Quote:
Originally Posted by Henry Schmidt
The cranks are forged not billet. The original Porsche cranks went through a process called "Tufftriding" a German process developed in the 1950s. It's a two stage liquid salt process that treats the surface with a nitride and carbonitride case.
What we are seeing here is probably a chemical reaction to the surface hardening.
There is zero integrity loss to the crank if properly processed. Dave@ Marine knows his shyt. The reason Porsche mechanics were hesitant to grind cranks undersized was simply the cost of undersized bearings. In today's world that cost doesn't seem to matter as much.
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Henry, splain. A crankshaft is machined from a forged billet of steel. Is that not how you do it. What is the diff between ''forged'' and ''billet''. Maybe we had shi**y machinest, but every broken crank shaft I have seen, 4 and 6 cylinder, had been turned. Cracked from fillet diagonally across the web. The machine procedure I was to understand, which was the cleanness of the cut and the radius, was critical at the fillet. Bob