I always apply a small amount of grease to the threads, and have never had a problem with lug nuts coming loose. However, I also make sure the *tapered *surface of the lug nut (or lug bolt), and the tapered surface in each hole in the wheel, are clean and dry. (See my post above). The mating of the tapered surfaces provides the friction that keeps the lug nuts tight, not the threads. As long as these surfaces are clean and dry when you put the wheel on, and you properly torque the lug nuts / lug bolts, you won’t have any problem.
You do have a good point about the risk over-torquing when applying oil or grease to threads. But I don’t think it’s much of an issue in this case, since (as mentioned above) most of the friction is due to the mating of the tapered surfaces. None-the-less, I should probably reduce the amount of torque I apply by a small percentage, since I do apply a small amount of grease to the threads. Say 95 foot pounds instead of 100 foot pounds.
I don’t have a cite, nor am I an ME, but it has always been my understanding that the tapered surface of the lug nut and the tapered surface of the hole (in the wheel) provide almost all the friction that keeps the connection tight.
Did you ever watch the pit crew change tires on a NASCAR or INDY car? They use air impact wrenches because they are quite accurate and fast. And that’s good enough for speeds in the 200 MPH neighborhood. Have no fears regarding pneumatic tools and their regulating torque output.
Here’s some info on bolt torque, and the percentage of the overall torque that goes to thread extension, thread friction, and nutface friction. I suppose if we wanted a factual answer for a wheel and lug nut, someone would have use their software, or some FEA software to model it.
Furthermore, what they do in NASCAR is not applicable to how *you *install a wheel on your vehicle. The impact wrenches used by NASCAR are quite special, as are the lug nuts.
But now that you’ve brought up the subject, I found this rather interesting:
Not to mention that a tire put onto a NASCAR race car is only expected to be on there for about 150 miles (tops - that’s left side tires on a track that encourages two-tire stops - most of the time it’s four tires every 75 or so miles). And the brakes are completely repaired/replaced every 600 or so miles (max), so practices that would cause long term damage/risk to your car aren’t really a concern for them.
I am a mechanical engineer who has worked extensively with bolted joints and threaded fasteners, and I assure you that this is not correct. There is of course some friction betweent the boltface and the mating surface, but because this interface is the most sensitive part of the joint to vibration and deformation (typically being less hard than the bolt head) and because it contributes the most variability in measured installation torque it is often desired to minimize this friction, hence the use of flat washers which provide a harder surface of specified flatness. The force that prevents the bolt from backing out is the friction on the threads developed by the preload tension in the bolt. The angle on the bolt face on automotive wheels and mating lug nuts is not for any fricitonal purpose but to ensure that the wheel is self-aligning on the studs so that there is no offset moment in the axis of tire rotation.
Note that anti-seize is not just any lubricant; it is a heavy grease with solid particulate in suspension such as copper or graphite designed specifically to minimize running friction. It is intended to be used for applications where mimimizing differences in preload is crucial, e.g. things like a the turret for a rotating manlift, or face seals on large diameter high pressure piping. If you want a lubricant that helps reduce running friction and protects against corrosion, a lightweight spray-on silicone or Teflon lube is more apprpriate.
BTW, based upon direct comparison with bolt stretch and torque measurements, finite element modeling, and classic empirical methods that have been used to develop industry standards, I have no faith in BoltCalc to provide good values for preload on all but the simplest bolted joint problems.
She did well, very well.
One of the very best mythbuster episodes i ever saw was when the flat tire was cut open (sidewall opened in 2 -3 places) and hand packed with grass and other debris. I was very impressed with the testing with a tire running flat vs running packed with bio-mass.
ETA; Not recommended for freeway travel!
Dad taught me that 50 years ago, and I’ve been doing it ever since.
In the old days, only because we drove a light truck, and the nuts were tight. Now, I drive a light car, but the garage tightens the nuts too tight to come off using the wheel brace & extension in the wheel kit.
