Torque number with Anti-seize

[yaidunno]

Meh. Not at home. How many people you see breaking out the torque wrench when putting on a donut or rotating wheels?

I know I know, floating rotors, and all that jazz but people don't really do it. They just torque it "tight" with a lug wrench. Different strokes for different folks.

(I do use a torque wrench for lug nuts though I didn't always do it).

I really don't care how many people do it. It is the proper procedure, no matter what way you cut it.

I've seen first hand the result of not torquing wheels. A former technician at our shop over torqued the wheels and not once, but twice had studs brake and wheels come off. These weren't 82 Honda Civics either, a classic Buick and a Testarossa were the victims.

I know how inconvenient it is to take the 2 minutes to torque wheels. And I know nothing i say, or logic i bring to the table will change peoples minds on the "tight enough" method. Like you said, to each their own.

 

[Adam.C]

A very light coating on the threads only to prevent corrosion and/or galling is all that's needed. As is the case with most Anti Seize applications, a little goes a long way.

Careful! Antisieze should be applied not only to the threads, but also under the head.

 

[Steinmetz]

Coefficient friction of a grade 8 bolt is 1.17. Multiply that by the coefficient of .8 for C5A antiseize. Then multiply that by your dry torque value, that is the torque required IF you use C5A. Neverseize has a coefficient of .45 or something very close btw.

Correct.

 

[Steinmetz]

The torque required for a bolted joint design comes from a long string of calculations, but boils down to a simple linear equation.

T = Wp x K x dn
Where T=torque; Wp=fastener preload; K=torque coeff; dn=diameter

The factor that changes with dry vs lubricated fasteners is the "torque coefficient" and is published for a variety of cases. Various values exist, mine are taken from DuPont Engineering Specification (10 pages of calcs). Examples:

Dry steel fasteners: K=0.20
Lightly oiled steel: K=0.15
Cad Plated: K=0.14
Anti Seize on steel: K=0.13 (as published by Bostik for their Never Seez products)
Graphite & mineral oil: K=0.10

Using Never Seize versus dry uncoated steel, multiply the specified torque by 0.65.

A very light coating on the threads only to prevent corrosion and/or galling is all that's needed. As is the case with most Anti Seize applications, a little goes a long way.

Correct also. This is taught in the Sturtevant Manual, as well as other places.

 

[Steinmetz]

Most people don't know how to properly use a torque wrench either. I was one of them up until about a year ago. I would always tighten a bolt down and then throw the torque wrench on it. If it clicked, it was good. Wrong wrong wrong. If it clicks without moving the bolt at all it could very well be over torqued. There are minimum and maximum torque specs.

The torque wrench should always be moved smoothly to the target torque. Don't jerk the handle. It adds an accelerative component to the torque.

 

[ishiboo]

There's an issue here though - the calculations are to get the same amount of stretch/load from the head, you torque it to the lower value calculated.

The head is only part of the game though - the threads themselves and the friction on them is also a big player in holding a fastener in place. By adding the anti-seize lubricant, even if torqued to the correct value for the anti-seize, the fastener is still more likely to back out. And of course in this application, locktite was necessary even with the fastener torqued dry to 100% of the stated torque value.

This becomes a bigger issue with anything involved in heating/cooling cycles, vibrations/etc... which a caliper bolt will be.

 

[arms1970]

Most people don't know how to properly use a torque wrench either. I was one of them up until about a year ago. I would always tighten a bolt down and then throw the torque wrench on it. If it clicked, it was good. Wrong wrong wrong. If it clicks without moving the bolt at all it could very well be over torqued. There are minimum and maximum torque specs.

Then you better make sure your wrench goes in for calibration anually also.

 

[Steve_P]

Lot of erronous info here.

The majority of friction is from the bolt head against the washer or part, it's something like 60%. The thread friction is quite minor in comparison- think about the relation between the two diameters of the thread OD and bolt head OD.

