Anti-Seize on a lug bolt ... good idea or bad ???
01-14-2002, 11:12 AM
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Anti-Seize on a lug bolt ... good idea or bad ???
I thought everybody understood the use of anti-seize until I spoke with a person who is ...err ...was very well respected in the automotive industry and sent him to school... So I thought I would share this info. If he didn't know I'm guessing alot of others wouldn't either.
Anti-sieze on a lug bolt is a very bad idea !!!
Here's why: Bolts or studs provide clamping force by being purposely stretched. Most torque specs bring a bolt well within its elastic limit. Then when loosened they will return to their original length and can be safely reused (Some bolts, including many head bolts, are purposely stretched past their elastic limit, and can not be reused). The torque wrench is the most convenient-but not the most accurate-method of properly stretching automotive bolts. Engineers spend hours correlating the proper bolt stretch to the required turning effort.
About 90% of a torque specification is used to overcome friction; only 10% of the specified twisting effort provides clamping force. It is no surprise then that most lubricant tables recommend a 40-45% reduction of applied torque when using anti-sieze on a bolt. So, a lugbolt coated with anti-sieze should be tightened to a maximum of 49 ft-lbs. Tightening this lugnut to 85 ft-lbs. means it is now over-torqued by 73%! Considering that most torque specs stretch a bolt to within 70% of its elastic limit, over-torquing by 73% will easily send the bolt or stud well beyond its elastic limit-and could be dangerously close to its failure point.
For this reason I would suggest to all forum members to never use anti-seize on your lug hardware.
Luke
877-522-8473 ext. 362
Anti-sieze on a lug bolt is a very bad idea !!!
Here's why: Bolts or studs provide clamping force by being purposely stretched. Most torque specs bring a bolt well within its elastic limit. Then when loosened they will return to their original length and can be safely reused (Some bolts, including many head bolts, are purposely stretched past their elastic limit, and can not be reused). The torque wrench is the most convenient-but not the most accurate-method of properly stretching automotive bolts. Engineers spend hours correlating the proper bolt stretch to the required turning effort.
About 90% of a torque specification is used to overcome friction; only 10% of the specified twisting effort provides clamping force. It is no surprise then that most lubricant tables recommend a 40-45% reduction of applied torque when using anti-sieze on a bolt. So, a lugbolt coated with anti-sieze should be tightened to a maximum of 49 ft-lbs. Tightening this lugnut to 85 ft-lbs. means it is now over-torqued by 73%! Considering that most torque specs stretch a bolt to within 70% of its elastic limit, over-torquing by 73% will easily send the bolt or stud well beyond its elastic limit-and could be dangerously close to its failure point.
For this reason I would suggest to all forum members to never use anti-seize on your lug hardware.
Luke
877-522-8473 ext. 362
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01-14-2002, 11:49 AM
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Seems to be a subject of great debate....
...for instance, I found this post that would say it's OK to use anti-seize on lug nuts/bolts:
<i>Unless indicated otherwise, the torque specifications listed in the automotive industry, are for threads LUBRICATED with 30 weight standard petroleum based oil. (No synthetics). Fasteners should not be installed dry unless specifically indicated with the torque spec.</i>
From:
http://www.eskimo.com/~dalus/bmw/all/tools/all_note_on_bolt_torque_specs.html
<i>Unless indicated otherwise, the torque specifications listed in the automotive industry, are for threads LUBRICATED with 30 weight standard petroleum based oil. (No synthetics). Fasteners should not be installed dry unless specifically indicated with the torque spec.</i>
From:
http://www.eskimo.com/~dalus/bmw/all/tools/all_note_on_bolt_torque_specs.html