Lug nuts and Anti-seize

[Dean]

This is yet another religious war like sway bars vs. springs, but I will wade in...

Disclaimer: Do whatever your owner's or service manual says to do. I am not responsible for anything you do after reading my words.

That said, it all depends what you believe holds things together... tension, or friction.

The friction advocates believe that anti-seize will either cause lugs to be over tightened or slip loose, or both depending on whether the anti-seize is used on threads mating surface or both.

The tension folks say tension in the lug / stud holds things together and only a minimal amount of static friction is required to keep things from loosening under proper tension and anti-seize keeps mating surfaces from bonding from any number of mechanical or chemical processes.

You will find well known web sites who should have technical staff that have each of these opinions.

You will also find anecdotal evidence of all forms supporting both positions.

Part of the problem is that torque wrenches are not really accurate for tensioning threaded steel rods, but that is a whole other discussion, and they are better than nothing.

I am not claiming to be a physicist or a material sciences expert, but IMHO, anti-seize has more pros than cons.

1. Your engine which has as much if not more vibration than your wheels is held together INTERNALLY by bolts that are constantly sprayed by some of of the most advanced lubricants on the planet. If lubrication caused properly tensioned threaded rods to come loose, your engine wouldn't last 5 minutes.

2. Static friction > dynamic friction. Torque requires movement and can be gauged much more accurately in a smoothly moving environment. Dry metal on metal dynamic friction causes torque extremes like a an earthquake fault. now somebody go invent a tectonic plate lubricant. When building an engine, almost everything gets "assembly lube" prior to being installed/torqued for this and other reasons.

3. Different metals in contact do all sort of nasty electrochemical things that can all but weld them together. Similar metals can bond in the presence of oxidation.

4. Paint and such change thickness and friction characteristics when heated and cooled under pressure.

5. Anti-seize can is messy when changing wheels.

So, to summarize, metal on metal interfaces should be properly lubricated, not with paint and wear gloves and/or wash your hands.

[MikeK]

I have been liberally smearing anti seize on my lugs every time I remove a lug nut for over 2 years now, and I have never had a problem. I do re-torque them regularly with all the events that we do though.

[sperry]

If NASCAR don't need it, neither do it.

Also, I always change my tires in under 15 seconds... 7 if I'm just doing the right sides.

[sybir]

I use a little bit of copper anti-seize on the studs, and that's it. I keep the mating surfaces clean to get thatsolid lock, but ensure that whatever lugs I'm using aren't going to corrode (whether it's rust, the cold welding you get with aluminum on metal, etc.)

I've never had a problem with wheels loosening up, but I'm also not leaving a single set of wheels on a car for more than 6 months either. I've got 250k and what has to be at least 100 wheel changes on the wagon, and I don't have any stud or lug issues.

[Dean]

Originally Posted by sperry

If NASCAR don't need it, neither do it.

Also, I always change my tires in under 15 seconds... 7 if I'm just doing the right sides.

That explains why you leave the lug nuts loose and have to pit a second time. Or you may have to come back in for a stop and go penalty for leaving the pit box with a piece of equipment or what they call a "hanger"...

[cody]

My aluminum lugs are really due to be replaced but I think anti-seize on the threads is about all that keeps them from cross threading. I don't use it on the mating surface and they have come loose over time so I check them frequently.

[AtomicLabMonkey]

I have never seen a lug nut loosen up because of anti-seize application. On my cars I give the studs a good wire-brushing and put a *light* coating of anti-seize on. The real danger when there is any lubricant on a fastener is over-torquing, since it lowers the friction coefficient on the threads. Most manufacturers spec a range of acceptable torque for lug nuts, like 80-100 lb*ft, or something like that - so if I'm using anti-seize I torque to the low end of their acceptable range instead of the high end.

[zpeed]

Originally Posted by AtomicLabMonkey

I have never seen a lug nut loosen up because of anti-seize application. On my cars I give the studs a good wire-brushing and put a *light* coating of anti-seize on. The real danger when there is any lubricant on a fastener is over-torquing, since it lowers the friction coefficient on the threads. Most manufacturers spec a range of acceptable torque for lug nuts, like 80-100 lb*ft, or something like that - so if I'm using anti-seize I torque to the low end of their acceptable range instead of the high end.

I always antiseize all my lug nuts but I did the opposite way. I torque to the max (same sample 100 Lbs-Ft). Because they can take more torque.

[sperry]

Originally Posted by zpeed

I always antiseize all my lug nuts but I did the opposite way. I torque to the max (same sample 100 Lbs-Ft). Because they can take more torque.

Yikes! Anti-seize does not increase the lug's torque limit! Proper torque is figured by the amount of stretch to the threads needed to allow them to hold tight.

Like ALM said, what anti-seize does is reduce the friction on the threads, so you actually require *less* torque to achieve the proper thread stretch. Which is why you don't need as much torque to tighten lubricated lugs.

[Dean]

OK, I am quoting somebody paraphrasing or drawing conclusions from SAE document J1701M - "Torque-Tension Tightening for Metric Series Fasteners" - so take this with a grain of salt or three... Any mechanics out there have access to this actual document?

Originally Posted by http://realbig.com/miata/1998-12/1649.html

You can generally use anti-seize on a bolt as you see fit by applying a
simple rule of thumb: With anti-seize, the torque needed to achieve the
same clamping force is 2/3 to 3/4 that of the dry bolt. A 100 ft-lb torque
specification becomes 70 ft-lbs with anti-seize.

So erring on the low end of a torque range using anti-seize is probably not a bad idea.

[zpeed]

Aha I learn something new today.