Use of Anti Seize on vehicle lug nuts 6

[John2004]

Hi everyone,

I would like to start a discussion on the use of anti seize on vehicle lug nuts. Searching the net, there are people that claim to have used anti seize on lug nuts for many years with no problems, and some people that advise against it.

I have two main questions I would like to address separately. The two questions directly below are related to the two main sources of controversy on the subject.

1. Will the use of anti seize on properly torqued vehicle lug nuts likely cause them to loosen over time, to the point where it could be dangerous ?

2. Will the use of anti seize on vehicle lug nuts cause a significant increase in the axial loads and/or stresses on the lug studs, that would likely cause a significant problem or danger ? If so, I would think you could simply reduce the specified torque by a certain percentage to compensate for the use of the anti seize.

I have a bottle of NAPA anti seize (item # 765-1674) and interestingly enough, it says right on the bottle to use anti seize on lug nuts.

I would expect most engineers and auto manufacturers to recommend not to use anti seize on lug nuts, even if they're not sure either way whether or not it would cause any problems, just because of safety liability.

On the other hand, one would think that a large company like NAPA also considered safety liability, and would not state right on the product bottle to use anti seize on lug nuts, unless it was a safe practice.

On the bottle of the NAPA anti seize product mentioned above, under directions, it states to apply the product, and then torque all bolts to manufacturers specifications.
The directions make no torque reduction allowance for the lubrication effects of the anti seize, and the effects it may have on increasing axial loads beyond those anticipated at OEM specified torques.

Also on the NAPA anti seize bottle, it recommends the use of the product on engine head bolts, but again, does not provide any recommendation for an OEM torque spec reduction with the use of the anti seize, which leads one to believe that it may not be a significant issue.

Most repair shops are not going to torque your wheels anyway, they will use impact wrenches which always over torque and many times warp rotors. Some shops use torque sticks on the end of the impact wrenches which is a good idea, but you would be hard pressed to find any shop using torque wrenches on lug nuts. It's just not fast enough for them. Even if you request that they use a torque wrench, they may likely forget, so you would have to watch them. I know because years ago I worked in an auto repair shop.

I have used anti seize on the lug nuts of one vehicle I have and I have not had any problems. I used it very sparingly, and I tried my best to make sure that there was no anti seize between the end of the lug nut (part that seats in the rim) and the rim. These were aluminum rims with closed end acorn style lug nuts. I re torqued after driving 50 miles or so which is standard practice on aluminum rims anyway.

The reason I used the anti seize is because I had to remove a tire once and the lugs were so rusted I could not remove the nuts without a breaker bar. I thought they might break. After that, I removed the lugs on all the wheels, replaced them with new lug nuts, and applied a small amount of anti seize to each lug stud at the time of replacement. That was years ago and I have not had any problems.

Many times cars will come into a repair shop with rusted lugs. Some lugs will come off with an impact wrench and others will break off because they are too rusted. However, just because the lug nut came off with an impact does not mean that the stud was not damaged, fractured, or over stressed when removing the lug nut, due to the corrosion present. This is another reason I can think of to apply something to lug nuts and studs to keep them from rusting.

Is there anyone out there that has had some real world experience with this, perhaps with fleet vehicles ?

I would appreciate any feedback or thoughts.

Thanks
John

 

[HeviiGuy]

Gentlemen,

A note from a Survivor...

A few of you have seen me rant and rave about the bizarre black magic voo-doo of trying to achieve a properly-calculated bolt stress by "torquing" a fastener. Well, this thread puts in into context:

Many years ago I almost became a road pizza, a veritable stain on the highway, as a result of this dangerous assumption. As I was heading up to see a client, I had noticed a black mass in the air, growing ominously larger as I realized that it was on a trajectory directly towards me. In spite of turning the wheel slightly and trying to duck behind the dash, this missle from the heavens smashed into the A pillar, raining chunks of glass upon me. Luckily, I was able to maintain control of the vehicle, pull aside (pull myself together) and try to find out what had just happened.

