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inch pounds vs ft.lbs question

Old May 16, 2023 | 01:20 AM
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GCH
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inch pounds vs ft.lbs question

Hi my brother should torque the two bands in a -66 727 transmission to 72 inch pounds and
then counterclockwise the bolts 2 turns and lock them.
Just wondering , have not heard so much about "inch pounds" as "ft.lbs" in torque . Is ft.lbs
the most common way to torque bolts.

72 inch pounds should be 6 ft.lbs = 8,13 Nm
Old May 16, 2023 | 02:20 AM
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Originally Posted by GCH
Hi my brother should torque the two bands in a -66 727 transmission to 72 inch pounds and
then counterclockwise the bolts 2 turns and lock them.
Just wondering , have not heard so much about "inch pounds" as "ft.lbs" in torque . Is ft.lbs
the most common way to torque bolts.

72 inch pounds should be 6 ft.lbs = 8,13 Nm
Hi Glenn -

In general, at the lower end of the scale "inch pounds" (correctly written "Lb-In") is a more precise & accurate degree of measurement. Some applications where use of an inch pound (correctly written Lb-In) torque wrench would be used are oil pan bolts, valve cover bolts, automatic transmission band adjustments & front wheel bearings. The SI unit is (of course) the Nm (Newtons per Meter). NOTE: The nomenclature is correct: The amount of force applied to move an object (lever) a certain distance from its pivot point - it is not the reverse (the amount of distance to move a Newton); your math is correct 72 Lb-In = 6 Lb-Ft = 8.1349076897 Nm. Nomenclature is important from an engineering perspective. Nm is correctly written as "N-m" (Newton-Meter); the correct term of what is commonly referred to as both inch pounds and foot pounds is correctly written as "Lb-In" & "Lb-Ft), respectively.

Last edited by Vintage Chief; May 16, 2023 at 03:51 AM.
Old May 16, 2023 | 03:17 AM
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Gut und tight.
Old May 16, 2023 | 05:58 AM
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Originally Posted by GCH
Hi my brother should torque the two bands in a -66 727 transmission to 72 inch pounds and
then counterclockwise the bolts 2 turns and lock them.
Just wondering , have not heard so much about "inch pounds" as "ft.lbs" in torque . Is ft.lbs
the most common way to torque bolts.

72 inch pounds should be 6 ft.lbs = 8,13 Nm
A ft-lb torque wrench will typically not be particularly accurate at lower torque levels. An in-lb wrench will usually cover the lower end of the scale and thus provide more accuracy and better control at those lower levels. If your ft-lb wrench is off by just one ft-lb, that's a 12 in-lb error. At a desired 72 in-lb, that's 16% off, which would be a bad thing on a band adjustment.
Old May 16, 2023 | 07:40 AM
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To add to what Joe P wrote, we generally do not use the lower 20 percent nor the upper 20 percent of any given torque wrench due to possibility of inaccuracies; I would also add that it is prudent to "exercise" the torque wrench 10 times at the set torque value just prior to use.
Old May 16, 2023 | 08:19 AM
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Thanks Norm , Joe and Jim for all info about this . My brothers Chrysler have been sitting still for a
couple of years due to different reasons but now he wants to drive the car again.



Old May 16, 2023 | 09:58 AM
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Like said, lb-feet is torque. Ft*lbs, correctly said as foot pounds (force) is work.
Old May 16, 2023 | 12:59 PM
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Originally Posted by GCH
Thanks Norm , Joe and Jim for all info about this . My brothers Chrysler have been sitting still for a couple of years due to different reasons but now he wants to drive the car again.
Glenn - I like the wheel-well fender skirts AND the dual antennas.
Old May 16, 2023 | 10:41 PM
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Originally Posted by Vintage Chief
Glenn - I like the wheel-well fender skirts AND the dual antennas.
i like this Chrysler also , he had a -68 New yorker long time ago with a little modified 440 . He,s
brother in law,s girl just purchased a -59 Olds 98.

Old May 17, 2023 | 05:06 AM
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I like it as well, particularly those rear windows in front of the C pillar. Are those vent windows or static? Either way loving it.
Old May 17, 2023 | 11:09 PM
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Originally Posted by Oldsguy
I like it as well, particularly those rear windows in front of the C pillar. Are those vent windows or static? Either way loving it.
Hi they are static and can not be opened.
Old May 18, 2023 | 06:01 AM
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Originally Posted by Koda
Like said, lb-feet is torque. Ft*lbs, correctly said as foot pounds (force) is work.
Isn't this all just the same thing? A foot-pound is the same as a pound-foot. (Multiplication is commutative.) Torque and work have the same units, force x distance. Or distance x force. The SI unit is Newton-meter.

Also, inch-pound/12 = foot-pound because there are 12 inches in a foot.

Any unit that has a length times a force is a unit of work or torque. 5280 foot-lbs is one mile-lb. You can make up any unit of torque or work that you want as long as it's a unit of force times distance. My favorite is the furlong-lb. I have a wrench calibrated that way. It's for tightening the lug nuts on a horse-drawn carriage.
Old May 18, 2023 | 07:51 AM
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Hey, you're not dead. Good.

It's a matter of nomenclature. Torque is angular force. We don't have a unit for angular force. We do have a unit for force, it's pounds force, or Newtons. Both of these are related to mass via an acceleration multiplier. 1 slug mass * gravity = 32.2 pounds force. 1 Newton is the force required to move 1kg at 1 m/s^2. These are LINEAR. To get ANGULAR, we have to multiply by the lever arm. Therefore, torque, in standard is lbf*ft. In SI, it's N*m, Newton meters.

I am putting 85 pounds force on the end of my 1 foot lug wrench, therefore I impart 85 lf*ft to the lug nut.

Now, we need to talk about WORK. Work is the amount of force you put on something times the distance you do it. Work is not used much, however, it's analogous to energy, which is used a lot. It's derivative with respect to time is power, and that unit gets used a lot. So, work is foot pounds, or newton meters (again), commonly called Joules.

So, Lb*ft are not equal to ft*lbs, because this is not multiplication, this is mechanical engineering or physics, and the feet are two different things; one's a lever arm, and the other is a linear distance over which you pushed something.
Old May 18, 2023 | 09:04 AM
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Originally Posted by Koda
...commonly called Joules.
Think his buddies called him JJ?
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