Thicker rear diff crown wheel on T/C puma?

[1nando]

Hi guys,

So on the 20th of January my truck is booked in to get a Detroit rear locker and hte axles. The person installing it recomended i dont do the axles as they may cause issues to my rear crown wheel. They said your better to leave the standard axles and have them break instead of causing to much stress to the diff and potentially damaging the crown wheel on TDCI defenders.

This person (dont want to mention who) also told me that the post 2012 110 and 130 pumas fitted with T/C have a thicker crown wheel in the P38 as apposed to previous models..once he looked up my model he said: "you have T/C fitted from factory so your crown is the thicker type, you will be fine"......"some of the earlier models have a thinner crown wheel".



Has anyone heard this or throw some light on this being true or not?

I would assume this person knows a thing or two about defenders as hes fitted plenty of rear lockers in them over the years

[Marty90]

Hi Nando,
So a thicker CW means you'll be getting the HD axles? What's the point in getting a bullet proof diff and still have a weak point in the axles.

[1nando]

Hi Marty,

That was my thinking.

Until he looked up my model he was adamant that i should keep the standard axles. His theroy was that its a lot easier in the bush to rip out a busted axle and still be able to limp to somewhere for help as opposed to busting the crown and potentially being stuck with a busted rear diff.......this theroy does make sense but i wanted things to be as strong as possible.

[rangieman]

Hi Marty,

That was my thinking.

Until he looked up my model he was adamant that i should keep the standard axles. His theroy was that its a lot easier in the bush to rip out a busted axle and still be able to limp to somewhere for help as opposed to busting the crown and potentially being stuck with a busted rear diff.......this theroy does make sense but i wanted things to be as strong as possible.

In a deefer if you break a c/w just rip the axles out and drop the t/shaft off you go .;)
By the way id do axles if your upgrading the centre to a locker . This theory of having a fuse in my opinion is flawed when all we want is a stronger diff axle combo setup . Whats the point if you only half do a job:confused:
Sorry plenty of standard c/w and pinion`s with lockers and axles out there in realy tuff rovers ;)
I for one have and do run lockers with heavy duty axles and standard c/w and pinion`s. I have never had a problem if the diff is set up right . Mechanical sympathy is your best friend. Im thinking who ever you have chosen to do the job is not the right person sorry for such a job .

[1nando]

Hi Rangieman,

I am doing the axles.

He didnt want me to at first and then confirmed that mine had the thicker crown wheel and said it would be fine.....

Im just finding it hard to believe that the pumas came out with different thicknesses of crown wheel's

[Vern]

I have read that when an axle snaps at the detroit end it can take out the detroit therefore everyone upgrades there axles.
I'd doubt landrover would have 2 different thickness crownwheels as a factory option in the puma!
They do have p38 type and normal rover type.

[Beery]

I reckon it makes sense to have a designed weak point. Its really no different to a shear pin in a piece of machinery to protect expensive, more difficult to replace parts.

The drive flanges would be the ideal 'shear pin' in this case, nice and easy to replace, small enough to carry spares etc.

[rick130]

I reckon it makes sense to have a designed weak point. Its really no different to a shear pin in a piece of machinery to protect expensive, more difficult to replace parts.

The drive flanges would be the ideal 'shear pin' in this case, nice and easy to replace, small enough to carry spares etc.

Naa, bugger that, I'd much rather have everything engineered and built so I never exceeded the fatigue and failure limits with what I do.

FWIW KAM make two piece CV's and front stub axles with a machined groove to do what you suggest for comp vehicles where it is easy to exceed design limits.

[Beery]

Naa, bugger that, I'd much rather have everything engineered and built so I never exceeded the fatigue and failure limits with what I do.

FWIW KAM make two piece CV's and front stub axles with a machined groove to do what you suggest for comp vehicles where it is easy to exceed design limits.