Turns out that I had been struck by an errant wheel whose lug nuts had let go. Why had they let go? Very likely because they hadn't been properly preloaded. Maybe some mechanic simply used an impact gun. Or, maybe equally as useless, he may have used a torque wrench. Perhaps it was even a calibrated torque wrench.

Since torque has dubious or little, at best, relationship to a fastener's residual preload in the real world, it cannot alone be used to control a fastener's "tightness". "Torque" just describes how much resistance there is to turning the nut. There are myriad factors conspiring to add to (or detract from) such resistance. For the most part, many are uncontrolled. Thus, their values, in terms of the K factor, are unknown.

So, whether lube is used or not, unless you measure the final result of the torquing exercise, you're still stabbing in the dark.

Ciao,

HevïGuy

http://www.heviitech.com

 

[John2004]

HeviGuy wrote:
"So, whether lube is used or not, unless you measure the final result of the torquing exercise, you're still stabbing in the dark".

In the case of lug nuts, is there a cost effective efficient way for auto repair shops to measure the final result, bypassing the torque wrench ?

What about the guy who just likes to work on his own vehicle now and then ? I'm assuming anything that measures the final result more accurately than a torque wrench may be expensive.

Cory wrote:
"As Mr. Clark mentioned, using different thread handedness is only useful if the fastener shares the rotation axis with the joint, and only if the applied forces/torques are of the same magnitude as the preload/resisting forces".

I had thought about that, lugs are not like a table saw blade, the shaft the blade is mounted to, turns clockwise, but the nut that holds the blade on, tightens counter-clockwise, & this keeps the nut snug & things more safe.

In the case of the lugs, each lug and stud does not rotate about *their own* common axis but are located radially around a common rotation axis. It still *seemed* there could possibly be a somewhat similar effect, although less pronounced.

Just out of curiosity, why did Dodge design one side of the vehicle with LH lug threads and one side with RH lug threads ? Did they think it would help prevent loosening or were they aiming for something else ?

Cory wrote:
"Wheel to hub joints are designed to be robust against multiple tightening methods (hand tool vs. power tool) and conditions (lubricated vs. non). However, liberal use of anti-seize on newer parts is not part of it, and definitely could lead to damaged parts".

I would think using anti seize would be very similar to the "lubricated" condition the engineers designed for. As for being designed for power tool use, torque a lug & stud coated with anti seize by hand with a torque wrench, or torque it dry & non-lubricated with an impact that sometimes breaks studs, which one produces more axial load ? I would bet the impact on a dry stud. I have seen impacts break studs off, but I bet nobody has broken a stud with a hand torque wrench and anti seize.

If they're designing for the use of impacts (and they should be becasue many shops use them & in the past almost all shops used them), then it would seem plausible the parts could probably handle the use of anti seize with a hand torque wrench.

In my opinion, unless auto engineers can prove that their new fancy coatings will allow people to never worry about frozen & seized lugs again, in areas where road salt is used & under all practical conditions, then they should be designing for the use of anti seize.

John

 

[HeviiGuy]

Alas, for applications such as this, there really isn't a practical answer (with the exception, perhaps, of colour-changing load indicating fasteners -used simply for their "go, no-go" indicating ability). Industry makes use of technology such as ultrasonics to measure the stretch of fasteners before and after they're tightened. The resultant Delta L provides a definitive indication of the fastener's preload. Plain and simple. No guess work involved or assumptions having to be made. Basic dial indicators have also been used in this manner.

My point was to come out and say: "Hey people, the Emperor is naked!" and get them to really think about the application being fastened, the potential cost of its failure and, hence, the degree of control required to ensure that everything will be fine. Relying on torque alone results in a sometimes dangerous false sense of security

Ciao,

HevïGuy

http://www.heviitech.com

 

[MintJulep]

Alas, for applications such as this, there really isn't a practical answer

Yeah, we've only been mass-producing cars for 100 years.

