I don't know what everybody thinks about this so, I thought I would share some facts


Anti-sieze on a lug bolt is a very bad idea !!!

Here's why: Bolts or studs provide clamping force by being purposely stretched. Most torque specs bring a bolt well within its elastic limit. Then when loosened they will return to their original length and can be safely reused (Some bolts, including many head bolts, are purposely stretched past their elastic limit, and can not be reused). The torque wrench is the most convenient-but not the most accurate-method of properly stretching
automotive bolts. Engineers spend hours correlating the proper bolt stretch to the required turning effort.

About 90% of a torque specification is used to overcome friction; only 10% of the specified twisting effort provides clamping force. It is no surprise then that most lubricant tables recommend a 40-45% reduction of applied torque when using
anti-sieze on a bolt. So, a lugbolt coated with anti-sieze should be tightened to a maximum of 49 ft-lbs. Tightening this lugnut to 85 ft-lbs. means it is now over-torqued by 73%! Considering that most torque specs stretch a bolt to within 70% of its elastic limit, over-torquing by 73% will easily send the bolt or stud well beyond its elastic limit-and could be dangerously close to its failure point.

For this reason I would suggest to all forum members to never use anti-seize on your lug hardware.

Luke
877-522-8473 ext. 362

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I never have never do.. only thing I ever used was some locktite on items that required it.

I torque mine down to factory specs on my wheels.

Alon

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Luke:
Good post, and I agree with all of it except the torque wrench issue. I always go the extra step and torque wheel bolts with a good torque wrench. The type of specification used is "torque", so why wouldn't a torque wrench be the most accurate means to achieve proper stretch? HOW should I tighten wheel bolts?
Gilly

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The only reason I made the Torque wrench statement is because they can get out of adjustment if you have the "dial type" that clicks when proper torque is reach and not many people have them calibrated. The standard beam type tends to become a little fatigued after alot of use which will also lead to inaccuracies.

Luke

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OK, thanks Luke. At least you clarified that a torque wrench may be the most suitable tool for torqueing a fastener. The debate can rage like the "oil" posts about the most accurate torque wrench type. The "dial" type is usually the kind that have the "dial" that needs to be observed, you also mentioned the word "click" which is the "clicker" type, this is usually what is is referred to as. There is also the beam type, which has it's uses, but usually is considered the type you go out on Sunday afternoon and buy at the KMart auto section for $10.99 because you're "real" torque wrench is locked up at work and you "have" to torque something.
Most dial types are what seem to run the best accuracy in manufacturers spec sheets. Problem is that it's up to the individual as far as how close the needle falls to the desired number. Also take into account that to be accurate with the dial type, it's important to observe the dial from straight on, not angled. On higher torques, I just don't trust myself to land the needle right on, especially repeatedly, such as head bolts. Clicker-type accuracy is acceptable, especially when you consider that to a certain extent, it's not quite so critical to have 0.11% accurate torque loading as much as it is to have consistantly matching readings, this is especially true for a bunch of head bolts, and also true for wheel bolts. I much prefer the clicker-type, the one I use for wheel bolts is the Blue-Point "Brutus", which is a 1/2 inch drive clicker-type built into a 3/4 drive bar, excellent for this type of repeated torquing. The dial type may be good for some jobs, but in my opinion not good for wheel bolt work because the torque wrench dial will be down so low to the ground it is hard to look straight at the dial, then multiply by 20 bolts all in a row, not really a good scene, not for a line tech at any rate. It is possible to be fast AND accurate.
I would also state that it would be better to use a cheap torque wrench, such as "The KMart Blue Light Special" Than none at all, because by using even a cheap wrench, you can be somewhat assured that the torque is at least close, and more importantly that the torque loadings are at least somewhat even between all 5 bolts.
Gilly

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I have used either grease or anti-seize on lug nuts & bolts for years. Dramatically improves the ease with which tires can be rotated, or swapped out for winters when the weather's nasty. Not using grease I would think could lead to faulty torque readings, since turning resistance increases with age, use & corrosion that inevitably builds up.