Yeah fair point. You'd have to spend some serious money on the drivetrain though, probably not an option for many people who might only one day be unlucky enough to over stress the driveline.
That said, I'm considering 3 x Ashcroft ATB's this year haha

[rick130]

Yeah fair point. You'd have to spend some serious money on the drivetrain though, probably not an option for many people who might only one day be unlucky enough to over stress the driveline.
That said, I'm considering 3 x Ashcroft ATB's this year haha
Yep, agree, it gets exxy and so I've spent some time slowly building things as I think they should be.

Still haven't got to the front axle yet ! [emoji1]
At least the rear end, unis, t/case and front driveshaft have all been rebuilt/replaced/upgraded to where I want them, just don't ask how long it's taken.......

[Edit] oops, still have an upgrade to the Sals to go too. Have most all the bits, just other priorities over the last two years.....

[justinc]

Soooo lets break an axle at the differential end (which is where most seem to go/ twist off) and in this instance will take the detroit centre with it.... in my opinion mandatory axle upgrades with lockers the best thing. The p38 diff however, thicker crownwheel or not, ( not heard of this either ???) Is a piece of rubbish and shouldn't be in the defender .

Jc

[Blknight.aus]

when you're finished with that guy Ive got this browns gas generation system that ties onto a hiclone you might be interested in.

[ian4002000]

My 2012 130 has the P38 type rear diff and a standard type front diff.


Ian
Bittern

[1nando]

Blknight: That guy has a defender himself and has probably been working on them longer than the time you've spent out of your fathers testicles.....

[rangieman]

Blknight: That guy has a defender himself and has probably been working on them longer than the time you've spent out of your fathers testicles.....

Sorry if he owns a Defender does not mean he knows what he is talking about which he clearly does not !;)

[1nando]

He owns a opposite lock store and has probably seen more defender (any model) diffs than anyone else....

As a result i was very surprised to hear the "thicker crown wheel" spec on traction control pumas...

I would imagine with the amount of crown wheels hes seen over the years that he knows his stuff. Also d2 mentions something about the p38 rear diff being modified by LR on post 2012 models........might this be the difference?

Apparently when the puma diff was modified from a 2 pin to a 4 pin the crown thickness was thickened??
(source d2.net)

Someone here must know whether LR changed the crown thickness?

[Slunnie]

Here is something interesting...

This is from: DEFENDER2.NET - View topic - ATB (torsen) front and rear install (http://www.defender2.net/forum/topic13545.html)

Here is a Rover CW/P
https://www.aulro.com/afvb/images/imported/2016/01/644.jpg


Here is a P38 CW/P
https://www.aulro.com/afvb/images/imported/2016/01/645.jpg


And interestingly, here is an early type P38 CW/P (left) and a late type P38 CW/P (right)
https://www.aulro.com/afvb/images/imported/2016/01/646.jpg

[Blknight.aus]

Blknight: That guy has a defender himself and has probably been working on them longer than the time you've spent out of your fathers testicles.....

Care to bet your years pay on that?


FYI, I wasnt talking about the crownwheel issue, thats been a hassle since people have been trying to put 4.11s into 3.54 or 4.7s for the front carrier it was the other issue, actually the other 2 or 3 issues depending on which way you want to do it properly. (and your choice of deity help you if you want to try that on in for the sals and if you really want to talk about rear end strength did you know you can fit the td5 02 Sals 8ha with TC/ABS to the ford? did you then know that once you have that you have a whole new world of locker options?)

the other warning bell would be a workshop that supposedly knows rover stuff but doesnt know when ABS/TC became standard on the marque in the common version(s) (unless you have a 130/90 I dont know about)

I wont bother quoting other comments from the thread. But my primary concern has been mentioned twice prior to my post but hey, its your friend and your money

[Slunnie]

It would be interesting to know exactly why these things are more prone to failing when you would expect them to be stronger.

I have seen one in a heavy Defender with 35" Claws that was setup with a Maxidrive locker. This one snapped a maxidrive axle without damaging any of the diff. Thats not at all to say that it hadn't had CW issues in the past, but it seems that it could be setup to be strong without pegging etc.

