Torque: The definitive experiments

[Fred Munro]

-Scott opined:
<snip>
>T1 = F x D
>F= 516 lbs
>D = .5 ft + 1.0 ft(tool 2079) = 1.5 ft
>T1 = 516 lbs X 1.5 ft = 774 ft lbs

>T2 = F x D
>F = 64.5 lbs
>D = 4 ft + 1.0 ft(tool 2079) = 5 ft
>T2 = 5 ft x 64.5 lbs = 332.5 ft lbs

>T1 does not equal T2

>Back to the drawing board Fred!

Nope, more than enough blather from the drawing board, Scott.

It's off to the bench for some solid empirical data!

What is it with this list and 6 letter words that start with tor?

Experiment #1

Objective: Determine whether the torque applied by a "click-type" torque
wrench is affected by where you place your greasy mitt on the wrench or by
the use of a cheater pipe.

Apparatus:
1. one torque measurement device
2. one rigid bench mount for item (1)
3. one "click-type" torque wrench (Craftsman Microtork, 18" centre of drive
to centre of handle grip)
4. one rigid coupling to join items (1) and (3).

Method:
1. Set torque wrench to 50 ft-lb. Connect to torque measurement device.
Place hand on grip 18" from drive centre. Apply force until wrench clicks.
Observe torque readout.
2. Repeat (1) with hand placed on wrench 12" from drive centre.
3. Repeat (1) with hand placed on wrench 8" from drive centre.
4. Repeat (1) with a cheater pipe on end of wrench, placing hand 32" from
drive centre.

Results and Observations:
1. With hand placed on wrench grip 18" from drive centre, the torque readout
was 50 ft-lb. (I love it when a plan comes together).
2. With hand placed on wrench 12" from drive centre, the torque read-out was
60 ft-lb.
3. With hand placed on wrench 8" from drive centre, the torque read-out was
75 ft-lb.
4. With the cheater pipe on and hand 32" from drive centre, the torque
read-out was 45 ft-lb.

Conclusions:
1. The position of your grimy grub-hook on the torque wrench will affect the
torque applied.
2. The use of a cheater pipe will affect the torque applied.

Recommendations:
1. Use the grip, mate, and leave the cheater in the bin.

Experiment #2

Objective: Determine whether the use of differing length torque wrenches
affects the results when the Audi 2079 torque wrench extender is used.

Apparatus:
1. one torque measurement device
2. one rigid bench mount for item (1)
3. one "click-type" torque wrench (Craftsman Microtork, 18" drive centre to
centre of handle grip)
4. one beam type torque wrench (Industro Super, 14" drive centre to centre
of handle grip)
5. one Audi tool 2079 (torque wrench extender, 300 mm centre to centre)
6. one rigid coupling to join items (1) and (3,4,&5).

Method:
1. Set click wrench to 50 ft-lb. Connect to torque measurement device to
verify setting.
2. Connect click torque wrench to tool 2079 and tool 2079 to torque
measurement device. Apply force to torque wrench until it clicks. Observe
torque read-out.
3. Connect beam wrench to torque measurement device. Apply force until
wrench reads 50 ft-lb. to verify calibration.
4. Connect beam wrench to tool 2079 and tool 2079 to torque measurement
device. Apply force to handle until wrench reads 50 ft-lb. Observe torque
read-out.

Results and Observations:
1. Click wrench verified at 50 ft-lbs.
2. Click wrench (18" centre to centre) and tool 2079 generated 85 ft-lb
torque at a 50 ft-lb torque setting on the wrench.
3. Beam wrench verified at 50 ft-lb.
4. Beam wrench (14" centre to centre) and tool 2079 generated 100 ft-lb. of
torque at a 50 ft-lb. reading on the wrench.
5. Tool 2079 has a 3/4" drive connection, ergo it is intended to be used
with a 3/4" drive torque wrench. These torque wrenches tend to be 3 - 4 feet
long.

Conclusions:
1. The length of the torque wrench does affect the torque generated at the
socket end of tool 2079 as predicted by Scott J and others.
2. A few simple experiments can save a considerable amount of bandwidth.
3. Certain members of this list will never be described as "men of few
words".

Recommendations:
1. Length matters. Before using tool 2079, e-mail the length of your torque
wrench to Scott and ask him to calculate how much torque you should apply
:o)

There you go, Scott - feed that data into your equations. Knock yourself
out, bud!

Good (if much too lengthy) thread - I hope it all is clear as crystal now;
it is to me, at least.

Also learned never to read (much less respond) the Quattro list after
dragging myself home from a Christmas party!

Fred Munro
'94 S4