Blew my Diff .... :(

[mike_beecham]

Well...
I have a collapsed bearing in my rear diff (02 Defender). If anyone has a spare one in their back shed....yell out!

Did it in Dargo yesterday. No - l wasn't being silly! This is the second Rover-style diff l've had die on me. The last one was on LR as was under warranty. Not so lucky this time.

Mike

[rangieman]

That would be a p38 type centre , If it was a rover one id have a spare in Lang Lang your more than welcome too;)

[mike_beecham]

Well that is a bloody pity.....

[uninformed]

unless of coarse he has a 90 ;)

If it is a 110/130 then yes the P38 type diff. Since you have done 2, I would look into Ashcrofts HD replacement diff for this type.

[mike_beecham]

I have only done one in my current Defender.
I am not THAT rough!

[Drover]

I've got one out of SVX 2008 Puma. 40,000k's quite no noise, no faults.

Spare as I fitted the Ashcroft HDP38, before anything went wrong.

PM with an offer if your keen.

Cheers
Grant

[Barra1]

unless of coarse he has a 90 ;)

If it is a 110/130 then yes the P38 type diff. Since you have done 2, I would look into Ashcrofts HD replacement diff for this type.

Or a Salisbury replacement. After doing 3 diffs I'm glad I took this option especially after more than 120,000 kms without further rear diff problems.

I hope the person who signed off on putting the P38 diff into a Defender has a thousand fleas in his bed, starch in his underwear and no hot water in the morning.

[Hall]

Well Dargo has claimed another. I too have had a major mechanical failure near Dargo a couple of years ago. So are you with RACV or could you still get it home?
Cheers Hall

[uninformed]

I have only done one in my current Defender.
I am not THAT rough!

I can only go by the information in your posts, in your first one you said you had "done 2 Rover style" Since you thought the P38 was a Rover type diff, I took that as being the second diff in this vehicle…..

[noogie]

[QUOTE=Barra1;2051644]Or a Salisbury replacement. After doing 3 diffs I'm glad I took this option especially after more than 120,000 kms without further rear diff problems.
QUOTE]

Yep I gotta agree. Bite the bullet and do the salibury transplant.
You will save money in the long run.I did the swap over a year ago and it's just a good feeling you've got an exceptionally strong rear diff. While ya at it throw in a maxi drive locker and hd axles&flanges.
:D

[Drover]

If you are going to spend the extra $$$, then Ashcroft's HDP38 complete centre ( with air locker ) is your best option.

Easy fit up as it bolts straight in, strong as a Salisbury if not stronger, maintain your ground clearance, it's brand new of the shelf (won't have hundred's of thousand km's on it) and dollars will be within the ball park for Salisbury replacement.

Just my thoughts......

[djam1]

Bold statement


strong as a Salisbury if not stronger,
...

[uninformed]

Bold statement

maybe he is taking into account housing strength?

They are both good options, For me if I didnt have the Sals already, id have to do the complete cross pricing very carefully, as Id probably prefer the Ashcroft P38. Reason being: better housing, better ground clearance, easy strong enough for what we do. Shafts, stubs, hubs etc are going to be same so no difference there.

If the owner already has the P38 type, it may be cheaper to just go Ashcroft??? What is the Sals sources isnt set up for ABS? does that complicate things??

[voltron]

Can someone state what the cost of the Ashcroft HDP38 with locker is please??

[isuzurover]

...strong as a Salisbury if not stronger, ...

:D:D:D:D:D:D:D:D:D:D:D:D:D:D:D:D:D

That may be one of the funniest things I have read all year.

[Bush65]

I give Drover the benefit of doubt and assume he meant what Uninformed alluded to, which I have little argument with except the it hasn't been proven, one way or the other, that the P38 style housing strength is greater than the HD Salisbury as fitted to 130's.

Taking Drover's words literally, it was in reference to "Ashcroft's HDP38 complete centre ( with air locker )", which is so obviously far from true. So I think probably just some exuberance due to Christmas spirit, or the like.

Up to that claim it was good advice.

[Drover]

Com'on fella's,

Enough of the banging on about the attributes of the Sal's.

The new Ashcroft HDP38 is a custom developed entirely new new centre.
Hy-Pod gear design, extra 75mm spacing on the pinion gear, Ashcrofts locker (2280 unit sold zero failures), P38 housing.

It's okay to call the sal's as stronger.....but where is your back up ?

[Sitec]

It's okay to call the sal's as stronger.....but where is your back up ?

