Race and rally gearboxes 901/52 etc

[rower]

Hi Hugh,

sorry I am wrong.
Rowers gearbox 9284107 is a 901/74, not a 901/54 Nürburgring. So my calculated number of 110 Nürburgring 901/54 gearboxes was based on rower's number 9284107.
It seems, that we do not know a lot about the 901/74 gearboxes?

https://www.early911sregistry.org/fo...g-to-find-info

So what's the difference in between the 901/74 and 901/54?

Claudius

And mine isn’t in a 1968 SWB, but rather one of the earliest 1969 LWB cars.
But a late July 1968 build. And Nürburgring gears picked to race at ... Nurburgring!

[68S_SK2]

The difference between the 5x series and the 7x series is the differential; 5x has the old "regular" differential, and the 7x has the newer "simplified" differential. Simplified in construction perhaps, but prone to catastrophic failure when the tips of the bolts on the output flange wear, and then break off. When the tip fails, the internals are not held in position and it usually results in total differential failure and case damage. There was a fix, a kit I think, after a time but there are ways to use parts from a 914 transmission to correct the problem.

That were my thoughts: There is a different bevel-ring gear setup of the differential!

[Brad Davis]

A few pictures of my 906 R/P. It seems the castle nut arrangement is a carry over from 356 design?

[davep]

Great 906 parts Brad!
Claudius, the simplified diff has nothing to do with the ring and pinion, they did not change. The difference is in the guts of the diff itself where the spider gears are and how they are supported. The simplified diff has bolts that secure the output flanges into the diff. There are tits on the end that can wear and break off; when they do the damage is catastrophic.

Good information in this thread and links from it:
https://forums.pelicanparts.com/pors...ferential.html

[68S_SK2]

I got it. I thought it is a different shape of the bevel-ring gear, but they are the same in both simplified and normal.