bb69

Where does all this fear about using lubrication on wheel studs come from? To be very clear, the torque values aren't for dry threads, they are for CLEAN threads. Rusty/corroded threads are pretty much always dry, but they aren't clean. The reason they are supposed to be clean is so you can get consistent load in the fastener with the same torque value. As soon as a thread is knicked, corroded, has a little aluminum from the wheel in it, dirty, etc, you aren't getting the same bolt load.

Using lubricant AND lowering your torque value is an absolutely acceptable method and has the very real benefit of helping to prevent corrosion. Anybody who's ever tried to change a wheel on something in the Rust Belt that hasn't had any lubricant knows how much fun broken studs are.

Here is a good thread I found with many good links. Check it out:

http://www.engineersedge.com/wwwboard/posts/13070.html

StKnoWhere

Very interesting!

hklvette

Indeed. This is a really good post here: http://www.engineersedge.com/wwwboar...070.html#13090

SouthernSon

Probably more useful on a DD that sees years between removal. My track car sees the nuts removed at least monthly. Therefore, I go with clean and dry.

On another note, trying to remove a fixed pitch propeller from the crank hub on an airplane can be really challenging from time to time but you won't find many AP mechanics that condone lubing it when installing.

Charley Hoyt

You are incorrect...but, do what you want, it is your vehicle/ safety/ money. In my opinion that article has technical misinterpretations all through it. For example, the writer states “ The anti seize bottle states to apply the anti-seize and then torque to the manufactures specification” Then he assumes that because the anti-seize manufacture doesn’t recommend a reduction in torque that full torque should be used. A more reasonable interpretation is that if the Manufacture RECOMMENDS using anti seize then follow their recommendation and torque appropriately….if they recommend using a dry torque then don’t use anti-seize. I worked my way through college as an aircraft (A&P) mechanic and I have worked in the Aerospace engineering and manufacturing business for almost 30 years…. The manufactures go to great lengths to engineer their products. They know more about them than you do. If they say to use a dry torque….it is wise to use a dry torque.

Best of luck...

bb69

I know absolutely how far the manufacturers go to design their parts as that's what I do all day long....in the automotive business. I can also tell you that the people that write the service manuals aren't the same people that design the parts. Service manuals are written for the dealerships, not the assembly plants because the dealerships don't have the production type equipment. During the original assembly of a vehicle, critical fasteners all most likely not tightened to a torque value, but to a torque followed by a number of rotations. That's because the bolt stretch can vary more than the allowable amount using just torque. That's in the original production environment using brand new studs/bolts/nuts from PPAPed processes and tooling. For service, they have to come up with a process that can be performed by an owner, so they develop a torque and then cover their *** by saying the threads need to be dry and clean. Please try and define dry and clean. I would much rather use a consistent amount of lube and eliminate a varying amount of corrosion.

SouthernSon
My lug nuts on the track car come off at least 3 times per weekend and I still prefer some anti-sieze to help prevent mis-threading. Clink through the links and you will see a great paper that was written specifically about helicopter rotor attachment. The conclusion was that using antisieze was the proper procedure, but it was only to be applied to the threads and not the whole fastener. Now, when a propellor on a plane falls off, you still have wings and can glide. When a helicopter rotor falls off, you plummet to the ground immediately.

bb69

Here are a few more decent links. You will notice reading through them that several times it is noted that the use of lubrication helps reduce variation in bolt load. It also mentions the benefits during disassembly including the reduction of material transfer between the bolt and nut. The Fastenal paper specifically remarks on the tendency to overdesign bolted joints because of the large variations in bolt load due to variations in friction while tightening a bolt/nut.

