Thread: Life of Puma Rear Diff's

Originally Posted by wrinklearthur

Hi Bill

I run a 110 Defender with a Salisbury fitted with maxi drive axles, mainly for the heavy towing that I do.
With the axle housing tubes, I have noticed that in heavy going some have broken those tubes where they enter the diff centre's cast housing.
Is there a proven way to strengthen that weak point?
.

Greater wall thickness - common method used for the similar Dana 60's in USA.

They also bridge over the cast centre, but normally that is to suit modified upper links.

Not disregarding what Bill said, and a mate of mine went Rover type on his heavy portal custom because he could laminate and strengthen a rover housing easier than a Sals, plus more clearance, But remember the total number of Sals out there doing there thing and total number of casing failures.

I think we are getting away from facts and reality a bit. What some do with their trucks is not what many do.

I have a MD locked and loaded Sals in my 110, I have 65-1 low range. I tow 1.8t 80-90% of the time, I have done a fair amount of medium 4x4ing. No signs of failure.

I know Rick has a heavy 130 that is laden most of the time, it is 98 vintage and still going fine Sals wise.

I think we need to sort/worry about the P38 before the Sals.

And again, If you feel worried about any rover stuff, Just get a Sixty9. This is a full new custom housing by RuffStuff Specialties, The Center casting section is made by JRat Offroad. This makes a D60 into a removable 3rd with Fab'd housing. By nature of the castings, you can set it up either hi or low pinion. It has massive carrier bearings. You can mod a D70 gearset to fit inside it. You can run 35 and probably even 40 spline axles. At 35, you will need custom stub axles new bearings and modded hubs. At 40 you may not be able to run LR rims due to the sheer size.

Or any number of full spec Ford 9 inch fabed housings, with upgraded castings for the 3rd, HD race spec gears carriers bearings etc.

Or the custom desert racing 10inch gearset...TT's are winning on these

Even the big 14b now has been customed into a removable 3rd...

Or just get Steve Gresner (sp) to build you some custom D80/Rockwells....he does them for mud racing/jumping trucks with over 1000hp....I think they will just be ok in a 130

Originally Posted by uninformed

So back to reality. IF you have a Rover diff with Ashcroft locker carrier and a P38 type diff with Ashcroft Locker carrier, what is the weak point?

R+P....lets say both are stock OEM 3.54....how much difference is there?

The P38 type is thinner, but the carrier has a larger shoulder to help this. The pinion is short and bearings close together but is this a real problem?

The close spacing of the pinion bearings is the major issue. Bearing loads are higher, deflections are greater so tooth alignment is adversely affected and shifts the tooth load to a short section of the teeth, instead of distributing it across the full tooth width.

Really for those that are now having problems with them it is mostly set up as they are failing in road type driving....If it were due to off roading or overloading and finding the limits then yes a full upgrade is needed, but is it?

I do wonder for those that have had more than one replaced under warranty, is it a matter of the dealership workshop just getting a complete 3rd out of a box and fitting it? in which case, the factory bad set up would be finding its way back in the vehicle....

Have materials used been changed/got worse in the last 2-3 years???

Are people having problems with the Rover fronts in their "Puma's"?

Originally Posted by rick130

So easy to fix compared to making a decent diff out of a Rover rear.
Shaving it doesn't take that long or is very hard.

Having said that I'm impressed by the bracing and gusseting on 130man's ex Telstra 130 bigcab Rover diff.

Telstra were pulling Sals axle tubes by grossly overloading their 130's so LR retrofitted Rover rear diffs that look like they came out of a Desert racer.

BigJon's seen them as most came from up where he used to work.

IIRC Dave Ashcroft said the reason Land Rover replaced the salisbury with P38 style diffs was because they could easily make the housing stronger for the military Wolf.

Btw, at some point all Land Rover housings have failed. I have seen stock ones on stock trucks cracked. (these housings were kept as proof )

housing flex is another reason R+P fail.