So, if some of us insist on using grease, would you recommend decreasing our torque to something closer to like 50 ft/lbs?

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I have been using the anti-seize on lug nuts for years too and I tighten them up with the lug wrench that is in the trunk (no torque wrench). When I tighten them up I keep in mind that if I have a flat tire I will have to use the same wrench I am using to tighten them up with. I have never had any problems with this method.

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You can not get an accurate reading without something on the bolts.

Just as you would but oil on head bolts, you put anti-siez on lug bolts. A dry bolt will not torque correctly

John

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Good points one and all. My biggest concern is two-fold:
First of course is liability. If a wheel ever comes off on an owner (not that it should when the wheel is properly torqued) but if it should, I want to be able to say "I torqued all the wheel bolts with (heaving up my torque wrench) BRUTUS here. Any questions?"
The other concern is overtorquing. Never had a bolt snap as has been warned. I've had a few stuck one's though, and fellas, that ain't fun, 'bout the worst job there is. Especially on the ones with the long shanks that go through the deep holes in the rim, think of a 16 hole 124 or 126 rim.
If you have a method that work good for you, by all means stick to it.
I don't think Luke is pulling this info out of his, ahem, hat. He does state that 90% of a torque spec is used in overcoming friction, so if that's true, then you would have to agree that dry threads are what is intended in the torque spec. Maybe not corroded and full of dirt, but clean and dry. In extreme torque loadings, yes the threads are meant to be oiled, but the torque for the wheel bolts are far from being considered "extreme" to most people, and if MB indended the wheel bolts to be lubricated, I think we would know about it.
One exception I do take to the info Luke gave, (besides the whole torque wrench, get out the "bolt stretch indicator" to tighten wheel bolts thing) was the notion that engineers spending hours to calculate proper bolt stretch statement. Hey, there are 2 wheel bolt torques, it doesn't really float around that much, well at all. If you have the fat bolts (140, 220,215,163 for sure, not sure about the G Class) they are torqued to 150nm (110ft/lb), everything else that I'm aware of uses 110nm (80ft/lb). They calculated it once, I don't think they need to revisit these torque specs again.
Gilly

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well, I was actually referring to all lug hardware not just MB vehicles .... but good point.


Luke

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Luke -

Firstly, the forum is the best source of technical expertise and just plain common horse sense for MB issues ever.

While I do not profess to be omniscient about automotive threaded fasteners, I feel compelled to take issue with your response on using anti-seize on lug bolts as I believe your response, while well intended, does not adequately address all issues associated with threaded fastener preload via torquing.

I do have some expertise in designing and specifying threaded fasteners, particularly in deriving a designated pre-load by using a specific torque range on aerospace and nuclear applications.

1 - Common engineering practice is to design threaded fasteners such that, in an over-torque situation, the bolt head would break off due to a combination of shear and tensile stress before stripping out threads (mostly a shear failure). This hopefully results in some bolt body being left to allow removal of said bolt should overtorquing break the head off.
1a - However, that being said, my observations of my 300TE lug bolt thread engagement does indicate that the length of thread engagement (about 8-10 threads) would result in thread stripping before bolt head failure. While I have not run the stress calculations, another good engineering practice is to design the threaded fastener such that the bolt (external) threads would strip out leaving the hub (internal) threads. The reason being that the bolt is the cheaper item to replace.
1b - To add another curve to this, the hub appears to be a high carbon low alloy steel (that's why they rust) and it is quite likely that is has a yield strength significantly lower than the high alloy low carbon Corrosion Resistant Steel (CRES, aka Stainless Steel) lug bolt. I would need to know the material composition of both items to determine the yield stress and ultimate stress to allow accurate stress/strain calculations. One would hope the superior engineering qualities of MB would accommodate the aforementioned common engineering practices.

