How to determine Ft/Lbs?

Beigg

Beigg

Club Member
If during the installation for some hardware required for a torque value, yet was only possible by using some degree of angle & extensioning, how would you figure that out? Included below is a quick paint shop image for reference to better help explain the situation.

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Thank you.
 
I don't think the 20 degree angle will change the torque. What will change the torque is the torsional force of the long extensions pushing back against you. That is IF you can keep the constant 20 degree angle on the extensions. If you are swaying back and forth while tightening the bolt, then it is impossible to determine the torque difference.

If you use moly lube on the bolt threads and seat, you can reduce your actual torque number by something around 20% (I think) over plain oil on the threads.

Been 45+ years since I got out of college...I forget stuff...Hahaha

Gary
 
No torque loss unless there is radial deflection. So if you can keep the pile of stuff rigid and you don't have loss in torsion it will be the same.

In reality, you're going to have some loss depending on components. For example, I lose 10ftlbs in my 48" antique Crapsman 1/2" extensions. It seems rigid until you measure it and you realize a lot of energy is being lost in loading up the extension.

Can you mock up the same setup using a coupler to an old style needle torque wrench from your normal torque wrench?
 
I have my original Craftsman needle torque wrench in the original box from the 60's if you want to borrow it...

Gary
 
I always just assumed there was some torque wrapped into an extension. So I always SWAG it and add 5 ft lbs, (assuming a number of around 100 ft lbs). That way you'll probably be within a couple ft lbs and not enough off the mark either way to matter. Have never had a problem this way. I know that's probably not good enough for some applications and it would be good to know for sure how to calculate actual numbers.
 
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The drive head pushed farther "away" from the socket begins with and ends with the torque to be achieved. It's the angle that I'm concerned with.
IF a crowsfoot were used, or an offset attachment, then that will change the torque value too.

I'm not looking for the person's need of adding effort, I am trying to maintain the specification needed at the head of the bolt from the socket using a click-type torque wrench.

Think of it as a driveshaft angle. Pinion angle not only impacts reliability and durability, but it can play around with how much effort is needed to turn the universal joint at the rear end if that degree is excessively pitched.


moneypit said:
ill ask where did you get a 6 foot 1/2 drive extension?
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two extensions at 36" + the little addition.
The stability is sound, no wiggling/wobbling around as it is all supported in some way or another.
 
mf'n PTO bolts.

If it is able to apply torque this way, it'll save a lot of knuckle busters and time.
 
Depending on the kwality of your extensions and the amount of torque you're putting through them, you will lose torque in winding them up. Just like how torsion bars in a truck work. A shitty universal will lose torque in it also. The good ones (that use 3 ball bearings, like a CV joint) lose less. This is assuming you're working with a static load (fastener not moving, versus a kinetic load where it would be). If you're measuring when it's moving (dealing with kinetic friction after overcoming static friction) then there is no loss but I doubt you're doing that as it would be pointless.

When I worked at Michigan Tech I had access to some sweet labs including the Keweenaw Research Center. One of the many hillbilly things I did is experiment with things like that. It made it easier for this dumb EE to deal with Statics and Fluids classes (for smert MEs) when I could do things hands-on.
 
Stick the bolt in something and torque to spec. Then add your extensions and try again. Almost all automotive specs have a +/- of 10%
 
1BADAIR said:
Stick the bolt in something and torque to spec. Then add your extensions and try again. Almost all automotive specs have a +/- of 10%
Click to expand...

Normally, that is what I'd do if possible and in question for torque specification. Unfortunately, that is not feasible in this case.
 
The first person that used a german torque value made it necessary to use new hardware this go around.

That or they were practicing Russia's methodology...
 
Beigg said:
Normally, that is what I'd do if possible and in question for torque specification. Unfortunately, that is not feasible in this case.
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why not? clamp a nut or bolt of the correct size in a vise, add the bolt/nut you use to mount the PTO, torque with your extension setup, then torque with just a socket
 
dave89iroc said:
why not? clamp a nut or bolt of the correct size in a vise, add the bolt/nut you use to mount the PTO, torque with your extension setup, then torque with just a socket
Click to expand...

It would require a jig to gain the angle for replicating the situation. Not feasible currently. If a formula was known, figuring out the equation would be less involved me thunks?
 
Beigg said:
It would require a jig to gain the angle for replicating the situation. Not feasible currently. If a formula was known, figuring out the equation would be less involved me thunks?
Click to expand...

Sadly there is no formula for this. Too many variables based on extension and universal quality/metallurgy. Your best bet is to replicate the angle the best you can in a vise and compare torque values. With out some very expensive tools you are not going to get it +/- 0%. You should very easily be able to get it +/_ 5% depending on the calibration of the torque wrench you use.

Also where the hell do you get a 72" extension and how much was it. I can only imagine what that cost.
 
the wrench being used was calibrated less than a couple months ago. It's now just being used for the first time. Snap-on/Bluepoint iirc. Less than 10% for a +/- variance is acceptable, just don't want to be reliant on the clicker being set at 165 when the end number might be 20+% lower than the setting compounding that with an "error rate" of 10% max thus being off by 30% overall.
 
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