techkelly
Well-known member
The best thing about working in the oil patch. The joints are 30 feet long, the dope comes in 5 gallon buckets and
there is a pusher on every rig.
Learning more about anti seize products
- Thread starter GophersGarage
- Start date
there is a pusher on every rig.
Big Bad Dad
Well-known member
I always use it on the threads of the star wheel self adjusting screws when I do a drum brake job. Keeps them from sticking and not working.
The wheel/rotor and rotor/hub interface are the LAST place you want to have a lubricant of any kind. The drive and braking loads are supposed to be passed by the friction of this interface. Lubricating them could allow movement between those surfaces placing all of that load in bending on the wheels studs (or bolts) that are NOT designed for a bending load of any kind. If you want a SAFE way of keeping those interfaces removeable, I find that cleaning them off properly (glass bead best) and sparying a coating of "cold galvanizing" (i.e. zinc rich paint) on each side allows alloy wheels to come off easily. The hub/rotor interface is iron on iron so no where near as bad for corrosion but the aluminum/iron interface of the wheel/rotor sure as Hell IS.
laser3kw
Well-known member
I thought the same thing until I stuck my test leads directly into the bottle and checked resistance. nothing measurable
Uofime
Well-known member
From above the reduction in friction from dry is between 10 and 30%. Do you think that reduction is outside of the factor of safety in the bolted connection at the wheel rotor and hub interfaces?
Are we talking about F1 cars or minivans here?
dr_clyde
Well-known member
Fella I used to work for was a master mechanic, been fixing things for his whole life. Arguably one of the smartest men I've ever had the privilege of working with. We worked on ANYTHING. Farm equipment, boats, fire trucks, passenger cars and trucks, heavy duty trucks and semis, aircraft, highly modified customs, machine tools, you name it we probably wrenched on it at some point.
Anyway, his motto was to never put a threaded part together without some kind of treatment. If it ever needed to come apart again, it got anti-seize. If it was supposed to stay together it got loc-tite. Never had any issues. Was always a treat when a particular vehicle came back years later for something and it came apart super easily and without grief.
Apparently when he was a young man working for a motor freight carrier, one of the first things they did when they got in a new semi was to basically take the whole tractor apart, anti-seize everything, and put it back together. According to him this saved them thousands of dollars down the road in service time and ease not fighting rusted and seized fasteners.
When I worked at a brewery, I had to educate everyone how stainless fasteners will gall up and never separate if you're not super careful. We used food grade loc-tite for any threaded joint in the plant. You risked losing the part if you didn't.
I keep nickel, copper and food grade in the cabinet, and I use it whenever appropriate. Which in Michigan is pretty much anytime you want to get something apart again.
Anyway, his motto was to never put a threaded part together without some kind of treatment. If it ever needed to come apart again, it got anti-seize. If it was supposed to stay together it got loc-tite. Never had any issues. Was always a treat when a particular vehicle came back years later for something and it came apart super easily and without grief.
Apparently when he was a young man working for a motor freight carrier, one of the first things they did when they got in a new semi was to basically take the whole tractor apart, anti-seize everything, and put it back together. According to him this saved them thousands of dollars down the road in service time and ease not fighting rusted and seized fasteners.
When I worked at a brewery, I had to educate everyone how stainless fasteners will gall up and never separate if you're not super careful. We used food grade loc-tite for any threaded joint in the plant. You risked losing the part if you didn't.
I keep nickel, copper and food grade in the cabinet, and I use it whenever appropriate. Which in Michigan is pretty much anytime you want to get something apart again.
I would not count on any specific value for reduction of friction, especially when the range your assuming is 300% wide!!!! F1 cars use drive pins, the bigass nut just holds the wheel in place. Pretty much EVERYTHING else relies on clamping friction provided by the wheel fasteners.
Wiz02
Well-known member
Hi @cannuck ,
Do you have any data that supports your assertion? I don't see how a properly torqued lug nut is going to permit motion between the rotor hat and the wheel. BTW galvanizing appears to add some lubricity near as I can tell from this article:
Solid-Film Lubrication of Galvanized Sheets
Drawbead simulation (DBS) tests were conducted on materials representative of cold-rolled, galvannealed, electrogalvanized, and hot-dip galvanized sheets used in the automotive industry, with paraffin wax, microcrystalline wax, stearic acid, tristearin, and Na-stearate solid films. Lubrication behav
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True, though I'm the exception, mainly for brakes. We keep our cars, and I do most of the maintenance work, so I've had multiple occasions where I've pulled rotors and said to myself "good thing you put anti-seize on the hub". I don't mind making it easy for the next guy, either.Pretty sure it doesn't matter. With very few exceptions, wherever you use anti-seize on a vehicle, it won't still be there when you take it apart again.
-Ryan
If you're slathering enough on to create significant lubricity... maybe. But I don't think so in correct amounts. I'm pretty judicious with anti-seize in general, and when I've pulled stuff apart (mainly rotors), there is still force required to "unstick" things. It's just that it's not corrosion. I must be misunderstanding what you're trying to say, because it sounds like you're implying that the corrosion is an intended and desirable effect.
VolvoRyan
Well-known member
Depends on where you put it, I guess. There are a few places that I'll use it religiously: belly pan fasteners, spark plugs, and all the goofy little fasteners that keep the front of a Volvo 740/940 together.
Thick grease works better in some applications. We also keep cars forever. Very weird to revisit things that I did 15-20 years ago.... with a very limited toolset... and wondering how I managed to get it done.