Applying anti seize to the threads only will lower the torque spec by something like 18%. I have done the math on this at work going thru the K for anti seize and the bolt friction breakdown for threads vs washer face.



Originally Posted by basspro
Coefficient friction of a grade 8 bolt is 1.17. Multiply that by the coefficient of .8 for C5A antiseize. Then multiply that by your dry torque value, that is the torque required IF you use C5A. Neverseize has a coefficient of .45 or something very close btw.

not correct. Think about it. If a mfg says tighten a bolt to 100 lb-ft do you then multiply it by 1.17? No. ANd the "grade" of the bolt is not related to the coefficient of friction: it's the finish, whether blackened, cad, zinc, etc.

And 1.17 X .8 = .94 this is basically what you're starting with and essentially changes nothing- you're using the dry torque value.

You take the recommended torque value for the fastener and multiply it by how much the anti seize lowers the friction factor. And this will vary if you apply anti seize under the head or to the threads or both. This comes back to T=KFiD And you have to figure whether you use anti seize on the threads or head or both.

Common K values are .2

 

[955point9cummins]

Then you better make sure your wrench goes in for calibration anually also.

I use torque wrenches at work that get checked much more often than that.

 

[nicksnothereman]

Hub? Im talking about the hat of the rotor that the aluminum wheels sit against when they're tightened. Corrosion there and the wheel needs to be smacked off when you go to remove it again. That's the other area I anti-seize.

Nah. You're saying you use anti-seize on that? So like 1/2 of a decent sized tube? Nah.

You have to rotate or change tires relatively frequently not to mention brake pads and/or rotors. You're telling me within 2-3 years of use (probably less if you rotate neurotically) that level of corrosion is going to magically freeze your wheels to your rotors to your wheels? Nah.

Sorry dude. I'm just not getting the need.

 

[zkling]

Nah. You're saying you use anti-seize on that? So like 1/2 of a decent sized tube? Nah.

You have to rotate or change tires relatively frequently not to mention brake pads and/or rotors. You're telling me within 2-3 years of use (probably less if you rotate neurotically) that level of corrosion is going to magically freeze your wheels to your rotors to your wheels? Nah.

Sorry dude. I'm just not getting the need.

Somebody doesn't live in the rust belt. At least once a week I have to use mechanical means to remove a wheel AFTER removing all the lugs. Then again I do work on some pretty neglected vehicles. I've even been called out to help a friend change a flat that he couldn't get off the hub because it was so corroded on. (Rear alloy wheel).

True story, I was painting my license plate screws tonight, pondered if I should torque, anti seize, loctite or all the above on installation, them things are valuable, don't want to loose one now.

 

[nicksnothereman]

I really don't care how many people do it. It is the proper procedure, no matter what way you cut it.

I've seen first hand the result of not torquing wheels. A former technician at our shop over torqued the wheels and not once, but twice had studs brake and wheels come off. These weren't 82 Honda Civics either, a classic Buick and a Testarossa were the victims.

I know how inconvenient it is to take the 2 minutes to torque wheels. And I know nothing i say, or logic i bring to the table will change peoples minds on the "tight enough" method. Like you said, to each their own.

Your example is of a guy who "over torqued" wheels; that's not tight enough that's (probably) with an impact wrench without a torque stick. That'll snap lugs though I see a bunch of guys doing it. Going hand tight plus with a 4 way pretty much ain't. I rolled on that for years in a FRONT WHEEL drive(!) car with around 280 ft/lbs to the wheels without any issues. If you about fwd "performance" cars there can be a ton of wheel hop in the lower gears and if it were that much of an issue it probably would've thrown a wheel or snapped lugs (nothing happened).

If this were that much of an issue wheels would be flying off vehicles left and right and that's just not the case. If it was THAT unsafe in modern vehicles they probably wouldn't sell lug wrenches without torque measurements.

