I take my car into my local Firestone dealer every 3000 miles to have the tires rotated, which is part of the deal they gave me when I bought the tires. Every time I get the car home, I recheck the lug nuts for correct torque. Most of the time some of the nuts are over tightened - beyond the 76 ft lbs specified in the owners manual for alloy wheels. Last time, the front left wheel made terrible sounds after they rotated the tires. When I got home and tried to loosen the nuts, I had to use a “cheater bar” to get them loose. Once I reset the nuts to the proper torque with my torque wrench, the noise went away. So I went back to the store, told them what had occurred, and asked how they know that they have the right torque set on the wheels. The mechanic explained that once they spin the nuts on with an air wrench, they then torque the nuts with a torque wrench. Pursuing the technique further, I found that the torque wrench they use only has one direction, i.e. to tighten. So the guy checks the torque and if the wrench clicks right away, he assumes the correct torque is reached. But what if the torque is too high, I asked. He said that the wrench only tells if it has enough torque. So I know now what the problem is. My suggestion to the Dealer was to have the guy tighten the nuts, but back them off a bit to “finger tight” then use the torque wrench to snug the nuts to the proper torque. He didn’t seem to understand the need to do that! So am I wrong on this or should I be taking Firestone to task and get them to use my finger tightening method or get a two way torque wrench to enable the mechanic to back off the lug nuts and re-tighten the nuts properly? Is there a better method?
By using an air gun to put the lugs on they are over tightening them. Their explanation of using the click on the torque wrench does not make sense. The nuts will have the minimum torque but could easily be way over tightened as you found. The best way is to finger tighten then use a manual torque wrench to spec.
You’re not wrong but probably shouldn’t be going to Firestone anyway. Most places use torque tubes so just continue re-doing it when you get home again. That’s what everyone does. You won’t get anywhere with the tire shops.
The shop should be using a torque bar. That is a socket and an extension that is a skinny rod to that limits torque that the impact wrench can apply. They come in different torque values and socket sizes. It prevents over tightening.
Since they don’t seem to have one, they should set the air wrench to a lower setting to snug up the lug nuts to about 50 ft-lbs and then finish with a torque wrench with the proper 76 ft-lbs set. If the nut does not turn before the click it is NOT torqued correctly. Your post is right about that. They should also use a star pattern. Over tightening can damage studs and wheels. If they won’t comply, it might be better to take it elsewhere.
BTW, unless you have an old Ford van or truck (or some other car that eats tires) 3000 mile rotation is a bit much. Every oil change is fine, whatever interval you use (we don’t need another discussion about oil change intervals…)
What’s the year, make, model of your car? I don’t think I’ve ever heard of an overtightened lug nut causing a noise.
Ideally the lug nuts will be run down until they are snug, then the car lowered enough that the tires are just touching the ground, and the lugs tightened in a criss-cross pattern until the torque is reached, and then double checked.
You’re never going to get the guys at that store to tighten your lugs to exactly 76 ft/lbs by using that method. This has nothing to do with you or your car, but rather how mechanics on “flat-rate” are paid and the fact that this is a complimentary service to you. Assuming that a simple tire rotation is being done by a junior mechanic and not a journeyman level technician, the kid doing the work might–MIGHT–be making $15/hr. Assuming they pay him .3 hours to do the job (and that’s a stretch), he’s supposed to do all that for less than $5. Not gonna happen. His only goal is to get this time-waster out of here so he can move on to some paying work.
I’m not saying this is right. It isn’t right. And there’s no reason a customer should be in the middle of this. But here we are. I think if I were you I would skip the free rotations from now on and have them done as regular maintenance at your regular mechanic. Save the frustration. I think you’ve found the price of the “free” rotation is pretty high.
Everyone else pretty much covered the torquing process. One thing I noted was this comment-
Every time I get the car home, I recheck the lug nuts for correct torque.
You can’t really “check” the torque. The break free force required to overcome the friction of the interface spoils that measurement. Try it yourself. Torque the lug nut and then see how much force is required to loosen it. It should be higher than the initial torque setting. The only way to “check” torque is to loosen them and re-fasten to the correct setting.
BTW- I have no doubt they were cranked down WAY beyond reason. I believe some shops do that intentionally in a misguided attempt to avoid callbacks for loose lug nuts.
I always do a quick check with the dinky bar about a week after I re-install any of my alloys. They have more tendancy to loosen than a steel wheel. YMMV.
Judging from the number of broken lugs (sometimes TWO of 5 on a wheel) I see when I walk my dog, improper tightening is pretty common.
I do my own tire rotation, but I occasionally have to go get wheels re-balanced.
I always loosen and re-torque the lugs when I get home, so I don’t get an unpleasant surprise if I have to change a flat.
Just on the offchance there may be some erroneous statement or misinterpretation by either side at the shop I might add this; with caps for emphasis.