-Ryan
endmill
Well-known member
Yep living in Ohio wth the salt and humidity we use it for everything
Grant Gunderson
Well-known member
That’s become my go to. I started using it with Titanium and AL parts on high-end carbon bikes. It just works better than the typical stuff. So I now use it for all anti-seize applications, except for high-temp applications such as vehicle brake calipers. For high- temp I use the copper based stuff from Pernatex.On boats we use Tef-Gel to keep the stainless fasteners from galling and to inhibit corrosion against aluminum.
You will note that the intended lubricants for forming galvanized were used. in high shear the zinc coating (that is very different from zinc rich paint) was present. I won't take you down the tribological rabbit hole of how solid films under sheer can behave but note this is for SOLID film, not minor amount of flakes. What I can tell you in support of my assertions this is how the head of fastening engineering at one of the big3 will tell you and also what assumptions I use in designing wheel ends for trailers.Hi @cannuck ,
Do you have any data that supports your assertion? I don't see how a properly torqued lug nut is going to permit motion between the rotor hat and the wheel. BTW galvanizing appears to add some lubricity near as I can tell from this article:
Solid-Film Lubrication of Galvanized Sheets
Drawbead simulation (DBS) tests were conducted on materials representative of cold-rolled, galvannealed, electrogalvanized, and hot-dip galvanized sheets used in the automotive industry, with paraffin wax, microcrystalline wax, stearic acid, tristearin, and Na-stearate solid films. Lubrication behavwww.sae.org
I don't have any idea what amount of anti-seize will result in what amount of change of co-efficient of friction for anti-seize, but I feel it can be significant from how easily it changes bolt tension vs torque. I certainly am not implying corrosion is an intended or desirable effect. Many rotors have a coating to prevent corrosion from occurring between alloy wheels and iron rotors, but in absence of such I use zinc rich paint to PREVENT corrosion as a sacrificial anode placed between two metals far apart in the Galvanic series.
Based on your other post, it sounds like you have professional experience here, but I'm still not seeing something more substantial in terms of actual information. I'm happy to learn, but I'm inherently a skeptic without some kind of details. In other words, take me down the rabbit hole a bit.
Based on your other post, it sounds like you have professional experience here, but I'm still not seeing something more substantial in terms of actual information. I'm happy to learn, but I'm inherently a skeptic without some kind of details. In other words, take me down the rabbit hole a bit.
Slip-critical joint - Wikipedia
Slip Coefficient of Bolted Connections: What is it and Why is it Important?
So what is the slip coefficient of a bolted connection? Quite simply, it is the coefficient of static friction (m) from elementary physics.
kta.com
What I might do is refer you to the Holy Bible of fastening: Shigley's Mechanical Engineering Design, now in it's 8th Edition. It will teach you all you ever need to know about non-permanent fastener joints.Based on your other post, it sounds like you have professional experience here, but I'm still not seeing something more substantial in terms of actual information. I'm happy to learn, but I'm inherently a skeptic without some kind of details. In other words, take me down the rabbit hole a bit.
I just had this discussion with one of the engineers I (and literally hundreds of others - his credentials quite impressive) hold in high esteem. He posted this in support of my similar posts on a design site:
"Let's check that against field experience. Most, but not all wheels I have removed from cars over the last 48 years slip off the hub easily when lugnuts are removed. Some are firmly held by corrosion products at the wheel contact with the hub. Most recently, I pulled four alloy wheels from my Focus ST for replacement with other wheels and tire, and two have light witness marks in the pilot bore. The other two have corrosion products in the bore that interfered with the pilot on the hub. So maybe we have some support by pilot, but it does not look like much...
Let's review the loads on the wheels. There is the weight of the car downward trying to slip the wheel upward along the hub. There is braking or acceleration trying to slip the wheel fore and aft along the hub. There is torque applied either from power or braking that attempts to slip the wheel in rotation on the hub. And there is cornering which is compressing the joint between wheel and hub for part of the rotation and increasing tension on the joint during the other half of rotation. Let's see how the piloted hub works (or doesn't work) to restrain the wheel against movement on the hub.
I ran a simple calculation using specified wheel lug torque (100 ft-lbs), lug diameter (14 mm), and contact ring radius (2.625") for my Focus ST. I assumed coefficient of friction of 0.15 on the contact ring, which is low end, but gives us a minimum to work to. Using standard calcs (from Shigley), preload from tightening each lug nut is 10,700 pounds. Five lug nuts makes the total preload 53,500 pounds. Why do we suppose Ford put that much preload in?
Even a low estimate of coefficient of friction of 0.15 means the wheel will slip across the hub when 8000 pounds is applied across the hub. The biggest loads I can get from vertical force plus max braking is on the order of 1200 pounds - a factor of safety of 6.7! This system is NOT slipping radially, so the hub pilot does not really provide any support against these loads;
Checking wheel torque against slip of the wheel on the hub - tractive limits set torque at about 11300 in-lb while torque to slip the wheel on the hub is about 21000 in-lb, with a factor of safety of 1.86. Hmm, resisting torque has way less factor of safety than radial slip. Being as the pilot is about 1" radius, if there was 11300 lb of friction between pilot and bore, the pilot could resist these torques, but then you would need extraction devices to remove the wheel for service - not present on any car I know of. So, the pilot does not provide rotational support to prevent fretting and stud/wheel fatigue - it comes from friction that the stud system provides;
I also checked the cornering moment from sideways traction at the tire patch and found that the joint stays loaded up with large margins, so fatigue of the studs is unlikely;
In short, nothing we do while driving the car will make the wheel slip on a hub that has been preloaded with properly torqued lug nuts. Crash forces might exceed these limits, but not driving. This is all due not to the pilot but due to friction provided by the preload from properly tightened lug nuts.
