Overtightened lug nuts for a short time

[rationull]

I'm getting up close to 5k miles on my new tires, and the place where I bought them offers free rotations. I'd like to take them in because it's kind of a PITA to jack the car all the way up to rotate them, but there are two things making me not want to do this:

1) It's easier to do a good brake inspection when I take the wheels off anyway.
2) I'm afraid of the tire place overtightening the lug nuts and damaging the studs/rotors.

The first one isn't that big a deal b/c I can still see and measure the pads through the spokes on the alloy wheels. But the second one worries me.

If I take it in, I'll probably watch and make sure they use a torque wrench, but they normally tighten the wheels with an impact I'm pretty sure (like everywhere else seems to). If they overtighten them a little, and I back them off and retorque them at home after, say, 30-40 miles of driving, will any permanent damage be sustained?

 

[Liquid_Turbo]

When a bolt is tightened and untightened, it undergoes loading and unloading. (It literally stretches as the nut pulls it apart, giving it preload)

Overtime this can lead to fatigue failure, if the correct grade of iron is not selected properly.

However, I would guess with a very high confidence that car manufacturers design in case users overtighten etc. The only danger is stripping the threads, but other than that, no permanent damage whatsoever.

 

[jldcol]

Most of the torque is friction of wheel nut cone upon the wheel lug hole area, and less is force on threads. Depends on how much overtorque, is any damage. The proper amount of force on a threaded connector is to stretch it into elastic limit area, it then will clamp parts properly and at the strength limit of material, over torque will place it in plastic range and now it will be damaged if removed.

 

[AcuraTech]

Most likely no harm done unless they really get into it with the impact gun.

Take it home and re-torque them. It's the only way to be assured it was done properly. Peace of mind is worth the 5 minutes of time it takes to check them.

 

[AcuraTech]

Originally Posted By: jldcol
Most of the torque is friction of wheel nut cone upon the wheel lug hole area, and less is force on threads. Depends on how much overtorque, is any damage. The proper amount of force on a threaded connector is to stretch it into elastic limit area, it then will clamp parts properly and at the strength limit of material, over torque will place it in plastic range and now it will be damaged if removed.


+1.

 

[rationull]

Originally Posted By: AcuraTech

Take it home and re-torque them. It's the only way to be assured it was done properly. Peace of mind is worth the 5 minutes of time it takes to check them.


Either way I'll be torquing them. I don't mind retorquing them at all, but if the damage is already going to be done then I'll just do the whole thing myself and not even take it in for the rotation.

Sounds like I'm being paranoid.

 

[The Critic]

There's nothing wrong with using an impact gun to "snug" up the lug nuts, lower the car, then finish with a torque wrench.

You will not overtighten the lug nuts this way.

 

[AcuraTech]

Originally Posted By: The Critic
There's nothing wrong with using an impact gun to "snug" up the lug nuts, lower the car, then finish with a torque wrench.

You will not overtighten the lug nuts this way.


Problem is way too many lazy techs that can't be bothered to use a torque wrench or torque stick.

One guy I used to work with never used either, he would just tighten them down with a (high powered) impact gun. I worked on cars that he had worked on previously, lug nuts were always way too tight.

I asked him about it, his response: "My impact gun is turned to the low setting"

 

[Silk]

They might be using torque sticks - you will hear them slamming away with the rattle gun,but it only goes up to the value of the stick.

The problem is not doing them up,but loosening.If done up too tight the stud stretches beyond it's limit...and stays there,the thread pitch of stud and nut are now different.When the rattle gun spins it off the nut friction welds to the stud,and either shears the stud,or strips the thread of both nut and stud.The blame is put on over tightening breaking the stud,or stripping the thread...sort of right,but the thread pitch difference is the cause.

 

[labman]

I like putting a dab of antisieze on the stud and torquing 80% myself. Since there is always some residual antisieze on the studs, the dry thread spec is already too high, let alone what they might be tightened.

 

[StormRider]

When you take the car in ask if they use torque sticks (which any shop thats worth a [censored] does) and ask them to use it on your wheels. IIRC they are sized from about 30-100 ft-lbs and are color coded based on a chart for make/model/year.

 

[mechtech2]

Your brake rotors may have to relearn where the belong.

 

[Junior]

Originally Posted By: The Critic
There's nothing wrong with using an impact gun to "snug" up the lug nuts, lower the car, then finish with a torque wrench.


Other than what an inpact socket and inpact wrench do to chrome plated lug nuts and alloy wheels!

 

[The Critic]

Originally Posted By: Junior
Originally Posted By: The Critic
There's nothing wrong with using an impact gun to "snug" up the lug nuts, lower the car, then finish with a torque wrench.


Other than what an inpact socket and inpact wrench do to chrome plated lug nuts and alloy wheels!

Never had a problem.

 

[dishdude]

They will crack chrome plated lug nuts...but i'd worry more about overtightened lugnuts warping my rotors, I think that is the biggest thing to be concerned about. Anytime I have to have a shop pull my wheels, I loosen them at home and then retorque them with a torque wrench.

 

[Junior]

Originally Posted By: The Critic
Originally Posted By: Junior
Originally Posted By: The Critic
There's nothing wrong with using an impact gun to "snug" up the lug nuts, lower the car, then finish with a torque wrench.


Other than what an inpact socket and inpact wrench do to chrome plated lug nuts and alloy wheels!

Never had a problem.


At the very least it will leave hammer marks on the surface of the nut. Impact sockets have thicker side walls compared to a standard socket and sometimes don't fit in the socket clearance of aftermarket wheels very well thus leaving scratches. My guess would be a vast majority of people just don't care.

To your point, your method won't over torque the nut. I just prefer to take the extra time and do it by hand.