Lubrication on threaded fasteners or anti-seize

[Joe L.]

Re: Lubrication on threaded fasteners or anti-seize

I use anti seize on my daily drivers because they (and I) live in an area where salt is used liberally on the roads in winter. The Corvettes are not on the road in those conditions and so I don't use it on those cars.

Terry------

It's true that salt is not used on the roads during the period when most Corvettes are driven. However, a lot of salt that's deposited on the roads in the winter remains there long after the snow and ice are gone. Then, during a summer rainstorm or shower, it's re-mobilized to "wreak its havoc". Once salt-induced corrosion is initiated it proceeds inexorably.

This is the primary reason that I'd always be skeptical of any car that's lived even part of its life in areas of the country where the roads are salted even if that car was never driven in the winter.

[Mark E.]

Re: Lubrication on threaded fasteners or anti-seize

When should threadlocker vs antiseize vs nothing be used? I'm thinking of suspension and driveline fasteners.

Any advice about this? I'd like to hear from the experts out there.

[Keith M.]

Re: Lubrication on threaded fasteners or anti-seize

Any advice about this? I'd like to hear from the experts out there.

Mark
I really can't answer but share interest in any answers. And If I may I would add vs WD40. I include that as I view it as something better than nothing with little to no risks...AFAIK.
keith

[Terry M.]

Re: Lubrication on threaded fasteners or anti-seize

Any advice about this? I'd like to hear from the experts out there.

Mark
When I taught auto shop the department head, who had worked for many years in a Buick dealership, advocated using a light duty thread locker to prevent moisture penetration into the threaded interface. I can tell you that it worked, but the exposed threads of the fastener were just that -- exposed. On the other hand any anti seize compound would be washed off those exposed threads eventually. So long as the fastener is exposed so it can be heated I think it is no harm or foul, Such an arrangement might even pass judging whereas anti seize definitely will not pass.

[Joe L.]

Re: Lubrication on threaded fasteners or anti-seize

Mark
When I taught auto shop the department head, who had worked for many years in a Buick dealership, advocated using a light duty thread locker to prevent moisture penetration into the threaded interface. I can tell you that it worked, but the exposed threads of the fastener were just that -- exposed. On the other hand any anti seize compound would be washed off those exposed threads eventually. So long as the fastener is exposed so it can be heated I think it is no harm or foul, Such an arrangement might even pass judging whereas anti seize definitely will not pass.

Terry------

The important application point for the anti-seize is the interface between the cone of the lug nut and the cone of the nut seat in the wheel. This is where the galling occurs making lug nut removal difficult and eventually ruining the wheel (at least for use with stock lug nuts). Judiciously applied with any "squeeze-out" removed no one will ever know it's there.

As far as the threads go, the anti-seize helps there, too, and carefully applied no one will ever know it's there, either.

[Terry M.]

Re: Lubrication on threaded fasteners or anti-seize

Terry------

The important application point for the anti-seize is the interface between the cone of the lug nut and the cone of the nut seat in the wheel. This is where the galling occurs making lug nut removal difficult and eventually ruining the wheel (at least for use with stock lug nuts). Judiciously applied with any "squeeze-out" removed no one will ever know it's there.

As far as the threads go, the anti-seize helps there, too, and carefully applied no one will ever know it's there, either.

I should have been clearer Joe. We didn't use the thread locker on lug nuts, but on other chassis fasteners. I forgot the original posts were about wheel fasteners.

You are correct about the lug nut and wheel interface. That is an important junction that needs the application of a lubricant. It is important to remember to reduce the torque value of lug nuts when a lubricant is used.

I have some reservations about the use of a lubricant on this interface with alloy wheels, however, but I am sure galling is an issue with those wheels also. I am just not sure of the chance of additional wear and/or the loosing of the lug nut with alloy wheels. Steel wheels are designed for the web to flex when the lugs are tightened. I don't think alloy wheels are designed for the same method of operation.

[Michael G.]

Re: Lubrication on threaded fasteners or anti-seize

Guys, it all has to do with friction. Torque is meaningless, just an approximation, and not a good one.

When GM designed these fastened joints they tested bolts, nuts, and components that had threads and contact surfaces that were representative of the production surface friction of each of those parts. Most times, back then, they set the torque spec by assembling the joint, and simply torquing the fastener to failure when assembled in its expected joint. They monitored torque during each such test and graphed torque versus bolt rotation angle.

Such a tightening graph is usually a straight diagonal line until the fastener reaches its yield point then the line begins to bend. The Gm engineer determined at what torque this yield occurred for each sample, then averaged those values it to determine the minimum yield torque for that joint. They utilized that yield to set the upper end of the torque spec. (Some percentage of that yield point, most times). They then set the lower end of the torque spec range at what’s achievable with the intended tool. They then set the torque for their test vehicles at the lower end of this spec and validated the vehicle performance at that level. (This is a very simplified discussion, there are much more complex ways to do this, monitoring or testing many other things, but most of them weren’t practiced in the 60s.)