Pilot fit of hub to wheel centers the wheel for tightening the lug nuts, but once that is done, the design of the lug system and contact between hub and wheel is sized to have excess torque and radial friction capacity to prevent movement of wheel on the hub. Experience with these systems and analytical approaches bring us to the same conclusion - the wheel is held in place by friction from large preload, while the pilot serves to get things decently centered before we tighten the lug nuts.
Now if the wheels were to be held in place by the pilot, but friction was inadequate to hold the wheel in place, pilot clearance seen in the field would allow the wheel to orbit or nutate on the hub. The lug system would see substantial variation in load as the vehicle is driven, and I would expect fatigue and failures of the stud and/or the wheel. This is exactly the failure mode seen when lug nuts are inadequately tightened - there is fretting (wear from small but real slipping back and forth of surfaces) at the contact between wheel and hub, studs break off and/or lug nuts get pulled through the wheels, then wheels depart the vehicle.
One historical point that occurred in the 1980's IIRC. A car had been repeatedly brought in to the dealer complaining of large vibration on one corner, with the dealer unable to solve the problem. Eventually a wheel and tire departed from that corner of the car, and a tragic accident occurred. All five studs had failed in fatigue. During the I subsequent teardown of the live rear axle, the axle shaft was found to have red paint on it and the hub face was found to be crowned so that wheel contact from tightening the lug nuts occurred near the pilot instead of out near the periphery of the hub, as specified in the part drawing. Red paint denoted scrap parts in the factory that built the axle. Other evidence included much fretting of the wheel, brake drum, and axle hub, all near the ID of the wheel, indicating much movement and slipping about under load. The wheel was firmly held on near the pilot, but this provided little capacity against small but real slipping of the wheel on the hub, and cyclic loading of the studs. It also did not support the wheel in a uniform manner, negating any dynamic balance of the wheel, and the resulting vibration. In this case we see friction resisting rotational movement was low, the pilot did not provide support, and the studs failed.
The attempts at universal fit aftermarket wheels with no piloting except the studs and lugnuts can result in substantial and non-repeating imbalance. Yes, the pilot fit between wheel and hub is useful and probably needed. To conclude that the pilot holds the wheels in place only covers radial loads (the easiest part) but provides absolutely zero support from slipping rotationally under accel and braking loads. Indeed supporting torque is the defining issue and one only reasonably achieved with preload and friction..."
Brother - I didn't ask you to google for me. I'm asking you to connect the dots if you have deep experience/knowledge here.Slip-critical joint - Wikipedia
en.wikipedia.org
Slip Coefficient of Bolted Connections: What is it and Why is it Important?
So what is the slip coefficient of a bolted connection? Quite simply, it is the coefficient of static friction (m) from elementary physics.
Here's my understanding of things. Wheels sit on the hub - a metal flange - and are fixed in place to the broader face of the hub/rotor by the clamping force of the lug nuts or lug studs. This wouldn't seem to describe faying surfaces or a slip-critical joint since the load sits at the hub flange/wheel, not at the facing surfaces of the wheel and the hub.
I've seen situations in the BMW world where someone is trying to use wheels from one series (E39) on others series where the bolt pattern is the same but the hub size is slightly larger. If you fail to use hubcentric rings, the results can be pretty ugly, but typically people figure it out from the damage to the studs and the noise (in other words, bad stuff is happening because the lug studs are now exposed to load, but I can't recall hearing of anyone who has been stupid enough to let it get as far as catastrophic failure). Apparently there's at least some margin in the design (for BMW at least, but likely others) - not enough to run the wheels permanently that way, but to mainly avoid stuff flinging off the car. And simple hubcentric rings entirely fixes that problem - some of them are even made of plastic (which I refuse to use, but whatever).
Net: there is minimal-to-no load on the facing surfaces of the hub/rotor/wheel. Wheels sit on the hub flange and are fixed in place by the lugs/studs.
My point is that if anti-seize used on hubs to limit corrosion represented a legitimate threat to safety in the application we're discussing, it would be a widely-known thing, especially in the connected world today.
It's entirely possible I'm wrong. I'm not an engineer or an expert on cars. If you can explain where I'm wrong using your words (and not disconnected links), I'm happy to learn something new.
This is probably the best post to cite when discussing the change of co-efficient of friction at the wheel/rotor(drum or hub) interface. As you Dear Old Dad wisely said: "A litte goes a long way". I don't know the threshold of coverage and behaviour of various anti-seize formulations under very high shear stress. What I DO know is that MANY different materials behave very differently than expected under such conditions. I deduce this from our eldest daughter's thesis in which she first had to figure out how ZDDP works (literally, nobody in the world had EVER done that, but a couple of years at the Synchrotron and she did just that - for the purpose of designing EP lubricants that would be environmentally friendly - which ZDDP in its manufacturing process decidedly is NOT). The EP characteristics of ZDDP do not occur until surpassing a certain level of shear stress (actually cleves some of polar molecules that are oriented by their charge). From her rather considerable research into lubricity at high sheer I now suspect there is a LOT more to be learned about the tribosystems and dry film systems (and, in case you were wondering, in those days I was the lead tech resource to a lube manufacturing and packaging facility). There is a fair bit of engineering done on calculations based on observed results rather than actually understanding the science that causes them.