Ruffstuff Specialties is coming out with a bolt in HD front Rover housing.

John are the pinion bearings on the P38 type bigger or wider than those on a Rover type?

Originally Posted by rick130

Here's the modified Rover housing.

I can't recall who did this, John posted or re-linked the the photo's, he'll remember.

I think you had to weld the ring onto the housing and I'm guessing a pipe cap front cover ?

The mod was done by another member. My only contribution was some measurements and suggestions, based upon stuff I had at hand and because I have a hybrid front axle that uses a H233B high pinion centre with ARB in a landcruiser 60 series rear housing with landcruiser 105 series front halfshafts and Longfield 80 series cv's with 105 series hubs, etc. All stock parts if it should break anywhere.

Edit: those pics of rover housing, most of the cuttout is to clear the carrier bearing housing - the bearings are plenty large enough Serg, widely spaced in a strong housing. The ring gear/crown wheel is between 9" and 9-1/4" and stock gears are good quality.

The spacer in the last pic below is to be welded to the rover housing. With a little work a jig could be made to locate on the rover housing (after removing diff) so new bolt holes can be drilled and to allow accurate marking where to cut the flange. After cutting, bolt the Nissan diff with the spacer and weld the spacer to the housing to compensate for the material cut out. Those pics were just a trial to prove the concept and the flange was cut out of an old nissan housing, then machined to the required thickness.

I believe recent ARB's allow 80 series side gears to fit H233 lockers, so that opens up the possibilty of fitting rovertracks (forgot Keith's new business name) halfshafts and cv's.

Originally Posted by wrinklearthur

Hi Bill

I run a 110 Defender with a Salisbury fitted with maxi drive axles, mainly for the heavy towing that I do.
With the axle housing tubes, I have noticed that in heavy going some have broken those tubes where they enter the diff centre's cast housing.
Is there a proven way to strengthen that weak point?
.

Does your Defender have a Boge load leveller fitted Arthur?
One of the many things that convinced me that LandRover engineers were/are amatures is that they didn't specify an increase in tube wall thickness when the axle was widened 6'' over the previous series 3 dimension. Not only that, but they also fitted a Boge unit over the centre to impose a greater bending load on the assembly.
Having said that, the majority of broken axle tubes I've seen were off Perenties, and they don't have Boge units fitted.
I was talking to Mal Story (Maxidrive) years ago, and he told me that he didn't believe thicker walled axle tubing was the answer, because he reckoned the casting would break. Not sure about that though. This would certainly apply to the early Salisburies fitted to late series 2As, but the ribbing of series 3 and 110 castings were significantly more substantial, and at any rate the FC101 axle tubes are very thick and I've yet to hear of their castings failing.
A bridge as John suggested would be easier to do than retubing the axle assembly.
Bill.

This all said gentlemen, I have tallied up the total kilometres I've done in Land Rovers (early R6’s and Defenders) over the years (boring habit of logging all fuel an associated kilometres/miles) and the grand total to date with my current Puma 90 is 1,424,564km. While I've broken various bits over the years (more often my fault than the car's), ALL of these kilometres were done on 100% standard differentials.

Building roads in Central Africa I’ve towed water and fuel bowsers many hundreds of kilograms over the vehicles rated capacity/ability in the worst possible off road conditions and except for the odd snapped half shaft (and never while towing), I’ve never had issues with Rover or Salisbury diffs.

So, while manufacturers of aftermarket products will always slate OEM equipment, there is no substitute for “Mechanical Respect” for the moving parts of any machine. This includes preventative maintenance, regular oil changes (especially when there is a hint of moisture) and easing off the throttle when it's clear the car is not happy with what you are putting it through!

The golden rule of bush maintenance: The further you retrace the path of power (wheels, final drives, half shafts, diffs etc) the more complex and expensive the repair. Install bullet proof halfshafts and you will lose a diff. Install bullet proof diffs and you will eventually lose your gearbox...

The choice is yours...