Thanks for the heads up, I have watched a couple of YouTube videos so was aware of that. The garage that repaired it last time have messed me around soo much I don't really want to take it there and its kind of forced me to look at things my self. I aways used to do these things myself.

What I don't want to do is put the props back on next Friday and find I do need a new Front Diff. Feeling like get a cheap one from eBay and if needed fit that if it goes wrong again i have a spare that I might be able to liberate parts from.

From what I have heard you can fit a 4 pin rear diff to the front? Its a 4.6L V8 Petrol 1997, if thats the case then I would potentially have a spare for either if its not required.

You can, but you'll have to pay more for a 4 pin- either used or off Ashcrofts. Despite many internet fables to the contrary, I think we on here have concluded that LR never fitted a 4 pin front diff to production line P38s.
Having a spare diff on the shelf just in case is a bit of a luxury though.

A 4 pin rear diff will fit on the front but will be noisier as the gears are cut the opposite way so you'd be best to fit a 2 pin unless you want something that whines like a London bus. Have you actually found the source of the noise yet? If there's no slack or tightness in any of the UJs, then it isn't going to be them. With the prop off you can get one front wheel off the ground and see if the noise is there when you spin the wheel. Same goes for the rear diff.

I haven't got to the end of the problem yet, It has truly pissed it down today, there is at least three times as much play in the front diff with the car on the ground as there is in the rear diff. If Amazon had actually honoured prime and got the circlip pliers to me on time I would have gone out in the rain and fitted the two props back on, until then I can't get it off and back on the ramp.

I am out of the country for the next 4 days so will look into to it again next Friday, hence why wanting to get a diff ordered just in case. I can either A) keep it as a spare, B) Sell it.

I've got a 4 pin rear diff fitted to the front of my 01.

There was a 2 pin in it when I took it out, and from how much of a job to get the hubs off, I don't think it had ever been changed before. SA don't think the later ones were ever fitted with 4pin from the factory.

I don't get any more noticeable whine from it being cut the other way.. my whine comes from the transmission itself I've concluded.

I've had the diff fitted for over 5 years/ 25k miles now and at last fluid change there was no more filings/ metallic gunge on the magnetic drain plug than the rear diff did.

Well a quick update, The diff arrived from No10Chris, thanks! Replaced the Union Joints on the props, Fitted the rear prop and tomorrow will replace the front diff and hopefully fix all of it.

Got a cold so its a bit more difficult. Decided that I need a workshop for this so will order a shed soon.

Thanks for all your help.

I had one of these for a few years. Makes a much better alternative to a shed!
Blooming noisy in any kind of strong wind though. Joints on the frame creak a lot!
https://www.machinemart.co.uk/p/clarke-cig1224-heavy-duty-instant-garage-24x1/

Yes thought of one of those but given I live on a welsh mountain, i don't think it will last for more than a month. Only really needs a bench, however i would be nice to be able to get the car in. When its not in there store the caravan in it. Only real problem is the best place to put it would mean it blocks the view from the living room.

Ok, nearly there just can’t pull the diff off, all 10 bolts are off. Axles are pulled out on both side. Will not budge. Any tips?

Edit... it’s now loose but will not clear track rod. Can’t seem to free track rod now.

Edit 2... Quick chat with Chris and track rod is now loose and front diff can be changed tomorrow. If the weather is not completely awful tomorrow I may do a reverse picture dialogue.

Orangebean wrote:

Gilbertd wrote:

Viscous couplings don't usually just fail though, they need some abuse to kill them.  They also cause the car to hop around when manoeuvring on full lock at low speeds as the front wheels are scrabbling for grip.  So even someone not used to a P38 would know something isn't right.

---

A little wager? Bottle of warm ale or something?
Diff failed, now possibly prop, together with:
"...when going along it pulls to either side like its stuck in the tram tracks on the roads the trucks leave in the road..."

OK so who wants to know..

November - £1550, Purchase Price
November - £400 - New Front Diff, Blew up on M25, on way home from collection
December - £600 - Replaced Front Diff again, UJ's in pursuit of problem turned out to be Rear Diff, Cost Includes Hire Car
January - £210 - 4 New wheels and Tyres, Fixed handling issue
January - £30 - Tracking and Alignment
January - ???? - Viscous Coupling causing vibration at high speed and wheels to rotate and lock at low speeds.

I don't see how a seized VC can blow through a diff in a month - unless there was something wrong with the first replacement one that you got.

The following youtube videos are a good way of testing the VC - driving around in circles on full lock is one way, but I still get the occasional scrubbing/squealing from my tyres on tight corners (in parking garages etc) and I checked my VC not so long ago, so know it isn't seized.

Might be worth getting the garage to try this just to be sure.

Viscous Coupling Test 1

Viscous Coupling Test 2

Not a wager I was hoping to collect on :(
If you can face lying under it and dropping the front prop again, test as per the following on the nut in the flange at transmission end.
It's the LR way to test the VC on the Classic- which has the same VC, and recommended by Ashcrofts as well. Removes any torque multipliers from the "do it on the hub nut" test. You may struggle to get 20C ambient though.

_Viscous unit - rolling resistance Bench check NOTE: Testing should be carried out in an ambient of 20 deg C.

1) Secure the output shaft ... (handbrake on, in neutral)
2) Apply a clockwise torque of 27 Nm to the (front propshaft) output flange nut. If no resistance to turn is felt, unit requires replacing.
3) If resistance to turn is felt, apply a clockwise torque of 20Nm to the (front propshaft) output flange nut for 1 minute, this should result in a rotation of approximately 25 deg - 30 deg. If no rotation or a greater force is required, unit requires replacing. _

Out of interest, I've done this test on both of my cars, and they both required 40-45 Nm to get the required rotation in 1 minute.

I'm thinking of going under it tomorrow or Saturday and removing the front prop and running the car in rear wheel drive only for a few weeks. That should in theory bypass the problem I am led to believe. When i have done this I will give it a try but I don't have a Torque Tool.

One of these bad boys would be good enough. Served generations of back yard mechanics before clicky and then digital ones came along.
These days you can probably buy them in Poundland :)
https://www.ebay.co.uk/itm/Draper-1-2-Square-Drive-0-21Kg-M-Or-0-150Lb-Ft-Powerset-Torque-Wrench/362208550063?
And yes, removing the front prop will decouple the front and rear axles.

I tried my old P38 without the front prop on when trying to chase a vibration years ago.

I reversed it out of the shed at my folks, put it on a full lock and reversed gently to turn around on their gravel driveway and the thing got stuck. The rear wheels were spinning but the car wasn't going anywhere. I also had trouble getting up the hill to come out of the carpark at the vets when I did it!

With all the drive going to the rear wheels, they are pretty tail happy so be careful.

I've heard reports of running it with the front prop removed can knacker the viscous coupling... might not be an issue though if you suspect it's already buggered.

David.

OK, replaced the rear discs and pads as the right rear pads had disintegrated. Thats completed, Island 4x4 now use DPD instead of InterLink by the way. Parts arrived at 0900 this morning which was nice.

Took the car out and vibration comes along at 45mph to 55mph, then from 60mph there is no vibration.

Turned it round on a junction where I can do full circle and I could hear the rear inside (drivers) side tyre scrubbing for grip. I am now sure the Viscous Coupling has a problem. Will keep your all posted.

Interlink is now DPD local, they are rebranding and have been for some time (we use them at work)

From what I understand the seized VC symptoms is scrubbing on the front wheels, yet you mention rear inside wheel...

Do the VC test in the youtube video if you don't have the front prop off - if it's seized the wheel won't turn.