You got that exactly backwards. The wheel nuts (as explained) provide the clamping surface pressure that holds the wheel against the rotor/hub face. The reason people can and do design such joints with plastic centering rings is that they DO NOT carry any load IN A PROPERLY DESIGNED AND TIGHTENED joint. Your BMTroublyou failures are the result of inept installation, not inadequate design (I hope). If you look at wheel and hub design specs and tolerances, you will find typically 0.1mm (0.004") clearance between the hub pilot and wheel centering hole. If the wheel studs carried that load, you would seem movement and fatigue failures (as my citation of good friend's post above also points out).
If I'm reading that correctly, the failure he's dissecting is due to a wheel essentially supported only by the lugs. That's certainly not going to last long, but it isn't what we're discussing. I'm also thinking he's using a less-than-complete set of parameters in his analysis (I'd think some load forces are mitigated at least somewhat by the tires/suspension).
I'm not sure I'm following his point on the rotational aspect. The rotor and wheel are fixed to the hub mechanically by the lugs. As long as you're operating with the wheels that meet correct specifications (sits properly on the hub flange, isn't too large, etc.) and the lugs are correctly installed/torqued, I don't see the presence of reasonably-applied anti-seize changing that mechanical relationship.
Your use of the shouty caps and silly swipes at BMW aren't helping your communication.
I'm not disagreeing that the nuts/lugs provide clamping pressure that holds the wheel against the rotor/hub face. I'm not seeing anything you've posted that would say that is what provides the load-bearing of the weight of the vehicle.
I'm sure the stupid hooptie fad would-and-does create a massive escalation of forces being applied to the whole assembly. I'm also sure some of them create failure conditions. But it isn't widespread enough to make those ugly things illegal for safety reasons. And if such an extreme overload of those forces (with and without anti-seize) isn't killing people all over the place, I'm guessing I'm not changing the engineering enough with my thin application of anti-seize.
Even barring regulatory limitation, the lawyers would have an image of a wheel with a big X over it on the packaging of every container of anti-seize if you were right. I read one of your earlier posts to allude that you might be an engineer that designs wheel assemblies for trailers. I guess I misunderstood.
You need to read it again as well as my other related posts. THE STUDS DO NOT CARRY ANY BENDING LOADS, such loads are BY DESIGN 100% from the friction of the clamping force between the wheel and rotor face. Adding a friction reudcing factor to that interface risks LOADING the studs/bolt in bending and they WILL fail if any such movement happens (as what you relate in the improperly installed BM wheels).
The "weight of the vehicle" loads are minor. Once again, read carefully what was written.
I'm not seeing how anti-seize is reducing clamping force. I could see how it would allow shear if it were introduced between surfaces that could move, but with properly-torqued lugs and a wheel sitting on the hub flange, I don't see a shear condition.
The failure I'm mentioning from the BMW wheels (installed by people who don't know what they're doing) is where a wheel bore of slightly-more than 1mm introduces a shear effect (to my understanding). If it were purely the clamping force of the lugs (which are the same size/bolt-pattern) against the face, an un-treated assembly that was properly torqued would be OK by my understanding of your assertions. But it definitely isn't - the wheel needs to sit on a hubcentric flange.
The very definition of "properly tightened" involves an engineer designing a joint with an assumed co-efficient of friction between the mating surfaces. Reducing the value with a friction modifier (anti-seize) would mean the same calculation of desired friction in the joint would require more clamping force (i.e. greater torque on existing fasteners). Bolts and studs have to work within their elastic limits of deformation (literally they act as springs in tension) and increasing fastening torque beyond the yield point (as we DO with TTY bolts - that are NEVER used on wheel ends) greatly reduces the strength and fatigue life of the fastener - thus why there is an upper limit be design on torque and an assumption (not often enough stated and specified) on the condition of the thread (i.e. clean, dry or lubricated with things such as anti-seize)
Once again: the wheel needs the centering ring to be mounted concentrically, NOT to support it once the wheel fasteners are properly tightened. Read/learn Shingley, do the calcs and get back to us.
The takeaway you need from all of this is that bolted joints are seldom loaded in shear. The clearance between stud and hole vs. the tolerance of drilling the bolt circle or bolt pattern would mean very random loading on only one or two fasteners and thus joint failure. If you really want a shear loaded fastener, you use rivets, Huck bolts, tapered pins or drilled and reamed interference fitted close tolerant ground bolts. No competent engineer would ever pass the load to a lug nut as it is not even a shear load, it becomes a bending load (thus why wheel studs break off with loose nuts).
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I need to respectfully disagree here. Shigleys is a quick undergraduate level reference at best. The actual Holy Bible of Fastening is Bickford's "Handbook of Bolts and Bolted Joints" which is the reference for highly engineered connections. If you ever find yourself awake at night and can't fall asleep, reach over, turn your light on, and pull out your trust copy from your nightstand. You'll be soundly asleep in no time.
Possibly you could help bridge here. I'm not asking for homework, I'm asking for someone to share some knowledge in a digestible way. (that's what a lot of us come to places like GJ for)
As I've said repeatedly, I'm not an engineer, but I can't agree that the wheel is completely dependent on the clamping force of the lugs to the hub/rotor assembly, or that some anti-seize meaningfully changes changes the equation.
I say that not because I fully understand the engineering, but because it is far too reliant on a huge population of people to get something right to avoid introducing what he's representing as a major threat to the overall assembly (anti-seize on the facing surface of the hub to the rotor) - with major damage, injuries and deaths as result. If it were that simple to create a significant opportunity for failure, there would have been lawsuits, CSPC action, warning labels on the product (and, probably a sticker on new rotors that screams "No Anti-Seize!").
It's a common practice (albeit I'd agree a lot of people over-do it), that would have far higher visibility as a dangerous thing to do it he's correct.
