Race and rally gearboxes 901/52 etc

[davep]

So for 1967 there appears to be two programs for 901/5x transmissions. The first was just marking the special type on the cases along with a regular serial #.
901/5x known in 901/02 series 10xxxx
901/5x known in 902/1 series 13xxxx

Perhaps this became confusing, and by calendar year 1967 they had set up special serial # series for the various types
option 9591 type 901/51 10001 highest known 10004 ratios for Hillclimb
option 9592 type 901/52 20001 highest known 20008 ratios for Airport
option 9594 type 901/53 30001 -------------------- ratios for Fast Race
option 9593 type 901/54 40001 highest known 40004 ratios for Nürburgring

when a ZF limited slip differential was installed during assembly the numeral 9 was stamped between the type and serial #

[2.5MFI]

Adding to these special transmission type's, I have a very odd Ring & Pinion set. I have brought this up before ( thanks Jon ) and hoping maybe now there is more information out there. I have a 8:35 R&P set for a 901/911 gearbox. Porsche part number 901.332.252.00. I can't find any information on it at all. It's like it never happened, never produced, doesn't exist. Must be another one out there? Photos below.

[gled49]

This pinion shaft, with the castle nut, was in a 901/51 “R” trans.

[davep]

Okay, so here is my wild guess. There is another set of 901/5x transmissions, but probably sharing the same serial sequence as the "normal" 901/5x series.
These would be the 901/5xR series, differing in the R&P, with the 8:35 set

[Jon B]

Mark & Gordon, those are both pretty rare and interesting items.

I have a very odd Ring & Pinion set. I have brought this up before ( thanks Jon ) and hoping maybe now there is more information out there.
I have a 8:35 R&P set for a 901/911 gearbox. Porsche part number 901.332.252.00. I can't find any information on it at all. It's like it never happened, never produced, doesn't exist...

Mark, I think I've posted this before. It's the only reference I've run across on the 8:35 R&P ratio.
This is dated Feb 69, but your pinion appears to be dated Nov 66, so quite a bit earlier. And it looks to be NOS... a very nice set!

This pinion shaft, with the castle nut, was in a 901/51 “R” trans.

Gordon, I've seen this arrangement on a few early 904 pinions too. Is the shaft dated?
The castle nut was used on the earlier 356-era pinions, as below, so your example is a rare transition between the 356 and 901/904.

You've got a nice selection of diff shims there too... ;-)



Jon B.
Vista, CA

[Jon B]

This pinion shaft, with the castle nut, was in a 901/51 “R” trans.

Gordon, the similar 904 pinion shafts I've seen were drilled completely through, from one end to the other... is yours as well?
You could drop a pencil through them :-)

Jon B.
Vista, CA

[Chris Pomares]

Will this work with all 901’s or only a few?

[2.5MFI]

Thanks Jon. And yes it's a NOS R&P.

[Xavier PJB]

May I ?

[gled49]

I think the castle nut pinion was probably 904/906. It was not hollow, and it would work in any 901/911 trans. I also built a gearbox with the 8:35 R&P, not in the 911R’s. The 901/51R was a 911R trans but the other 2 we built didn’t have that kind of pinion shaft.