And while every once in a while a wheel falls off the hugely overwhelming vast majority of them don't

Apparently the wheel-to-hub connection has evolved to a point where it can tolerate a really big range of preload. Torque or no torque. Impact gun or fat guy jumping on a cheater bar or average Jill using the stupid little wrench that comes with the car. Four out of five, or three out of four. Cross-threaded, rusted in place, cones the wrong way and all the other things that can and most certainly are done wrong.

And still most wheels don't fall off.

Sometimes good-enough is good enough.

 

[btrueblood]

How would you use an ultrasonic or dial indicator to indicate lug stretch with acorn-style lug nuts?

 

[HeviiGuy]

"How would you use an ultrasonic or dial indicator to indicate lug stretch with acorn-style lug nuts? "

You can't. One needs clear acces to one end of the fastener if measurement is intended.

Sometimes good-enough is good enough.

Until somebody gets hurt. That's when the fecal matter hits the fan and the litigation machine gets fired-up

Ciao,

HevïGuy

http://www.heviitech.com

 

[hydtools]

So, HeviiGuy, should anti-seize be used on lug nuts or not? What detrimental effect would there be if it is used?

Ted

 

[HeviiGuy]

Hello Ted,

There would be no detrimental effect whatsoever if anti-seize (or "bolt snot" as we over here sometimes refer to it as) is used if the residual preload can be verified. This would result in the amount of applied torque being irrelevant to the torque spec: You only apply an amount of torque which will result in the required elongation.

In the absence of being able to verify the load (which in the case of lug nuts would be quite difficult to do), as MintJulep suggests, tell Bubba not to apply all of his weight to the cheater bar :-(

Ciao,

HevïGuy

http://www.heviitech.com

 

[John2004]

Mintjulep wrote:
"And while every once in a while a wheel falls off the hugely overwhelming vast majority of them don't"

"Sometimes good-enough is good enough".

In general I agree with both statements, I never had a wheel that I have put on come off, but I worked in a shop where other people had a couple come off. It really is a bad thing to have and see happen. Usually, it's when people get rushed that things start going wrong, but I have seen a few employees that were generally lazy and/or unfocused.

I guess you will always have human error and things will always go wrong, but when you get your vehicle worked on, you want to be able to count on the wheels being installed correctly. There's too much at stake, and being busy or in a hurry is no excuse for not making sure it's done right. That goes for owners, managers, and all employees.

Even if it only saved one life, would it be going too far to implement standards that shops must follow to insure it's done right ? I know that could cause some problems & would still not be fool proof, and then the question of how to enforce it comes up.

I guess all you can really do is try to find a shop you trust or do it yourself.

John

 

[zeusfaber]

In this part of the world, lots of commercial vehicles have checkpoints fitted.

http://www.cpsafety.com.au/

They don't stop wheelnuts from loosening, but they do make it really obvious to anybody who's looking that something is going wrong long before it causes an accident.

I stopped a van fitted with these last week because I could see from twenty feet away that one of his wheelnuts was working loose.

A.

 

[HeviiGuy]

Indeed, I've seen them too. They're a tremendous improvement over the status quo!

Unless I'm missing something, there is, however, a bit of a cavaet with their use as well, isn't there? For example: The concept is that relative movement would alert somebody to the fact that something was gone awry. I would think that achieving the proper bolt stress in the first place, is a key factor. Otherwise, an affected indicator would be showing a "false positive".

Ciao,

HevïGuy

http://www.heviitech.com

 

[bentwings2]

My Dodge 1 ton dually actually has a bearing built into the lug nuts. These are supposed to be lubricated at install and then tightened to a given torq value. I rotate the tires occasionally and do torq the nuts down to the proper value. They do not come loose..ever. Infact it takes a 24 in cross to loosen them by hand or a very stout impact tool. Most 1/2 inchers won't do the job. I don't think I have ever heard of lug nuts coming loose on any of the 6 truck forums I frequent.

