They are obviously not backing off the lug nuts before re tightening with a torque wrench. That you know more then they is not unusual. You get what you pay for and you have a personal interest in the car while they don’t. It got to a point with me where years ago I just bought my own compressor and in winter months had the dealer instal and rotate tires for a price and not as a for free package. Again, you get what you pay for and these free add are really rush jobs in some places. Agree with @Keith 100%. Often, all they are concerned about is that the tire doesn’t fall off and tighter is better…Dah. Like many of us, we keep going back hoping they will change because it’s free or cheaper. (When it really isn’t)
Same experience with tire shops. Always idiots. The inside of the lug nuts on my f150 actually call for 150 ft lbs. After 3000 miles on my new tires I developed an annoying wobble. Felt like they were out of round. Well being out of town I had to take it to a sister shop of the chain I bought them from because there weren’t any near me. Guy said my tires were all way out of balance and the rims were slightly bent. That’s funny because I never hit anything nor had an issue prior to the new tires.
I want to comment on the idea that a customer can go back and instruct the dealer on the right way to do something - BAD IDEA!! Customers are never considered experts on a subject - even if they are. (I know, I’ve been on both sides of that!)
So someone off the street trying to “correct” a dealer is just wasting his words.
I always loosen and retighten after getting tires. I’ve found way too many over-tightened lug nuts from tire shops.
I have an old “Rockwell” electric impact gun that I always use. It works great for me on wheels, but I still have to get out the 30inch breaker to loosen some that others have tightened. This post just made me wonder just how high of a torque it doe’s put out. I have a car today, with a bearing hub to replace and then rotors and brakes. I’ll have to check and see what torque my normal method ends up to be with that gun.
I know this gun is not the best for removing stubborn nuts and bolts and there is nothing on the label that says the max torque, but now you all have me wondering.
Luckily I only forgot once to tighten the lugs and it was my own truck years ago. I had used the cross bar to snug them after a brake job and must have forgotten to tighten them after I lowered the truck. Three days later and I felt a vibration and thought “brakes last week, now a U-joint, what next”. Pulled over, got out the wrench and found my problem at once.
Yosemite
@ Yosemite, my old Jepson 1/2" electric impact wrench also doesn’t say, but I remember it was advertised at 240 ft-lb which I take as as the maximum after maybe 5 seconds of “impacting.” When I tighten lug nuts with it, I run it to barely “impacting”, then snug down with a cross bar.
There is a problem with taking your vehicle home and loosening. then properly retorquing. The problem is that if the shop over torqued the lug nuts, the damage is done. Proper retorquing will not repair the damage.
Aluminum wheels have special needs that I am not fully competent to address, but I can address what happens to the studs when they are over torqued. As you increase the tension on the stud (torque on the nut), the stud stretches. Their is a property called modulus of elasticity which is the maximum the stud can stretch and still rebound to its original size when the tension is released.
When the modulus of elasticity is exceeded, the stud is permanently distorted. For awhile, the modulus of elasticity can be exceeded for a small amount and the distortion resulting is so little, that the stud can work the next time, and many more times after that, but each time, the stud is getting closer to the time it will have to be replaced. If properly torqued every time, the stud should last the life of the car.
But greatly exceeding this modulus of elasticity greatly shortens the life of the stud. While Capri Racer is correct about managers not listening to customers, they listen to me long enough to do my car correctly, then afterwards there is a followup call to the corporate HQ and HQ does listen to customers, if you approach them correctly.
@keith
And the alternative is to let it be ? The lug nut may be over torqued and the damage may have been done, but at least from an equal stress point of view, I will feel better about knowing the lug nuts are all the same. Seldom do these jamokes over tighten all of them to the same “wrong” number of wrong ft./lbs.
“One guy at a Sams Club store told me his air compressors were calibrated”
What rock do they find these guys under?
dagosa, the alternative is to only use shops that do it right or do it yourself in the first place, and to lodge a complaint when it is done incorrectly, and to lodge that complaint effectively.