The front diff and CDL... :D :wasntme: (You'll never need it with a Salisbury rear!!.... Sorry!) :)

[uninformed]

Com'on fella's,

Enough of the banging on about the attributes of the Sal's.

The new Ashcroft HDP38 is a custom developed entirely new new centre.
Hy-Pod gear design, extra 75mm spacing on the pinion gear, Ashcrofts locker (2280 unit sold zero failures), P38 housing.

It's okay to call the sal's as stronger.....but where is your back up ?

I think you mean "hypoid" and Bush65 may just be well qualified to comment on these or any diff/gear design ;)

[isuzurover]

Com'on fella's,

Enough of the banging on about the attributes of the Sal's.

The new Ashcroft HDP38 is a custom developed entirely new new centre.
Hy-Pod gear design, extra 75mm spacing on the pinion gear, Ashcrofts locker (2280 unit sold zero failures), P38 housing.

It's okay to call the sal's as stronger.....but where is your back up ?

Ashcroft themselves admit that they were constrained by the (poor) geometry of the P38 diff. (polishing and turd spring to mind).

The sals is far from the world's best diff, but it is a heap stronger than any rover size diff, and there are thousands of upgrade options.

To make it simple for you:

Rover vs Sals (the P38 diff is physically the same size as a rover diff).
https://www.aulro.com/afvb/images/imported/2014/11/201.jpg
http://www.lrfaq.org/Series/images/RoverVsSalisburyDiff2.jpg

(I previously posted a pic of P38A vs rover diff centres side by side in another thread).

The Ashcroft design is great, but at the end of the day it is a custom design available from only one supplier. The sals is most definitely stronger, and has been proven over 55 years (including Dana 60 variants). Parts are available from thousands of suppliers worldwide.

p.s. the word you are looking for is hypoid.

[Drover]

Happy for ones more learnard than I to impart their knowledge :). ..... But always to benifit of all to hear your technical explanation for you statements.

The size difference is surprising, half the reason why it's know as the plough...lol

Oh and the saying is " polishing a turd.....":wasntme:

Merry Xmas all !

[uninformed]

Happy for ones more learnard than I to impart their knowledge :). ..... But always to benifit of all to hear your technical explanation for you statements.

The size difference is surprising, half the reason why it's know as the plough...lol

Oh and the saying is " polishing a turd.....":wasntme:

Merry Xmas all !

Ok, so it sounds like you made your comment not knowing what a Sals really is. As has been pointed out many times on this forum, it is an English adaption of the famous Dana 60. It shares many physical similarites in the diff centre itself.

It is Hypoid just like the new Ashcroft HDP38. So the questions you need to ask to have the HDP38 any chance of being stronger than the Sals are:

What are the hypoid offsets? (the distance from pinion centre line to ring gear centre line)

What size are the ring and pinions?

What are the size and spacing of the pinion bearings?

What size is the output spline of the pinions?

What size are the carrier bearings?

Are material type and treatment close?

Gear design, is one gear design better(stronger) than the other? And if it is the smaller of the two, is it enough to make up the differnce in size?

Cast housings, is one prone to deflection more than the other?

Merry Christmas

[rangieman]

Ok, so it sounds like you made your comment not knowing what a Sals really is. As has been pointed out many times on this forum, it is an English adaption of the famous Dana 60. It shares many physical similarites in the diff centre itself.

It is Hypoid just like the new Ashcroft HDP38. So the questions you need to ask to have the HDP38 any chance of being stronger than the Sals are:

What are the hypoid offsets? (the distance from pinion centre line to ring gear centre line)

What size are the ring and pinions?

What are the size and spacing of the pinion bearings?

What size is the output spline of the pinions?

What size are the carrier bearings?

Are material type and treatment close?

Gear design, is one gear design better(stronger) than the other? And if it is the smaller of the two, is it enough to make up the differnce in size?

Cast housings, is one prone to deflection more than the other?

