I hate touch pads! I asked the owner of the tire shop to be sure and have
the lug nut torqued. He said no problem. They do it by hand. Well I have
been thinking about this since yesterday when they did it. The guy working
on the truck cinches all the lugs with an air impact wrench ( I had the
tires rotated too) then goes around and checks the torque with a torque
wrench. He didn't just snug it with the impact he tightened it all down.
Like I said. I'm no mechanic or tire guy. But this makes no sense to me. I
think I should go home and loosen everything and re-torque according to the
What do you guys think?
If the specified torque was reached (or exceeded) using the impact driver,
using a torque wrench afterward would serve only to verify that the lugs are
torqued to *at least* the specified torque. However, the specified torque
likely has a *range* of values (ie 65-70 ft/lb). If the torque wrench
didn't turn the lugs, they're overtightened. It sounds like this is what
happened to you. Aside from making it difficult (or impossible) to change a
flat alongside the road, there's the potential to do damage to the wheels,
nuts, lugs, and/or rotors.
FWIW, even when I've specified it as you have, I've never found a tire shop
that properly torques lug nuts/bolts. The last time I had a tire shop
install tires/wheels ('69 Barracuda) , I specified they not use an impact
driver at all and that they must torque to the 55 ft/lb specification using
only a manually-operated torque wrench. They torqued the 7/16" lugs to over
150 ft/lb (the limit of my torque wrench)! If I can avoid it, I no longer
let tire shops install tires/wheels.
I called the guy. He said bring it in Monday he would gladly loosen and
retighten them. I think for my own edification. I'll borrow a friends torque
wrench and do it myself. It sure looked to me like they were being way over
tightened. Like you said. If the nuts don't move with the torque wrench
they're tightened to "at least" that torque. Who knows how far beyond.
Not always so, the only time a torque wrench reading is accurate is when the
fastener is moving. It takes more torque to get a stalled fastener moving
than the actual torque when it stopped.
IOW, if the desired torque on a fastener is 60 ft. lbs. and the fastener is
actually torqued to 55 ft. lbs, it might take 65+ ft. lbs. of torque to get
the fastener moving again. Therefore, if the fastener doesn't move after
applying a torque of 60 ft. lbs. it doesn't verify that the desired torque
had previously been reached or exceeded.
It's a good idea to spot check two lugs on each wheel. See if you can
get em off with a hand wrench. Cause that's what you'll likely have
with you when you get a flat tire. Unless you're like me and always
carry a breaker bar and deep impact socket.
Christopher A. Young
You can't shout down a troll.
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