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If you live in an area where the roads are salted and there are 4 seasons, a little anti seize on the hub surface is great. Extremely thin film — I wipe after applying. In contrast, I have had to repeated kick with full force to get untreated wheels off.
I would not paint the surfaces. That is a good way to get vibrations. Every now and then I read about someone who had their wheels powder coated and the coater did the backside of the hub and then the car owner complains of vibrations. Never had a problem with anti seize the way I apply it. Never had any issues with lug nuts or studs or the wheels somehow rotating back and forth due to play on the lugs or studs and not enough friction between the wheel and axle hub.
I would not paint the surfaces. That is a good way to get vibrations. Every now and then I read about someone who had their wheels powder coated and the coater did the backside of the hub and then the car owner complains of vibrations. Never had a problem with anti seize the way I apply it. Never had any issues with lug nuts or studs or the wheels somehow rotating back and forth due to play on the lugs or studs and not enough friction between the wheel and axle hub.
Sadly I have to admit: that is EXACTLY the kind of reading that keeps me awake! Wheel interface is hardly a highly engineered joint, so Shigley (IIRC I wrote SHINGley - either my Chinese time or roofing worries dominates) should be more than adequate.
Now I have to go buy another ******** book....this place costs me money!!!
I'll answer a few things as a non-automotive mechanical engineer. (Cannuck's engineer quotation is gold, that's something from a practitioner in that specific industry who has done these calcs and knows the assumptions.)
The max friction that this joint will develop is (the combined tensile preload of the fasteners) multiplied by (the coefficient of static friction of the faying surfaces).
Almost all engineered joints of this type rely on friction, because friction isolates the fasteners from cyclic/reversing loading and motion that would promote fatigue and fretting failures. Also, see next section:
The weight-of-car loading has huge safety factor, and there are the mentioned backup load paths. That might even work OK with very low friction and without preloaded fasteners.
The second load case he analyzes is where it gets interesting. This is the braking force (and acceleration force if we're talking about a monster torque car). In that direction, the force from the rubber-ground interface has a huge lever arm compared to the small-radius bolt circle. This is where it becomes clear that the friction is very critical in keeping that joint from slipping, and where the backup load path is quite weak (no hub in shear, only the studs in shear, which have leverage working against them and may not all load evenly).
The third load case is cornering loads, where the wheel is trying to be pried off, which again is high leverage against the joint, and is reacted by differential compression changes in the joint that is preloaded tightly together by the fasteners. This is again nice/necessary because it isolates the fasteners from the repeated loading. But this load case isn't really affected by any faying surface friction assumptions.
Following the manufacturer's directions for any assembly is always the best bet.
On a similar note I wish they were better about specifying torques on dry vs lubricated fasteners.
The centering hub is indeed a backup load path for resisting the weight-of-car-direction loads. (As are the studs/bolts themselves in shear.) But the hub's main purpose is to center the wheel and hold it there until it is fastened in place, at which point the friction of the joint reacts most loads in nominal operation.
The max friction that this joint will develop is (the combined tensile preload of the fasteners) multiplied by (the coefficient of static friction of the faying surfaces).
Almost all engineered joints of this type rely on friction, because friction isolates the fasteners from cyclic/reversing loading and motion that would promote fatigue and fretting failures. Also, see next section:
He's analyzing the friction joint, with an assumed 0.15 coefficient of friction. He's doing a quasi-static analysis, which is reasonable, the tires/suspension might affect things dynamically but the peak/limit states are well captured with conservative statics.
The weight-of-car loading has huge safety factor, and there are the mentioned backup load paths. That might even work OK with very low friction and without preloaded fasteners.
The second load case he analyzes is where it gets interesting. This is the braking force (and acceleration force if we're talking about a monster torque car). In that direction, the force from the rubber-ground interface has a huge lever arm compared to the small-radius bolt circle. This is where it becomes clear that the friction is very critical in keeping that joint from slipping, and where the backup load path is quite weak (no hub in shear, only the studs in shear, which have leverage working against them and may not all load evenly).
The third load case is cornering loads, where the wheel is trying to be pried off, which again is high leverage against the joint, and is reacted by differential compression changes in the joint that is preloaded tightly together by the fasteners. This is again nice/necessary because it isolates the fasteners from the repeated loading. But this load case isn't really affected by any faying surface friction assumptions.
See above other load cases, and that if those others are to be resisted, you get the weight-bearing one for free.
Correct.
The really bad shear would exist in the direction of rotation of the wheel, second load case.
Correct. It's all about the assumptions, which as far as I know aren't public. Maybe the manufacturer did analyze it lubricated and it's fine, but absent specific knowledge on that, I'd avoid adding lubricant where it isn't called out. (Edited to add: seems like a lot of manufacturer manuals do specify the clamped surface be cleaned, which makes sense per the above.)
Following the manufacturer's directions for any assembly is always the best bet.
On a similar note I wish they were better about specifying torques on dry vs lubricated fasteners.
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I think there's a lot of correct and incorrect information being mixed together in this thread. There are nuances in the designs of different wheel hubs (I am not familiar with trucks/heavy equipment) but, in general, the primary mechanism for force transfer in passenger cars is static friction between the assembly stack (Hub, rotor, wheel) when properly tightened.
