a wrench or crows foot onto the socket end of the torque wrench into the situation
Posted By: Evil Spirit

Re: Let's talk a little torque tech?????????????/ - 12/28/11 07:08 AM

Quote:

Quote:

The bolt really doesn't care where you place your hand to turn it, only how hard you turn it. You don't measure torque at the handle of the wrench, that is applied force . Torque is measured at the socket end, as a measurement of rotational force.




i never said you measured torque at the handle (though in reality you do) but given the amount of applied force and length of the handle you can calculate the amount of torque applied this is why torque is given in POUND FEET a measure of force AND a measure of LENGTH. torque is a measure of a turning force but the value assigned to it is a measure of length and force. my point was that the longer the wrench if you apply the same force the torque will be greater. i was trying to give a little explanation of the law of the lever. i may not be a theoretical physicist but i do have a little smarts you know.



Please explain why you would measure force at the handle - given using a modern electronic, click, or beam style wrench.
Posted By: jamesc

Re: Let's talk a little torque tech?????????????/ - 12/28/11 07:16 AM

"Give a man a fish, you have fed him for today. Teach a man to fish, and you have fed him for a lifetime."

i was trying to give an explanation and examples of how this works. i could have just simply said the extension makes no difference and left it at that.

this is NO shot against Dave he came here and asked an honest question and in his question it shows he is not familiar with the law of the lever which i'm sure a lot of people don't understand. it's a very simple principal that can be a little hard to describe without pictures, similar to hydraulics and pressure.
Posted By: jamesc

Re: Let's talk a little torque tech?????????????/ - 12/28/11 07:20 AM

Quote:

Please explain why you would measure force at the handle - given using a modern electronic, click, or beam style wrench.




you're right i give up
Posted By: Evil Spirit

Re: Let's talk a little torque tech?????????????/ - 12/28/11 07:35 AM

Quote:

"Give a man a fish, you have fed him for today. Teach a man to fish, and you have fed him for a lifetime."

i was trying to give an explanation and examples of how this works. i could have just simply said the extension makes no difference and left it at that.

this is NO shot against Dave he came here and asked an honest question and in his question it shows he is not familiar with the law of the lever which i'm sure a lot of people don't understand. it's a very simple principal that can be a little hard to describe without pictures, similar to hydraulics and pressure.



We're just on the same book - different pages deal here, James. He introduced the length of the wrench into the math. My point always was when using a modern torque wrench that figure doesn't matter. You set the wrench - you pull on the wrench till it clicks - done like dinner. The head of the torque wrench does the "math" - distance from center to center and force applied. I was just trying to get him to forget about a figure that he didn't need.
Posted By: Evil Spirit

Re: Let's talk a little torque tech?????????????/ - 12/28/11 08:01 AM

And back to the second part of the question, about the extension changing torque - here's some food for thought. I have a 30" extension for trans bolt removal - I'm pretty sure it's a Snap-on, so it's a quality tool. There is a lot of times that I've had this extension twist 1/8 - 1/4 turn and need over 100FT/LBs to break loose a 3/8 bolt. Common sense tells you that you will twist the head off a 3/8 trans bolt LONG before 100FT/LB's. Where's all the extra torque going? It's being absorbed by the extension. So I just went out to the garage and did a little experiment. I put a 3/8 nut in the vise, tossed a couple washers on a grade 8 3/8NC bolt and using my click torque wrench set to 75LBS and using the 30" extension, tightened the bolt. There was over 1/8 turn of twist in the extension. Removed extension and started setting the torque wrench at 35, 40, 45 etc till the bolt started tightening again. It was good at 50, but started to move at 55, telling me that the extension absorbed about 20 FT/LBs torque. Granted, the 30" extension is an extreme case, but I would have to say if the extension is being twisted hard enough to deflect it is absorbing torque.
Posted By: jamesc

Re: Let's talk a little torque tech?????????????/ - 12/28/11 10:26 AM

read up on Sir Isaac Newton's third law of motion.

if the torque wrench clicked off at 75# with the extension what was stopping the socket from turning? the nut/bolt assembly was exerting 75# of resistance when the wrench clicked, fact. the extension stored energy it didn't absorb it (technically speaking it did absorb a tiny amount, the extension heated up a little under load), there was recoil when you released the torque wrench.

trust me for every action there is an equal but opposite reaction...i don't make these laws i just follow them.
Posted By: 540DUSTER

Re: Let's talk a little torque tech?????????????/ - 12/28/11 01:25 PM

take two head bolts and tighten one with an extension and one with a short socket to 100 foot pounds.Now measure the bolt that was tightened with the extension with the short socket and see what happens.
Posted By: SportF

Re: Let's talk a little torque tech?????????????/ - 12/28/11 01:25 PM

Looking at the original question, I think the confusion is actually in the "extension" part. Some if not all of the math formula is using the length of the torque wrench in there. This type of formula (which I just can't agree with) comes from the internet formula for an "extension" that moves the square of the torque wrench away from the center of the bolt, like a crows foot would. That is why, I think, this added lever has reduced the torque required. But this formula has been incorrectly stuck in there using a height "extension".
Now, as for the height extension abosorbing torque? Sure does, you can buy these extensions that limit the torque applied to head bolts. Put on one of these extensions and they just twist when the correct torque is reached, eh? But for a short stout 4" extension I think you can pretty much forget about it.
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