universal sockets and torque
- Thread starter DHCrocks
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Merkava_4
Banned
Lose torque with universal sockets? That's a new one on me. 
peter_x
Well-known member
I thought that u-joints actually increase torque.
DavidtheDuke
Well-known member
- Joined
- Jan 6, 2008
- Messages
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Try taking off a really tough fastener with an impact swivel at it's max angle. Usually doing so takes most of the torque from the impact away before it gets to the bolt head. Aka, it doesn't take it off unless you can figure a way to get straight on it.
krusty the clown
Member Emeritus
if you are talking about tourqing with a tourqe wrench it's insignificant. you do lose some of the power of an impact though.
Charles (in GA)
Well-known member
Same experience here.
I would not use a u-joint or swivel socket for torque unless absolutely straight on. No way of judging or calculating the change in torque.
Charles
eschoendorff
Well-known member
You sure about that? I thought that it definitely affected torque...
scofo
Well-known member
Well in real world engine compartments you do your best with the room available.
krusty the clown
Member Emeritus
only if it is held at such an angle there is a difference in length from the fastener to the center of the drive of the torque wrench.
i guess i should have used the word minimal instead of insignifiacant.
this can explain better than i can
http://www.etorque.com/html/dial_wrench_calculations.htm
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Uncle Buck
Banned
I always try and avoid flex sockets if at all possible for torqueing applications, I only use one when I have no other choice.
nissan_crawler
Well-known member
We use them all the time in aircraft to the specified torque, never had a problem. Any time you add anything to an impact, be it an extension, long socket, etc., you're going to take some of the power away, that's just the nature of it. Hopefully you're drawing your torque wrench up steadily though, and not slamming on it.
garfunkle24
Well-known member
During my technical training I was advised by my instructors to add 3% torque for every inch of extention used and 5% for an adapter and 10% for a swivel or u-joint. I'm sure these are rough guidelines, and I don't know what it's based on, but it's what I was told.
GDA
Well-known member
From what I've read, I was under the impression that the specs on torque wrenches were spec'd for a certain point (distance) from the ratchet head based on a true single 90 deg attachment point to the ratchet. So that would be one socket attached and adding an extension would also tend to lower the actual torque applied. I would believe a universal will also impact this direct effort and result in some (albeit minor) level of torque at the fastener.
Charles (in GA)
Well-known member
Cannot say I've ever heard or seen any of this. Even if an extension twists, it is not absorbing the torque, it is still transmitting it to the far end, you can pile on a couple of feet of extensions, but if kept straight and square to the torque wrench, the torque will be the same at the fastener as if there were no extensions. I seem to recall a discussion similar to this a few months ago. Now a swivel, or u-joint, yes, as far as I'm concerned, it "eats" torque if you are at an angle. I suppose I could prove this by using my Craftsman digital inline torque measuring device and a torque wrench and a universal, extensions, etc, and see how much the torque wrench varies from the digital readings when different attachments are used.
Charles
GDA
Well-known member
I agree that extensions will not impact applied torque if.... they are kept straight and square to the wrench. However, analagous to golf shafts the longer the extension and given level of flex, the overall repeatable accuracy of the applied torque would be the one most impacted. Also known as repeatable shot dispersion.
I am not an engineer so I'm just posting what I understand from reading about the proper use of torque wrenches and application to a similar concept.
You can use univeral sockets with torque wrenches if you know the offset angle. You must set your torque wrench to a greater torque if the plane of rotation of the torque wrench head is not parrallel to the bolt head plane of rotation. If you have any offset angle the torque applied to the fasterner will be less than the torque wrench setting so you must adjust for this.
If I remember correctly the impack swival sockets have a 30 degree offset MAX. You need this information to calculate the torque setting for your torque wrench.
I think the equation is
TA = T/cos^
where TA is the applied torque or torque wrench setting
T is the torque applied to the fastener
^ is the offset angle.
So if your wrench is parrallel to the fastener ^ would be zero and if the fastener spec is 100 Nm torque then TA = 100 Nm/cos(0) or 100 Nm which is the same as your torque wrench if you are using a regular socket.
If however, you use a swival socket and the offset angle is 30 then
TA = 100 Nm/cos(30) or 115.47 Nm
If the angle is only 20 then you set your wench to only 106.42 Nm
The greater the offset angle the greater you much increase your torque wrench setting.
If I remember correctly the impack swival sockets have a 30 degree offset MAX. You need this information to calculate the torque setting for your torque wrench.
I think the equation is
TA = T/cos^
where TA is the applied torque or torque wrench setting
T is the torque applied to the fastener
^ is the offset angle.
So if your wrench is parrallel to the fastener ^ would be zero and if the fastener spec is 100 Nm torque then TA = 100 Nm/cos(0) or 100 Nm which is the same as your torque wrench if you are using a regular socket.
If however, you use a swival socket and the offset angle is 30 then
TA = 100 Nm/cos(30) or 115.47 Nm
If the angle is only 20 then you set your wench to only 106.42 Nm
The greater the offset angle the greater you much increase your torque wrench setting.
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nissan_crawler
Well-known member
Only if you're at one hell of an angle. That's assuming you have good ones.
nissan_crawler
Well-known member
which is the accepted error in a torque wrench. If your torque wrench is accurate, it's not a big deal. Each to their own, though.
Merkava_4
Banned
the reason I was asking was I had to tighten down some bolts in an aluminum block and because of the tight access I couldn't get a straight shot so I had to go to the universal socket. it was so tight even that could barely fit. I had to use a 10" extension and I'd guess I was about 2"-3" off centerline of the bolt. Very hard situation I had to even use my flex head torque wrench so I know the with all the those things going on the torque value as a little off . Yes it was a good socket, it's a SnapOn and no it didn't bind. If it's only off 4% or so no biggie I guess.
nissan_crawler
Well-known member
They don't worry about it on turbines, I doubt it'll matter on an engine block.
There are some fasteners that are very critical and must be stretched precisely so that the tension in the threads is near perfect. Most fasteners are not that critical and only require torque in a certain range and for the most critical , strain and angle guages are often used instead for better accuracy. Fasteners are torqued to spec so that the bolts are stretched enough to increase tension so they do not loosen but not so much to damage the threads. This is why torque wrenches are used but they are less accurate due to friction between the bolt head and washer.
Only use univeral swival sockets with torque wrenches when you must because it does introduce some error that would otherwise not be an issue. It is usually quite small though if the offset angle is not too large, but you can increase the torque setting to compensate.
If you are using wobble extensions with your torque wrench increase the torque setting by about 2 to 3%. It is usually better to under torque slightly than over torque. If you are using impact swival sockets use the maximum 30 degree offset and increase the torque setting by about 14%. This is slightly less than the spec torque but probably close enough.
Only use univeral swival sockets with torque wrenches when you must because it does introduce some error that would otherwise not be an issue. It is usually quite small though if the offset angle is not too large, but you can increase the torque setting to compensate.
If you are using wobble extensions with your torque wrench increase the torque setting by about 2 to 3%. It is usually better to under torque slightly than over torque. If you are using impact swival sockets use the maximum 30 degree offset and increase the torque setting by about 14%. This is slightly less than the spec torque but probably close enough.