I also have aluminum wheels on my streetrod. These have long studs that protrude thru the lug nuts. The Lug nuts have washers which I use never-seize on. Never have problems with them. The same goes for the top fuel funny cars. Never had lug nuts come off. For the most part they are hard to get off once torq to the right value.

 

[plasgears]

I have used spray moly anti-sieze on studs and nuts. Instead of using a torque wrench, I judge from the 'creak' at the point of final tightening. Could this spell danger from tire shop torque wrenches? Hasn't occured yet with me.

 

[HeviiGuy]

Ciao,

HevïGuy

http://www.heviitech.com

 

[John2004]

Plasgears wrote:
"I have used spray moly anti-sieze on studs and nuts. Instead of using a torque wrench, I judge from the 'creak' at the point of final tightening. Could this spell danger from tire shop torque wrenches? Hasn't occured yet with me".

My main concern would be not so much that anti seize would increase axial load to dangerous levels with the use of a hand torque wrench, but that an impact and the use of anti seize would always create a problem.

As long as you don't forget to make the repair shop torque the lugs to specs, then no problem I guess. Unless someone uses anti seize and does not know that it can change the axial loads, then the guy or gal at the repair shop runs the lug down with an impact. Even if they have a good feel for torque on a dry stud, I tend to think they would probably apply way to much force on the anti seize coated stud. Then you could get broken lug studs, or worse yet, compromised lug studs that seem OK but fail while driving. Not to mention warped rotors.

Requiring repair shops to always use torque sticks with impacts many not be a bad idea. Torque sticks seem decent, but I tend to think a hand torque wrench on average may be more accurate & consistent. That's just an unfounded suspicion though, I never did a side by side test.

I contacted Permatex & NAPA about this & I will let you know what they say when I get their replies. I suspect they will play it safe and say they no longer state on their anti seize bottles to use it on lug nuts, but perhaps they will surprise me with a real answer.

John

 

[John2004]

I found some info regarding wheel stud failure here...

http://www.boltscience.com/pages/failure4.htm

The link directly below goes to a page with some interesting information regarding the difference in axial loads obtained when coating only the thread with anti seize, and when coating both the threads and under the bolt head. Apparently, if the information is reliable, there is a huge change in axial load when you coat both the threads and under the head.

http://www.mechanicsupport.com/articleTorqueWrench.html

If you look at the table / charts provided near the bottom of the page, using anti seize on the *thread only* shows slightly less axial load than using no lubricant at all. Is this an error or is there some reason for this ?

The article references another article titled "Failure of bolts in helicopter main rotor drive plate assembly due to improper application of lubricant" by N. Eliaz, G. Gheorghiu, H. Sheinkopf, O. Levi, G. Shemesh, A. Mordecai, H. Artzi, Published in Engineering Failure Analysis #10, pages 443-451,

http://www.sciencedirect.com/.

Apparently, it was the anti seize application method that was causing the problems with the rotor.

I wish I could see the full article but science-direct wants $35.00 bucks to see it. I may be able to get it from the Library.

A wheel coming off is one thing, but a Helicopter main drive rotor getting loose or coming off is about as bad as it gets. And to think it happened not because of the use of, but the improper application of anti seize.

You would think that they would certainly have a fool proof bolting system for helicopter main rotor drive plates, that would not depend on the proper application of anti seize.

John

 

[HeviiGuy]

You don't need to spend $35 on a report. It's pretty simple: The salient point being made in the article is that one can get a huge variation in preload with a fixed input torque. Bottom line is: if you don't know what the friction of the assembly is, lube or no lube, your 'chopper main rotor drive plates (and just about everything else) are at risk.

It's not the anti-seize which is at fault, it's the assumption-laden process.


Ciao,

HevïGuy

http://www.heviitech.com

 

[hydtools]

Here is the report:

http://www.eng.tau.ac.il/~neliaz/Papers_Files/C27.pdf

Field techs did not follow defined proceedure. The result was higher bolt tension and bolt failure. Spraying anti-seize full bolt length reduced (I'm guessing) under-head friction. Tightening by turning the bolt instead of, as specified, the nut resulted in more torque going into bolt tension rather than being absorbed by bolt head friction.