At first glance, my opinion is that the concerns over a thin coating of anti-seize on the hub faces is wildly overblown and I use it on all of my vehicles. Other factors like the stiffness of the overall joint, hardness of the materials being clamped, surface finishes of interfaces, tolerances, and the clamping force will all be more consequential than the use or omission of anti-seize. Yes, conical lug nuts help center the wheel, but they also increase the bearing area to allow increased clamping force by reducing bearing stress to reduce deformation/creep in order to maintain pre-load to ensure the wheel remains secure. I have not personally calculated it, however I'm fairly certain that established designs have a very healthy safety margin in order to account for the real-world variability outlined above that the joint will encounter when in service. If this was not the case, you'd likely see significant deformation in bolt hole as the wheel slammed into the studs under acceleration and deceleration, making them oblong.
To help convince you the friction from the clamping interface is what carries the load, imagine the axle, hub, and brake rotor is welded completely solid, and let's focus on the brake rotor hat to the wheel interface. The wheel system is represented by the picture I found online, below. Imagine this interface is a nut and a bolt, and the lug nut bolt circle is you with a short wrench on one side and the wheel is you holding the head of the bolt with a socket on a long breaker bar. In practice, you know that it takes a lot more force on the short wrench to counteract relatively little force on the breaker bar, right? We have the same scenario going on in a car. The frictional force of the small diameter wheel to hub interface needs to be significantly higher than the force generated between the tire and the pavement because of the shorter moment arm.
Let's simplify the system down to just the basics and make some generous assumptions to illustrate the point. Assume:
- Static friction coefficient of the tire to asphalt is 0.72, and the rotor to aluminum wheel coefficient is .45, per this table
- 3000lb car with 50/50 static weight distribution, so 750 lbs normal load "Fz"(represented as the purple arrow in the image below) per tire. During braking, let's assume weight transfer doubles this to 1500lbs per front wheel.
- 6" Diameter lug nut circle (Green arrow, ignore the "2F rotor" label and pretend this is the bolt circle) and the clamping force exists only along this bolt circle
- 1/2" Threaded lug nuts torqued to 100 ft*lb
- Using this calculator, assuming 1200 lb-in (100 lb-ft *12 in/foot), .5" stud diameter, 0.2 thread friction coefficient, that connection produces 12,000 lbs of clamping force.
- 13" Rolling Radius (the distance between the center of the axle and the contact patch when the tire is compressed under load) 10" radius on a 20" rim, and another 3" of rubber sidewall. Sound reasonable?
- The wheel is infinitely stiff, and the number of lug nuts is sufficient to get even clamping force all around the wheel to hub interface.
- Clamping force does not result in bearing stress that causes meaningful yielding/deformation.
In our example, the interface needs to provide 14,040 lb*ft of reactive torque in order to not slip and cause the studs to take up load. Let's assume the frictional force of the clamp acts tangential to the bolt circle at the bolt circle (green arrow). Working backwards, our moments need to balance, so 14,040lb*ft / 3" radius (one half the 6" bolt circle) means the clamp interface needs to provide 4,680 lbs of reaction force. If we assume the wheel to steel interface has a Mu of 0.45, that means we need 10,400 lbf of clamping force between the rotor hat and the back of the wheel to balance the forces.
Going back to the above assumptions, we see that the 0.5" stud with 0.2 kf torqued to 100lb-ft gets us 12,000 lbf of clamping force. So, the friction from the clamping interface provides enough torque to counter the force from the wheel. This is obviously a simplified example that negates them impact of combined and dynamic loading from cornering, bumps, potholes, compliance in the rims, etc. We also assume that the clamping force acts as a point load at the bolt circle diameter, but some of the clamping force is at a larger radius, Also, in reality, one single wheel stud isn't enough because the rotor/hub system isn't infinitely stiff, surfaces aren't perfectly flat and/or parallel, not all studs are evenly torqued, etc, so you need multiple studs to ensure clamping force is maintained and the bolts remain sufficiently preloaded to prevent fatigue.
Keep in mind, bolted connections aren't always designed this way for bridges and buildings and other applications. Many do take into account additional shear loading of the fasteners, because the tolerances are difficult to control, interfaces aren't sufficiently stiff, etc. In these cases, you'd approach the calculations differently and calculate the combined load on the bolt pattern from shear etc. Threaded bolts aren't typically used for these types of loads either, as you have a big stress riser from the threads.
Its an expensive one, definitely look for it used.
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I really appreciate the time and effort that took! Exactly what I was hoping to see. Thanks!!I think there's a lot of correct and incorrect information being mixed together in this thread. There are nuances in the designs of different wheel hubs (I am not familiar with trucks/heavy equipment) but, in general, the primary mechanism for force transfer in passenger cars is static friction between the assembly stack (Hub, rotor, wheel) when properly tightened.
At first glance, my opinion is that the concerns over a thin coating of anti-seize on the hub faces is wildly overblown and I use it on all of my vehicles. Other factors like the stiffness of the overall joint, hardness of the materials being clamped, surface finishes of interfaces, tolerances, and the clamping force will all be more consequential than the use or omission of anti-seize. Yes, conical lug nuts help center the wheel, but they also increase the bearing area to allow increased clamping force by reducing bearing stress to reduce deformation/creep in order to maintain pre-load to ensure the wheel remains secure. I have not personally calculated it, however I'm fairly certain that established designs have a very healthy safety margin in order to account for the real-world variability outlined above that the joint will encounter when in service. If this was not the case, you'd likely see significant deformation in bolt hole as the wheel slammed into the studs under acceleration and deceleration, making them oblong.
To help convince you the friction from the clamping interface, imagine the axle, hub, and brake rotor is welded completely solid, and let's focus on the brake rotor hat to the wheel interface. The wheel system is represented by the picture I found online, below. Imagine this interface is a nut and a bolt, and the lug nut bolt circle is you with a short wrench on one side and the wheel is you holding the head of the bolt with a socket on a long breaker bar. In practice, you know that it takes a lot more force on the short wrench to counteract relatively little force on the breaker bar, right? We have the same scenario going on in a car. The frictional force of the small diameter wheel to hub interface needs to be significantly higher than the force generated between the tire and the pavement because of the shorter moment arm.