What you should be cognizant of here is the fact that although torque is what is measured and tested, torque has nothing to do with what holds things together. That instead being the clamp-load created in the joint. The relationship between torque and clamp load, is totally dependent on the amount of friction present on the threads and bearing surfaces in the joint. As this friction varies, so goes the actual clamp-load created in the joint during tightening. A small change in friction makes a big change in clamp-load. The more friction, the less load and vice versa.

So, for instance, if you utilize a cadmium coated bolt, the friction will be minimal and the load created high, so yield is reached at a lower torque. If you utilize a zinc coated bolt the friction will be high and the load created much lower and yield will occur at a much higher torque. Similarly, if you use a zinc coated bolt and oil it, it will slipperier and the load will be much higher.

Things like this make a huge difference. If you oil a zinc coated bolt, you may well get so much load that you break or badly yield the bolt. If you wash a “phosphate and oil” bolt (a common 60s GM coating) it increases friction so that tightening to the maximum design torque does not develop the expected clamp-load, so the fastened joint falls apart.

There is no way you as a 2023 mechanic can duplicate the original friction. Wear, corrosion, galling, paint, cleaning and component restoration all affect the friction one way or the other. You can’t know what you’ve done. No matter how much you argue here about lubricants or anti-seize, or how well what you’ve done performs, no one knows whether the result is remotely close to the factory clamp-load. Your best bet is to tighten to the mean torque, and use anti-seize if you must. Most importantly, if you drive your restored classic Corvette, re-torque everything periodically and religiously.

[Dan D.]

Re: Lubrication on threaded fasteners or anti-seize

Hi Mike,

Interesting take on this subject. I agree with just about everything you say, except you say that friction with zinc plating is very high, but oil brings it way down. I would think zinc would be in line with cadmium.

You may have read a new post I put up last night that has a very inclusive set of torque charts. The author of these charts address plated fasteners as being lower friction than dry, but they do not define which plating(s). I would be interested in knowing why zinc has a higher coefficient of friction than cadmium, and how it relates to dry assembly.

How much difference is there between proof load and yield strength? Proof load lets the fastener stretch, as long as it returns to its original length. Yield strength is a permanent deformation, and tensile strength is fracture. I would think that once loading has exceeded proof load, tensile failure would not be far behind. Once steel starts to stretch, it wouldn't take much more loading before it fails completely. Would this be true?

Please read my post and let me know what you think.

Dan

[Ed S.]

Re: Lubrication on threaded fasteners or anti- eize

For what it is worth the standard I apply is, if a fastener is likely to be removed in a short period of time (a year or less), such as a lug nut then I put a dab of oil on the threads - not a drop, just enough to wet the threads. If the fastener is not going to be removed to perform routine maintenance for a long time (years) then I apply a light coat of anti-seize compound on the threads. I always clean the male & female threads with acetone or alcohol and a wire brush before assembly. I have been doing this for decades on a lot of cars - works for me.

[Michael G.]

Re: Lubrication on threaded fasteners or anti-seize

Dan, you are welcome to disagree, but, let’s just say the “interesting take” I expressed in my opinion on zinc vs cadmium was formed as I personally tested these finishes on real GM fasteners, in real GM joints, over many years, many, many times, using sophisticated test equipment. It’s not conjecture.

To answer your questions:

The “yield point” of a bolt is the load at which it stops elastically stretching and permanently deforms. “Proof load “ is the minimum load that one can expect any fastener of a certain size and grade to yield. Because every fastener in a given heat-treatment lot receives slightly different properties, the actual strength and yield point of every fastener in a heat-treatment lot varies somewhat. The “proof load” is the minimum permissible load at which any fastener in that lot will yield.

Bolts do not actually immediately fracture when a load above the yield value is applied - significant plastic deformation occurs first.

Today in normal assembly, critical bolts are often deliberately tightened slightly above their yield point without serious deformation. This “torque to yield” technique is one of the well-known complex strategies I mentioned earlier that are used today, wherein the assembly tool detects yield (an electronic version of the graphing technique I discussed above) and stops the tightening. After the tightening stops, the removal of torsional load drops the fastener slightly below its yield point, with minimal deformation having occurred. Experienced mechanics often unknowingly utilize this technique when they tighten until a “give’ is felt, then stop. It works.

The torque charts you posted are not really valuable in tightening automotive fasteners. All vehicle fastened joints have a multitude of relevant finish, metallurgical, and lubricant variances not taken into account by those charts. That’s why they are tested to determine the ideal range and those values are posted in the AIM.

I hope that helps,

[Michael G.]