Merry Christmas
Thats all good but the sals on the other hand has one very important weakness which is a show stopper which is well documented that the rover diff does not suffer from:p
Housing failure :eek:
And at the end of the day nothing is inderstructable
Ducking for cover :angel:

[Sitec]

Thats all good but the sals on the other hand has one very important weakness which is a show stopper which is well documented that the rover diff does not suffer from:p
Housing failure :eek:
And at the end of the day nothing is inderstructable
Ducking for cover :angel:

Only when stupidly overloaded by muppets... and from what I've seen on the net only a few that have made good coverage because of the rarely of it happening... How many bent Rover casings have we seen on off road racers etc... Hundreds, but because its common, its no longer of interest... I've had many a vehicle with Salisbury's, the current one having 2, and I've never broken one. (Tho that could be about to change!! :twisted:). I've broken 60% of the Rover axles I've owned! :)

[uninformed]

Thats all good but the sals on the other hand has one very important weakness which is a show stopper which is well documented that the rover diff does not suffer from:p
Housing failure :eek:
And at the end of the day nothing is inderstructable
Ducking for cover :angel:

Seriously, how many Sals housings have failed, world wide? Consider that they are not just in 110/130s, but in series III 109, Stage 1, One Tons, 101s and I think even in FCs?

I would bet money on more stock Rover assemblies causing a "show stopage" than Sals...

[djam1]

Don't see many posts with people saying I broke my Salisbury diff housing on the weekend.

They certainly can fatigue and break eventually I know one of the prime examples in a post on AULRO has done 800 000 ks of extreme work in Africa.
More disturbing was the one in the Kimberleys.

[rangieman]

Seriously, how many Sals housings have failed, world wide? Consider that they are not just in 110/130s, but in series III 109, Stage 1, One Tons, 101s and I think even in FCs?

I would bet money on more stock Rover assemblies causing a "show stopage" than Sals...

Id have a broken Rover centre any day . At least with a stuffed rover centre the car can still be driven with a little bit of effort ;)
Look personly i like the sals but you guys seriously take it all too personal that a sals is undestructable which they are not :p

[uninformed]

Id have a broken Rover centre any day . At least with a stuffed rover centre the car can still be driven with a little bit of effort ;)
Look personly i like the sals but you guys seriously take it all too personal that a sals is undestructable which they are not :p

Never said it was, and personally have never been a fan of the housing. Mainly beacuse of its shear size, weight and design. I have no fear about it failing in my enviroment either though. Maybe we are not saying that it is indestructable, maybe we are just trying to bring fact to these threads…

So on that note here is a little info I can add:

hypoid offset: Ashcroft HDP38 1.5 inch or 38.1mm, Sals 8ha 1.125 inch or 28.575mm

What does that mean, AFAIK, the greater the offset, the larger the pinion head becomes for a given ring gear dia. This means more tooth contact in mesh with the ring gear, which is stronger. I think it makes the pinion teeth physically bigger which is also stronger. But there is a trade off, the larger offset creates more thrust load (I think), is less effiecent (more heat build up) and I think weaker in reverse?

Ring gear dia: Aschroft HDP38 8.54 inch or 217mm Sals 8ha 9.75 inch or 247.65.

What does this mean, AFAIK the larger the ring gear dia, the larger the pinion has to be to suit. Since the Ashcroft HDP38 has a larger offset and the Sals 8ha a larger ring gear, we need a picture of both ring and pinions side by side to compare ;)

Ring gear thickness: Look at the picture Ben posted of the Sals, now compare that to the pics of Ashcroft HDP38 ring gear. In my mind a thicker ring gear is going to less prone to diflection. Of coarse how it is fastened to the carrier ie bolt size, number of bolts and bolt PCD will matter as well. Maybe thickness allows a different tooth design? (pure speculation on my count, but given too little meat in the ring gear and I think it could limit tooth design?

Pinion diameter: Not sure on either of these. There is more than one measurement ato consider. Inner bearing, outer bearing and output spline minor dia.

Pinion bearing spacing and size, carrier bearing size: (note, not just dia but width). Again I do not have these. If someone can add them Ill edit them in here. Sals and Rover type for the carrier bearings as the HDP38 uses a Rover type centre.

Happy for any of the usual suspects to correct any and all info I have posted. Infact I would not take anything I have said as fact until it is confirmed or corrected.

[Ancient Mariner]

Real men have 9 inches:o

[djam1]

I spent a lot of time on the Stuart Highway in the 1970s before it was sealed

The main diff housing failures were Ford 9 Inch:p

[uninformed]

Real men have 9 inches:o

look stop teasing us :p. I saw the pics of your own made custom Rover9s. Cant find the thread you posted them in?. Where did you source the ford 9 housings from? what ford 9 centres did you go with?

cheers
Serg

[uninformed]

I spent a lot of time on the Stuart Highway in the 1970s before it was sealed

The main diff housing failures were Ford 9 Inch:p

The axle housing of the cast diff housing?

what trucks were these in?

where the heavily overloaded?

