torque wrenches

Dude where do you get your info. Costco doesn't torque tires? They install the lugs with a torque limited impact gun (limited to about 50 foot-lbs) so they don't overtighten them. THEN they torque them to
manufact spec WITH TORQUE WRENCHES that the calibration is checked MONTHLY. I can't speak for WalMart or any other outlets but get your info straight before you spread your "wisdom".
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Oz wrote:

And what is the source of your wisdom?
Matt
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He stayed at a Holiday Inn Express :-)
Eric
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Eric G. wrote:

LOL! Good one!
Matt
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Matt Whiting wrote:

And you know that EVERY mechanic at EVERY Costco does this? Have you checked this out personally?
Why do I get the impression that this "Oz" character is just "Shaman" reincarnated?
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I don't need multiple identities on the net, Shaman is the one and only nick name I use.
Now, you can believe me or not.
I think that Oz is a troll more than anything. Re-post and answering old thread...
But He is right on this one, at least for my Costco shop. They use a torque impact tool, then after they torque the nuts at 80 Lbs by hand with a torque wrench. Seen it with my eyes. Open.
And you, Brian, are you a reincarnation of something?
Shaman
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Shaman wrote:

I would want to be sure that they are actually stopping below the proper torque with the impact wrench. The very nature of the way an impact wrench works makes them prone to overtightening. Torque on fasteners is based on both the stretch of the bolt/stud and the friction between the stud and the nut. An impact operated tool effectively removes the friction force and thus it is very easy to get a torque that is too high. I don't have exact figures or know where to find them right off-hand, but I do know that an impact wrench set to 50 lb-ft will tighten a nut much more than will a manual torque wrench also set to 50 lb-ft.
Each impact cycle of the impact wrench is exerting much more force than is a smoothly applied force. If you don't believe me, just look at any structural dynamics text book. Typically, an impact from a force of a certain magnitude is considered to provide approximately twice the affect initially as provided by that same force applied slowly and smoothly. Most building codes also build in this 2X factor so that is another source.
So, I would not at all be surprised that an impact wrench set at 50 lb-ft would torque a lug nut as tightly as would a manual torque wrench set at 100 lb-ft.
The bottom line is that an impact wrench should be used only to remove fasteners, never to install them.
Matt
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Shaman wrote:

No argument there.

That's fine by me.

I've been here for a while, you're the newbie. Also unlike you, I don't hide behind some silly pseudonym. For better or worse, I at least have the guts to put my name on what I write.
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So what's the point to compare me with that "Oz" guy? Even if I put my real name, with my street adress and phone #, that doesn't tell if I am Oz or not. Maybe you are Oz, and I just don't give it a f**k
Shaman
Shaman
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