[Blknight.aus]

because middle managers prefer to listen to profit margin maximising accountants and marketeers that will advertise something based on its one time capabilities rather than the engineers who would rather build something that delivers reliability.

[Slunnie]

because middle managers prefer to listen to profit margin maximising accountants and marketeers that will advertise something based on its one time capabilities rather than the engineers who would rather build something that delivers reliability.
I'm sure its cost them more at the moment. I'm sure there is more to it than this.

[1nando]

I agree...and ive had 3 rear diffs!

Ive also heard in the past that that bolts are bigger in the P38, whether this is true or not im not sure. I honestly believe these diffs are a "setup issue"....

[Brad H]

I thought I would ask this question as it is closely related to your discussion. My Defender 110 (2012 model with 80K on the clock) gets a whirring noise at around 80km hour in the back of the car and this goes when you get past 90+Km hour. It is now off warranty and I have taken it to a local mechanic (recommended by locals with Defenders). He (the mechanic) though it was the left hand back wheel bearings and these have been replaced. But this did not solve the issue. I suspect it is the diff. Has anyone experienced this before?


Happy for some input. Cheers! Brad

[1nando]

I thought I would ask this question as it is closely related to your discussion. My Defender 110 (2012 model with 80K on the clock) gets a whirring noise at around 80km hour in the back of the car and this goes when you get past 90+Km hour. It is now off warranty and I have taken it to a local mechanic (recommended by locals with Defenders). He (the mechanic) though it was the left hand back wheel bearings and these have been replaced. But this did not solve the issue. I suspect it is the diff. Has anyone experienced this before?


Happy for some input. Cheers! Brad

Does it make the same noise or worse when your foot is off the throttle?
If yes its more than likely the diff.

[Blknight.aus]

It might not be the diff, on other varients I've had similar noises turn out to be

the backing plate on the handbrake scuffing and ringing at certain speeds and it sounds like its coming from down the back.

a brake backing plate vibrating in harmony with an out of balance wheel.



if you can modulate the noise by applying and backing off power while maintaining speed it might be the pinion nut starting to come loose and the mesh is just starting to go a little out.

[Simon]

I have exactly the same thing in my 2013 110. Like a whine from the rear.

First was between 80-90, but now also sometimes around 30. Also seems worse when towing.

Can't modulate it by power up / down but can get rid of it by moving out of those speed ranges.

Dealer in Townsville reckoned rear diff and keep an eye on it (I was passing through). Now back in Sydney and have asked local dealer to look at it (warranty) as it's getting worse.

Simon

[Blknight.aus]

check the pinion for free play, if you can poke it in and out or wiggle it round thats a pointer to the problem.

as a short test its worth pulling the rear shaft and taking it for a very short drive (fully unloaded) with the CDL locked see what that does for the noise. Make sure you mount the handbrake drum properly or remove it.


it might also be the carrier bearings letting the crown wheel shift sideways, but Ive only ever seen one diff do that without lots of metal in the diff oil.

[Simon]

I wish I had the knowledge to follow your advice.

As a lad I had no interest in learning mechanics, not even an oil change. Something that is a regret to me in later life when I have the interest but not the knowledge

Simon

[Brad H]

Hi Guys, Some interesting comments. To answer some of the questions in the post. The whirling starts at about 80k and stops as you increase speed and visa versa. If you back of the throttle quickly is stops immediately but there is no clunking from the diff. As you increase speed again the whirling kicks in at 80K. I have done this repeatedly and no real clunking from drivetrain. The local mechanic I use is experienced with Defenders but he is unsure what it could be. I don't want to spend a fortune on trying to guess what it might be.


I will get him to look at the ideas you have come up with. Keep you posted.


Thanks for your help!


