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Torque wrench question #973356
04/14/11 10:26 PM
04/14/11 10:26 PM
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JoesMopar Offline OP
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When using a torque wrench, does using an extension affect the amount of torque being applied to the fastener? I wasn't sure if using an extension will throw off the actual torque from what the wrench is set at.

Thanks

Re: Torque wrench question [Re: JoesMopar] #973357
04/14/11 10:30 PM
04/14/11 10:30 PM
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court9155 Offline
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Ive heard it does so I avoid using an extension if I can.

I guess one way to tell is to torque something with an extension then remove the extension and check the torque setting to see.


67 charger
Re: Torque wrench question [Re: court9155] #973358
04/14/11 10:32 PM
04/14/11 10:32 PM
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Cincinnati, Ohio
Challenger 1 Offline
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Quote:

Ive heard it does so I avoid using an extension if I can.

I guess one way to tell is to torque something with an extension then remove the extension and check the torque setting to see.






It definetly affects it.

Re: Torque wrench question [Re: Challenger 1] #973359
04/14/11 10:35 PM
04/14/11 10:35 PM
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Extension doesn't change the torque, as long as it's 90 degrees to the lever arm. You're still rotating about the same point.

Only when you extend the rotational point outward does the torque change.

Good info here:

http://www.specialpatrolgroup.co.uk/spooky/torque/torque.html


Re: Torque wrench question [Re: Challenger 1] #973360
04/14/11 10:36 PM
04/14/11 10:36 PM
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Thanks

If that's the case, do any of you know for sure if there are "clearance" problems with torqueing a set of heads on a 383 in a '69 Road Runner? I was trying to keep from pulling the engine to bolt on the heads. I can't remember from pulling the old ones how much room there was exactly, plus I wasn't removing the old head bolts with a torque wrench. The car has manual brakes and steering also if that helps

Re: Torque wrench question [Re: JoesMopar] #973361
04/14/11 11:07 PM
04/14/11 11:07 PM
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Lee446 Offline
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AN extension on the handle affects torque, that is what the referred article is about. Using a socket extension would also affect torque as it acts like a torsion bar and twists under strain which would absorb some of the imparted torque before the bolt head receives it. I doubt that it is much, but somewhere there is undoubtably a formula to figure it out. I use the shortest extension possible, using a black, hardened impact type extension. Better yet, if you can use a deepwell impact socket by itself with no extension and I just add a couple of pounds to compensate. You probably have more error in your Torque wrench than you will lose to the extension.

Re: Torque wrench question [Re: Lee446] #973362
04/14/11 11:53 PM
04/14/11 11:53 PM
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That's exactly what I meant by extension. I didn't realize everyone thought I meant an extension on the handle....I meant a socket extension, like a 3 or 6 inch. The torque wrench I have is the click type.

Re: Torque wrench question [Re: JoesMopar] #973363
04/15/11 12:13 AM
04/15/11 12:13 AM
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Chino Valley
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They (who are 'they'?) say no, but there are "torque sticks" used to tighten wheel nuts. You can use one with an impact and it will prevent overtightening.
I'd try to find a setup that works on the bottom row of bolts and use that for all of them. It's more important to get them even than to an exact number.

Re: Torque wrench question [Re: RodStRace] #973364
04/15/11 08:02 AM
04/15/11 08:02 AM
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Niles , Ohio
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therocks Offline
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Ive tried a few times checking torque with and with out an extension.Never really saw a difference.Ive done a bunch of heads in car and never had a problem using an extension.My 440 and my kids 413 were done a few years ago.No problems at all.I do use a good torque wrench.Mine is a SnapOn.Rocky


Chrysler Firepower
Re: Torque wrench question [Re: court9155] #973365
04/15/11 08:24 AM
04/15/11 08:24 AM
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Grand Haven, MI
patrick Offline
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Quote:

Ive heard it does so I avoid using an extension if I can.

