140NM Wheel Nut Tightening Torque

Good video and well explained. It comes down to whether the specified bolt torque is on dry or lubricated threads and if wet, then even what type of lubricant used. This is why most bolts are specified dry, as this can be related to material yield a lot easier without having to also consider friction factors of the lubricant on top of the friction factors between the threads and mating faces.

One point I noted is dry the bolt reached 60% of yield and wet it reached 90% of yield. So this is a 50% 'increase' in preload for the same bolt, not a 30% increase as stated, as the difference between 60 and 90 is 30, and 30 is half of 60. The video does show how easily bolts can be over loaded by using a thread Lubricant. More easily done if the bolt selection and torque specification is supposed to take the bolt to just below yield, as is common if designing joints to DIN. This is also why most high strength bolts are single use only. They get preloaded close to yield, the in service loads never get that high, but when undone, the bolt does not return to its unloaded length and therefore can't be reused and preloaded to the same value as its more likely to fail.

Interesting & not unexpected.
I have used nickel anti seize on my un-torqued wheel nuts for 45 odd years now & have never had a failure.
Also lucky I guess.

In a perfect world that youtube is fine, but it isnt the entire story. It really depends on the conditions you drive your car.

I work in mines and the minerals exploration setting in high corrosion environments where a bit of anti-seize is useful and prevent snapping wheel nut studs.

its easy for that youtuber to do a bench test, but like much of the internet, it isnt the real world.

Yeah, nothing wrong with using anti-seize on wheel nuts.

Many reasons to do so, especially depending on your circumstances .. eg. if you live in a salty air environment near ocean .. they can rust up and snap when you remove them.

My dad had an old Inter for deliveries back in the day. Horrible thing to drive and use. Just about every time it needed wheel work(new tyres or whatever) without fail a wheel nut would be rusted on so hard the stud would snap upon trying to remove.
The problems associated with sea side living.
Having then moved out to the 'country' in the deep far outer suburbs ... never had this trouble.

For torquing up, I use a torque tube.
Got a set of 5 or 6(can't remember) .. from about 90 - 200+Nm. I don't use the LR supplied wheel brace, I use a 1/2 drive ratchet and 6 point socket with extension .. and the extension is the 120Nm torque tube. You feel it begin to twist ... torqued up .. 'good enough'.

The point being the torque and hence preload to the fastener being applied needs to be specified accordingly.

If you use the torque setting for dry threads on lubricated threads, it is likely that you are entering the elastic deformation zone of the bolt, and more likely to fail.

Similarly, if you use a torque setting for an oiled thread on a dry bolt, you will not achieve the preload required and the bolt is also likely to fail, perhaps even more so.

So if 140Nm is specified for a wheel stud (dry), if applying that same torque to a lubed thread, chances of overloading the stud are real. According to the video, potentially adding 50% more preload.

I guess why people get away with it is the preload likely sits at 50% of the nut bolt combo so even with the additional preload they’re luckily within elasticity. It doesn’t make it right, it just likely means the engineers account for it when designing these things. As I said, designed for the lowest common denominator [emoji4]

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Originally Posted by DiscoJeffster

I guess why people get away with it is the preload likely sits at 50% of the nut bolt combo so even with the additional preload they’re luckily within elasticity. It doesn’t make it right, it just likely means the engineers account for it when designing these things. As I said, designed for the lowest common denominator [emoji4]

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I think 'lowest common denominator' is a little unfair here. I'd say 'designed for the real world with all its permutations/combinations of requirement'. As various people have said, differing conditions and situations may preclude a somewhat OCD approach to this. I am (probably like many here) old enough to have learned to drive on a car with no synchromesh, and had to gain mechanical sympathy the hard way.

A full military career reinforced this: if the Army teaches you anything, its that 'good' kit is that which will be easy to maintain and not require 'taking care of' when the situation needs you to focus on other things - its been properly designed if it can take a bit of abuse..My favourite bit of kit was probably my bayonet - no moving parts, over-engineered, and did one job only. (I still managed to break 2 of them!) It's different if you're engineering the James Webb telescope - be as pedantic about use cases as you like, because you need that precision to achieve the design objective. Do we have an epidemic of failing wheel hubs killing and injuring people? No...

In short, I've spent over 40 years taking wheels on and off vehicles, on 4 continents, in all conditions, up to and including 70 tonne MBTs. All had nominal torque settings - none failed as a result of time/lack of right kit/laziness/fatigue meaning that they just 'got a good heave on the bar' to lock them off. If the engineer and the factory's any good, and designing to be fit for purpose, the bolt will cope with a good heave, with or without lube on it. Too many other things to focus on, and most of the time I get them off by standing on the bar...I've never had a wheel or a nut come off or fail as a result. Does this make me a lowest common denominator?

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Originally Posted by Jpdv

I think 'lowest common denominator' is a little unfair here. I'd say 'designed for the real world with all its permutations/combinations of requirement'. As various people have said, differing conditions and situations may preclude a somewhat OCD approach to this. I am (probably like many here) old enough to have learned to drive on a car with no synchromesh, and had to gain mechanical sympathy the hard way.

A full military career reinforced this: if the Army teaches you anything, its that 'good' kit is that which will be easy to maintain and not require 'taking care of' when the situation needs you to focus on other things - its been properly designed if it can take a bit of abuse..My favourite bit of kit was probably my bayonet - no moving parts, over-engineered, and did one job only. (I still managed to break 2 of them!) It's different if you're engineering the James Webb telescope - be as pedantic about use cases as you like, because you need that precision to achieve the design objective. Do we have an epidemic of failing wheel hubs killing and injuring people? No...

In short, I've spent over 40 years taking wheels on and off vehicles, on 4 continents, in all conditions, up to and including 70 tonne MBTs. All had nominal torque settings - none failed as a result of time/lack of right kit/laziness/fatigue meaning that they just 'got a good heave on the bar' to lock them off. If the engineer and the factory's any good, and designing to be fit for purpose, the bolt will cope with a good heave, with or without lube on it. Too many other things to focus on, and most of the time I get them off by standing on the bar...I've never had a wheel or a nut come off or fail as a result. Does this make me a lowest common denominator?

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Your experience is the difference between the real world and a bench test... which the numbers people here are promoting.

Btw, the youtuber said it was a little anti-seize - that was a lot in my experience.

I wouldn't overthink it .
The standard torque setting for a 14MM bolt/nut is .

14MM

160FT lbs

215Nm

So at 140NM you are WAAAAAY under the correct torque even.

Regards PhilipA

Maybe someone can do a controlled experiment. The fastener is designed to stretch under load. The torque value is designed to stretch the fastener that amount when applied with 140NM on a dry thread where the nut is located retaining a wheel (it'll stretch more or less if it's not in that precise spot).
If we had a way of reliably measuring the stretch, several tests could be done using differing lubricants to determine the appropriate torque values. It's done in industry all the time.

Now we've looked at the thread, what about the wheel? Different materials, and alloys all have differing coefficients of friction. So in theory doing up the same nut on the same thread retaining a steel wheel will be different to an alloy wheel. Is that in the manual? What about a dry thread and lubricant on the wheel/nut interface? Corrosion on the wheel? Aluminium oxide has a different coefficient of friction to clean aluminium. Is the wheel anodized?

It's more than just "dry good, lubricated bad, ugh".