[djam1]

Mostly F100s and the like generally not anymore overloaded than anything else in those days.
Housing failures

[Ancient Mariner]

Mostly F100s and the like generally not anymore overloaded than anything else in those days.
Housing failures
Do you think you could have a look at the pic of my F100 housing and tell me where they fail as have never seen that happen ? Plenty of Dana type in 150 and 250 but not the 9.375" Housing Pic under 9" fabricated diff post

Thanks AM

[djam1]

To be honest I probably couldn't it was a long time ago and I cant remember exactly where they broke but recall it being really common.
I think it related to where the tubes were welded to the centre part of the housing.
2 guys I knew in Alice were repairing them and I know it wasn't a difficult job to repair or strengthen them.
Really compared to a Salisbury it was dead easy to prevent it from happening.
I commented to a mate about it the other day while looking at his Ford ute and he was aware of it so it wasn't purely a NT phenomenon.

[djam1]

I know that this is a Pajero but it was a similar scenario to this

[uninformed]

I finally found AM's thread on his "Rover9s" as im calling them (ford 9 diff and housing custom built with LR hubs and bracketry) :)

http://www.aulro.com/afvb/isuzu-landy-enthusiasts-section/162331-diff-ratios.html

[noogie]

Thats all good but the sals on the other hand has one very important weakness which is a show stopper which is well documented that the rover diff does not suffer from:p
Housing failure :eek:
And at the end of the day nothing is inderstructable
Ducking for cover :angel:

When you say housing failure do you mean the back plate?
If so, get yourself an ARB rear cover.
Bloody strong bit of kit.

Love my sals

[n plus one]

When you say housing failure do you mean the back plate?
If so, get yourself an ARB rear cover.
Bloody strong bit of kit.

Love my sals

http://www.aulro.com/afvb/technical-chatter/175745-salisbury-diff-housing-failures-9.html

See post 87.

[rangieman]

When you say housing failure do you mean the back plate?
If so, get yourself an ARB rear cover.
Bloody strong bit of kit.

Love my sals
Here is a forum members broken sals like i said a show stopper = flatbed:cool:

[rick130]

Do you think you could have a look at the pic of my F100 housing and tell me where they fail as have never seen that happen ? Plenty of Dana type in 150 and 250 but not the 9.375" Housing Pic under 9" fabricated diff post

Thanks AM

They fail where the outer tube meets the centre section.

Had mine fail there numerous times and that was only with road use, for off road use they would need gusseting.

[Bush65]

The diff used in the Salisbury is way over strong for a Land Rover intended for the use that most here put them to.

There is no getting away from the facts about Salisbury downsides, e.g.


heavy
diff doesn't "drop-out" for major diff maintenance
large, which reduces ground clearance
too light wall thickness of axle tubes in the standard 110 version, if the vehicle will be driven over many km's of rough roads while overloaded. Note this is unlikely for Salisbury's used 130's as they have thicker axle tubes. The problem with the wall thickness is not the strength, they are comparable to rover axle tubes, but the stress raiser created by the sudden change in stiffness at the transition from the rigid housing to the more flexible axle tube, which can cause a fatigue failure.

The strength limit of a Salisbury rear axle assembly (leaving aside 101's for this post) is the 24 spline half shafts. If more strength is required 35 spline half shafts are readily available and a relatively easy up-grade, which many have done. The diff itself can have 40 spline half shafts, but then there are problems with the spindles and hubs, for no good reason (35 spline is overkill for most here).


For anyone to suggest that a rover diff has remotely similar strength to a Salisbury diff is ludicrous.


IMO, a suitable match for a Land Rover is somewhere in the middle ground between the rover diff and Salisbury diff.


The P38 diff should have been that, but someone stuffed up the design.


What Ashcroft have done to remedy that, will suit many people. IMHO, given 24 spline half shafts being the weak link, it is not unreasonable to suggest/argue that a P38 style axle assembly upgraded with the Ashcroft diff, will match the Salisbury axle assembly strength.



There are other diffs and axle assemblies out there in that middle ground. Ford 9" has been mentioned, but the list is long, given so many 4x4 wagons in the market place with stronger axle assemblies than Land Rover's.

[rick130]

Here is a forum members broken sals like i said a show stopper = flatbed:cool:

And the only way Rover could make the Rover housing stronger than the HD Sals was with extensive gusseting and bracing like an off road race rear end.

