[Healeys] Torque Wrench

[Richard Ewald]

Torque and wrenches, two of my favorites topics.
A few things you might consider when looking at torque wrenches.
Beam types are as reliable as a crowbar. (because that is basically what
they are), however they are big, damn near impossible to get into some
places and can be damn hard to read at times with my eyes being no longer
20 years old.
Twist the handle click type wrenches are convenient but they too have some
drawbacks.  They have to taken back to their minimum setting as soon as you
are done or they will go out of calibration.  They can and will go out of
calibration.  Sometimes massively.  A click type torque wrench needs to be
calibrated to know it is accurate.  When I was working on the line as a
tech I sent mine in once a year for recalibration.  IIRC ISO 9000 specifies
a once every 6 months calibration.
Also and this is a huge also, no matter what the big print says about the
accuracy of the wrench, that is at or near full scale.  At 20% or less of
full scale the accuracy is out the window.  Generally accuracy of about +/-
20% of the setting.  So if you have 10-150FtLb torque wrench, at setting of
say 25 Ftlbs you can be anywhere between 20 and 30 FtLbs.  Hell, I can get
that close with a hand ratchet.
There is a second type of clicking torque wrench, the handle does not turn,
it has a small stem on the side like a watch and window with a pointer and
a dial so you can see what is your requested torque.  According to Snap_On
this style wrench does not need re-calibration.  rather than a click, this
type makes more of a snapping noise when the preset torque is reached.   It
also does not need to turn down to it's minimum setting as soon as your are
finished.  I have only seen them in the higher torque values, mine is
50-250 FtLbs.
One type of wrench that hasn't been mentioned is the electronic torque
wrenches.  They use an electronic strain gauge, which I am told shouldn't
go out of calibration.  Dead nuts accurate and easy to use, the downside is
they are spendy.
As far as brands go, with precision measuring I only go with name brands.
All of my torque wrenches are Snap-On, of course I bought them when I was
twisting wrenches for a living.  If I had to buy wrenches again, I would
look for an electronic wrench and see what I could find.  I can tell you
where I wouldn't shop and that would be Harbor Freight.
A good wrench is not cheap.  But consider if you buy a cheap wrench, if the
wrench mechanically breaks and you elbow slams into something solid and
does serious damage how long will you be laid up with a broken elbow?  Or
perhaps the wrench is way out of calibration and you pull a head stud out
of the block, how much time, labor and $ is it going to cost you to repair
the damage?
I have seen both of the above happen.  And frankly I approach engine
building as if Mr. Murphy is standing behind me saying Go ahead, it OK, you
can take this short cut, I'll watch out for you.
Like hell he will.  He is waiting to screw me at every corner.  That is why
I use quality measuring tools and follow procedures exactly.  I don't trust
Murphy.
$.02
Rick
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