Mercedes-Benz Forum banner

1 - 3 of 3 Posts

·
Registered
Joined
·
0 Posts
Discussion Starter #1
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.<br> <br> Anti-sieze on a lug bolt is a very bad idea !!! <br> <br> 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<br> automotive bolts. Engineers spend hours correlating the proper bolt stretch to the required turning effort.<br> <br> 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<br> 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. <br> <br> For this reason I would suggest to all forum members to never use anti-seize on your lug hardware. <br> <br> Luke <br> 877-522-8473 ext. 362
 

·
Registered
1991 420sel
Joined
·
267 Posts
Luke--The anti-sieze on the lug bolt question is a good one, but the answer is not so simple. The mercedes manual specifially says that the torque specifications for bolts are for bolts and contact surfaces "lightly oiled", unless specifically stated otherwise. The manual then goes on to describe one such instance--the spherical surface of the lugbolt (and wheel) should be clean and dry, no oil of any kind. So long as the part of the lugbolt that touches the wheel is dry, the torque will be fine. Indeed, the manual seems to say that the threads should be lightly oiled. And I can see little difference between lightly oiling the threads and using a bit of anti-sieze on them, so long as the contact surface is completely dry. Charlie Wagner, 1989 and 1991 420sels.
 
1 - 3 of 3 Posts
Top