Torque wrench on lug nuts?

[Adam Grund]

Re-torquing lug nuts after a determined amount of time is nonsense, and often a cover your ass recommendation from shops. If the mating surfaces are clean and no rust or corrosion buildup, and nut/ studs are clean- there’s no reason a properly tightened and torqued nut is going to loosen up after 100, 500, 1k miles.
Wheels are the only thing I’ve ever read the re-torque disclaimer on, I’ve never seen an engine manual that said to torque a head down then drive it 500 miles and re-torque it.
I manually check torque when I need to, or when something just didn’t ‘feel’ right, otherwise it’s an air impact with a torque stick and we’re off to the races. When I have checked the torque stick against a torque wrench, it’s within a few ft. Lbs, which is close enough as far as I’m concerned
But if it gives you peace of mind, it doesn’t hurt anything and there’s value in that.

[John Ziebron]

The posters that talk about a torque stick are correct in that reputable tire shops are supposed to use them. But frequently I think that they may not get used or that "Joe" is using the one that "Sam" needs so Sam just grabs a higher rated one. I don't care about what any manufacturer claims about not using anything on lug studs. If any of you have ever had to change a flat where the studs and nuts have rusted for years you'll know what I mean.

I have been rotating the tires on my vehicles for 55 years and the first time I do the studs get coated with anti-seize. I keep a foldable 4 way lug wrench in my vehicles (you all know how good the manufacturer's lug wrench is) and anytime I get new tires I use whatever means necessary to loosen each lug nut then re-tighten them with my lug wrench (do this one at a time). That way, I know I won't have a problem if I have to change a flat in the middle of nowhere. I have never used a torque wrench for a lug nut (back in the day a mechanic would laugh at you for that) and I have never had a nut or wheel come loose. Be sure to use the opposing tightening sequence though.

[ChrisA Edwards]

Had a round trip from Memphis, TN to Tacoma WA, towing and enclosed trailer. With 5500 miles calculated, took my truck in to my GMC dealership for a service and tire rotation. They also installed my current set of tires (price matched Discount Tires).

I asked them to check my brake pads as I'm still on the original set at 72K miles. They said they were good, but not being 100% confident that they had checked them, I decided to remove the left front and rear wheel to check them myself.

Well, my impact, both pneumatic and air, wouldn't budge the lug nuts. I normally use the electric impact to remove a 180ft/lb nut on the rear axle of my Ducatis, so the truck lug nuts should have spun off easily. My neighbor came down with his 1300ft/lb pneumatic impact and we did get the lug nuts off.

I checked the brake pads and all was good. I used my Snap On (CDI) Torque wrench set the the GMC spec (140ft/lbs I think). After doing that, I tried loosening one just to make sure the 30" breaker bar would work out on the road if necessary.

I will say, I normally use Discount Tire for most of my tire requirements and am one of those guys who watches the whole tire change process ( I had a pneumatic tire changer for changing mine plus friends motorcycle tires for several years), so I like to watch how the 'Pros' do it.

The Discount Tire guys use a torque wrench (at my location) for final tightening.

[Ronald Blue]

As to Johns initial comment I can't remember the last time I have had tires rotated, replaced, or whatever that they didn't use a torque wrench. In fact at Sam's at least a second person verifies the torque and signs off on it as well.

We were always taught to lube everything we were torquing. Even the studs being torqued to 2400 foot pounds. This was with a hydraulic torque wrench or a 16 to 1 multiplier and 1/2" drive torque wrench. If you are installing a head on a John Deere for example the torque procedure is as I recall 3 steps. First 2 were to so many pounds. Then the final was an additional amount of degrees. All with lubricated threads and bolt heads. I have never ran across anything that was supposed to be torqued dry that I recall. So easy for threads or bolt faces to become galled and increase the resistance. The key is that all you do is "stretch" the bolt or stud by torquing it. If the stretch isn't sufficient such as on a head the likelihood of a gasket failure is high.

[Thomas McCurnin]

If you do any offroad stuff, it is recommended that you re-torque those lug nuts every 2,000 miles, but no one I know actually does that.

[Mike Henderson]

I just looked up the recommendations on torque sticks. The recommendation is to use a lower value torque stick and then a calibrated torque wrench to finish.

Mike

[Edwin Santos]

Question from a non-mechanic - do impact wrenches have any kind of clutch mechanism to prevent over tightening?
A few years ago I had my eyes opened to the use of the clutch setting on cordless drill/drivers, and I've now trained myself to always use them when driving fasteners in wood.

