p38 whining ?

hi guys well you help me solve prob after prob and new ones keep cropping up ..
i have been getting a noise like a whining noise that i was told my local landrover specialist in saxilby that it was the transfer box . i have now changed this and yet i have exactly the same noise and now the garage who fitted it are telling me its something on the back end ? .
i have also noticed my fuel usage has gone up dont know if its linked .
please if anyone could help i would be grateful as after spending 500 quid to sort the prob im still in the same situation and even more skint .

Diff ???

mine is whining and using more diesel I have found a split in the turbo hose

ohgoon2006 said:

hi guys well you help me solve prob after prob and new ones keep cropping up ..
i have been getting a noise like a whining noise that i was told my local landrover specialist in saxilby that it was the transfer box . i have now changed this and yet i have exactly the same noise and now the garage who fitted it are telling me its something on the back end ? .
i have also noticed my fuel usage has gone up dont know if its linked .
please if anyone could help i would be grateful as after spending 500 quid to sort the prob im still in the same situation and even more skint .

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Then you will be even more skint by the time you have fitted a new diff. I would suggest your local Land Rover specialist sells up and takes up knitting if he missed that one.

ITS UR REAR DIFF myn went the center diff sizes up and distroys ur back diff jack up 1 wheel off the ground and see how much playis init fore and aft myn went setin off from lights near home it smashed to bits and went throught the casin take ur front prop off thats wot i did all was well

navi said:

ITS UR REAR DIFF myn went the center diff sizes up and distroys ur back diff jack up 1 wheel off the ground and see how much playis init fore and aft myn went setin off from lights near home it smashed to bits and went throught the casin take ur front prop off thats wot i did all was well

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There is no centre diff, just a crappy viscous coupling, but you are right, it seizes, then things break due to tranmission wind up

How does taking the front prop off help the rear diff? Genuine question, not being snarky. All I know about auto mechanics I've learned through trial and error on my P38! I have a whine too. I changed the diff oil, gear oil, transfer oil, engine oil and still had it. I drove at speed and then free-wheeled and it went away (so guessing its not hubs). I took of the front prop on Sunday thinking to isolate the front diff but though the car feels more free or light and my mpg is improving, I still have the whine.

Datatek said:

There is no centre diff, just a crappy viscous coupling

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LR beg to differ (pun optional), as I said the other day there is a seperate mechanical centre diff as well as the VC, take a look at RAVE Sect 41, pages 5 & 6. The VC only comes into play if there is major slipage between front and rear wheel speeds, the rest of the time the mechanical diff operates just like any other.

kernowdragon said:

LR beg to differ (pun optional), as I said the other day there is a seperate mechanical centre diff as well as the VC, take a look at RAVE Sect 41, pages 5 & 6. The VC only comes into play if there is major slipage between front and rear wheel speeds, the rest of the time the mechanical diff operates just like any other.

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As Wammers said. that is just an epicyclic gear set that gives high and low ratios. If there was a centre diff the VCU would have no effect because as with any diff if one side slips there is no drive to the other side which is why diff locks were invented. The VCU does away with the need for a diff as it allows a certain amount of slip and then progressively locks. A locked VCU would have no adverse effect if there was a diff because, as in the axle, the diff would accomadate the different rotational speeds and thus if the front prop was removed the car would not move, which it does whether the VCU has failed or not.

Datatek said:

As Wammers said. that is just an epicyclic gear set that gives high and low ratios. If there was a centre diff the VCU would have no effect because as with any diff if one side slips there is no drive to the other side which is why diff locks were invented. The VCU does away with the need for a diff as it allows a certain amount of slip and then progressively locks. A locked VCU would have no adverse effect if there was a diff because, as in the axle, the diff would accomadate the different rotational speeds and thus if the front prop was removed the car would not move, which it does whether the VCU has failed or not.

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Sorry, but that's not what LR say, and whilst thankfully I've never had to strip one down and find out, LR are quite specific that there is a mechanical centre diff, seperate to both the VC and high/low selector, which is on the other side of the transfer box on a seperate shaft.

kernowdragon said:

Sorry, but that's not what LR say, and whilst thankfully I've never had to strip one down and find out, LR are quite specific that there is a mechanical centre diff, seperate to both the VC and high/low selector, which is on the other side of the transfer box on a seperate shaft.

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Nonsense. The viscous coupling IS the centre diff. As i said before the item shown on the page entitled "differential" on RAVE is the reduction gear set. RAVE is wrong. The item shown if you know anything about gear boxes is clearly an elyptical reduction gear set with no differential gearing in it whatsoever. Please read and understand the page "How the transfer box works".

the whine is the gears in the worn/fialing diff at the rear i think u would be able to adjust the bearing in the rear diff to save it myn went before i knew wot it was if i was u id take the assembley out degrease it n clean it put blue on the teeth and ajust it then take the front p/shaft off but no foot to floor departures tho.

navi said:

the whine is the gears in the worn/fialing diff at the rear i think u would be able to adjust the bearing in the rear diff to save it myn went before i knew wot it was if i was u id take the assembley out degrease it n clean it put blue on the teeth and ajust it then take the front p/shaft off but no foot to floor departures tho.

