Quote:
Originally Posted by Matt Monson
The thing to keep in mind is that the set up numbers porsche provides have historically been based on quietest running. That doesn’t always coincide with the best pattern if one prints it.
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Quite correct. I've said this before on this forum, so forgive me if I sound like a scratched record (if any of you know what that means...) The "bluing" aka. pattern marking does not work for two reasons.
- Porsche (well, Getrag) determines the ideal depth by loading the transmission. That is, there is torque applied to the input and (opposing) output shafts. This shifts the pattern on the teeth, and the contact patch you see while static testing on the bench is not where the patch is when driving the transmission.
- The specified tolerance is +/- 0.05 mm. You will never see that delta with your eyes and bluing.
I'll give you points for initiative in coming up with your own tooling. But there's no way you can take confidence that you've got it right.
Bear in mind that a hypoid gear design puts significantly greater stresses on the pinion teeth because the pinion-to-crown contact patch moves both up and down the tooth (like a non-offset spiral bevel gear set), and inward and outward, that is radially with respect to the differential's axis. Porsche's reference to "quietest running" should be taken to be synonymous with "least mechanical noise, stress, and heat energy." The 915 pinion gear is not generous with its tooth root width and length, which are the critical dimensions when considering its mechanical strength and ability to tolerate non-optimal set-up.