[Bush65]

And the only way Rover could make the Rover housing stronger than the HD Sals was with extensive gusseting and bracing like an off road race rear end.
Exactly.

This pic shows the strengthening of the Wolf rear axle housing.
http://www.aulro.com/afvb/attachment.php?attachmentid=70441&stc=1&d=1388019688

[130man]

Hi all, my ex-Telstra 130 extra cab's rear axle looks very like that in Bush65's photo. Does anyone know if they are internally improved, i.e. extra pinions etc? Cheers, 130man.

[isuzurover]

...


What Ashcroft have done to remedy that, will suit many people. IMHO, given 24 spline half shafts being the weak link, it is not unreasonable to suggest/argue that a P38 style axle assembly upgraded with the Ashcroft diff, will match the Salisbury axle assembly strength.

...

That could be simplified to: Both the salisbury and the Ashcroft hypoid p38 are stonger than the 24-spline half shafts.

[mike_beecham]

Hi All,
I have read all this with great interest (and amusement at times). What dif does my 02 TD5 have? P38 or LR?? Or are they interchangable anyway?

Can l fit a diff from a 2010 Defender?

Mike

[Bush65]

Hi All,
I have read all this with great interest (and amusement at times). What dif does my 02 TD5 have? P38 or LR?? Or are they interchangable anyway?

Can l fit a diff from a 2010 Defender?

Mike
Depends what type of Defender you have.

If it is a 90, you have rover diffs front and back.

If it is a 110 or 130, you have rover in the front, and either Salisbury or P38 style in the rear. IIRC 02 was the when the change over occurred. If it is a 130 and Salisbury it will be the heavy duty version.

But since you had a bearing failure then it is a odds on that you have the P38 style rear diff.

Edit, you can't easily fit the rover diff into the P38 axle housing, or vice versa. The Ashcroft upgrade for the P38 style, has a special diff housing made to fit the axle housing.

Edit 2, yes you can fit a diff from a 2010 Defender, as long as you have the right one. But remember the 2010 Defenders used the same weak P38 style diff in the 110 and 130 models.

It will not be an upgrade, so why not repair you diff with the failed bearing?

[mike_beecham]

Hi,

I have a 110 Wagon. My mechanic is fairly sure it is a bearing - but hasnt pulled diff apart.

So P38/Rover are interchangeable..?
I have sourced a diff from a 2010 Defender, 3.5 ratio (l assume that is standard). It is an LSD also - would that be right??

Thanks again,
Mike

[mike_beecham]

So a 2010 Defender has a P38 diff? Same as an 02 then?
I am just chasing definative answer - as no good having a diff l can fit!!!!

Mike

[bee utey]

So a 2010 Defender has a P38 diff? Same as an 02 then?
I am just chasing definative answer - as no good having a diff l can fit!!!!

Mike
You may have missed the bit where Bush65 said there were 3 different diffs fitted to the rear of a Deefer, depending on whether it is a 90, a 110 or a 130 and what year.


Depends what type of Defender you have.

If it is a 90, you have rover diffs front and back.

If it is a 110 or 130, you have rover in the front, and either Salisbury or P38 style in the rear. IIRC 02 was the when the change over occurred. If it is a 130 and Salisbury it will be the heavy duty version.

[uninformed]

And no good knowing the names if you dont know what they look like. If you knew what they look like, you would not be asking IMO.

Google image: Rover diff, P38 diff and Sals 8ha diff. Then compare to what you have in your driveway ;)

[Drover]

So a 2010 Defender has a P38 diff? Same as an 02 then?
I am just chasing definative answer - as no good having a diff l can fit!!!!

Mike


If your diff has an inspection plate on the rear of the housing, held on by series of bolts then it's a Salisbury.

If no inspection plate then it's a P38(110) or the Rover(90).

A 2010 diff centre will be a p38(110) or Rover(90), so interchangeable with corresponding model.

[isuzutoo-eh]

Hi,

I have a 110 Wagon. My mechanic is fairly sure it is a bearing - but hasnt pulled diff apart.

So P38/Rover are interchangeable..?
I have sourced a diff from a 2010 Defender, 3.5 ratio (l assume that is standard). It is an LSD also - would that be right??

Thanks again,
Mike

If it's a standard factory item it won't be fitted with an LSD.

[uninformed]

…. For anyone to suggest that a rover diff has remotely similar strength to a Salisbury diff is ludicrous.


