Thread: P38a diff in 'fender problems

I could be totally off base here, but I seem to recall a rumour that the Defender went to the P38 style rear diff for cost reasons (what else ) as that is what is fitted to the Pommy army Wolf's.
The UK defence forces wanted an easily serviced rear diff with the same centre as the front to minimise spares inventory.

They didn't get it then. Poor pommy's.

I would suggest people examine the thickness of the crownwheel compared to the Rover diff, and you'll see exactly what I mean. It is about 40% thinner

i did just that when i was putting the detroit in! my front and rear gear sets ARE exactly the same as the old 92 diff center i have out of my s1 disco! i wanted to know this if i ever needed to use it as a spare gear set.


cheers phil

Originally Posted by discowhite

i did just that when i was putting the detroit in! my front and rear gear sets ARE exactly the same as the old 92 diff center i have out of my s1 disco! i wanted to know this if i ever needed to use it as a spare gear set.


cheers phil

Hi Phil, as you say, the 90 gets the rover rear end! I have a '05 90 as a customer and I'll have a good looky next time!! Sorry about that, but I was certain the 90 had a P38 rear like the 110.

JC

was told this when i bought it also, thats why i measured/compaired everything i put in it, that way i know what will fit in emergancy situations.
i was later told that the p38 diff was only in the US 4.6l versions and it had a 4pin diff? truth or not i dont know, and neither would LR

cheers phil

I think P38s had a 2 pin in the front & 4 pin in the rear didn't they?

Anyway, yes I was getting a bit nervous about diff noise in mine, when on 3.54s. The front, being swapped from my old disco, had about 400,000 kms on it. Never broke it, & this was the era for me of breaking County CVs every few months. Never the CW&P.

The diff noise proved to be the p38 rear, no backlash, worn through the case hardening. Couldn't be salvaged. That was with 80 or 90,000 kms up.

So yes I've gone to 4.11s. A retired engineer in WA had organised a batch, sold through one of the WA specialists, GBR, etc. I couldn't find out who made them, only "Europe". These are probably Mal's too.

Have been told before there's only a couple of places in the world who can properly make CW&Ps, one being in Spain.

I'm happy with the P38 rear now. The Salisbury is just too much of a plough in mud, & especially when the going gets tough in rockhopping. It's always the Salisbury cars that get hung up.

Regards
Max P

max,
what hi ratio and tyre size you runnin??
i was thinking about 4.11's but might go with an MD lo gear set??

cheers phil

The 4.11s & the MD 50% rockcrawlers multiply to a crawl ratio of about 75:1.. very very handy.

2nd low is about the same as 1st low is in standard form. 1st low, if you need it, is the same as winching speed, no more playing the clutch.

And in lo-lo you can stay away from the clutch when rockhopping. It won't stall, its like having an automatic. Without the torque convertor "windup" in an auto. You can walk it it lo-lo, or if a bit of momentum is needed, go up to 2nd or 3rd.

Ah, you asked about hi-range. I've got the D2 quiet gears, which are 1.2s. The 4.11s drop about 15%, going from 1.4 to 1.2 lifts it about 15%. So back to about standard on 32" tyres, just quieter. Put 35s on, & that lifts the gearing another 15%. My 35" all terrains are the most relaxed touring tyre. 110kph is about 2500 rpm on 35s, compared to about 3000 rpm on 32s.