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Use of Anti Seize on Vehicle Lug Nuts Awesome
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Posted by: john2003

10/29/2008, 19:27:14

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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 long breaker bar. I thought they might break. Had I have broken down somewhere without that breaker bar, I would have been stranded. 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. Due to corrosion, after removing a lug nut, you could have a fractured or structurally compromised lug stud(s) and not even know it. 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 on the subject.

Thanks
John


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: Use of Anti Seize on Vehicle Lug Nuts
: Use of Anti Seize on Vehicle Lug Nuts -- john2003 Post Reply Top of thread Engineering Forum
Posted by: Fordman1

11/02/2009, 14:10:45

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My personal experience is very positive. I have used anti-seize on my Fords for years, and since I change my tires myself, this is the only was to ensure a DYI job is done right. Also the added benifit is if you are stuck on the side of the road, you can actually change your flat yourself! Garages discourage anti-seize because it cuts into their money making stud replacement charges.
So, go ahead, put anti-seize on your studs. It works and works right with no loosening of the nut. They stay on tight like they should and remove like a dream.

Fordman1


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: Use of Anti Seize on Vehicle Lug Nuts
: Use of Anti Seize on Vehicle Lug Nuts -- john2003 Post Reply Top of thread Engineering Forum
Posted by: randykimball

10/30/2008, 12:59:11

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The only comment I have here is that I have used it since I had problems with seized lugg nuts back in the 70's. I have never lost any wheels or have I found any loose. My sons did loose several wheels (dauh) off their VW bahaa's when they were in high school, but I'm fairly sure that was due to their hurried, hap-hazard change from mud to street tires on their way to dates with cuttie-pies. Besides... I seriously doubt they took the time to use anti-sieze.

See: Anti-Seize Compound Application Review


The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.


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: : Use of Anti Seize on Vehicle Lug Nuts
: : Use of Anti Seize on Vehicle Lug Nuts -- randykimball Post Reply Top of thread Engineering Forum
Posted by: john2003

10/30/2008, 13:31:57

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Thanks Randy,

Based on the feedback I have gotten from another Engineering forum, it seems the general consensus is that anti seize will not cause the lugs to loosen, but perhaps could possibly cause too much axial force to be applied to the lug studs.

I think this is debatable though because in the past most shops just used impacts to torque the lugs down, and many still do. I have seen impacts break dry studs off, but I bet nobody has ever broken a stud off using a hand torque wrench and anti seize on the lug studs. I think an impact wrench on dry lug studs will probably produce more axial force than a hand torque wrench on lug studs coated with anti seize.

The parts have held up to the use of impacts on dry or lightly oiled lug studs for years, so it seems plausible they are strong enough to use with a hand torque wrench and anti seize.

Also, several people from the other forum said they had been using anti seize on lug studs for years with no problems.

John


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: : : Use of Anti Seize on Vehicle Lug Nuts
: : : Use of Anti Seize on Vehicle Lug Nuts -- john2003 Post Reply Top of thread Engineering Forum
Posted by: john2003

11/01/2008, 22:33:38

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I did a little more research on this and here is what I found...

The general consensus seems to be that the use of anti seize on vehicle lug nuts that are properly torqued, is not going to contribute to the lug nuts loosening. It seems wherever I posted, more people reported using anti seize on lug nuts for years without any problems, than people advised against it.

It also seems to be considered that the application of lubricants in general to properly torqued fasteners will not contribute to their loosening. It is generally considered that traverse movement is what causes fasteners to loosen.

However, it probably makes good sense that the anti seize be very sparingly applied to *only* the lug stud thread and *not* the contact or interface point between the end of the lug nut and the rim. The question of whether or not to decrease the manufacturers torque specifications to account for the application of anti seize is debatable, but if you can keep the anti seize off of the contact point between the end of the lug nut where it seats in the rim, you are probably better off staying with the manufacturers specified torque. The following information will explain why.

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 (preload) obtained when coating *only* the threads with anti seize, and when coating both the threads *and* under the bolt head or nut. Apparently, if the information is reliable, there is a huge change in axial load when you coat both the threads and under the bolt head or nut, as compared with hardly any change in axial load when you apply anti seize to *only* the threads and not under the bolt head or nut.

If you look at the table / charts provided near the bottom of the page at the link directly above, using anti seize on the *thread only* shows slightly less axial load than using no lubricant at all. This is probably due to the wide variation in friction of identical bolts with dry un-lubricated threads, which can be as much as +/- 25% to +/- 50%.. See the following links for more information.

http://www.engineersedge.com/engineering-forum/showthread.php/3762-Screw-Design-Calculation-Document?p=10510

http://www.engineersedge.com/material_science/bolt-preload-calculation.html

They say that about 90% of the input torque of the torque wrench is consumed by friction, with 50% of the friction being between the bolt head and mounting surface, 40% of the friction being in the threads, & only 10% being the stretch of the bolt which produces the axial force or preload.

The article at mechanicsupport.com 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

Here is a link to the article published in engineering failure analysis.

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

Regarding the article at the link directly above, it seems it was not the use of anti seize that was causing failure of the helicopter rotor bolts, but rather the improper application of anti seize that was causing failure, namely applying anti seize under the bolt head or nut instead of only applying it to the fastener threads. Applying anti seize under the bolt heads and/or nuts increased axial loads substantially. It also appears 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.

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/or 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 Bolts Science 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 nut studs 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.

If anti seize is used however, it seems wise to be extra careful to make sure that any shop you take your vehicle too only uses a hand torque wrench to tighten the lugs to the correct torque.

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. Based on the information given above, & my experience, 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 outrageous. Shops warp rotors all the time with power impact wrenches, 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 brake pulsations, then you probably have not overstressed the lug nuts & studs to a point of any real concern. Impact wrenches break lug studs off all the time, I doubt anyone has broken a lug stud off with a hand torque wrench, whether coated with anti seize or not. I doubt any rotors have been warped with a hand torque wrench, anti seize on lug studs or not.

John

Modified by john2003 at Sat, Nov 01, 2008, 22:35:50


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: : : : Use of Anti Seize on Vehicle Lug Nuts
: : : : Use of Anti Seize on Vehicle Lug Nuts -- john2003 Post Reply Top of thread Engineering Forum
Posted by: mapistilli

01/17/2009, 13:44:11

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I have review your article and found some helpful information. I am a Bus mechanic and it helps to understand the thory and reschearch behind the type of work I perform everyday.

Aloca wheels specify a Lower torque for lubed threads verses dry threads on when mounting bus and truck wheels. This would seem to support your article. However, some manfactures specify no use of lube on the studs threads, and as I indicated above some have specifications for dry or lubed. The use of lube under the lug nut where in meets the wheel is not recommended by any manfactures I have found so far.


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