Dial Torque Wrench
This is the torque wrench for those really, really
fussy mechanics. Torque wrenches don't get much more
accurate than this Precision Instruments 0-25 ft/lb.
It comes with a calibration compliance
certificate that certifies the wrench to MIL STD 45662A
and ANSI/NCSL Z540-1-1994 with accuracy traceable to the
National Institute of Standards and Technology.
It's accurate to ±1% from 20% to 100% of its capacity
in either direction. One percent calculates to
plus or minus 0.25 ft/lbs. at its maximum application of
25 ft/lbs. This is just the ticket for those tiny
little hex head cap screws that secure the flimsy
aluminum side covers on motorcycle engines.
It's way too easy to apply too much torque, even with
a basic torque wrench, and this goes double for
motorcycles, which use soft
aluminum just about everywhere.
We have two
micrometer type torque wrenches in the webBikeWorld
garage in addition to an old beam type torque wrench
that we only use for nuts over 75 ft/lbs., but I don't
trust them at all.
Some of the cheap torque wrenches don't even list an
accuracy figure; others are accurate to within 5% or so.
This can mean as much as 2.5 foot pounds over or under
the actual recommended torque at, say, 50 foot pounds.
But most of the cheaper torque wrenches list their
accuracy at a certain static number, like 20% of their
capacity. For example, on a 100 ft/lb. torque
wrench with 5% claimed accuracy, this would mean that
it's only within 5 ft/lbs. when applying 20 ft/lbs.
So what happens when it's used at 80% (80 ft/lbs)?
Who knows, but I've heard too many horror stories of
stripped bolts during a motorcycle repair.
One thing I do to help prevent this from happening is
to sneak up on the ultimate torque setting. In
other words, if the bolt is to be torqued to 30 ft/lbs,
I'll first set the wrench for maybe 20 ft/lbs and
tighten, then 25 ft/lbs., and finally 30. Kind of
like a "measure twice, cut once" approach.
But this approach may not work with small torque
settings. Our Sears Craftsman "Microtork"
micrometer torque wrench is supposedly calibrated from
25-250 inch pounds (2 to 20 ft/lbs.) with a plus or
minus 4% accuracy at 20% of total capacity, which is 50
inch pounds, or 4.16 ft/lbs.
The micrometer type torque wrenches use
an internal spring, and springs are notoriously
non-linear in their application of force as they get
wound up. Precision is more important with small
torque settings, because it's the smaller nuts and bolts
that will have a greater potential to strip or break
with the incorrect application of torque.
We're very pleased with our
Precision Instruments split-beam-type torque wrench, both because of it's accuracy
but also because it doesn't use a spring that must be unwound down to 0 ft/lbs. after use.
It's such a simple yet accurate instrument that it's a
surprise that all torque wrenches aren't made the same
The Precision Instruments 0-300 in/lb. dial torque wrench
shown here really does look and feel like the precision
instrument that it's name implies. Besides the certificate of calibration
compliance, it also meets international requirements
like BS6073:1988 and ISO 6789, among others. It's
a wonderful instrument (tool) to own and use, and I feel
much better knowing that the exact torque (or as close
as I can get) is being applied.
It's very easy to read the dial, which is calibrated
from 0 to 25 ft/lbs. in 0.5 foot pound increments.
The ability to read the dial and the smooth working
inner mechanism allow the user to apply a slow, careful
application of torque.
It's thin and the end is tapered, which makes it fairly
easy to fit into the tight spaces on a motorcycle.
Precision Instruments claims that it has an "Exclusive Torsion Bar Design",
which connects the 3/8" square drive directly to the
dial. This allows the user to get a reading
directly. They also claim that the position in
which the hand holds the tool is not critical, unlike
other torque wrenches, which must be held at a certain
spot along their length to get a correct reading.
The 0-300 in/lb. torque wrench is 9-29/32" long
overall; 2-11/32" wide and weighs 1 lb., 2 oz. (510
grams). It comes with a plastic molded case and
carries a one-year warranty. It's finished in a
shiny nickel/chrome plating. Note that this is not
a ratchet wrench -- torque can only be applied in one
direction and the wrench does not ratchet back and
Tool freaks will definitely want this one and the
Precision Instruments beam-type torque wrench in their
toolbox. This should provide all the accuracy
you'll ever need for a lifetime of motorcycle wrenching!
Review: Dial Torque Wrench, 0-300 in/lb.
Retail Price: $179.95
|Sizes: Many sizes and capacities
Comments: Smooth operating, high quality yet simple tool is
calibrated to provide about the greatest accuracy that can be expected
in this price range.
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