An impact gun seems to tighten a nut as far as it will go therefore I guess this is over tightening.

If over tightening can cause wheel studs to damage/break then why do most mechanics use impact guns and why do we rarely see wheels coming off?

  • The major cause of fastener failures is insufficient preload. That is ,they were not tightened enough . Aug 18 '18 at 19:49

Most mechanics will only use an impact to take them off. They'll use a socket/wrench to put them back on, then a torque wrench to tighten them to spec. It's someone at a tire shop (without guidelines) who will use an impact gun to put the lug nuts back on. A good tire shop will at least use torque sticks to ensure the lugs are not over tightened when they use an impact gun. That gets them in the ballpark and then they torque it down the rest of the way.


This problem is caused by a combination of lack of training, laziness, ignorance & overconfidence. A properly trained auto "technician" would NEVER use a pneumatic impact gun to tighten ANY threaded fastener on a motor vehicle!

  • There are correct & incorrect ways to use tools. Use of a torque stick is common practice these days. You should withhold judgment since you have incomplete information.
    – Tim Barber
    Aug 22 '18 at 18:07
  • Using non-English words is dysfunctional to this forum.
    – Tim Barber
    Aug 23 '18 at 20:53
  • I was responding to your post. You had distorted my claim about auto technicians being improperly trained. You were trying to start an argument with me. I was NOT being judgemental. If you are a troll, you will get VERY frustrated with me. :-)
    – Tim Barber
    Aug 23 '18 at 21:38
  • Once again, you are showing your ignorance. There are torque sticks and torque wrenches. TWO DIFFERENT TOOLS! You desperately need more information.
    – Tim Barber
    Aug 24 '18 at 23:06

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