Anti-seize and bolt torque = confusion, help please

[67c10rustbuket]

Soooo this topic comes about after I stretched a brand new bolt, one after a dozen or so successfull (all brand new grade 8) bolts...

The bolt in question, 3/8-16, according to my info the torque should be 45 FT LB dry, 35 FT LB wet.

I use the torque settings (dry where indicated) either from a hardware chart, assembly manual, or service mauals.




My problem is that according to permatex the instructions say to "reassemble parts using normal torque values"


Does "normal" refer to normal dry or normal wet ??

Some internet sources say you should torque bolts with anti seize to 60% of the "dry torque" which for this scenario would be 27 FT LB. This is lower than even the "wet" torque setting.

I have used multiple lubricants on engines and other parts with specific torque values with different lubricants and never had a problem. Yet experience, common sense, and other information says any lubricant on the thread will lower the torque value and excessive use and lubricant under the bolt head and or nut would also lower the torque value.

Maybe I am being too anal but I want to assemble my truck to last another 50 years or so. That being said would you:

1: ditch the anti-seize

2: use anti-seize with normal dry torque settings (assuming I had a bad bolt??)

3: use anti seize with normal wet torque settings

4: use joe blow method on the inter blabber of 60% dry torque



Yeah I may be over thinking this.... I have a tendency to do that.
Yes I am crazy

[mgchevyparts]

If you used 45ft/lb with lubricant instead of 35ft/lb that bolt still should not have stretched to the breaking point. Either a bad bolt (maybe cheap) or torque wrench setting is off. I would use the wet setting of 35ft/lb with anti seize. I don't feel anti seize is necessary on most areas on the truck.

[Spartan]

^ that was my thought...bad bolt. A grade 8 tends to fail catastrophically and just snap. Unlike a grade 5 which will "neck down" ans stretch before failing.

As for the answer to you dilemma I hope somebody chimes in with the answer cuz I'm curious. I have always torqued to spec even with anti-seize but never really gave much thought to the bolt maybe needing to seize a little to reach spec.
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[67c10rustbuket]

Originally Posted by mgchevyparts

If you used 45ft/lb with lubricant instead of 35ft/lb that bolt still should not have stretched to the breaking point. Either a bad bolt (maybe cheap) or torque wrench setting is off. I would use the wet setting of 35ft/lb with anti seize. I don't feel anti seize is necessary on most areas on the truck.

Exactly what sparked this thread, I was surprised to have stretched the bolt! I have a Kobalt torque wrench that is maybe 3 years old and always stored in a platic hard case, used to assemble one engine and my progress on my chassis but It could even still be off. I agree that anti seize is not really needed but is nice when servicing or replacing parts. Another note according to engineers at work and others a bolt can only be torqued once, then additional torquing is only stretching the bolt further.... I may just have to stop using the anti-seize.


Any body else have input?? Burn the truck to the ground? replace all previously torqued bolts?

[Stocker]

Probably a bad bolt..... Has the torque wrench ever been calibrated? Do you set the torque value to zero when it is stored? As to using antisieze, I do on most things simply because it helps when it's time to take things apart again, often years down the road -- but I use it very sparingly.

[Lee H]

Originally Posted by Stocker

Probably a bad bolt..... Has the torque wrench ever been calibrated? Do you set the torque value to zero when it is stored? As to using antisieze, I do on most things simply because it helps when it's time to take things apart again, often years down the road -- but I use it very sparingly.

Agree, Also, I use the dry value with anti seize and wet value with oil, moly lube, etc. Wise to get torque wrench calibrated every few years.
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[Square_78]

I only use anti seize on things that heat up a lot and expand and use two different metals like steel bolts into aluminum. For example the bolts on a super trap muffler baffles. Other than that its not really needed.
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[TBONE1964]

What exactly are you torquing? I agree with Square_78, I only use anti seize on things like exhaust manifold bolts, spark plugs and t-stat housing bolts.

[motorcritter]

I agree with the above suggestions, and add one- use anti-seize on wheel jobs where the wheel contacts it. Don't use it on wheel studs or nuts, though- much potential for mayhem!
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[Gorn]

If you are buying Grade 8 bolts from hardware store they are most likely NOT grade 8. The problem is there is no one policing the hardware stores. They buy the cheapest they can find. They do not certify the bolts they sell so the most they can be help reliable for is the cost of the bolt not the damage caused by the failure.


I am a manufacturing engineer who used to make bolts. Hardware stores sell grade 8 bolts for less per pound then I can buy the correct raw material to make them. This made me curious so I grabbed a hand full and sent them to our testing lab. I did not mark the bolts as an outside purchase. Man I had a whole team of QA people at my desk wanting to know where the grade 3 bolts with the grade 8 markings came from. LOL

[67c10rustbuket]

Originally Posted by Stocker

Probably a bad bolt..... Has the torque wrench ever been calibrated? Do you set the torque value to zero when it is stored? As to using antisieze, I do on most things simply because it helps when it's time to take things apart again, often years down the road -- but I use it very sparingly.