2 - Not using a lubricant on threaded fasteners results in other issues.
2a - The friction in a threaded fastener can absorb a wide range of torque load, depending on thread pitch, class, quality, geometry, condition, lubrication, and foreign material (dirt, rust, etc.). Controlled condition tests using stud tensioners shows this loss can range from 5 to 95% of torque. By far, the best way to obtain consistent preload from a threaded fastener is to keep the threads clean, in good condition, and to use an appropriate lubricant. This will typically limit the loss of torque load (due to thread friction) to a general range of 15 to 25 %. I am hard pressed to believe that MB would ignore the importance of clean, lubricated threads in their threaded fastener and torque specifications.
2b - Again, I would have to run calculations, but from general observation, I would wager that the components of the lug bolt fastener system (the lug bolt, internal and external threads, as well as the compressed area of the wheel material) could easily withstand 150 to 200 lb-ft of torque before reaching the elastic limit (i.e., yield stress) of any component of the fastener system.
2c - Another issue is galling of material. Wheel lug nuts are probably cycled more than any other threaded fastener on an automobile. Tribology (the study of interaction of materials smearing across one another) shows that the more a threaded fastener is used, the more galling takes place. Proper lubrication reduces, and can eliminate, this galling.
2b - Lubricant material is another issue. Given that most never seize has a copper base, galvanic corrosion can be an issue, particularly where the threaded fastener materials have a high level of galvanic separation. For example, common automotive never seize should not be applied to spark plugs threaded into an aluminum head (unless appropriate threaded inserts, such as helicoils, are used). The copper in the never seize provides a high galvanic potential with the aluminum, and the aluminum head threads can actually corrode into the spark plug threads, particularly if the spark plug thread material is CRES.
However, while most lug bolts are CRES, this should not present a problem with the forged high carbon steel wheel hub threads. Conversely, there could be some issues with aluminum wheels, particularly if the finish (paint, anodize) is damaged where the shoulder of the lug bolt mates with the wheel hole chamfer. Never-the-less, a marine grade never seize is the better choice as their lubricant base is usually a tin/lead rather than copper.

As I have worked this issue professionlly that resulted in both material and process changes on how we torque lubricated bolts on all Boeing commercial airplanes I thought I will share some of the highlights.

1) All lubricants are not equal. Some will hold a torque and some won't.
2) Some will work itself loose, some won't.
3) Need different torque for different lubricants.

Of course all these only addresses brand new bolts and threads. Now throw in rusty bolts and threads
and now nothing is clear.

I guess the bottom line is keep the bolts and thread clear of rust and dirt, and torque them per spec without lubricant is the best thing to do.

If you decided to clean off the rust and dirt with penetrating oil or lubricants, be sure to remove the residue with a cleaning solvent like MEK or MPK.

I'm with Tommy. I'm no engineer, but here's one little thought to chew on:
I've removed wheels from brand bew Mercedes, and those threads are dry as a bone, so to speak. I think that MB would lubricate (oil, grease, anti-sleaze) the threads at the factory if they thought they should be lubed also in the field.

On one vehicle I recently repaired, it was neccesary to remove the brake calipers that the owner had installed (on the wrong side of the car!). The guy used anti-sieze on the threads of the CALIPER bolts! You can carry this a little too far. FYI for those that don't know why I find this amazing, the bolts are to be installed with a thread locking compound, not any type of lubrication or anti-sieze! I maintain that dry threads in good condition and proper MEASURED torque is the best insurance against seized wheel bolts.
Gilly

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This runs counter to what Stu Ritter, Technical Director "The STAR" magazine, and independent shop owner posted a couple of years ago.

1) use a small amount of anti-seize compound ONLY on the the first 5mm of the lug-bolt's threads, NOT on the ball/shank;

2) the ball/shank is what makes friction contact with the wheel and needs to be clean & dry for proper torque measurements.

Comments?

:-) neil
1988 360TE AMG
1993 500E

BTW: our local MB dealer and my independent MB tech does the same- only the threads, and not the ball/shank.

Well Mercedes dosen`t put it on the front hubs either.

When we put snow tires on our 1999 C280 at 1 week old, we had a hell of a time getting the wheels off. We had to loosen the lugs and turn the wheel back and forth, to seperate the wheels from the hub. This was a brand new car.

You can bet that anti-siez when on the hubs before the snow tires!!!!

John

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