 

[nicksnothereman]

Somebody doesn't live in the rust belt. At least once a week I have to use mechanical means to remove a wheel AFTER removing all the lugs. Then again I do work on some pretty neglected vehicles. I've even been called out to help a friend change a flat that he couldn't get off the hub because it was so corroded on. (Rear alloy wheel).

True story, I was painting my license plate screws tonight, pondered if I should torque, anti seize, loctite or all the above on installation, them things are valuable, don't want to loose one now.

Aluminum wheels stick to steel rotors with rust? You wanna stick to that story?

 

[zkling]

You laugh at me, but be careful your ignorance is showing.

 

[Adam.C]

My guess is every fastener they install at the factory is essentially lubed with something. Either its got dry film lube or oil from its manufacture. I assume they don't put any dry hardware in. So I use the factory torque specs when I reinstall hardware with oil or anti-sieze. What makes people think the numbers given are for bone dry, slightly corroded bolts?

Most bolt torques i encounter on cars are fairly low. Even if I am wrong and my preloads are all 10% too high, is that a big deal? I think in most cases having them close and similar is what is most important.

 

[Skin]

Aluminum wheels stick to steel rotors with rust? You wanna stick to that story?

Rotors aren't steel, they're cast iron, and they absolutley corrode together. Its just a quick brush on coating from the bottle to help. I don't bother with girly sized tubes of the stuff.

 

[MrMark]

aluminum wheels corrode to cast hubs in California, you don't have to be in the rust belt. I use a light smear of grease, although I have used the antiseize too. Mercedes and other German cars with hubcentric wheels are famous for this. I generally hate the thought of the anti-seize and rarely if ever use it, but rotor hats are one place where it is needed here.

 

[CJKaz]

Lot of erronous info here.

The majority of friction is from the bolt head against the washer or part, it's something like 60%. The thread friction is quite minor in comparison- think about the relation between the two diameters of the thread OD and bolt head OD.

Applying anti seize to the threads only will lower the torque spec by something like 18%. I have done the math on this at work going thru the K for anti seize and the bolt friction breakdown for threads vs washer face.



Originally Posted by basspro
Coefficient friction of a grade 8 bolt is 1.17. Multiply that by the coefficient of .8 for C5A antiseize. Then multiply that by your dry torque value, that is the torque required IF you use C5A. Neverseize has a coefficient of .45 or something very close btw.

not correct. Think about it. If a mfg says tighten a bolt to 100 lb-ft do you then multiply it by 1.17? No. ANd the "grade" of the bolt is not related to the coefficient of friction: it's the finish, whether blackened, cad, zinc, etc.

And 1.17 X .8 = .94 this is basically what you're starting with and essentially changes nothing- you're using the dry torque value.

You take the recommended torque value for the fastener and multiply it by how much the anti seize lowers the friction factor. And this will vary if you apply anti seize under the head or to the threads or both. This comes back to T=KFiD And you have to figure whether you use anti seize on the threads or head or both.

Common K values are .2

Good additional info. I cut and pasted my info from my earlier post specific to wheel lugs. Anti seize on the tapered seats can cause them to move, fret and deform the wheel's seating surface (old school steel wheels in particular), hence the threads only recommendation.

Agree that the head, washer (if used) need to be coated as well. Condition of the threads is important as well, cleaned and chased. The error on small fasteners on cars is negligible, but on big equipment it can be significant. We use Teflon coated fasteners (studs, nuts, hardened washers) to ensure consistent torque and corrosion protection (high hazard chemical plant making Teflon).

 

[mattygee]

Only on GJ could a simple case of someone not tightening something sufficiently (it is the root cause of the pin falling out [Yes, It's happened to me, too]) could turn into an argument over torque formulas and package labeling. Gotta love it!

 

[pepi]

Unless the manufacture or fastener manufacture specifies a lubricant of any stripe. The best practice generally accepted is that the torque value is to be obtained DRY.