IMO, a suitable match for a Land Rover is somewhere in the middle ground between the rover diff and Salisbury diff.


The P38 diff should have been that, but someone stuffed up the design.


What Ashcroft have done to remedy that, will suit many people. IMHO, given 24 spline half shafts being the weak link, it is not unreasonable to suggest/argue that a P38 style axle assembly upgraded with the Ashcroft diff, will match the Salisbury axle assembly strength…..



John, given that the arguement was based on the diff alone, I still think it a big call to say the new HDP38 stronger than a Sals.

I am in no way saying it a bad or negative thing, this HDP38. I think its great, but I do like fact rather than fiction.

[n plus one]

So a 2010 Defender has a P38 diff? Same as an 02 then?
I am just chasing definative answer - as no good having a diff l can fit!!!!

Mike

A 2010 110 will have a P38 rear diff. An 02 110 may have a P38 or it may have a Salisbury (can't remember the exact change over timing but it was around tgat time).

As others have said, if your rear diff has a bolt on rear inspection plate then it's a Sals, simple as that.

If your replacement P38 is LSD, then it has an aftermarket centre fitted, possibly an Ashcroft ATB or a Truetrac? Either way it's a good thing.

[mike_beecham]

Thanks all. I definately dont have a Sals rear diff. I realise this. I just wasnt sure if it was P38 or Rover.

P38 it is!

Thank you to all!!!!

Mike

[n plus one]

Thanks all. I definately dont have a Sals rear diff. I realise this. I just wasnt sure if it was P38 or Rover.

P38 it is!

Thank you to all!!!!

Mike

And for future reference, you have a Rover front diff.

I'd be interested in a few pics of the failed internals if you get the chance.

[Bush65]

John, given that the arguement was based on the diff alone, I still think it a big call to say the new HDP38 stronger than a Sals.

I am in no way saying it a bad or negative thing, this HDP38. I think its great, but I do like fact rather than fiction.
If you only compare the two diffs given:


similar material and heat treatment of the gears (a reasonable assumption)
similar precision in the gear cutting and assembly (a reasonable assumption)
similar stiffness/rigidity of the gears and their supports, so as to maintain proper alignment between the mating teeth

then the diff with smaller gears will not be as strong.

With material for gears the surface hardness of the teeth has the most influence on both strength and wear, providing the core material has sufficient toughness to support the hard case. This is why strong shaft materials like 4340 are not good gear materials. High performance gears are made from case hardening steels, which can have much higher surface hardness. Another problem with through hardening steels is distortion during heat treatment. High precision of the tooth profile is critical to gear strength/wear and distortion is unacceptable. The tooth profile of high performance gears are finished in special gear grinding machines after case hardening.

Gear tooth strength is based upon a large number of factors, but the dominant one is, the allowable fatigue stress in the fillet radius at the root of the tooth, vs the actual stress at the root fillet.

The allowable stress is determined from the material, the actual stress is determined from:


the tooth load
thickness of the tooth at the root
the stress raiser caused by the root fillet


The 'tangential tooth load' is a function of torque and gear pitch diameter. 'Real tooth load' also involves pressure angle and helix angle of the tooth, but for this discussion, I'll stay with tangential tooth load.

The general equation for torque is load x radius and from this the tangential tooth load is:

Tooth load = 2 x applied torque / pitch diameter

So clearly increasing the pitch diameter reduces the tooth load proportionally.

Thus for the same torque load, the clearly larger diameter ring gear (AKA crown wheel) and clearly larger diameter side gears used in a Salisbury diff will experience lower tooth loads than those in the P38 or HDP38 diff.

Ignoring the fillet stress raiser, the stress at the root of the gear tooth is a function of the load and the squared thickness of the tooth at the root. Because it is squared the tooth thickness has a great affect on the tooth strength.

The Salisbury diff has larger gear teeth than either the P38 or HDP38, made possible because of their larger diameter.

So even if the tooth loads were the same the larger teeth will have much less stress at the root. But when we account for the lower tooth load for the Salisbury, the stress goes down even further.

Note the Ashcroft HDP38 ring and pinion have larger teeth than the stock P38, and they also adjusted the pressure ratio on either side of the teeth to increase the root thickness even further.

The full strength of gear teeth can only be realised if the load is distributed uniformly across the width of the teeth. However the tooth loads, tangential and 'separating' will lead to deflection and loss of alignment, which is why you usually see teeth broken at one side. This is where the stock P38 design is very poor.

