Need help with mystery ring and pinion

[David Goodman]

Here’s what I have so far.

New 8:39 Ring & Pinion purchased years ago from the now defunct Windward performance in Vermont, advertised at the time as original Porsche parts.

I’ve acquired this set and I am now looking to set it up properly. The problem is that I’m having difficultly deciphering the setup markings on this thing. Four different Porsche transmission shops couldn’t recognize them either.

The factory manual indicates that the pinion head is marked with a “r” value (denoted with a capital N followed by a number - example N23) and a pair code. It also calls out a design distance (“R” value) of 81.69 mm or 82.29 mm (depending on the transmission code). The Ring gear should have a backlash called out as well.

As can be seen from the pictures, there seems to be no “r” value, and the two “R” values don’t even come close to the design distance called out in the manual.

So here are my questions:

1. Does anyone recognize the manufacturer marking – triangle inside the oval
2. How about the setup information what are 2/1007/23 and 2/1010/15
3. Any idea on the R values?
4. How about the pair codes? Is it possible this is not a matched set?
5. How about the backlash?

Any help on this would be greatly appreciated,
Thanks,
Dave

[Geary]

While I can't answer most of your questions, the "R = 119.04" is puzzling. While the "R" would lead you to believe that a standard "Ro" measurement is used, the "119.04" could only mean that a "Po" measurement is used instead.

While "Ro" is the measurement from pinion head to diff centerline, "Po" is the measurement from the backside of the pinion head (which sits against the bearing) to diff centerline.

To arrive at Po (in order to use standard Porsche method of setting pinion depth), subtract the height of the pinion head (measured before installing the bearing) from 119.04mm. Example: 119.04 - 36.55 = 82.49.

[David Goodman]

That helps allot, I'll do some measurements and let you know what I come up with. This still leaves us wondering what the deviation is ("r") but it's a great start,
Thanks,
Dave

[Geary]

Deviation "r" is Ro minus Master gauge found in the manual (edit: AND minus the pinion head height)... but you already have the measurement you need to set pinion depth.

[Grady Clay]

Well,
This appears to be for a 930 Turbo 4-speed.

Unfortunately I'm off in Ft. Collins and my 930 Turbo manual is at home. That is where the info is.

I have a Spec Book out in the car. I'll report back if that is useful as it has the R&P settings also.

You realize this R&P will only fit a 930 and not a 915 or 901/911.

Best,
Grady

[David Goodman]

Geary,
Thank you very much for your help, I want to make sure I'm 100% clear on this. By master guage you mean "R" the design distance called out in the manual - 82.29 mm for a type 930/34.

I don't even need the deviation (r) number because it is part of the Ro (Po) calculation described above.

Grady,
Yes, thank you - confirming the numbers would be very helpful. And yes, this is going in a 930.
Dave

P.S. I would sure feel allot better about all of this if I knew the manufacturer and had a pair code.

[Geary]

David,

(see my edit above)

"r" = 119.04 - 82.29 - pinion head height.

"Ro" = 82.29 + "r"

But, as you say, you won't necessarily need "r" since you now know how to calculate "Ro" using "Po" - pinion head height measurement.

[David Goodman]

excellent! thanks. Now all I need is a reasonable comfort level that this set goes together. There is another board member with a similar set, I'm going to compare numbers and see what I can find out. I'll keep you posted,
Dave