Re: Lubrication on threaded fasteners or anti-seize

I think I missed one of Dan’s questions: when oil (or often, wax) is added to a fastener, that slippery substance becomes the determinant in the frictional equation. For example, years ago, GM switched its lock nuts from cadmium plus wax, to zinc plus wax. They could only do so because the wax largely nullified the frictional difference between zinc and cadmium. Even then, the stickiness of the zinc caused problems. Adding oil or wax always results in decreased friction and increased load.

I’m not well-versed in the function of anti-seize, but I believe it reduces frictional variation without a net effect on the mean coefficient. I may be all wet on that last comment.

[Dan D.]

Re: Lubrication on threaded fasteners or anti-seize

Hi Mike,

Thank you for your reply. If I insulated your intelligence or experience, please forgive me, I did not mean to. I was just looking for an explanation as to why dry zinc had a higher coefficient of friction than cadmium. and why is was sufficiently reduced with oil. In particular, it shoots big holes in the torque charts I posted that specifically state that plated fasteners are equivalent to lubricated fasteners. The charts do not specifically define the type of plating, but I think one can assume that in today's real world, plating in most likely zinc.

One other thing that has not been discussed in either of these threads is the possibility and effects of Hydrogen embrittlement. I assume that the heat treatment you say are for hardness and not to remove hydrogen embrittlement? The bright zinc plated, off shore made, fasteners that are so prevalent in big box stores thread on very easily with no load applied. I have a problem with these things as I have had them fail, most likely from Hydrogen embrittlement, and I have found grade 5 fasteners in grade 8 bins. Buyer beware.

I'm beginning to think that there is no way to accurately state specific torque values for anything, mainly because of the wide variations in friction. Except for deliberate over tightening until the torque flat lines, as you say, will more specifically determine clamp load as it takes friction out of the picture. Clamp load just cannot be accurately determined from torque charts. Friction is too high and too big a variable. Like I said, it gets complicated. I think most people today just torque fasteners dry and to the level indicated in some torque chart, and call it a day. This is most likely some level below desired clamp load and proof load/yield strength, but probably okay for most applications. If lubricant is applied, anti-seize in my experience, it is easy to exceed proof load and yield strength. I have been there. I hate it when torque flat lines.

Mike, tell me what you think. I have no education and little experience in this and I am just looking for education.

Thanks Mike,
Dan

[Michael G.]

Re: Lubrication on threaded fasteners or anti-seize

Didn’t mean to be testy, if I was, sorry.

My whole point is that restoring and rebuilding vehicles changes a lot of finishes on both components and fasteners, and that makes a lot of difference when it comes to tightening things. It’s probably folly to attempt to analyze what the effect of your changes are on the joint - even I don’t always know what the effect of changing finishes will be when I’m doing my cars, and, after developing thousands of assembly specs, I’m supposed to be an “expert”. Short of repeating the tests, it’s all Greek. As I said, if you’ve changed or restored anything, use the mean of production spec, and re-torque the critical ones occasionally, to be safe.

Anyway, to your concern: I doubt that problems with hydrogen embrittlement are what’s causing off-shore parts to be weak. To embrittle something made of carbon steel, it has to be hardened in the first place. The fact that they use crappy steel or often don’t bother with a little process called “heat treatment”, is likely a more of an issue than embrittlement. In the 80s, the U.S. passed a bill (the Fastener Act”, or something like that) to prevent exactly what you’re complaining about, as the off-shore producers (then mostly Japan) were saving cost by shipping non-heat-treated parts all over the U.S, causing havoc in some industries, even aero-space. Unfortunately the bill’s effects were minimal, as so many exceptions were allowed that it’s still easy to ship crap here, using paper companies, with bogus certs, then disappear if caught.

I wouldn’t use a big box store fastener on any vehicle I was riding in.

[Joe L.]

Re: Lubrication on threaded fasteners or anti-seize

I wouldn’t use a big box store fastener on any vehicle I was riding in.

Mike------

I feel the same way about most reproduction fasteners. When there is a situation in which reproduction fastener manufacturing sources are allowed to boldly emplace the manufacturer's ID mark of another manufacturer on a reproduction part, all of my confidence in that part evaporates. I regard this practice as the same as counterfeiting, regardless of the fact that it's done to satisfy restorers.

How do I know that this is actually occurring? Well, many of the manufacturers whose ID mark is seen on reproduction fasteners are long-since out of business. So, they could not be the manufacturing source of reproduction fasteners bearing their ID. Those that are still in business I doubt would do a very short manufacturing run of reproduction fasteners.

Also, trying to buy fasteners ANYWHERE these days that are not of foreign manufacture can be difficult or impossible.

[Michael G.]

Re: Lubrication on threaded fasteners or anti-seize

I agree, Joe. The whole point of head marking is to make fasteners traceable when someone gets killed by a substandard part. Unfortunately, our hobby is helping these criminals by insisting on long defunct head markings in critical applications.