Funny torque tricks

[Fred Munro]

-----Original Message-----
From: quattro-bounces at audifans.com
[mailto:quattro-bounces at audifans.com]On Behalf Of SJ
Sent: December 3, 2003 5:53 PM
To: quattro at audifans.com
Cc: apowell at gocougs.wsu.edu
Subject: Re: Funny torque tricks

<snip>
>*****Right. The wrench length makes no difference at the original "point of
>turn" which is the working end of the torque wrench. 100 ft lbs is 100 ft
>lbs.
>Hang a 50 lb weight at the end of a 2 foot breaker bar and you got 100 ft
>lbs of torque at the "point of turn".
>Now add a 1 foot extension to the point of turn. The new "point of turn" is
>at 3 feet from the 50 lb hanging weight. What is the torque at the "new
>point of turn"?  50 * 3 = 150 ft lbs and not 100 ft lbs.

>Lets try a 100 lb weight a the end of a 1 foot breaker bar. Again we have
>100 ft lbs of torque.
>Add the 1 foot extension, and the new "point of turn" is 2 feet from the
>hanging weight. The torque at the new "point of turn" is now 100 * 2 = 200
>ft lbs and not 150 ft lbs, or 100 ft lbs.

>The length of the torque wrench does make a difference at the new "point of
>turn".

><snip>

Fascinating erudite debate here - it's gone around so many times I'm getting
dizzy.

I'm with Al on this one.

I think the confusion stems from mixing up the force on the torque wrench
handle with the torque measured by the wrench at the bolt.

As SJ so aptly puts it in the attached text, 100 ft.lbs is 100 ft.lbs. His 2
foot wrench will take 50 lbs force on the handle to generate and measure 100
ft.lb at the bolt. His 3 foot wrench will take 33.3 lbs of force on the
handle to generate and measure 100 ft.lb at the bolt.

It doesn't matter whether you use a 6 inch torque wrench and 516 lbs on the
handle or a 4 foot wrench and 64.5 lbs on the handle - if both are connected
to the 2079 tool and click at 258 ft.lb, you'll be OK.

IMHO anyway.

Fred Munro
'94 S4