A couple of months ago my car developed what sounded like a whining diff. As I had replaced the rear not that many months previously it couldn't be that so I assumed it was from the front. There was a bit of up and down slop on the input and oil that did resemble metalflake paint so I figured that had to be it. Marty fitted new top and bottom ball joints to a spare front axle he had, I went to his workshop and we fitted that. On the way home it did seem to be much better and the front end felt much more precise so the ball joints had done the job. Over the last few weeks though, the whine still seemed to be there. I wasn't sure if it was me being hyper sensitive to it and do remember my missus once saying that it sounded like a bus and had almost come to the conclusion that it had always been there. The noise always seemed to be coming from the centre of the car. I'd changed the transfer case anyway and that hadn't made any difference so I was starting to suspect something in the gearbox. But dropping it into neutral didn't cause the noise to change and running it through the gears with the transfer box in neutral and it wasn't there.

Yesterday I decided to convince myself once and for all so crawled underneath and dropped the rear propshaft off. Took it for a run down the road and realised that it is most definitely the rear diff. What a difference with no drive through it, near silent just as I remember it! No noticale slop in it at all but something definitely isn't right inside. However, I did come very close to a major disaster. I got home, went to refit the propshaft and found the parking brake drum had almost fallen off. The countersunk screw that holds it in was on the last turn of it's thread and another half mile or so and the drum would have fallen off and shot out from under the car doing who knows what damage on it's way out to freedom. So if you are going to try running with no rear propshaft, make sure you put at least one of the nuts onto a stud to hold it in place.

A visit to Avenger 4x4 to pick up a replacement rear diff would seem to be my first call tomorrow. Unlike the front, the rear is a piece of piss to change......

I have never replaced a diff and am no expert, but wasn't there a discussion on the "other" forum about front and rear diffs being physically interchangeable but the teeth are cut differently? It yours has failed in just a few months it maybe the problem.

The original 300,000 mile rear diff had quite a bit of slop in it but was quiet so I swapped it with the one from the 130,000 mile SE. That stopped the clunk whenever I went from forward to reverse and I expected it to last for at least another 150,000. That is why I was convinced the noise was coming from the front. It's easy enough to tell if one has been changed before because the bead of silicon around the outside is a nice uniform size where it was put on by machine when the diff was assembled compared with it being all irregular where it has been put on by a man with a tube of RTV. So I'm 99% sure the one I took off the SE and fitted had never been changed beforel. Despite filling it with Millers synthetic gear oil, I suspect something isn't right in there.

The whine started off as a standard sounding diff whine but as the speed got up it turned into a howl and peaked at 70mph. I thought it was only audible inside the car until I went through a tunnel with the window open and realised that it sounded like a jet engine from outside! Avenger 4x4 supplied me with a warranted replacement for the grand sum of £60 and as I've got a slack day for work (and it isn't raining), I'll be out there changing it later today.

dave3d wrote:

I have never replaced a diff and am no expert, but wasn't there a discussion on the "other" forum about front and rear diffs being physically interchangeable but the teeth are cut differently? It yours has failed in just a few months it maybe the problem.

The front/rears are physically interchangeable, yes. I have a rear 4 pin diff in the front of '01. I put it in on the back of into from the 'other' forum where people said they were interchangeable - and this was before the discussion on the teeth being cut the other way, so going forwards, it is effectively running in 'reverse' (if it was fitted to the rear axle) all of the time.

That being said, I had swapped it before this was all discussed - and it's now done nearly 15K miles on it, and I haven't noticed any difference... All the whines I had before are still there (done UJ's, complete new front prop, brand new 4 pin rear diff that I got for a steal, replaced transfer case as the chain in my old one was stretched and skipped teeth under hard acceleration), so I've come to the conclusion that my whines are actually from the gearbox itself...

I'm coming up on a diff oil change again soon, so I'm going to take a good look at the filler plug and the oil that comes out to see if it looks like there is more than normal wear going on in there... I'm still expecting a second hand, 4 pin rear diff in the front to be stronger than the 2 pin one that Land Rover put in from the factory... all the rumours about the post '99 having a 4 pin front diff is a load of shite in my opinion... my front had definitely never been removed before and was original and I pulled a 2 pin one out!