Let's simplify the system down to just the basics and make some generous assumptions to illustrate the point. Assume:
In this case, the max friction force trying to rotate the tire before the tire starts sliding under heavy braking is Fz * Mu (greek letter, coefficient of friction) so we get 1500lbs * 0.72 = 1,080lbF (Pink Arrow in the diagram). This is just longitudinal force, so we multiply it by the rolling radius of 13" to get 14,040 lb*ft of torque that needs to get reacted under heavy braking at the interface of the wheel and the hub face.
- Static friction coefficient of the tire to asphalt is 0.72, and the rotor to aluminum wheel coefficient is .45, per this table
- 3000lb car with 50/50 static weight distribution, so 750 lbs normal load "Fz"(represented as the purple arrow in the image below) per tire. During braking, let's assume weight transfer doubles this to 1500lbs per front wheel.
- 6" Diameter lug nut circle (Green arrow, ignore the "2F rotor" label and pretend this is the bolt circle) and the clamping force exists only along this bolt circle
- 1/2" Threaded lug nuts torqued to 100 ft*lb
- Using this calculator, assuming 1200 lb-in (100 lb-ft *12 in/foot), .5" stud diameter, 0.2 thread friction coefficient, that connection produces 12,000 lbs of clamping force.
- 13" Rolling Radius (the distance between the center of the axle and the contact patch when the tire is compressed under load. 10" radius on a 20" rim, and another 3" of rubber sidewall. Sound reasonable?
- The wheel is infinitely stiff, and the number of lug nuts is sufficient to get even clamping force all around the wheel to hub interface.
- Clamping force does not result in bearing stress that causes meaningful yielding/deformation.
In our example, the interface needs to provide 14,040 lb*ft of reactive torque in order to not slip and cause the studs to take up load. Let's assume the frictional force of the clamp acts tangential to the bolt circle at the bolt circle (green arrow). Working backwards, our moments need to balance, so 14,040lb*ft / 3" radius (one half the 6" bolt circle" means the clamp interface needs to provide 4,680 lbs of reaction force. If we assume the wheel to steel interface has a Mu of 0.45, that means we need 10,400 lbf of clamping force between the rotor hat and the back of the wheel to balance the forces.
Going back to the above assumptions, we see that the 0.5" stud with 0.2 kf torqued to 100lb-ft gets us 12,000 lbf of clamping force. So, the friction from the clamping interface provides enough torque to counter the force from the wheel. This is obviously a simplified example that negates them impact of combined and dynamic loading from cornering, bumps, potholes, compliance in the rims, etc. We also assume that the clamping force acts as a point load at the bolt circle diameter, but some of the clamping force is at a larger radius, Also, in reality, one single wheel stud isn't enough because the rotor/hub system isn't infinitely stiff, surfaces aren't perfectly flat and/or parallel, not all studs are evenly torqued, etc, so you need multiple studs to ensure clamping force is maintained and the bolts remain sufficiently preloaded to prevent fatigue.
Keep in mind, bolted connections aren't always designed this way for bridges and buildings and other applications. Many do take into account additional shear loading of the fasteners, because the tolerances are difficult to control, interfaces aren't sufficiently stiff, etc. In these cases, you'd approach the calculations differently and calculate the combined load on the bolt pattern from shear etc. Threaded bolts aren't typically used for these types of loads either, as you have a big stress riser from the threads.
I have nothing against anti-seize and use it occasionally. But, more or less, EP2 grease does the same job. I have used it a lot over the decades simply because it's at hand and cheap. Moly grease is really good in this regard.
As already pointed out here: if oxygen and moisture can't get in, corrosion won't be a problem. So a sealant or "Loctite" (or equivalent) are perhaps the ultimate anti-seize in very corrosive environments. And perhaps good prevention against galling!?
Thankfully I hardly ever work on anything used in or at sea, but using sealant or Loctite makes good sense to me.
As already pointed out here: if oxygen and moisture can't get in, corrosion won't be a problem. So a sealant or "Loctite" (or equivalent) are perhaps the ultimate anti-seize in very corrosive environments. And perhaps good prevention against galling!?
Thankfully I hardly ever work on anything used in or at sea, but using sealant or Loctite makes good sense to me.
Wiz02
Well-known member
I think there's a lot of correct and incorrect information being mixed together in this thread. There are nuances in the designs of different wheel hubs (I am not familiar with trucks/heavy equipment) but, in general, the primary mechanism for force transfer in passenger cars is static friction between the assembly stack (Hub, rotor, wheel) when properly tightened.
At first glance, my opinion is that the concerns over a thin coating of anti-seize on the hub faces is wildly overblown and I use it on all of my vehicles. Other factors like the stiffness of the overall joint, hardness of the materials being clamped, surface finishes of interfaces, tolerances, and the clamping force will all be more consequential than the use or omission of anti-seize. Yes, conical lug nuts help center the wheel, but they also increase the bearing area to allow increased clamping force by reducing bearing stress to reduce deformation/creep in order to maintain pre-load to ensure the wheel remains secure. I have not personally calculated it, however I'm fairly certain that established designs have a very healthy safety margin in order to account for the real-world variability outlined above that the joint will encounter when in service. If this was not the case, you'd likely see significant deformation in bolt hole as the wheel slammed into the studs under acceleration and deceleration, making them oblong.
