Quote:
Originally Posted by Walt Fricke
Nice combination of a rounded (bullet nose)top (so the washers and nuts will drop on easily) and a hex so they can be screwed in easily with a tool, especially after cylinders etc are in place.
Though I kind of like the idea of using finer threads with flange nuts for the top, which the SuperTec studs have. Same benefit for hitting the torque specs as with the case through bolts Porsche ended up doing. Easy to use flange nuts on the regular threads, though, so the benefit of not messing with the barrel nuts isn't bolt specific.
(oops - found it)
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We have done a huge amount of testing on these studs and the procedures in tightening the nuts. We found in our testing that the stretch and tensile changed due to an increase in friction when the washer could turn some. The nut would bite into the washer and turn the washer on the base and this added to the friction the torque had to overcome.
We never tested a nut with a flange so the result of such a test is unknown. However, my thoughts would be that this would increase the friction more as there would not be any slip between the nut and the washer.
I idea is to minimize the friction in the threads, nut and the washer and eliminate the shearing friction between the washer and the softer head material. Removing movement between the washer and head decreased the friction dramatically.
The same can be said for the use of a stepped washer. This is my choice with these heads. The step eliminates the head from collapsing inwards towards the stud under compression. When this happens, the washer platform in the head concaves and the whole tightening function is compromised.