Help Using a Torque Wrench

[Canuck]

Need help with using a torque wrench.  

What I am trying to do is set the worm and pinion lash adjustments on a Saginaw steering box with various torque specs of between 4 and 10 INCH LBS.  The only wrench that |I have access to is a 600 Inch Lb bending beam wrench with the first minor indicator mark at 25 inch lbs., first major indicator mark at 50 inch lbs.
 
If using an extension in reverse, I think I can use a reading on the wrench in the 50 - 100 inch lb area of the dial to achieve the settings required.

I know that if you put an extension on the wrench, for example, you can use a wrench with a 150 ft lb limit to torque a nut to 200 ft lb.  As poorly illustrated by the diagram below.  The "X" being the socket, the "I" the end of the wrench/extension and the "O" the pivot point of the wrench handle

Extension.....Wrench
........................I================O
X~~~~~~~~I

What I am wondering is, if I use the extension in reverse, as illustrated below, would the wrench indicate a  reading that is a multiple higher of the torque actually achieved on the socket?

.....Wrench
I================O
I~~~~~~~~X
..Extension
     
The length of the extension would be determined using the following:

M1 = M2 x L1 / L2
Where:
M1 is the torque setting of the wrench.
M2 is the actual torque applied to the nut
L1 is the normal length of the wrench, pivot point to socket
L2 is the extended length of the wrench, pivot point to revised location of the socket

Am I on the right track with this.

Thanks for the help.
Canuck

[enjenjo]

yes you are.  It might be  easier to use a spring scale, like a postage scale, with a socket extension bar calculated to make one ounce equal to one inch lb.

[wayne petty]

my old boss... the pby flight mechanic did boxes himself..

he used a spring scale...  but... he had half a steering coupling  .. he actually had several..  that he could mount a bar on.. so he could put his fishing scale on the end to test turning torque without messing up the splines...

he also made his own wrenches to turn the big jam nuts with and the insert..


this article might be of interest also... it mentions the sizing of the torsion bars that change the feel of the power steering boxes..

http://www.carcraft.com/techarticles/ccrp_0901_gm_steering_box_upgrade/index.html

but i think this was covered a few years ago  on the main forum...


here is one on saginaw manual boxes

http://www.highperformancepontiac.com/tech/hppp_1008_steering_box_rebuild/index.html

[Canuck]

Thanks for the help guys, it is nice to have someone hold your hand a bit to make sure something is right especially steering.

Followed my 64 GM manual for everything except the torque specs (reguires special GM tool number 45287845287085908592458907582345089745), used the specs as listed on Harry's web site.  Box looked like new inside so just cleaned and replaced the seals and fresh grease and gasket.  The modified extension to the torque wrench worked largely thanks to GMs wide specs.  Just a piece of bar stock with a 3/8 hole near one end for the torque wrench and a piece of 1/2" rod ground to a 3/8 square welded on the other end for a socket at a distance that worked out for the torque wrench size.  Wouldn't want to use it every day though, a bit of a pain.

Got carried away a bit and ground down all the casting flash and rough surfaces on the box before re-painting.  No one told me the cover was aluminum and could be ground smooth and polished.  This is suppose to be a hot rod, not a street rod  

Thanks again.

Canuck

[wayne petty]

polished steering box tops....   what a great idea....

i know a rebuilder who has buckets full of them...  and a polisher ...

i wonder...    doing a few dozen for the next rose bowl swap meet...