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If the material is in question, I suppose a tensile test would put everyone with RZ studs at ease. Just doing some quick calcs on the OEM stud, assuming a M10 stud torqued to 43 fl-lbs, you end up with a Fi ~6500lbs and tensile stress of ~54ksi. If the OEM YTS is 130ksi it's within a 2.25 F.S. If the ramey stud material is Chro-moly or 4130, the YTS is only around 60ksi which would put it at around a F.S. of 1. I'm guessing if this was the case we would have seen a lot of them snap by now. If they are in fact a grade 8 then we should be good to go. If my calcs are correct, OEM studs have a good margin. This is assuming no bending or shear is involved and the stud is in purely a tensile load. It seems as you say, the stories of OEM studs snapping and causing engine failures because they are "weak" isn't the full story. Now I suspect the Ramey stud is a fear based product that in reality could be a weaker than the OEM stud. Guess we need a tensile test. An upgraded stud would have to be made out of something like PH 13-8 Mo, or Aremet to crank up the F.S. from a grade 8 fastener. You're talking mega materials now. The highest FS requirement I've seen was 4. You would need one of these UHS materials to achieve this. my 3 cents.
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Work on your own car, and don't half ass it. |
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15:18:13 08/09/17