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Hi Navi,

Would you mind explaining the procedure in a little more detail? Thanks in advance!

R

kernowdragon said:

Sorry, but that's not what LR say, and whilst thankfully I've never had to strip one down and find out, LR are quite specific that there is a mechanical centre diff, seperate to both the VC and high/low selector, which is on the other side of the transfer box on a seperate shaft.

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I agree thats what they say, but I'm sure thats just the marketing men talking. If you know how a diff works then if one side has no grip, there is no drive to the other side unless you can lock the diff. The VCU is on the front output shaft and is a self contained unit so cannot lock the mythical diff, therefore if you remove the front prop, you would also lose drive to the rear. To see how a diff works, jack one driven wheel on a 2WD car, chock the other 3 securely, start the engine, put it into gear and you will find that the wheel off the ground spins freely but the car does not attempt to move. The same effect would occur on the P38 with the front prop removed, the front output shaft would spin and there would be no drive to the rear. Also the VCU would be pointless as the diff would allow for rotation differences front to rear just as the axle diff does left to right when turning.

Anyhow, you have it your way and dream of your mythical diff:behindsofa:

navi said:

the whine is the gears in the worn/fialing diff at the rear i think u would be able to adjust the bearing in the rear diff to save it myn went before i knew wot it was if i was u id take the assembley out degrease it n clean it put blue on the teeth and ajust it then take the front p/shaft off but no foot to floor departures tho.

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I take it you can also walk on water, turn water into wine and feed five thousand with a Indian take away. The whine is usually the faces of the crown wheel and pinion breaking up. No amount of adjustment will alter that, it my make your whine louder though. Setting up a diff is a very serious bit of mechanicing even using the special tools required. It is possible to do without all the special spacer mandrels, it can be done with just with a DTI and a spring balance but you really,really have to know what your doing if you don't want an orchestra following you around.

wammers said:

I take it you can also walk on water, turn water into wine and feed five thousand with a Indian take away. The whine is usually the faces of the crown wheel and pinion breaking up. No amount of adjustment will alter that, it my make your whine louder though. Setting up a diff is a very serious bit of mechanicing even using the special tools required. It is possible to do without all the special spacer mandrels, it can be done with just with a DTI and a spring balance but you really,really have to know what your doing if you don't want an orchestra following you around.

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He He, I used to re-build the diffs on my race car, wasn't too worried about the noise as long as it ran free. Did one and it sounded like an air raid siren. At least the others knew when I was coming

Datatek said:

He He, I used to re-build the diffs on my race car, wasn't too worried about the noise as long as it ran free. Did one and it sounded like an air raid siren. At least the others knew when I was coming

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Just so. People thinking they can adjust the standard backlash into a diff that has been running for 50,000 miles and get away with it, live in cloud cookoo land.

Datatek said:

The same effect would occur on the P38 with the front prop removed, the front output shaft would spin and there would be no drive to the rear.

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Trying really hard to learn something from this thread, but a lotta reading between the lines required! The things is, I AM driving with the front prop removed at the moment and there is certainly propulsion from the rear. Also, there was a definite jerkyness when reversing slowly with full steering lock before I removed the prop which I only noticed now that its gone. From what I read..
TheViscous Coupling: How to Test & Replace it

.. this is a sign that the centre viscous coupling/diff was already in trouble. Where I'm a little confused is that if the rear wheels are driving and the front prop is missing and therfore the front bit of the VC is not turning, does that put the VC in full time lock? I know it has little resistance to deal with (from the front at least) but that can't be good??

christ i hope the solution does not end up being to throw a complete new drivetrain at this car. its just not worth the money anymore.

crabbing on turn on classic rr was sure sign of seized coupling

rasheed said:

Trying really hard to learn something from this thread, but a lotta reading between the lines required! The things is, I AM driving with the front prop removed at the moment and there is certainly propulsion from the rear. Also, there was a definite jerkyness when reversing slowly with full steering lock before I removed the prop which I only noticed now that its gone. From what I read..
TheViscous Coupling: How to Test & Replace it

.. this is a sign that the centre viscous coupling/diff was already in trouble. Where I'm a little confused is that if the rear wheels are driving and the front prop is missing and therfore the front bit of the VC is not turning, does that put the VC in full time lock? I know it has little resistance to deal with (from the front at least) but that can't be good??

christ i hope the solution does not end up being to throw a complete new drivetrain at this car. its just not worth the money anymore.

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No problem, if the VCU is seized it is just like a solid coupling, so with the front prop removed the whole VCU, including the "front bit" just rotates happily. As said before, if the VCU seizes, there is nothing to accomodate the different rotational speeds front to rear, this is most obvious when on full lock for example. Thats when the tyres start to hop to release the tension in the drive train. If left, the stresses caused by the seized VCU will destroy the front or rear diff