donmacn wrote:

blackwolf wrote:

Yet Land-Rover says there is no problem.

I have an ATB front, rear and middle, so not really asking for myself, and it means I’ve probably not been paying attention. What’s the problem and what year did it start?

Geobloke - I’m fairly sure I have a front 110 diff - either the original off my car removed during an axle swap ca. 2010 or so, or the Td5 diff that was in the axle. If you were happy to pay postage you’d be welcome to it short or long term. Might tide you over?

I often think I should sell these but I don’t think they’re worth a great deal.

Hi Don. That is amazingly generous of you. Thank you. But... I am reluctant to fit a 2 pin diff back in to Miffy. I think the time has come for her to have a stronger upgraded diff. The irritating thing is that I know I have the abilities to build up the current diff with an ATB centre but without a workshop, vice, press etc it would be a challenging thing to do

Such is life... So the choice as I see it are between a 4 pin, an ATB or a locker. None of which are cheap, but all of which are significantly stronger than the 2 pin diff.

blackwolf wrote:

The problem started in 2007 and is simply that the Puma engine is too torquey, probably in combination with an excess of torsional vibration, for the traditional two-gear differential especially on the heavier variants (110 and 130). LR recognised this and fitted the four-gear P38 diff at the rear (cheaper than the Salisbury diff) but left the classic feeble two-gear Rover diff at the front. When these started breaking LR designed a four-gear version of the Rover diff and ostensibly started to fit that in the front axle of 110 and 130 vehicles (IIRC from about 2012 onwards), however there is a mass of evidence that many or most Defenders built thereafter still got two gear diffs long after LR said they didn't. LR also stopped supplying the two gear diff as a replacement part for broken front diffs in 110 and 130 vehicles, insisting on the four instead.

What actually happens is that over time the holes for the cross pin in the diff carrier elongate, and eventually the cross pin falls out causing the differential gears to lock up and disintegrate. If you are lucky, as I was, all that happens is that it becomes virtually impossible to steer (just as though you had engaged a front diff lock), if you are unlucky, the front axle locks up solid.

Two gear Rover and P38 diffs are not worth much, but are useful if you want to rebuild them with an ATB or air-locker. Four gear diffs, especially the Rover pattern used in the front of (some) LWB Pumas, seem to fetch daft prices. Four-gear P38 diffs are slightly less daft since they were used on some variants of the P38 Range Rover (I think the 4-litre V8 version used them F&R).

That is exactly as I understand it. The additional problems arise when engines are remapped and tweaked, such as a TD5. Such as Miffy. Mechanical dominoes... Add something to one end of the scale and something will happen at the other end.

I think that I have heard that some of the the rear P38 axles of 110s and 130s from 2003 were fitted with the 2 pin variant of the P38 differential. Although I have no evidence of that at all.

I think it is time to grab the endoscope and take a look as Miffy has a 2003 P38 rear axle.

The Rover 2 pin diff can also fail when the planetary gears friction weld to the pin leading to either the pin shearing or the loss of gear teeth. Miffy's first 2 pin diff failed due to a sheared pin. I do not know why her second diff has chipped a tooth just yet. That will be something interesting to find out if it would only stop raining

I do keep reverting to the thought of what is too much power or more to the point, what is enough power. The reason for thought is that my 1992 Tdi was modified and tweaked and just as rapid as Miffy but never ate a diff. She went everywhere and just kept off going day in day out off road or crunching motorway miles. I do wonder if half the problems vehicles have when off roading are down to too much power and the components of the vehicle working at the limits of their specs. In my mind more power is better but too much is not a good thing, so how much is enough????

Anyway... The time is getting close to when I am going to need to make a decision on this diff... Or do I get both front and rear diffs upgraded

Quote:

Once the vehicle was in service it evidently became apparent pretty quickly that the two-gear Rover diff was unsatisfactory in the front of Puma LWB vehicle, so the four-gear Rover diff was (quickly) designed

steveww wrote:

Salisbury axle on a Puma

geobloke wrote:

Well I had hoped with many fingers crossed that the chunk of metal in the above post was in fact something leftover from the previous differential explosion... But it is not to be...


Click image to enlarge


Click image to enlarge

That is one of the planet bevel gears and almost all of the metal that came out with the magnetic diff drain plug, shows you they are worth their weight in gold...

I had expected that maybe one of the planet gears circles might have become dislodged or the pin may have broken or become worn, but there is nothing I can see. Circlips are in position and the pins do not appears to have worn the casing. Very odd.


Click image to enlarge


Click image to enlarge

The ring gear looks good though, no obvious pitting or chips out of that.

What it does mean is that a new differential is absolutely needed now. It was worth buying the borescope though as it has allowed confirmation of the suspicion without dismantling anything. Plus it will be of great use in the years to come I have no doubt.

So on to a list of parts, order... get her fixed...

v8bob wrote:

https://www.defender2.net/gallery/albums/userpics/13912/normal_IMG_2825.JPG
If you talking about the half moon heat marks, then my new cv joints were like this.
I presume to do with the manufacture, or just a local heat treat process?

Yes I think you are right about it being caused during manufacturing as all of the CV images I looked at yesterday had the same heat marks, a hardening process perhaps.