I understand Kieth’s point. THe damage is done and they will only rebound so much.
I use another tire shop now and I’ve never had any complaints with them.
But to bring home a vehicle and find that I have to add a cheater bar to my 30inch breaker just to loosen them…I want to know that today at my home or shop, not out on some road in the dark of night.
Even with the old shop I used there was never a big issue, but I wanted to check to be sure that they aere all within my standards.
I Do mine like insiteful mentrioned and today I checked and all were at between 68 and 76 ft/lb with the impact.
Yosemite
“The problem is that if the shop over torqued the lug nuts, the damage is done. Proper retorquing will not repair the damage.”
As I posted before, at least if I get a flat on the road I’ll be able to remove the wheel with the wrench supplied with the car.
I’ve had that problem before, too: not being able to unfasten nuts/bolts that were tightened by a shop with an air gun.
I know somebody opined that over-torquing was done as a liability concern regarding stuff working loose. I wonder if it’s possible shops do that to discourage DIY/ensure return business?
What i still don’t get is how these overtightened lugs caused any noise which then went away after being properly retorqued. Loose I could understand…
Keith said: “…There is a problem with taking your vehicle home and loosening. then properly retorquing. The problem is that if the shop over torqued the lug nuts, the damage is done. Proper retorquing will not repair the damage…”
I disagree. While there may have been damage, it is just as likely that things were just distorted - and retorquing would bring things back to normal. Certainly leaving the torque alone might allow the metal to creep and make the distortion permanent, but if done soon enough, this could be quite temporary.
I think he meant that the studs could be stretched already and you can t fix that, if they were torqued past a certain point, will be weakened and beyond repair. they could break off even after re torqueing them properly.
he wasn t saying just leave them torqued, he was saying the damage may already be done
I did mean that once you exceed the modulus of elasticity (Yield Point), the damage is done and it is permanent. That does not mean that the stud cannot be reused or is unsafe to use, they can be over stretched a number of times before they need to be replaced. Its just that the over torquing significantly shortens the number of times you can use this stud.
For informational purposes, an M14, 12.9 grade should have a yield point of somewhere around 131 ft/lbs, an M12, 12.9 grade should be somewhat less. It seems that typically the M14 studs are torqued to around 100 ft/lbs and the M12 studs are around 76 to 80 ft/lbs so I would not expect any distortion to occur at less than 100 ft/lbs for a 12mm stud or 130 ft/lbs for a 14 mm stud.
Maybe if the tire shops were aware of this, they would take the torquing of the wheels more seriously.
BTW, because of the property of jerk, aka starting torque, it takes a lot more torque to start loosening a nut than it took to tighten it. Because of this, if a tire man used an impact wrench and then checked with a torque wrench, and the torque wrench clicked immediately, the nut could still have less than the desired torque.
For example, if the spec was for 76 ft/lbs and the impact wrench took it to 70 ft/lbs, the starting torque to move the nut some more could be well above 76 ft/lbs so the torque wrench would click without moving, leaving a loose nut. Thats another reason the tire shop manager should make sure that each employee understands that the torque wrench must be moving when it clicks or the scale reaches the desired torque.
@Keith
Don’t get me wrong. Maybe I read you wrong but I would.d definitely re torque the wheels immediately as damage to the brake discs and other components can be alleviated. I can’t say that overly thin discs are more or less susceptible,but it did alleviate my problem. In many cases I agree, the lug nuts are damaged but still usable and safe if re torqued. To me it isn’t all or nothing but by degree. I ALWAYS check lug nuts after changeovers and rotations. If nothing else, it tells me how competent they are and who to trust. When the were not all the same, except for extreme cases, I had no other problems. In my experience, alloy rims are less apt to damage the discs as the softer metal absorbs the over tightening without damaging the disc behind as steel would.
@circuitsmith is absolutely right. Nothing is as frustrating as having a flat and trying to remove a lug nut with the supplied wrench that’s impossible to remove.