Thread: Chinese diff locks

Originally Posted by Tikka7mm08

Very nice spring days. Off in the boat scalloping and fishing on Thu.

So my 90 Puma def has no Salisbury - does it mean not strong enough to cope with a rear locker?

AFAIK the Puma 90 has the rover type diff front and rear.
The 110/130 Puma has a P38A type diff in the rear.

Any locker will be stronger than the OEM diff(s).

Originally Posted by Didge

Nice to hear things are good over there.
Salisbury?:Not at all; just uses a different locker. Apparently, and this is only from what I've read on here, the Puma (Ford) diffs don't quite get enough engagement between the pinion and crown wheel (I'm just waiting to be howled down here) so under a lot of load they can distort and disengage. When you install a locker, those potential problems are, from what I understand, resolved.

I think you are confused between the rover and P38A type diffs. One of the biggest problems with the P38 type diff is the short pinion which is not fixed by fitting a locker.

Most of your comments apply to rover diffs as much or more than P38.

Some batches of Puma P38 type diffs also seem to have suffered from poor quality materials or poor assembly.

Quote:
I think you are confused between the rover and P38A type diffs.......
end quote.


Hi Isuzurover, this is one of the many threads I'd read that gave me that impression:

http://www.aulro.com/afvb/90-110-130...4708-life-puma rear-diffs.html

especially the following comment which is the 3rd response in that thread.

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They aren't set up correctly from new and thats what stuff's them,Ashcrofts had a photo showing the pinion barely meshing with the crownwheel on a brand new replacement center. Pat

I know nothing of either diff but have read many times that the Ford diff was relatively weak. Still learning

Originally Posted by Didge

Quote:
I think you are confused between the rover and P38A type diffs.......
end quote.


Hi Isuzurover, this is one of the many threads I'd read that gave me that impression:

http://www.aulro.com/afvb/90-110-130...4708-life-puma rear-diffs.html

especially the following comment which is the 3rd response in that thread.

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They aren't set up correctly from new and thats what stuff's them,Ashcrofts had a photo showing the pinion barely meshing with the crownwheel on a brand new replacement center. Pat

I know nothing of either diff but have read many times that the Ford diff was relatively weak. Still learning

There were (apparently) a number of P38 (in the rear of 110 & 130s since 2002 (?)) diffs that were incorrectly setup from the factory HOWEVER the main issue with them is that the pinion bearings are too close together - minor pinion wear consequently reduces C&P engagement significantly. Lockers don't fix this, but a longer diff nose (ie an Ashcroft replacement third member) does.

Not sure where the 'Ford diff' nomenclature comes from, but the P38 housing is (anecdotally) stronger than a Sals - in theory a Ashcroft converted P38 should be a very strong option.

90s have Rover diffs front and rear, 110s & 130s have them in the front.

Hope this is useful.

RR! see what ya started????
I only have an old girl with an old arb locker in the rear. Is the p38 housing the one that was in the p38a RR? (it was p38a wasn't it?).
I'm not even sure what the exact difference between a banjo and salisbury diff is. I mean I can tell the difference on my car obviously, but apparently there is a technical difference and not solely the shape. Is it something to do with the diff covers, the fundamental mechanisms?

Originally Posted by Didge

RR! see what ya started????

Good, innit?

Originally Posted by Didge

RR! see what ya started????
I only have an old girl with an old arb locker in the rear. Is the p38 housing the one that was in the p38a RR? (it was p38a wasn't it?).
I'm not even sure what the exact difference between a banjo and salisbury diff is. I mean I can tell the difference on my car obviously, but apparently there is a technical difference and not solely the shape. Is it something to do with the diff covers, the fundamental mechanisms?

Yes the P38 type diff is so names because it first appeared in the P38A RR.

As for banjo (rover and P38) vs salisbury, There are 2 main differences:

The rover and P38A diffs have an 8.25" crownwheel, the salisbury 9.75"

http://www.lrfaq.org/Series/images/R...sburyDiff2.jpg

The sals is hypoid, the rover is spiral bevel. Hypoid diffs are stronger (going forwards) as they have much more tooth contact between pinion and crownwheel for the same geometry and ratio.

http://lh5.ggpht.com/_EhOQGW2GHBg/TM...jpg?imgmax=800

In short, the sals diff centre is probably about 4x the strength of a rover or P38A

Wow, thanks Isuzurover - that's fantastic. I didn't realise the difference was so great. I knew Sals were "basically" indestructible but that photo makes it look like father and son.

RR! you're a funny man hehe

How much weaker are the rover front diffs then the Salis?