To help convince you the friction from the clamping interface is what carries the load, imagine the axle, hub, and brake rotor is welded completely solid, and let's focus on the brake rotor hat to the wheel interface. The wheel system is represented by the picture I found online, below. Imagine this interface is a nut and a bolt, and the lug nut bolt circle is you with a short wrench on one side and the wheel is you holding the head of the bolt with a socket on a long breaker bar. In practice, you know that it takes a lot more force on the short wrench to counteract relatively little force on the breaker bar, right? We have the same scenario going on in a car. The frictional force of the small diameter wheel to hub interface needs to be significantly higher than the force generated between the tire and the pavement because of the shorter moment arm.
Let's simplify the system down to just the basics and make some generous assumptions to illustrate the point. Assume:
In this case, the max friction force trying to rotate the tire before the tire starts sliding under heavy braking is Fz * Mu (greek letter, coefficient of friction) so we get 1500lbs * 0.72 = 1,080lbF (Pink Arrow in the diagram). This is just longitudinal force, so we multiply it by the rolling radius of 13" to get 14,040 lb*ft of torque that needs to get reacted under heavy braking at the interface of the wheel and the hub face.
- Static friction coefficient of the tire to asphalt is 0.72, and the rotor to aluminum wheel coefficient is .45, per this table
- 3000lb car with 50/50 static weight distribution, so 750 lbs normal load "Fz"(represented as the purple arrow in the image below) per tire. During braking, let's assume weight transfer doubles this to 1500lbs per front wheel.
- 6" Diameter lug nut circle (Green arrow, ignore the "2F rotor" label and pretend this is the bolt circle) and the clamping force exists only along this bolt circle
- 1/2" Threaded lug nuts torqued to 100 ft*lb
- Using this calculator, assuming 1200 lb-in (100 lb-ft *12 in/foot), .5" stud diameter, 0.2 thread friction coefficient, that connection produces 12,000 lbs of clamping force.
- 13" Rolling Radius (the distance between the center of the axle and the contact patch when the tire is compressed under load) 10" radius on a 20" rim, and another 3" of rubber sidewall. Sound reasonable?
- The wheel is infinitely stiff, and the number of lug nuts is sufficient to get even clamping force all around the wheel to hub interface.
- Clamping force does not result in bearing stress that causes meaningful yielding/deformation.
In our example, the interface needs to provide 14,040 lb*ft of reactive torque in order to not slip and cause the studs to take up load. Let's assume the frictional force of the clamp acts tangential to the bolt circle at the bolt circle (green arrow). Working backwards, our moments need to balance, so 14,040lb*ft / 3" radius (one half the 6" bolt circle" means the clamp interface needs to provide 4,680 lbs of reaction force. If we assume the wheel to steel interface has a Mu of 0.45, that means we need 10,400 lbf of clamping force between the rotor hat and the back of the wheel to balance the forces.
Going back to the above assumptions, we see that the 0.5" stud with 0.2 kf torqued to 100lb-ft gets us 12,000 lbf of clamping force. So, the friction from the clamping interface provides enough torque to counter the force from the wheel. This is obviously a simplified example that negates them impact of combined and dynamic loading from cornering, bumps, potholes, compliance in the rims, etc. We also assume that the clamping force acts as a point load at the bolt circle diameter, but some of the clamping force is at a larger radius, Also, in reality, one single wheel stud isn't enough because the rotor/hub system isn't infinitely stiff, surfaces aren't perfectly flat and/or parallel, not all studs are evenly torqued, etc, so you need multiple studs to ensure clamping force is maintained and the bolts remain sufficiently preloaded to prevent fatigue.
Keep in mind, bolted connections aren't always designed this way for bridges and buildings and other applications. Many do take into account additional shear loading of the fasteners, because the tolerances are difficult to control, interfaces aren't sufficiently stiff, etc. In these cases, you'd approach the calculations differently and calculate the combined load on the bolt pattern from shear etc. Threaded bolts aren't typically used for these types of loads either, as you have a big stress riser from the threads.
Its an expensive one, definitely look for it used.
@908Jim, Thanks so much for helping an old EE with the calculations! Last time I did
calculations that were anything like this was 40 plus years ago for the EIT exam, which sadly I passed but never sat for a PE.
This is a hugely informative thread, and as @M635_Guy said, your and @cannuck and @AdAstra responses are what make the GJ great.
Oh and thanks to the OP for starting this thread, which has deviated just a tad from the original post!
CoreyB
Member
Not to add fuel to this fire, but some vehicle manufacturers do explicitly tell you to put anti-seize on the wheel hub to wheel centerbore interface.
Here is an example.
Castrol Optimoly TA is just silver anti-seize. Cleaning and lubricating the wheel hub is necessary and not doing so can lead to an improperly mounted wheel. At least according to Porsche, a company devoted to engineering.
They also reference cleaning and using anti-seize on the area of the hub that centers the rotor.
The area I circled comes from the factory with anti-seize applied to it. This area is a precision fit with the rotor. The five points center the rotor on the hub.
Anti-seize should never be applied to the hub face, rotor face or wheel face. I'm not sure if this is what your quoted post is saying, or if you are telling people not to grease the wheel hub to wheel centerbore. I know other manufacturers make similar suggestions in their service manuals, I am just most familiar with Porsches.
Porsche also recommends using anti-seize on their silver wheel bolts used from about 1997-2012. Around 12-13 they switched to a black coating on wheel bolts and anti-seize became a major no no at that point. The only time I'd ever recommend anti-seize on wheel bolts or lug nuts is when the manufacturer specifically calls for it in their service information.