Ashcroft greatly rectified those design deficiencies as well as increasing the tooth strength with the HDP38. I expect time will show this diff will perform well in 110 and 130 Defenders, and the weakness will shift to the strength of the 24 spline half shafts, as it is with a Salisbury.

IMHO the HDP38 diff is a good upgrade for those with a P38 style diff, offering advantages over a Salisbury swap.

[mike_beecham]

Hi all,
Ashcrofts can supply a 'spacer' so you can fit the Rover diff in a P38 casing.

Is this an option? Work well? Anyone done it?

Link: P38 Spacer Ring - Ashcroft Transmissions - (Powered by CubeCart) (http://www.ashcroft-transmissions.co.uk/diy-rebuild-kits/p38-type-differential-rebuild-kits/p38-spacer-ring.html)

Thanks,
Mike

[isuzurover]

Hi all,
Ashcrofts can supply a 'spacer' so you can fit the Rover diff in a P38 casing.

Is this an option? Work well? Anyone done it?

Link: P38 Spacer Ring - Ashcroft Transmissions - (Powered by CubeCart) (http://www.ashcroft-transmissions.co.uk/diy-rebuild-kits/p38-type-differential-rebuild-kits/p38-spacer-ring.html)

Thanks,
Mike

No, the rover diff is even weaker than what you have in there already.

The 2 viable long term options are either the ashcroft hypoid conversion or a salisbury. Dave S picked up a NOS salisbury from LR cheap. not sure if they still have them for sale...

[mike_beecham]

No worries. Thanks.
Who supplies Ashcroft in Victoria???

[isuzurover]

No worries. Thanks.
Who supplies Ashcroft in Victoria???

Don't know, but I have always ordered direct from Ashcroft UK and received the items in a week or less.

[mike_beecham]

This may be a dumb question - am l just as well off to pull the diff centre out and have a Diff Specialist replace the bearings?

I realsie this is not an upgrade - l am not fussed however. We will trade this vehicle on a new 130 later next year. This is not a long term keeper so to speak.

Mike

[isuzurover]

This may be a dumb question - am l just as well off to pull the diff centre out and have a Diff Specialist replace the bearings?

I realsie this is not an upgrade - l am not fussed however. We will trade this vehicle on a new 130 later next year. This is not a long term keeper so to speak.

Mike

In that case yes. If the CW&P are OK, then just get a diff specialist to repair it.

[Bush65]

No worries. Thanks.
Who supplies Ashcroft in Victoria???
Les Richmond Automotive (Thomastown from memory)

[n plus one]

Les Richmond Automotive (Thomastown from memory)

They're quick on postage too, I got Ashcroft CVs off them the other day.

[tazd]

Ok so this has answered several questions for me. just hit 275k on my rover diff.
After having my sals rear diff with arb cover for sale and no interest its time to fit it to my 03 130. new cranked trailing arms and bushes, hubs, rotors bearings, calipers, and now to decide if i get the maxidrive axles now or wait a little while, as i can just drop them in.
Diff is open oil bath, only other thing is do i look for a diff lock??? suggestions?
was worried about the clearance issue but after doing the front diff a month ago just turning around in the drive its crunch time.

[110 Pete]

Well...
I have a collapsed bearing in my rear diff (02 Defender). If anyone has a spare one in their back shed....yell out!

Did it in Dargo yesterday. No - l wasn't being silly! This is the SECOND Rover-style diff l've had die on me. The last one was on LR as was under warranty. Not so lucky this time.

Mike

Hi Mike

If its your second, two words diff locker :P :wasntme:

Cheers

Pete :)

[n plus one]

A locker will strengthen the centre for sure, but it won't address pinion bearing issues - and that's what seems to be the issue in this case (not sure about the last time though?)

[frantic]

Ok so this has answered several questions for me. just hit 275k on my rover diff.
After having my sals rear diff with arb cover for sale and no interest its time to fit it to my 03 130. new cranked trailing arms and bushes, hubs, rotors bearings, calipers, and now to decide if i get the maxidrive axles now or wait a little while, as i can just drop them in.
Diff is open oil bath, only other thing is do i look for a diff lock??? suggestions?
was worried about the clearance issue but after doing the front diff a month ago just turning around in the drive its crunch time.