I guess one way to tell is to torque something with an extension then remove the extension and check the torque setting to see.




shouldn't change it a meaningful amount...it may a skoash if the extension is long enough, because you'll potentially be absorbing some of the torque with angular deflection (twist) in the extension....but that will be minimal with even a 1' 1/2" drive extension...

removing the extension and checking would be more inaccurate, as there is a breakaway torque to overcome the static friction and then the dynamic torque from the dynamic friction as you're rotating the head. using a torque wrench, you're measuring dynamic torque. the static torque required to break it away will always be higher than the dynamic torque, so checking it after you've stopped rotating the bolt head tells you nothing...


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1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
Re: Torque wrench question [Re: Lee446] #973366
04/15/11 08:33 AM
04/15/11 08:33 AM
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Grand Haven, MI
patrick Offline
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Quote:

AN extension on the handle affects torque, that is what the referred article is about. Using a socket extension would also affect torque as it acts like a torsion bar and twists under strain which would absorb some of the imparted torque before the bolt head receives it. I doubt that it is much, but somewhere there is undoubtably a formula to figure it out. I use the shortest extension possible, using a black, hardened impact type extension. Better yet, if you can use a deepwell impact socket by itself with no extension and I just add a couple of pounds to compensate. You probably have more error in your Torque wrench than you will lose to the extension.




torsion bars spring rates are determined by the material's modulus of elasticity, free length, and diameter. All steels have the same elastic modulus. the harder steels just have a higher yield point. the shorter the free length and the larger the diameter, the higher the spring rate.


1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
Re: Torque wrench question [Re: JoesMopar] #973367
04/15/11 09:32 AM
04/15/11 09:32 AM
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the key here is
'has the wrench handle come nearly to a stop and is not changing in speed'

an extension
between the ratchet and socket
does not affect 'steady speed' torque
as long as the handle is not
accelerating or decelerating

think of the extension as a type of
'torsion bar spring'

when you apply torque to a spring
the torsion bar will at first speed up its twist
until the bar is applying an equal and opposite torque
back to whatever is applying the torque

This is Issac Newton's famous 2nd Law:
Force=Mass times acceleration (straight line)
Torque =Mass times acceleration (circular equivalent)
where acceleration = 0 = steady state
in this case

to carry the idea to a silly extreme.....
if you used a 10 foot long extension
of a small diameter (think coat hanger wire)
but made of very strong steel
as you applied the torque
the handle would make several rotations
as the tiny extension bar twisted round and round
but as long as you don't exceed the 'yield point' of the steel of the extension
as the handle slowed down and came to a stop
where everything was 'balanced'
then the torque wrench would show the correct torque

you might think the above example silly
but it actually describes a very common
'real world' situation
... an oil well where 25,000 feet of strong steel drill pipe is twisting a rotary bit at a steady speed deep underground

Re: Torque wrench question [Re: 360view] #973368
04/15/11 10:12 AM
04/15/11 10:12 AM
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s.w.fl
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bonefish Offline
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Re: Torque wrench question [Re: 360view] #973369
04/15/11 10:15 AM
04/15/11 10:15 AM
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick Offline
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patrick  Offline
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Quote:

the key here is
'has the wrench handle come nearly to a stop and is not changing in speed'

an extension
between the ratchet and socket
does not affect 'steady speed' torque
as long as the handle is not
accelerating or decelerating

think of the extension as a type of
'torsion bar spring'

when you apply torque to a spring
the torsion bar will at first speed up its twist
until the bar is applying an equal and opposite torque
back to whatever is applying the torque

This is Issac Newton's famous 2nd Law:
Force=Mass times acceleration (straight line)
Torque =Mass times acceleration (circular equivalent)
where acceleration = 0 = steady state
in this case

to carry the idea to a silly extreme.....
if you used a 10 foot long extension
of a small diameter (think coat hanger wire)
but made of very strong steel
as you applied the torque
the handle would make several rotations
as the tiny extension bar twisted round and round
but as long as you don't exceed the 'yield point' of the steel of the extension
as the handle slowed down and came to a stop
where everything was 'balanced'
then the torque wrench would show the correct torque

you might think the above example silly
but it actually describes a very common
'real world' situation
... an oil well where 25,000 feet of strong steel drill pipe is twisting a rotary bit at a steady speed deep underground




very good point I overlooked...


1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)






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