Brad

[justinc]

Almost certainly a differential noise and likely to be a failing pinion bearing. I have even seen a carrier bearing set fail in these diffs so badly that you could actually push the crownwheel away from the pinion a mm or so by hand....

Jc

[Blknight.aus]

I'm sure its cost them more at the moment. I'm sure there is more to it than this.

nahh, that just means the short term gains didnt last long enough for the long term loss to occur outside of warranty.

or alternatively.

So the managers listened to the accountants instead of the engineers, that just means 1. that the accountants were wrong and 2. theres probably a handful of emails going from engineers to managers with contents something like this

"you know when we told you that it was cheaper to just do something properly the first time and that the accountants were cutting too much out of it again and how you would describe it later as hindsight is 20/20 and we would say told you so? well...
1. Its only hindsight if
a, you didnt already have previous examples of ignoring these sort of facts costing money and
b, you werent provided the same sort of facts in this case.
If you have both of those its not hindsight its stupidity.
2. Told you so."

[Simon]

So it's finally being looked at by the dealer. Took it in 3 weeks ago and it wouldn't make any noise, so they replaced rear diff oil just in case that helped; nope, was whining within 10mins of me picking it up. Of course they were then booked out until now.

Took it back today and the tech guy agreed the whine was real, but "never heard that noise before, if it was the diff would expect it to be constant at all speeds". Also said perhaps the pinion but would start off looking for obvious wear where it shouldn't be.

Left it with them and got a call this afternoon. They greased the shafts but not cured. Then said it sounds like it is coming from both sides so suggest "as a first step" replacing brake pads (I might have misheard but I think they also said the disks). At my cost obviously....

Hmm, now why am I paying for fault finding by part replacement????

Tonight dug out service notes (Townsville) - rear pads replaced and brakes tested, all fine. The whine was there before then and was there after, and that dealer said could hear noise from diff when they put it on their rolling road!

May be an interesting call tomorrow. Don't mind them replacing parts, but at their cost if it doesn't cure the problem.

[Longtimer]

I had my MY14 90 serviced, non dealer, on Friday, and they changed out the oil in the front diff because it was black.....
It was golden 10K before that..... And it had all the bolts tightened on the centre as it had started to leak around it.

Now I am starting to wonder if through the centre being tightened into the housing, it is now sitting too far into the housing and wearing the splines on the shafts......
Your thoughts gentlemen???


I have 62K on the clock, so now I am wondering what's going to go wrong next.....

I suppose if it fails, it is still under warranty....

[Marty90]

It can only be tightened to where it's supposed to be:D

[4wheeler]

I had my MY14 90 serviced, non dealer, on Friday, and they changed out the oil in the front diff because it was black.....
It was golden 10K before that..... And it had all the bolts tightened on the centre as it had started to leak around it.

Now I am starting to wonder if through the centre being tightened into the housing, it is now sitting too far into the housing and wearing the splines on the shafts......
Your thoughts gentlemen???


I have 62K on the clock, so now I am wondering what's going to go wrong next.....

I suppose if it fails, it is still under warranty....

My 2013 Defender had the problem of discoloured front diff oil. I told the dealer at 18,000 km service the oil did not look clean considering the Km travelled. They suggested it had been contaminated but I told them the truck had never been in any water. I suggested shot axle seal or seals were leaking grease into the diff /axle case and mixing with the oil. The dealer disagreed and insisted on contamination.

Anyway, Defender was on holiday at the dealer again recently for a rear main leak and I told them the diff oil was off again. Only 22,000km then and no water work. They checked it and suggested that they thought it was probably leaking axle seals and they needed to be replaced! Now why didn't I think of that?

[El Rey]

Threads like this seriously make me think I should have a recording or video app running on my mobile phone during all conversations with mechanics.

1. Disagreement
2. Denial
3. Playback of evidence that you're right
4. Dealer turns nasty when caught out, if human nature is anything to go by
5. Owner still experiences the satisfaction of being right
6. Hmmm... maybe not a good idea then