There is NOTHING wrong with running lug nuts down with an air wrench.
There IS something wrong if the person running them down is hammering on them at full bore.
Air wrenches are adjustable so tapping the button doesn’t necessarily mean 300 Ft. Lbs. of torque.
Some guys who do enough wheels with the same air wrench can get very close on the torque with the adjustment knob on the air wrench due to sheer habit and feel. I’d feel comfortable in saying it would be in the +/- range of a torque wrench; and even more so if the torque wrench has never been re-calibrated.
I fail to see how overtightening lugs can cause noise in any way.
These free services tend to have crappy quality attached to them to discourage their use. My suggestion is; 1) Either continue to re-torque the lugs yourself every time, or 2) Rotate the tires yourself.
I have a similar situation with the local pepboys (I know hit me for using them, but their tire prices are more reasonable for me). They provide “free rotation”, but if you go there at any given time, they will make you wait until they are done with other cars and some. So, essentially I rotate my own tires, or my back is really hurting, esp on the heavier car, I pay someone to do it ($10), which is well worth my time saved.
Why do you keep going back there? Clearly they know not what they’re doing.
Fool me once, shame on you. Fool me twice, shame on me.
You are correct. The only way to correctly toque something, the torque wrench must be moving when it reaches the desired torque. I had this same argument with the manager of the tire shop at Sam’s Club, they kicked me out and while that manager was there, I wasn’t allowed to buy tires there anymore. I never bought another tire from Sam’s Club after that so the feeling was mutual.
finally a subject I m an expert on.
I fabricated structural steel for 20 yrs, most of them at Crystal Steel Fabricators, an AISC certified shop.mostly doing govt type work, schools ,universities, military bases and installations, museums court houses, etc.
some of those years were spent as quality control supervisor. I have extensive experience torqueing boltsand checking the torqued bolts.
some of the impact guns we used weighed upwards of 60 lbs and would snap high strength bolts of like they were dry twigs.
you have received some good advice.
an experienced guy who knows his impact gun can torque the nutscorrectly by feel, snugging the nut and then hitting the trigger and listening to the sound and feeling the connection.
an idiot can over torque and compromise the structural integrity of the bolt.
some connections we used were slip critical and the bolt is not even used in calculating the strength of the connection, the friction of the mating surfaces is what holds the connection, not the bolt.
I won t go into the many different specs and practices but I ll tell you one. its called turn of nut method. in this method you tighten the nut to a standard of the strength of the standard man with the standard spud wrench and then you mark the nut and the bolt end and turn the nut a specified distance depending on size. two nuts out of every connection are then checked with a torque wrench that is calibrated every shift with a Skidmore-Wilhelm torque gauge.
you DO NOT want to over torque nuts and bolts, or studs and nuts in your case, beyond a certain percentage of torque. in addition to damaging your wheel you will stretch the bolt especially after repeated incidents. if we loosened a torqued connection, we could re connect it with the same bolt , but it had to be in the same connection, and only once.
the only way for you to get an approximate idea of what the torque is after its done at the tire shop, is for you to keep adjusting your wrench up until you can turn the nut more and get your click, your torque will be slightly less than your setting. that said, you can t trust what your wrench says to be very accurate unless you calibrate it frequently on the very expensive machine mentioned above. we paid no attention to what the settings on the wrench said. we calibrated it on the skidmore every day and taped the adjuster in place.
probably more than you wanted to know but what they are doing is BAD! take it to an experienced guy or do it yourself
I hope your studs and wheels are ok
wes
Because over torque can cause warped rotors, my brake guys will retourqe lugnuts for free after anyone else messes with my lugnuts. ps wes, tell us the histoey of your avatar or pic of photo you use.
If you overtighten all the lug nuts it won’t cause a noise but if you vastly overtighten some of them it can give a temporary warp to the rotor until the uneven pressure is corrected. That can make noise rubbing the shoe or wear indicator.
that is my great grandmother, Mary Hopkins" @Barkydog the history is in the thread titled “credentials thread”
There is no two way torque wrench.
Other than using torque sticks I believe very few shops properly torque lug nuts, or even attempt to. One guy at a Sams Club store told me his air compressors were calibrated. I told him he does not know what he is talking about or he is a liar.
Keep on doing what your doing. When you get home loosen the nuts and torque to proper settings.
Wes it is wonderful to appreciate family history. In the thumbnail your pic reminded of a kid in class o 72 high school, then I looked at your profile and realized it was not you. Course barky dog pic is not me but my dog, your pic is of gram cool np @wesw
what does np mean @Barkydog?
I wish I had talked to her more about our family history…
@wesw np is internet lingo for no problem. Yes my grandmother told stories also wish I had written them down as To who and where, but dar and quakers are our blood, and one old lady by the words of the bible, if whatever, pulled a cataract eye from her head because it offended her and gOD.