Identifyin Diffs

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Dorset VogueSE

Dorset VogueSE

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In the petrol station - thanks to the supercharger
I seem for some totally unknown reason :rolleyes: I seem to keep killing rear diffs in my Disco.

Seems strange that I have never done a halfshaft yet, but diffs just collapse at the first sign of a bit of hard work.


Now I have seen/read about 2 pin and 4 pin diffs...............

My questions are;

how do you spot one from the other?

Is one better than the other - in terms of strength, better design etc,

will the better one (whichever it is) fit in the rear axle of my Disco 1

I'm currently after another one after last weekends trip on the plains and will look for the best to fit (without going to the expense of lockers etc).

advice please............................
 
one has two more pins than the other.
The rover (2pin) type diff comes in 10 or 24 spline, 3 or 4 bolt drive flange, 3.54 ratio and imperial or metric.
4 pin is betterer. The 4 Pin Diff assembly, Takes only 24 spline halfshafts, will fit 90, 110 front, Disco I or II & Range Rover Classic motors.

In fairness, i dont think its a pin, as such, it is how many bevel (planet) gears run inside the ring gear.
All P38A differentials fitted into the rear of the 4.6HSE incorporate the 4 pin diff, if yu can get a couple :).
 
said website yields this:

"In many applications, 2 pin differentials are not up to the job or in simple terms, not strong enough. They are perfect for the normal on road going vehicle and some gentle green laning or light off road use. Many of you reading this will know all to well that they break easily. The reason for this is as follows.

What is known as the differential carrier, houses the 4 gears. The gears do not move around while the vehicle is being driven in a straight line. They only move when the front or rear wheels are travelling at different speeds. They rotate around to allow the wheels to rotate at different speeds, hence the name, differential.

For normal road use, these work fine. But, when the vehicle is being driven off road, circumstances change.

For example, if one wheel on the same axle is allowed to spin much faster then the other maybe due to the vehicle being stuck, all of the torque is diverted into the centre of the diff where the gears do their job. They spin around very fast, throwing all of the oil off them which causes the centre pin to overheat and break due to poor pin and carrier design.

This often results in the gears being spat out of the diff pan and a few hours of repair. Not much fun in a cold muddy field.

Now, for those of you who wish to prevent breaking your differentials but gain no more torque, 4 pin diff will solve your problem. (Check out the 4 pin diff link). Limited slip or locker option will also prevent this from happening. "
 
Dorset VogueSE said:
I seem for some totally unknown reason :rolleyes: I seem to keep killing rear diffs in my Disco.

Seems strange that I have never done a halfshaft yet, but diffs just collapse at the first sign of a bit of hard work.
Click to expand...

Do they all fail in the same way? Post pictures of the failed diff. That may help.

4-pin 24 spline is the strongest Rover option. Can be found in the rear of V8 90 CSW as well as the P38A. IIRC the P38 diff may not be a straight swap into an early casing. Imperial and metric differences.

Give me time, I'll see what else I can find/remember :)
 
andyb66 said:
Do they all fail in the same way? Post pictures of the failed diff. That may help.
Click to expand...


Generally yes, the last 2 have both failed on the shaft that supports the planet gears, this has ended with bits of metal going round being contated by bits that aint.

Lots of bits of chewed up gears an teeth in the bottom of the casing. The link provided to Crown Diffs seems to describe whats occuring.

I have still got to pul the current diff apart to see whats occured but the symptoms and noises indicate a similar failure to previous ones.

It would seem that the 4 Pin is the preffered option even though it requires a degree of work to get it in.
 
Thinking along similar lins myself for next year and thinking aloud so probably not coherent .. but is it possible to make the 2-pin diff into a 4-pin?

Is it a simple addition of gears, shafts and bearings, or is the carrier completely different? When I did my diff last time I simply replaced like for like without thinking about it much. Now I can see that next year when I get even larger tyres and use it more off-road then it's likely to break more, unless I can beef it up a bit first

Locking diffs are too expensive right now ...
 
Paul D said:
Thinking along similar lins myself for next year and thinking aloud so probably not coherent .. but is it possible to make the 2-pin diff into a 4-pin?

Is it a simple addition of gears, shafts and bearings, or is the carrier completely different? When I did my diff last time I simply replaced like for like without thinking about it much. Now I can see that next year when I get even larger tyres and use it more off-road then it's likely to break more, unless I can beef it up a bit first

Locking diffs are too expensive right now ...
Click to expand...


"You can fit the 4 pin diff centre to the 90/D1 diff casing but you need a new crown wheel and pinion, TBH100050"
"and the P38 diff isn't exactly reknowned for long life either"
 
Are you spinning up opposite wheels constantly making the diff center work hard? Ive neveer done a diff yet even with big tyres and quite a bit of abuse i would rarther reverse out try again than sit tthere spinning up wheels going nowhere. For comp use 4 pin is the way forward.
 
when you have put it back together do you use new half shafts?
my old series i did a v8 converstion had 2 diffs go and both went after i had broke a half shaft , a old machanic guy i know said the reason they went was because i fitted a single new half shaft.he says replace both with new as it unbalances the diff (both times the planet gears broke up)
 
buckshot said:
when you have put it back together do you use new half shafts?
my old series i did a v8 converstion had 2 diffs go and both went after i had broke a half shaft , a old machanic guy i know said the reason they went was because i fitted a single new half shaft.he says replace both with new as it unbalances the diff (both times the planet gears broke up)
Click to expand...


Cant see any reason to fit 2 new shafts unless you have stressed the one that didnt break beyond its limits you will usually see some twist in the splines (I had a britpart shaft do this) and or its mega worn.
 
jai_landrover said:
Cant see any reason to fit 2 new shafts unless you have stressed the one that didnt break beyond its limits you will usually see some twist in the splines (I had a britpart shaft do this) and or its mega worn.
Click to expand...

well only saying what this old guy said he was a pretty hot machanic he balanced and tuned racing engines for years (spoke to a few peeps he'd tuned engines for and they all said he made a vast improvement )
 
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