Dan, I apologize if I misinterpreted your comment as sarcasm. Reading it again, it sure seems that I read you wrong.
I just went back to the book to answer some of these questions, but unfortunately, "Screw to Win" makes only one recommendation with regard to stainless steel fasteners -- don't use them. Smith discards all stainless fasteners as worthless due to their reduced ultimate tensile strength versus standard steel.
When researching the yield strength of stainless, I found that the tensile strength of 304 is about 15% less than that of grade 8.8 steel, while 316 is virtually identical. This means that 316 can be swapped for 8.8 (and 304 substituted as an upgrade for lower-grade steel fasteners, such as the sort I found in an RX-7's suspension over the weekend).
With that said, let us consider this dangerous experiment conducted this evening to replace some bolts. Realize that this is an academic exercise, so if you're not interested, feel free to ignore:
I need to replace some non-metric motor mount bolts (thanks, Instant-G) with some M12 bolts in order to run WEVO mounts. For reference, the torque spec for stock motor mount bolts (grade 8.8, I believe, I don't actually have one) is 65 ft-lbs.
Burnishing a 304 fastener and torquing to 40 ft-lbs, which is the torque spec indicated by WEVO, cold-welded the bolt to the nut. I next used anti-seize and torqued to 40 ft-lbs. -- perhaps putting me above the elastic limit of the fastener, let alone the recommendation from WEVO.
This may be a textbook scenario in which the hardness of stainless could be dangerous. In fact, I found recommendations to use stainless only in simple clamping and never in mechanically-loaded applications. The physics of which forces are applied to this bolt are way beyond my ken.
So the question is, what will cause a failure of the bolt first?
Also, Dan raised the subject of heat. What role might heat play? I can't find anything specific to stainless steel here, while on the other hand, I found suggestions to use stainless in exhaust manifold fasteners.
Thanks for your thoughts.
