Here is a question that I asked numerous service centers and various speed shops. No name no pack drill.
I also Googled it and the best I could find was about a Ford 9" diff. This diff was set up at 5° to the horizontal plane. I could not get the answer to the angle of the front diff of the Disco 1 or II.
What I did was install Disco 1 diffs in my Series IIA 88. There was no real problem setting up the back diff. I went with the 5° to the horizontal and it works great.

What I came up on the front diff due to the parabolic springs and the shocks on the front wanting to use the same space that the track rod also wanted use. The shock mount was easy the track rod was another matter. I had to space the diff away fro the springs by 25 mm= 1" then set the diff up to 12° from the horizontal so that the diff cleared the springs

The question I have is "What is the correct angle to the horizontal plane on a Disco 1 or Disco II? .

 

The only information I have seen shows with a D1's and D2 that you were able to buy caster correcting bushings or radius arms to change the angle by 3 or 6 degrees to set the pinion as close to horizontal as possible to better lube the pinion bearings.

 

Hi Disco Mike thanks for that info. The lube of the bearings with to much of an angle was my concern with the Disco diffs that I installed in my Series IIA 88. Up to now at 12° on the front looks OK. May consider installing an extra filler plug higher up but then there will be oil in the Axel tubes. This may not be good for the cv's. What are your thoughts on this
Here is a correction. It was not the diff that needed to clear the springs it was the track rod that needs to clear the springs. Sorry about the confusion

 

It sounds like you installed complete Disco axle assemblies and not just diffs since Disco and Series diffs are the same aside from spline count. True?

As for the angle, too much angle will risk causing a dry input bearing as mentioned. But it will also require you to use a double cardan propshaft. I can't remember the point at which you should use one but at 12 degrees you're close IIRC.

 

Hey antichrist
You are right about the complete Disco diffs in the front and back of my 88. Made 2 minor mistakes with the back spring perches so the 88 leans slightly. Still got to look into getting that sorted out.
Also got my ARB lockers back from GBR in Utah with 7 X29 ring and pinions installed. Front is reverse cut so I am looking forward to getting them installed.
Up to now there are no vibrations from the shaft or the rest of the mods but I have a double cardan shaft hanging out in my shed so got that covered.
I have another front diff that I want to work on but I don't want to go more than 12° because as you say the pinion gear front bearing will starve for oil.
Disc brakes make the world of difference and also give the 88 a ready for anything look.
The Disco diffs are 4 inches wider than the 88's. I am still running 750X16's Michelins

 

Wheel track is wider. Diffs are the same.