Thread: Life of Puma Rear Diff's

Originally Posted by PAT303

All they need is to have the backlash set-up correctly,do that and they are fine.Like all things LR everyone has an opinion,the strongest from people who don't even own a puma. Pat

Well its the Puma owners who decieded to call it a Puma. As you know that is just the engine code name. The diff itself is also seen in P38's and other non Puma 110's. It has shown problems in the past and more so now. Yes set up is a very important part of the problem. But you can not take away from the design and materials. I have heard from a very reliable source that when they first saw them from the outside, hopes were high. When the opened them up they were soon disapointed. Carriers are week by design, Ring gear is thinner than standard rover type. The casting and the housing has the room for a bigger Dia ring gear, larger carrier bearings and pinon bearings. A built rover diff is stronger than a built P38/late 110 rear diff.

Originally Posted by PAT303

All they need is to have the backlash set-up correctly,do that and they are fine.Like all things LR everyone has an opinion,the strongest from people who don't even own a puma. Pat

Dave Ashcroft may not own a Puma, however he knows LR diffs better than anyone else.

For the puma diffs (unlike the P38 diffs) they may have let the work experience kid set them up, but they still have inherent design problems.

Originally Posted by ashtrans

the problem is the bearings wear a little and as they are so close together this lets the pinion move out of the correct meshing position and this causes noise,

it may well be fine for many more miles like this but I would advise to maybe put a new ring and pinion and timken bearing set in
this is a very very common problem in the late 110 rear axle, and the issue as I see it is that the diff is just too small, I like the idea of making a bolt in upgrade :

new ring and pinion, make the pinion 50mm longer, to get the bearings further apart, less leverage and load on them,
shortened rear prop, (salisbury may fit to keep it stock LR)
make new hypoid casing, about 1.5" offset, low pinion, loads stronger
35 spline 4340 halfshafts, (never break)
air locker as standard
new stub axles, machines hubs and new bearings due to bigger shafts
new 10 bolt drive flanges

You can spend half of that on an ARB and 24 spline HD shafts and the diff is just as weak,

what do you think ?

Dave Ashcroft

Originally Posted by isuzurover

Dave Ashcroft may not own a Puma, however he knows LR diffs better than anyone else.

For the puma diffs (unlike the P38 diffs) they may have let the work experience kid set them up, but they still have inherent design problems.

These 2003 on 110 / 130 rear P38a diffs are rubbish. Period. The inherent design is weak, and they aren't up to it.

I agree with the comment ashtrans made about fitting an airlocker and HD axles to them, basically a waste of time IME.

I just fit salisbury diffs to them now, end of issue.

JC

Hi,

as per the above post we have designed this diff and I see no reason why if we make it, it cannot be supplied as just a replacement diff with HD 24 spline halfshafts or as per the above spec with the larger diameter shafts (35 may be overkill) and stub axles, hubs and flanges to suit,

one further complication with either option is a new propshaft will be required as the diff flange will be further forward,

due to the bolt hole positions we are not able to bolt the diff directly to the axle housing, we will have to fit a steel adapter flange to the axle housing then fit the diff to this, this does have a further advantage though, with a slightly different flange and machine the diff housing slightly differently it will be possible to fit this same diff as a 'rover diff' replacement for the 110 front or 90 or disco,

hopefully as time goes on more people will recognise the P38 diff is not upto the job and demand will grow and we will get this into production,

Dave

Originally Posted by ashtrans

Hi,

as per the above post we have designed this diff and I see no reason why if we make it, it cannot be supplied as just a replacement diff with HD 24 spline halfshafts or as per the above spec with the larger diameter shafts (35 may be overkill) and stub axles, hubs and flanges to suit,

one further complication with either option is a new propshaft will be required as the diff flange will be further forward,

due to the bolt hole positions we are not able to bolt the diff directly to the axle housing, we will have to fit a steel adapter flange to the axle housing then fit the diff to this, this does have a further advantage though, with a slightly different flange and machine the diff housing slightly differently it will be possible to fit this same diff as a 'rover diff' replacement for the 110 front or 90 or disco,

hopefully as time goes on more people will recognise the P38 diff is not upto the job and demand will grow and we will get this into production,

Dave

Thanks Dave, a few q's for you regarding your design for a HD P38 diff:

The new R+P, is the ring gear a larger OD? is it thicker?

Did you end up doing a hypoid offset? If so Im guessing a whole new diff casting must be supplied?

why do so much mod on it which now brings it close to the Force9? or is it based of the same parts?

I would have thought that more sales be had in something that could be done well without getting to full blown, for 90% of Puma owners Id think 4340 or better 24 or 30 spline enough. Which again requires less mods.

I know that if you were to mod and install bigger bearings in them that would mean an exchange 3rd or a machine shop....But would that not be better than a whole new casting?

Dave, just do it! We can easily soak up $2K AUD supplying and fitting an appropriate salisbury to a Puma or late Td5 110/130, so your setup will retain good ground clearance etc and be strong enough so I for 1 would happily sell them in preference to an 8HA. In fact, I would fit one to my 110 (as I have several empty 110 P38a housings lying about now...) to gain some ground clearance back....

JC

Originally Posted by ashtrans

Hi,

as per the above post we have designed this diff and I see no reason why if we make it, it cannot be supplied as just a replacement diff with HD 24 spline halfshafts or as per the above spec with the larger diameter shafts (35 may be overkill) and stub axles, hubs and flanges to suit,

one further complication with either option is a new propshaft will be required as the diff flange will be further forward,

due to the bolt hole positions we are not able to bolt the diff directly to the axle housing, we will have to fit a steel adapter flange to the axle housing then fit the diff to this, this does have a further advantage though, with a slightly different flange and machine the diff housing slightly differently it will be possible to fit this same diff as a 'rover diff' replacement for the 110 front or 90 or disco,

hopefully as time goes on more people will recognise the P38 diff is not upto the job and demand will grow and we will get this into production,

Dave

Dave, a great idea. On the tailshaft idea don't worry too much, retubing is pretty cheap, and yes I agree 35spline is a bit of overkill, (A good option for people who like 35" tyres though...) and could you also utilise the same factory axles etc for a 'budget' version?, as these diffs are failing even with light use sometimes, they don't even last long enough to wear out factory axles and flanges so that would aid lower costings. Something to drop in to a standard housing using standard stubs , axles etc would be very attractive IMO.

I am waiting....

JC

Originally Posted by justinc

Dave, just do it! We can easily soak up $2K AUD supplying and fitting an appropriate salisbury to a Puma or late Td5 110/130, so your setup will retain good ground clearance etc and be strong enough so I for 1 would happily sell them in preference to an 8HA. In fact, I would fit one to my 110 (as I have several empty 110 P38a housings lying about now...) to gain some ground clearance back....

JC

and can we have a high pinion version for the front please ?

Would Dana 44 CWP's be strong enough for this, that'd save tooling costs.

I didn't realise there's an 8.9" version of the 44 too.

The Dana Spicer Max momentary output torque FT-lbs

• Low pinion Dana 44 30 spline............3460 [ft/lbs]
• High pinion Dana 44 30 spline...........4170 [ft/lbs]
• Low pinion rear 8.9" dana 44 32 spline..5340 [ft/lbs]