As an engineer who deals with threads quite a bit, I can agree with Stranger to an extent. The use of a lubricant on threads that are not designed for lubrication is a bad idea, for the reasons he stated; it will result in over-torquing. That is, the pre-load on the threads will be higher than without the lubrication. It will not make the nut easier to loosen due to vibration, etc. In fact, it can make it more difficult if exposure to the elements washes away the lubricant.
Controlling the preload by controlling the torque is a pretty piss-poor way to control the preload because there are just too many unknowns (surface finish of threads, fit of threads, mating surfaces, and, of course, lubrication). In many cases, it is the best solution, however. I don’t think using grease or a light oil is a good idea, but I don’t really have a big problem with anti-seize. As Stranger mentioned, anti-seize is a grease with finely divided metal in to (usually aluminum or copper) which increases the friction coefficient over straight grease. While may result in maybe 10% overtorque, the lugnuts will have that much built into the design. This does make it more critical to control the torque, but if you are going to do that anyway, the anti-seize will make the removal torque more consistent (it won’t reduce the removal torque below what the tightening torque was).
I’m not an ME but I can tell you from a lifetime of experience that I have to disagree with you.
You and I are lucky we live in sunny California. No snow, no slush, and no salt used on the road.
Back where they salt the roads if you don’t use anti seize and don’t regularly remove the lugs they will seize (notice the word) in place. I have had techs bend a 1/2" Snap-On breaker into a J shape using the great ceremonial cheater pipe in an attempt to remove a lug. We are probably talking in excess if 1200 ft-lbs of force here. This is why many air wrenches have a much higher torque rating in lefty loosy direction.
In these cases a cutting torch has to be employed. Depending on the skill of the torch operator a new wheel might be needed.
I had this happen on a medium sized truck it took a 3/4" breaker bar and a 6’ cheater pipe to get the lugs off 1 front wheel. In this case they had been on for about 6 months installed with a standard impact but the metal galled and seized. Not fun.
Anti seize prevents this from happening. In my entire career I have NEVER read or heard of a wheel coming loose due to the use of anti seize.
Oh a tip for the others in this thread use anti seize not grease. Brakes (and lugs) get hot. Grease melts. Anti seize also melts but not till about 1400F so it will stay where you put it.
Not much is needed like brill cream a little dab will do ya.
GusNSpot said "Good also on spark plug threads that get exposed to the weather a lot. Motorcycles, lawn equipment, etc… "
This works well, However, be sure to not get any inside of the combustion camber.
As Rick said “Oh a tip for the others in this thread use anti seize not grease. Brakes (and lugs) get hot. Grease melts. Anti seize also melts but not till about 1400F so it will stay where you put it.
Not much is needed like brill cream a little dab will do ya.”
The combustion chamber gets much hotter than 1400F. The resulting ash/residue will gum up the end of the spark plug, causing it to foul. This defeats the purpose of installing new/good spark plugs in the first place. If this ash/residue extends out beyond the OD of the treads of the spark plug, it can ruin the internal threads in the head as the plug is removed. Very bad! AMHIK.
Lanzy, I love the ingenuity of your daughter. I am a fair-sized boy, and I have used this trick on semi tires. It works well even in conjunction with a cheater bar.
As far as left-hand threads on auto rims, Dodge has no corner on that market. Studebaker, Rambler, Nash as well as others did this back in the day.
I always put a little Never Seize on the spark plugs when I change them in my cars too.
The key is a little dab on the top of the threads and rub it into the threads with your finger. None on the bottom where it might get inside the combustion chamber.
Then wash your hands and wipe any excess off of the threads, leaving just a little inside the groves and none on the end. A little goes a long way.
Brings back a memory of a co-worker who was into radio controlled airplanes.
the last time he flew his planes he was at a club event and while landing someone was bitching at him for something and when his plane was on the ground he then was able to focus on the whiner that didn’t like something he had done. well that Dudes voice octave hit a high pitch as Old Stymie put a squeeze to his junk and then as he was walking away a couple ladies commented that what had just transpired was a long time due and thanked him.
Well back to the Tire Lug NUTS, Thereafter when someone in the shop was having a difficult time breaking nuts loose the common remedy was to go get Stymie!!
