D90 pinion.

[Greg S]

Seems I've broken the tip off my rear diff pinion. It's a two cross pin, 24 (23?) spline unit.

There is still all the parts there, it's just part of the threads broken off inside the pinion flange and still kept captive because the drive-shaft is still bolted to the pinion flange, it just isn't connected to the diff.

I'm guessing it's a 4.7:1 diff, but would it be? Military D90 with 2.5na, did they have 4.7's or 3.54? Bill? Phil? Anyone else?

I have a third member from a RRC that might fit but it'll be 3.54, would it fit?

[red90]

3.54 for sure...

Can you look at the axle serial number? It is either a 2 pinion 10 spline diff or a 4 pinion 24 spline diff. Pull a halfshaft out to check. They are ALL 24 spline at the wheel....

[Greg S]

Okay, it's a 3.54, so would one from a RRC fit and use the same drive shaft?

[HeadDamage]

As long as the RRC one has the same spline count on the side gears it will work but it will not be nearly as strong as the 4 pin military diff (assuming that's what you have). I'm not sure what RRC would have had the 24 spline. The front diff from a Disco one should also be what you are looking for as far as the spline count goes.

[Greg S]

... I'm not sure what RRC would have had the 24 spline. ...

I'm not sure what I have in the way of spare parts kicking around here. If you saw the place you'd know what I'm talking about. I bought a bunch of RRC parts a few years ago and there are some axle shafts with the same inner spline count so I'm thinking they must be from the rolling chassis I have, so the diff must fit if I can find it.

[red90]

Pull a halfshaft and see what you are dealing with. It takes 30 seconds.....

Most RRCs are 10 spline. All diff centers are interchangeable. You just need the same spline count. If you plan on going off road, avoid any of the 2 pinion diffs.

[rezdiver]

I believe all RRC were 10 spline except 1994 and 1995 which were 24 spline, all discos were 24 spline. someone correct me if i am mistaken.

If its the parts you got from me, they would all have been 10 spline 3.54 diffs, i think the parts were from 1991 and 1992 range rovers..

[Greg S]

Shafts are all out a long time ago, that's how I know I have axles with the right spline count, I just have to find the diff that matches the 24 spline RRC rear axles I have. And yes, they are the ones from Reza. The diff in my 90 IS the four pinion military one. But I can't understand how anyone could call them stronger. I just broke one on a flat piece of road with a Defender that has rarely been off road and hasn't got enough miles on it to be worn out yet. My 109 has had a H*!! of a lot more abuse than this 90 has ever seen and it has the much more wimpy 2 pinion 10 spline diff that gives many tens of thousands of kilometers between diff/ axle problems.

Funny thing is, I was really glad to see this diff in the 90 and felt elated that I'd never have diff or axle problems again. ha ha A few short month later---

[Greg S]

(egg on face) Here is a general notice going out! Don't believe anything I say! Seems I'm full of "it".

The axle I found in the barn with the 24 (23?) spline is not out of the RRC or at least not out of the rear. So my search in the barn for the diff didn't go far. That being said, will a RRC pumpkin and axle shafts c/w drive flanges, simply bolt onto the D90 giving me a ten spline inner but get me rolling again? The overall width is the same isn't it?

[HeadDamage]

No... the drive flange bolt pattern/measurements and shaft lengths are likely different. I know that my RRC shafts will not fit my exmil 90 drum rear axle.

The 4 pin diff center is much stronger than the two pin. Yours must have been set up wrong or really abused.

[red90]

You did not break the diff.... You broke the pinion. That is something completely different. Keep the 4 pinion diff along with the HD 24 spline axles you should have with it.

Replace the Ring and pinion. You can swap the 4 pinion diff into one of the other diff centers that currently have the 10 spline diffs. You only need to set backlash and all should be well.... I would change the side bearings though as it is quick and easy.

As HD states, you need Defender shafts from that era for the correct length.

[HeadDamage]

Sorry, missed that it was the pin shaft. The ring and pin gears are the same for either 2 or 4 pin diff centers. Note that I'm using the term "pin to describe two different things which is likely confusing ;)

[Greg S]

It's all sounding like things will work out. I have Dixon sourcing a pinion for me and if all else fails I can cannibalize one of my old third members. The ring and pinion don't have to be a matched set? Yes, I know 46 and 13: but not machined as a matching set?

Thanks for the information.

[rezdiver]

i think if they are used components then they should be a match set because of wear pattern.
if you are going to break it again then it really doesnt matter does it. :wink:

[red90]

Yes, if used, they should be kept as a pair. If you have a good used 10 spline center, you can swap in the 24 spline diff to it. It is very straightforward as you do not need to setup pinion height and preload. Just bolt in, adjust backlash and it should be good.