So, again, I ask where the fear comes from? Who has had a wheel stud break because they used lubricant? I'm perfectly happy to be PROVEN wrong, but I have yet to see it. I have had to drive my truck around for a few MILES with the lugnuts loose trying to break a wheel free and I have broken numerous studs that weren't lubricated.

http://books.google.com/books?id=NaZ...0joint&f=false

http://machinedesign.com/fasteners/p...-or-lose-clamp.

https://www.fastenal.com/content/fed...t%20Design.pdf

Charley Hoyt

You are an engineer in the auto industry? Are you a mechanical engineer or another type? I am not asking that to insult you... I'm asking it because your opinion seems unintuitive. I certainly agree with the benefits of wet torques... That is why most torques ARE wet torques. However, being an automotive engineer you must agree that lubricating the threads of a stud will allow the lug nut to rotate further on the stud due to the reduced friction. This is what causes the problem. You keep referring to fear.... I have no fear, I have knowledge.... First hand knowledge. Learned the hard way. There was a time when I was not aware that lug nuts should be installed dry, so I torqued them wet (like is done with most fasteners). At that time it seems like the lug nuts were hard to torque because they kept rotating. One time as I was torquing my wheels the lug nut was tightening and then it started getting looser as I turned so I realized the stud was stretching. I took off the wheel and saw that it was stretched. That is when I investigated further and discovered that lug nuts are one of the few fasteners that should be torqued dry.... And I have been doing it that way ever since and have had no problems. Many times since then when I meet people that have lug nut problems it almost always is because they are using lubrication. So you can do what you want to your car.... I am following the factory recommendations and using dry torques. Here is a picture of my stretched wheel stud.....

SouthernSon

My owner manuals sure get mighty specific about a lot of things such as capacities, OEM lubricant numbers, procedures for this and that. Hard to believe they suggest clean and dry simply to, as you say, CYA. Anyway, good luck with whatever method you choose.

bb69

Hence my original comment: "Using lubricant AND lowering your torque value is an absolutely acceptable method and has the very real benefit of helping to prevent corrosion."

I did my best to emphasize the word "AND" to make sure it was clear that I understand that reducing the friction in the assembly requires a lower torque value. So, if we can clear that up, are you saying there is any other reason to not use lubrication on the studs? Is there anything special in the joint design of a wheel stud that makes it different from all the other joints referenced above where the use of lubrication is allowed and even suggested? You suggest that many of the people you meet with problems are having the problems because of lubrication. It seems what you mean, is that they used lubrication but did NOT lower the torque setting they were using. That suggests the problem is overtorquing the lug nuts caused by someone not understanding the system. Lubrication may have been involved, but that's not really the problem. If someone can't understand the effects of adding lube to the threads, they should just follow the book and trust the man behind the curtain.

To answer your questions, I'm a mechanical engineer with an automotive specialty and I have spent my whole 20 year career (except for a two year stint in defense) in the automotive industry.

SouthernSon
Just because it's hard to believe, doesn't mean it's not true. The technical term for CYA is safety factor. For a safety item such as a wheel stud, OEM's are probably using a safety factor of 5. Also consider that the OEM didn't specify a different torque for all the things that change for people racing:

-different wheel/tire mass
-higher loads due to cornering and braking
-different lug nuts (open ended, different number of threads, different surface finish, different coating, different contact area, etc)
-different operating temperature

yet those things do affect the required clamp load and/or torque to reach that load. Are you adjusting your torque values for all of those things or just relying on that safety factor to cover all those?

SouthernSon

Another good reason they use a lot of safety wire. Personally, I don't safety wire my lug nuts.

Charley Hoyt

This is a ridiculous conversation and I am not going to waste any more time on it. This will be my last comment.... I saw your use of "and" in your previous post but dismissed it. When you lubricate the threads on your lug nuts, what reduced torque do you use? How did you calculate that? Or did you just guess?

In short it is your car / safety / money. Do what you want. I think it is a poor practice, but if your fear of corrosion on lug nuts (that you remove regularly) scares you so much that you feel it is better to ignore the manufactures recommendations and make up your own torque values for a safety critical part.... Go right ahead. Good luck with that