Rick O. is right of course about the addition of lubrication affecting
torque wrenching. The difficulting of reporting "how much" stems from
what lube is used and the amount of thread tension being sought. As a
general rule, the difference is less, somewhere between 10 and 20% at
the lower numbers, when comparing dry vs. motor oil vs. anti-sieze.
(graphite and Vaseline?)...the latter being the most "slippery".
As the torque setting goes up, the affect of lube becomes greater and
can be as high 100% the amount of tension that the torque wrench sees.
The last thing we want is to stretch a bolt or stud beyond its plastic
limits.
For a far better explanation on the subject, I'd recommend reading what
race car engineer such as Caroll Smith has to say. This can be found in
his writings titled: "The Mechanics of Tightening Threaded
Fasteners---or How Tight is Right. Found in his book ENGINEER TO WIN.
Dick
From: trinitygadget@alltel.net(Rick or Lori O) To:
mhooper@digiscreen.ca ('Mark Hooper'),
Mark--Lubricating threads does change (lower) torque settings. Someone
else here will chime in on a more specific percent reduction.
Rick O.
72 TR6
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