In these critical joints bolt tension sensing should be used rather than indirect torque monitoring and expecting desired tension.

Ted

 

[John2004]

Thanks for the report link Ted.

What about the chart at the link below that shows applying anti seize on the *threads only* actually reduced axial load by a small amount compared to dry unlubricated threads ? Is this an error or is it just due to normal friction variation in threads ?

http://www.mechanicsupport.com/articleTorqueWrench.html

Would it be unreasonable to require engineers to design all *critical* threaded joints & related components (wheel lugs, helicopter rotors, etc. anything where a life may be at stake) to be able to withstand the maximum axial loads produced by torquing lubricated threads to specs with a torque wrench ? The lubricants vary, so they should design for the lube that produces the lowest friction.

It seems anti seize and lube on threaded joints is a good idea in most cases, plus applying the lube produces more consistent and accurate transmission of torque, so it would appear to make sense to always design for a lubricated joint.

I have also read that research has shown that not lubricating the thread and nut face will result in the friction value increasing on re-tightening which subsequently reduces the preload for a given torque value. This would be especially important regarding lug nuts, which are being removed & re-tightened frequently for tire rotations.

It seems all torque specifications should specify both dry and lubricated threads for reference, & if lubrication or anti seize is required or recommended, it's exact application method should be specified. Although ideally the joint would be designed to withstand a worse case scenario application of lube on both the threads and under the bolt head.

At the

http://www.boltscience.com

website, they say that it is actually transverse joint movement that causes loosening of threaded fasteners. In the case of a wheel, friction between the wheel and the hub prevent traverse movement. The friction is generated by the axial force generated by the torqued lug nuts.

Because of traverse movement causing joint loosening, it's probably best to not use anti seize or any lube on the back side of the rim where it contacts the rotors, hub, or brake drums.

My feeling is the benefit of using anti seize on lug nuts outweigh any concerns of problems it may cause. I do think it is a good idea to apply the anti seize very sparingly to the lug studs, and to try to not get any anti seize on the contact point between the end of the lug & where it seats in the rim lug recesses.

The last time I used anti seize on lug nuts, I think the way I did it was to smear a small dab of anti seize on the end of the lug stud, then run a lug nut on the stud by hand back and forth until a thin film of anti seize covers most all the stud (almost up to the rim). I ran the nut back and forth on the stud enough times so that it did not push a glob of anti seize between the end of the lug and where the lug seats in the rim when I was ready to finally tighten the lugs down. I wiped off any anti seize at the lug end as required.

The main question that remains is whether to torque the lugs to manufacturers specs or reduce the torque by a percentage to compensate for any increase in axial loads due to the anti seize. My guess is to just torque the lugs to manufacturers specs, especially if you use the anti seize very sparingly and can keep it off the end of the lug nuts where they seat with the rims.

This has worked for me and I think the fact that it did not warp my rotors is a clue that the axial loads are not too outragous. Shops warp rotors all the time with impacts, and they might turn or replace your rotors, but they don't replace the lug studs as a precaution for the possibility of them being overstressed by the impact which warped the rotors.

This reasoning may not apply to all vehicles, especially larger tucks, but for most pickups and cars, I would think that if you have not warped the rotors and you do not feel any break pulsations, then you probably have not overstressed the lug nuts & studs to a point of any real concern.

John

 

[hydtools]

I think the difference in tension dry thread vs. lubed thread is small, 5%. What it does seem to indicate is that thread friction is much less significant than under-head or under nut friction. Anti-seize on threads only will not significantly change the lug or bolt tension at factory wrench torque. Anti-seize on the threads and under the bolt head changed the tension to 1.7 times the dry tension. So anti-seize on the wheel stud and on the lug nut face will significantly change the stud tension. Without knowing what the expected lug tension is for dry torque, there is no predicting what the fully lubricated tension would be. Limit applying anti-seize to threads only.

Ted