Wheels and Tires

Over-torquing Lug nuts.. Myth or Real

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  • Jul 14th, 2019 11:03 pm
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[OP]
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Jan 7, 2014
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Winnipeg

Over-torquing Lug nuts.. Myth or Real

So all mechanics are not equal.. right!!!
This mechanic to whom I took the car for tire swap, just used the pneumatic impact gun to tighten the nuts. He went in star fashion and did it once round for all five nuts.... Then he did one more round of tightening with the gun for the 4 nuts ( left out the nut with lock )
When I asked what about torque wrench, he said dont worry they wont fall... I said well must have over torqued then and must be difficult to loosen manually if required , he said dont worry they are 90 ft pound, only a woman might not be able to loosen but you can...I said well OK and drove off

So with two rounds using impact gun are they over tight? I have a breaker bar and torque wrench.. Should I loosen those a bit and re torque or just leave them in there...What hard can it cause..
53 replies
Deal Fanatic
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Oct 8, 2005
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Re-torque with a torque wrench.

Over tightening can warp your rotors.
Deal Fanatic
Aug 29, 2011
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Mississauga
You’re never supposed to use an impact gun to put lug nuts on because there’s no way to accurately control the torque that’s being applied.

Mechanics do it is because it saves time.
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Jan 27, 2006
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Woodbridge
I guess did it's the last time you let him touch your car.
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Oct 2, 2017
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he's just another lazy mechanic.
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Sep 2, 2006
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This could mean warped rotors...
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May 10, 2005
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mrweather wrote: You’re never supposed to use an impact gun to put lug nuts on because there’s no way to accurately control the torque that’s being applied.

Mechanics do it is because it saves time.
You can use an impact gun. Torque control can be achieved by air pressure or torque sticks.
I dare to say that 90% of shops use impact guns and without issues.
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[OP]
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Jan 7, 2014
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Poulet wrote: This could mean warped rotors...
well car will need new pads and rotors in a year anyways... last time only 3 mm pads were left
what about damage to the Bolts? and should I correct it
Doesn't driving loosens the nuts a bit anyways and I can just retorque after 100 kms or so
Deal Addict
Feb 7, 2005
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If your mechanic does not use torque wrench find another mechanic . The air gun almost always over tighten the bolts . Can damage your rotor . Plus try to get the lug nuts off on th side of the road when over tight . Plus I'm sure the insurence for the garage has a clause in the coverage that torque wrench must be used when mounting tires . Most garages set the air gun below the specified tightness . The mechanic will then use the torque wrench to finish the job . Real good shops will tell you to come back after 100km to re cheque the the lug nuts .
Still serving a 90 day suspension from " off topic "and "politics "May 21,2020.
[OP]
Deal Addict
Jan 7, 2014
2452 posts
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Winnipeg
pfbmgd wrote: If your mechanic does not use torque wrench find another mechanic . The air gun almost always over tighten the bolts . Can damage your rotor . Plus try to get the lug nuts off on th side of the road when over tight . Plus I'm sure the insurence for the garage has a clause in the coverage that torque wrench must be used when mounting tires . Most garages set the air gun below the specified tightness . The mechanic will then use the torque wrench to finish the job . Real good shops will tell you to come back after 100km to re cheque the the lug nuts .
I know .. stupid me... guess I will loosen them a bit and retorque... It does not need to be lifted right
Sr. Member
Mar 17, 2006
554 posts
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Most garages would rather over tighten lug nuts than risk a customer's wheel flying off while they're driving it on the highway (I know I would). I don't see how over torquing a lug nut 10-15 ft lbs or so over spec in a criss cross pattern can warp a rotor but I am not a mechanical engineer either.
I do all tire swaps myself. My wife's Nissan Rogue calls for 80 ft/lbs lug nut torque, which I always found on the low side. The first few times I swapped her tires, there was always some lug nuts that worked themselves dangerously loose (yes my torque wrench was well calibrated at the time). Never understood why. Now when I change her wheels, I torque it to 90 and sleep better at night (no warped rotors either)
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Dec 28, 2007
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Asker123 wrote: I know .. stupid me... guess I will loosen them a bit and retorque... It does not need to be lifted right
Over torquing stretches the studs. You can retorque them one at a time and you don't have to lift the car. You'll notice that when you loose them, they will all be a different torque or tightness. My Honda dealer always hammers them on with an impact, pisses me off.
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ur_too_crazy wrote: Most garages would rather over tighten lug nuts than risk a customer's wheel flying off while they're driving it on the highway (I know I would). I don't see how over torquing a lug nut 10-15 ft lbs or so over spec in a criss cross pattern can warp a rotor but I am not a mechanical engineer either.
I do all tire swaps myself. My wife's Nissan Rogue calls for 80 ft/lbs lug nut torque, which I always found on the low side. The first few times I swapped her tires, there was always some lug nuts that worked themselves dangerously loose (yes my torque wrench was well calibrated at the time). Never understood why. Now when I change her wheels, I torque it to 90 and sleep better at night (no warped rotors either)
Proper torquing (installation) technique using the star or criss cross pattern will prevent any rotor warping, that is one of the reasons you do this pattern, to distribute the load evenly.
Also, every shop will tell you to come back or have someone torque check (not re-torque) the nuts after 100 kms or so and, you should also do this at home. The amount you torque it to is not as important as the torque check.
The Government cannot give to anybody anything that the Government does not first take from somebody else.
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Asker123 wrote: I know .. stupid me... guess I will loosen them a bit and retorque... It does not need to be lifted right
Torque checked....not re-torqued.
Torque checking is making sure the torque has not changed and is as it should be. Re-torquing is loosening the nuts (bolts) and then torquing them again which, will require a torque check again 100 kms or so down the road.
No, it does not have to be lifted off the ground to do this.
The Government cannot give to anybody anything that the Government does not first take from somebody else.
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Feb 6, 2011
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Asker123 wrote:
So with two rounds using impact gun are they over tight? I have a breaker bar and torque wrench.. Should I loosen those a bit and re torque or just leave them in there...What hard can it cause..
Don't loosen, check all wheels with an accurate torque wrench.

Plus air guns are not supposed to be used on wheel locks, that's what is says on the instruction that nobody reads.

Let us know what you find.

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