Ashcroft supply 4 pin for the rear and two pin for the front, regardless of model year.

When pressed, they have no explanation as to why they don't make 4 pin fronts for the late models ...

I just fitted what they sold me, having little choice.

For completeness, only the 4.6 was fitted with a 4 pin rear diff, the diesel and 4 litre only got the 2 pin. But, having just come inside after taking her for a test drive, all I can say is, My God, it's quiet! The nose bearing on the one I took out had a decidedly notchy feel to it but the one I've just fitted turned nice and smoothly. What a difference though. I think all the other work I've done, on the incorrect belief that the rear diff couldn't be the source of the noise as I had only recently changed it, has tightened up everything. I can even hear the V8 rumble from the exhaust when I boot it even with the windows shut. Definitely 2 hours well spent.

For anyone wondering, it is a simple enough job. Sit the rear axle on axle stands and remove the rear wheels. Drain the oil from the axle and disconnect the propshaft from the diff (but it can be left attached at the front and suspended on a bit of string from the exhaust hanger to keep it out of the way). Remove the 6 bolts holding each hub to the axle and pull the hub and halfshaft out by a couple of inches. There's no need to even remove the brake callipers, they can be left in place as there is plenty of slack on the brake hose and ABS sensor wire. Undo the ring of nuts that hold the diff to the axle and pull it out. As Mr Haynes says, refitting is the reverse of the above.

Yeah, the rear is a nice piece of cake compares to the front... especially as the hubs have never been apart before!!

I think there is an option on the P38 front diff on the Ashcroft transmissions website to upgrade the diff centre from 2 pin to 4 pin - so I presume that they just fit a 'standard' front ring & pinion to the 4 pin centre... Extra £50 on top, plus apparently an extra charge if you then return a 2 pin unit - so I'm guessing somewhere in the £100 region on top to make the front one a correct 4 pin diff...

Also looks like they do 'HD' ring an Pinions in a 3.5 ratio (close enough to the stock 3.54) which are selectable for front/rear if you wanted to upgrade yourself just those components for a cool £195 an end!!

Wonder if it would tear itself in half if you only put the 3.5 on one end?!
:-)

Martyuk wrote:

Yeah, the rear is a nice piece of cake compares to the front... especially as the hubs have never been apart before!!

I think there is an option on the P38 front diff on the Ashcroft transmissions website to upgrade the diff centre from 2 pin to 4 pin - so I presume that they just fit a 'standard' front ring & pinion to the 4 pin centre... Extra £50 on top, plus apparently an extra charge if you then return a 2 pin unit - so I'm guessing somewhere in the £100 region on top to make the front one a correct 4 pin diff...

Also looks like they do 'HD' ring an Pinions in a 3.5 ratio (close enough to the stock 3.54) which are selectable for front/rear if you wanted to upgrade yourself just those components for a cool £195 an end!!

I would say that the difference between the 3.5 and 3.54 would be minimal, but I wouldn't recommend doing just the one end!! Would probably toast the viscous coupling before moving to the rear diff... but who knows what the outcome would be after that!!

Once the VC had seized I suppose it would depend which end had the taller gearing. If it was the front it would try to turn itself into a stretch limo, if the rear, it would try to fold itself in half in the middle. It would make the steering interesting though as the rear tried to push the front straight on everywhere.

You remember my front pads were a touch on the thin side when we swapped the front axle over, well I ordered a set to bung on it and, remembering you mentioned that one of my front shocks seemed a bit weak, I ordered a pair of OE Boge to bung on the front too. I really must stop looking at the Island website, it cost me money! But I have got another one of my 2,000 mile round trips coming up next weekend. Only problem now is that it's got a touch warmer but now it's bloody raining......

Pads shouldn't be too bad to change... the shocks are pretty quick to change on the front - but still not fun in the rain!

I know what you mean about the Island 4x4 website - though I haven't ordered from them again since the last time they sent out my new OEM waterpump loose, and the gasket box taped in the top of the box, which was subsequently torn in one place and the tape damaged the surface where it had gone across. Previously to the last couple of orders I wouldn't go anywhere else, but the last 2 orders have left me with a bit to be desired!

I will probably order from them again at some point as they do seem to be cheaper than most places - even for OEM parts...

I've always found them to be pretty good. Did you tell them about the badly-packed waterpump and gasket? Did they do anything about it?