Never been re-calibrated, I can have it calibrated at work though. I have not been very good about setting it to zero when stored. I agree very sparingly, sometimes I get sloppy

Originally Posted by Lee H

Agree, Also, I use the dry value with anti seize and wet value with oil, moly lube, etc. Wise to get torque wrench calibrated every few years.
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Great, thanks.

Originally Posted by Square_78

I only use anti seize on things that heat up a lot and expand and use two different metals like steel bolts into aluminum. For example the bolts on a super trap muffler baffles. Other than that its not really needed.
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Yeah I always heard that, thing that get hot and dissimilar metals, stainless especially.

Originally Posted by TBONE1964

What exactly are you torquing? I agree with Square_78, I only use anti seize on things like exhaust manifold bolts, spark plugs and t-stat housing bolts.

Pretty much everything starting with a bare frame. This particular bolt failure was the idler arm bracket to frame.

Originally Posted by motorcritter

I agree with the above suggestions, and add one- use anti-seize on wheel jobs where the wheel contacts it. Don't use it on wheel studs or nuts, though- much potential for mayhem!
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I have never used anti-seize on wheel studs but the contact surface of the nut to the wheel may me a good idea to prevent corrosion.

Originally Posted by Gorn

If you are buying Grade 8 bolts from hardware store they are most likely NOT grade 8. The problem is there is no one policing the hardware stores. They buy the cheapest they can find. They do not certify the bolts they sell so the most they can be help reliable for is the cost of the bolt not the damage caused by the failure.


I am a manufacturing engineer who used to make bolts. Hardware stores sell grade 8 bolts for less per pound then I can buy the correct raw material to make them. This made me curious so I grabbed a hand full and sent them to our testing lab. I did not mark the bolts as an outside purchase. Man I had a whole team of QA people at my desk wanting to know where the grade 3 bolts with the grade 8 markings came from. LOL

I believe that. These bolts 3/8-16 were $.51 each. Not sure how that compares to material. I buy at a local mom and pop type hardware down the road. We have Lowes but they never have what I need and a Tractor Supply who does not carry fine thread and seems to only carry bolts in 1/2 increments of length where I seem to nee 1 1/4" length etc.. I have been to known to snap "grade 2" bolts at work with a tiny ratchet and wrench, chinese hardware...


After removing the bolt and taking a closer look it appears that the failure was caused by a bad nut.... there was a bad spot at the outside end of the nut and it flattened the threads out as seen in the pic. I usually test fit every nut and bolt to make sure they are correct thread and dont have any burrs but I guess I missed on being in a hurry at the hardware store.

Looks like I was blaming the anti-seize when it was not it fault I have been using the anti-seize because after disassembling the entire truck I am sick of fighting rusted bolts I have read elsewhere that using loctite purple (medium) would be more ideal to keep corrosion out of the threads.

[88Ironduke]

The only real way to identify the various grades is to look at the head markings. Grade 2 has no markings, grade 5 has three lines radiating from the the center, grade 8 has six lines radiating from the center.

Like said above the hardware stores may be buying the cheapest bolts available. In most cases the average grade 8 bolt is a high carbon alloy steel. Typically a 1/2" bolt will safely carry 120,000 psi of force before any deformation of the bolt is present. It will also show signs deformation or yield around 130,000 psi and will has a minimum tensile (catastrophic failure) strength of 150,000 psi. Remember that stainless steel hardware is super cool because of its anti-corrosion capabilities but strength is severely diminished compared to its steel counterparts.

For me, I use grade 5 for interior security of items or items requiring low clamping forces. Use grade 8 just every where else on any vehicle. In the area of torque wrenches. Always store at zero torque, lube torque the wrench prior to use. This is setting the torque wrench to three various settings and snapping the wrench several times at three different settings. The distributes the small amount of oil in the head assembly and will help ensure accurate torque. Most torque wrenches (even mega-expensive Snap On - we use them on aircraft every day) are not considered accurate at the bottom 10% and top 10% of torque available to be dialed in.

Just my .02 cents
88Ironduke

[Lattimer]

Sounds like junk hardware to me. Anti seize vs. oiled should have very similar torque characteristics. The lubricity is basically the same. I know on pressure vessels when I design a head flange or body flange, we always specify lubricated bolts in the torquing instructions. In practice, I have seen no difference between oil and anti seize. (mechanical engineer here)

As noted by others, a real grade 8 bolt won't stretch much, it will snap if over torqued.

[Tom Vogel]

Originally Posted by Wise to get torque wrench calibrated every few years.
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Where would you get that done?

[volksworld]

I don't use anti seize on spark plugs ,I was told it insulates the plug from the head an makes it behave like its a hotter plug ... you're better off with a plated plug than a black one( like autolite) to keep them from seizing