[Lee DeRaud]

A few years ago I had my eyes opened to the use of the clutch setting on cordless drill/drivers, and I've now trained myself to always use them when driving fasteners in wood.

The first time I hit the stops on a cordless drill, I thought I'd broken it.
(A couple decades back, but still...)

[Tom M King]

My air wrenches have adjustments on them, but there is nothing to go by on the tool other than the knob to turn. My 1/2" Makita 18v impact wrench has more loosening torque than a 1/2" air wrench. It will take lugs off of anything here, from Dually to big tractor. I haven't used a 1/2" air wrench since I bought that Makita.

All the talk about lubed fasteners must have missed my earlier post with the link to the chart. It's fine to lube fasteners, just use the specified torque for a lubed fastener. It's different than for dry threads.

[Edward Weber]

I think you mean the torque applied to the bolt is identical whether it's lubed or dry but the clamping force will be higher if the bolt is lubed.

I guess I didn't word that correctly I hope you know what I was trying to say.

As for those who don't follow manufacturers recommendations, that's up to you. I simply point out that they're there for a reason. 99% of the time you can just tighten down on a lug nut and you'll be okay. That's only because they we designed well in the first place.
Be safe

[Derek Meyer]

I had in incident when I was in college. I took my car (1969 Ford XL, 2 door Galaxy 500 frame) in to have the winter tires swapped for the summer tires. They must not have torqued the nuts down properly, because then next week I was about 50 miles north of town on the highway, at night, and the rear driver's side wheel came off. I heard a *thump* and thought "that can't be good", so I pulled over. I got out and went to get my flashlight out of the trunk, and tripped. Turns out I tripped over the wheel, which was laying next to the car. The nuts had come loose, and the wheel vibrated enough that it reamed all the holes out so much that you could slip it over the nuts and off the hub. It sheared 3 of the 5 studs off completely - they had to be tapped and extracted before they could be replaced. The whell was toast, and I ended up with a used one. The tire place denied any wrongdoing, and since I couldn't prove anything I had to pay for it all. I only had liability insurance at the time, due to the age of the car.

The funny part is, I probably could have driven it on three wheels, as the car's weight was mostly in the front due to the size of the engine. When the wheel came off it got trapped in the wheel well, and I pulled of the road like nothing was wrong.

[Kev Williams]

I read a lightning expert's explanation as to why your rubber tires won't protect you if lightning strikes your car: "A 3 million volt bolt of lightning that's traveled 6 miles isn't going to be put off by 3" of rubber"....

Likewise, I am of the opinion that a nut or machine bolt that is being forced, metal to metal, against the opposing threads of its mating bolt or threaded boss, and an intermediate piece of metal (say, a wheel rim or a crankshaft main bearing cap), isn't going to change the readings of your torque wrench anything close to a significant amount just because there's some oil on the threads. Oil works by filling the space between metal parts with it's bearing-shaped molecules. When you're grinding 2 sets of threads together in order to stretch a bolt, there's no space between the opposing threads for any molecules... If oil on threads did significantly cause the user's torque wrench to under-report the actual torque applied, then there may be a whole lot of cars out there with engines full of over-tightened nuts & bolts...

--and anyway, torque values are not absolute, 'close' is okay. Like tire air pressure; I have 4 tire pressure gauges, all of them 'good' ones, and not a one of them give me the same readings

[Tom M King]

The reason torque on a bolt is important is because there is an optimum range for the metal in the bolt to be stretched to hold what it's designed to hold. Stretch it too much, and the metal will weaken, sometimes even to the point of breaking the bolt, or head off. The stretching of the fastener is the important part, and some assemblies even require the amount of stretch to be measured rather than torque.

Lubricant eases the amount of force required to get to this optimum stretched position. That's why torque charts have specs for dry, or lubed threads, with the lubed torque being lower. If you are lubing threads, and still torqueing them to the dry torqued measurement, they are being over-torqued. Not as important for wheel lugs, but if I'm inside the guts of some machine and want to lube threads, I'll use the torque on the chart for lubed threads.

It's been studied, and proven many times, and ways. https://www.engineeringtoolbox.com/t...ts-d_1693.html

[Jerome Stanek]

A friend of mine fas a torque socket for his 3/4 impact to change tires on his semi

[Rod Sheridan]

“Yes” + apply anti-sieze paste to all threads as well as backs of wheels.

Erik

Erik, most torque values are for clean, dry threads, that’s extremely important, as it guarantees a known frictional value.

Lubricating threads with anti-seize compound results in drastically over tensioned fasteners unless you use a calculated reduced torque value….Regards, Rod