Unfortunately by then it was about a month after I had received the order when I actually got to open it.... I had been away working and ordered the parts to (hopefully) arrive before I was due to go away so I would be able to have done the water pump aswell, and then not have to rush later... Parts didn't turn up before I left (again usually they have been really good - if things are in stock, which all my items were at the time, then they are usually there next day... and I'd left an extra day spare, but this time didn't turn up as quickly).

I tried calling them about it when I did return home and open the box, but got no answer on the phone, and I had to get the water pump done that day as I was having to drive somewhere that night for work, returning the next day, and then buggering off to Europe again the following day, so I ended up getting one from the local LR independent place so I could do the job.

My next order with Island 4x4 also wasn't great - there were a couple of parts that were 'to order' plus a couple of days... fine.. no problem.. but I then had to chase them up after a week to finally be told that the part I had ordered wasn't available from their supplier and they didn't have one of the other items in stock either (valve grinding stick - I tacked a few other tools onto the order to take it up to £50 to qualify for free shipping!).. Which is fine, if you don't have the parts, then no problem - but I shouldn't have to chase them up for an update a week or more down the line.

A bit like trying to deal with Land Rover themselves... ordered new keys for my P38 and the 2 restoration ones which had the keys nicked from the workshop.. on the 23rd DECEMBER... and trying to get any answers out of my dealer is like getting blood from a stone. I've called them 3 times now, and every time they have vowed to get in touch with JLR and call me back 'that afternoon' .. and every time have failed to call me back. Now it's been nearly 8 weeks, I've very tempted to walk into the dealer and ask to see the manager and ask if I would have had the same treatment if I'd walked in there to spank away £75K on a new RR, or if it's only because I've ordered 3 items for a 15+ year old vehicle that I'm being given shit service...

In the past they've been good but not perfect. Order something from Rimmers and it will definitely arrive next day but they tend to be a bit more expensive (quite a bit more sometimes) than Island. Island may take an extra day. This time I ordered the parts at 11pm on Monday, they were shipped on Tuesday and arrived with me at about 10am on Wednesday so can't say fairer than that. Well packaged too. I wasn't in any great rush as I knew I wouldn't get chance to fit them until this weekend anyway.

Right, got the pads and shocks changed before it started raining. I'll blame Marty for me spending money when not needed as it was him that said one of my front shocks felt a bit weak. Well they ain't! No sloppy area and just the same damping as the new ones I've just fitted. So if anyone needs a pair of Boge front shocks, I've got a perfectly good pair here going spare........

Can't hurt to put a new set in though with the kind of miles you put on it... you nearly do more in one trip to France than I do in a year! If it's any consolation, I got told off by my mate for giving you the axle as a straight swap with that front diff as he seemed to think that it probably wasn't that old and was planning on using it in his own P38..

My answer however was that it has been sitting there for the best part of a couple of years now with nothing happening to it, and as far as I was concerned it was going to be sent off as core to someone like Ashcrofts anyway...

But you didn't give me it, I seem to recall there was some folding stuff that changed hands too..... The diff in the axle we took off was probably fine, it turns out as it was the rear that was making the howling noise due to a very notchy feeling nose bearing. I've put it to one side and may well send that to Ashcrofts so I've have a known good one. I may do the same with the spare transfer box I've got sitting here too.

My last trip, setting off Thursday evening and back home Monday night, was 2,058 miles. I'm approaching 311,000 on the clock now. Only another 9,000 and I'll hit the half million kilometres mark.

mm, technically the diff/axle was from part of the joint thing with my mate, and since he had nothing to do with the buying of the ball joints, replacing of them, or the install of it with me and you onto your vehicle the folding stuff went in my pocket to reimburse me for the cost of the parts and my time to do the ball joints/help you swap the axle. But as you say - that diff is probably all fine (not that I was bothered if it wasn't - as far as I was concerned I was happy to swap the axle for nothing as it had been there so long! Funnily enough your old axle hasn't moved from where we left it anyway!

311K on the clock must be one of the highest for P38's out there.. it's almost double what's on mine - though I did take it out for a nice cruise today - and swung past the Land Rover dealer to pick up 2 of the 3 new keys.. it's nice to have the spare for mine now!