Surprised you didn't sell it:eek:
If your going maxi(hy-tuff) get a Detroit locker for the rear from lucky8 to fit the Salisbury. Set it and then it's right, no holes for hoses or wires. I have a Detroit with hy tuff in my sal and it has worked very well the last 3 years ,the only times I've noticed it is going around an off camber roundabout with to much pedal and when some :censored: put a nail in my rear tyre and it was 1/2 flat and it caused the tyre to skip going around a corner in the shops parking. That may have saved me from an accident as you could not see the tyre was flat unless you really looked at it, but it could have popped on the freeway home.

[mike_beecham]

Well,
Diff out and l cleaned the pan to find two bolt heads from the Crown Wheel in the base of the pumpkin. Some damage to the lip of the pumpkin to. (File that down).

One of the threads is still in the wheel BUT the other one is missing.....l am assuming it has prob been ground to nothing?!

When l turn the flange, it goers around fine for 3-4 turns THEN it gets very tight for a turn and a half.

Pics:

https://www.aulro.com/afvb/images/imported/2013/12/44.jpg (http://s1367.photobucket.com/user/WGAS1/media/IMG_1774_zpsc7789897.jpg.html)
Bolt Heads

https://www.aulro.com/afvb/images/imported/2013/12/45.jpg (http://s1367.photobucket.com/user/WGAS1/media/IMG_1778_zps63eac423.jpg.html)
Damage on bottom of pumpkin

https://www.aulro.com/afvb/images/imported/2013/12/46.jpg (http://s1367.photobucket.com/user/WGAS1/media/IMG_1780_zps0b6386e6.jpg.html)
Crown wheel


Is this a common failure for these diffs?
What is likely to be the issue problem with it (in terms of re-build)?

Thanks to everyone for their help with this.

Mike

[isuzurover]

...


Is this a common failure for these diffs?
What is likely to be the issue problem with it (in terms of re-build)?

Thanks to everyone for their help with this.

Mike

The cause is most likely incorrectly torqued or non-loctited bolts - are any of the others loose?

Check the crowhwheel and pinion teeth carefully for damage. It is likely the diff is cactus.

[mike_beecham]

I havent checked other bolts.
Dumb question - why does this render the diff un-serviceable?

Should l check the new one (2000kms old)???


Mike

[isuzurover]

I havent checked other bolts.
Dumb question - why does this render the diff un-serviceable?

Should l check the new one (2000kms old)???


Mike

The marks on the bolt heads are most likely from being crunched by the crownwheel and pinion gears. I would be suprised if there aren't heavy marks or chips on the gears - likely at the point on the crownwheel where it gets "stiff" to turn. Can you post a pic of the crownwheel teeth?

[justinc]

Well,
Diff out and l cleaned the pan to find two bolt heads from the Crown Wheel in the base of the pumpkin. Some damage to the lip of the pumpkin to. (File that down).

One of the threads is still in the wheel BUT the other one is missing.....l am assuming it has prob been ground to nothing?!

When l turn the flange, it goers around fine for 3-4 turns THEN it gets very tight for a turn and a half.



Mike


the above is a worry. the p38 diff suffers also from a thin crownwheel, ie easily forced away from the pinion and then teeth come off...the point is there may be some distortion in the crownwheel after the crunching episode, i would be checking it with a dial indicator for true before reusing that gear set.

jc

[slug_burner]

Check out the contact details on this e-bay link (http://www.ebay.com.au/itm/D2-S1-Range-Land-Rover-Discovery-front-rear-diff-4-bolt-flange-24-spline-/301051358236?pt=AU_Car_Parts_Accessories&fits=Make%3ALand+Rover&hash=item46180f2c1c) The seller is an Aulro member and will be able to send you what you need, he wrecks a lot of D2s and I am pretty certain they use the P38 diff, he will be able to confirm it for you.

[uninformed]

Check out the contact details on this e-bay link (http://www.ebay.com.au/itm/D2-S1-Range-Land-Rover-Discovery-front-rear-diff-4-bolt-flange-24-spline-/301051358236?pt=AU_Car_Parts_Accessories&fits=Make%3ALand+Rover&hash=item46180f2c1c) The seller is an Aulro member and will be able to send you what you need, he wrecks a lot of D2s and I am pretty certain they use the P38 diff, he will be able to confirm it for you.

AFAIK, D2 is not P38 diff in rear.

[mike_beecham]

Yeah all good.
I have a replacement diff (with 2000kms on it) to go in today. I will drop this buggered diff to my Rover mechanic, who does rebuild everything Rover, in the new year for him to look at.

Cheers,
Mike