Lost Drive!!

She already said in the first post that the rear shaft does not turn when driving the vehicle. That means no power to it, so she can forget about the diffs, they don't matter. The issue is in the T-case. The tranny pushes the Transfer case which power front and rear drive shafts, If she can drive it off of the front wheels, but not in 2wd to the rear then there is something wrong in the T-case..... Brits are dense

greenjeepster said:

If she can drive it off of the front wheels, but not in 2wd to the rear then there is something wrong in the T-case..... Brits are dense

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It's not an old Series with selectable 4x4, it's full time 4 wheel drive, so how's she going to drive it in 2wd to the rear?

Dense? yes, my brain is packed tightly with cells.

discomania said:

Its not chain drive.

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TRANSFER CASE DRIVE CHAIN (BORG WARNER) | Range Rover & Land Rover transmission Parts
If they are not....why does this place sell chains for them?
Goudy: How do you drive a awd vehicle in 2wd rear is a damn good question

Goudy said:

Dense? yes, my brain is packed tightly with cells.

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Probably so dense with cells all your sulcus are filled in.

I think you might have wondered in here mistaking it for a Range Rover Forum,
The Discovery is fitted with the LT230t (manual) or LT230q (auto) transfer box, NOT the Borg Warner, and according to land rover there isn't a chain in it.
It does have these little wheelie type things in there, that some call cogs, gears, sprockets, but not chains.

The link you kindly supplied if for a Range Rover, not Discovery.

Goudy said:

I
It does have these little wheelie type things in there, that some call cogs, gears, sprockets, but not chains.

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Are we talking transmissions or brain cells now?

He is right though, the borg warner has a chain, unfortunatly the disco doesn't have a borg warner.

But it must be confusing over the big pond, you know calling a bonnet a hood, a boot a trunk and a Discovery a Range Rover.

These people will be more help to you than anyone here I'm sure.
Ashcroft Transmissions Ltd 01582 496040

Ashcroft Transmissions

So she did green... Tcase must be gubbed indeed.

Goudy said:

He is right though, the borg warner has a chain, unfortunatly the disco doesn't have a borg warner.

But it must be confusing over the big pond, you know calling a Discovery a Range Rover.

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Never heard anybody call a Disco a Range Rover? I just assumed that it was chain drive because what she describes sounds very typical of a chain drive T-case. Also most are chain drive now, and I will bet that it will not be many more years before all of the rovers have them in them also (if they don't all ready). The American Disco II did have chain drive, but it doesn't look like the English ones did?

discomania said:

So she did green... Tcase must be gubbed indeed.

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How very confusing. I'll bet discolady regrets asking the question now
Just my 2 bobs worth, but if the rear shaft doesnt turn when driving in difflock as she stated, wouldnt that mean the is a problem at both ends?

1. if there is a problem at the transmission end, wouldnt the turning rear wheels automatically rotate the rear prop shaft as she moved along?
2. If there was a problem at the diff end, wouldnt the turning transmission drive the rear prop shaft too?

Perhaps someone needs to write a clear and concise set of step by step instructions for her. Seems that it would need to include difflock, prop shafts and wheels off the ground to solve the problem...that, or get a mechanic to have a look at it

Yes Outback, that's what we was trying to discover, if the props are moving or not. As ther lady discribed a "bang" the thinking was of something snapping, likely choice was a halftshaft.

As it is, it sounds like all the axles are still connected to the props and the hand handbrake still holds the car.

So it isn't a simple matter of a halfshaft failure, but as it drives in DiffLock, the whole transfer box can't be knackered.(if the chain snaps on a Borg Warner, it won't go anywhere)
Once the centre Diff has been locked and isn't able to slip it looks like it's driving the front wheels from the info given.

If we can take the above info as correct, it's difficult to tell without seeing the car ones self, I myself would tend to believe the problem was somewhere between the centre Diff and the rear prop, mainly the rear output shaft.
If one would want to check this, remove the rear prop, put the car in gear, in Difflock and try turning the handbrake drum it should try and turn the internals in the box, one could also remove the front prop and try turning the front output flange to see if it does the same.

If it is the splined rear output shaft, it won't turn try and turn the box.
It might be possible it repair it, and do it while it's still in the car, instead of scrapping the whole box as it might have been implied by others.

Just looking back at the original post, when she lost drive and obviously had it in gear whilst looking under the car, the front prop was turning and the back one was not.

As we found out later the hand brake still works.

So....

I believe that the rear is ok beacuse of the hand brake working, and thtransfer box is ok because it will always send drive to the end with least resistance is this case the front.

If she puts the diff lock on it locks the centre transfer box and is then able to drive the rear to get the car moving.

Therfore I believe the problem lies in the front, either half shafts or CV joints are the more common problem, than the diff.

well i've started some debate havent i!!!

i will jack up the front wheels and test like i did the rear ones. the clunk noise did seem to come from the front of the car but who knows.

thanks everyone, will let you know what happens once the front wheels have been tested.

Well, when you get it sorted out, let us know how it worked out....we all either have too few or too many brain cells on here to make good sence of it all
Is it a I or a II? If the half shaft broke engaging the diff lock will allow you to limp home in 2wd. On the II I have read that the diff lock is still there, but you have to crawl underneath it and turn it with a wrench.

What I would propose: Put the whole thing on jack stands or blocks. Start it up and shift into drive, get out and see what wheels are turning. Shift through everything and see when you do not have drive....

Hi,

well i tried what James suggested and jacked up each front wheel at a time and got a nasty noise from drivers wheel so seems like it is the CV joint or halfshaft on the front. Gonna take wheel off tomorrow and investigate. will keep you all posted!!


thanks again everyone

Nat

one more question everyone!!

can someone explain to me how a damaged CV joint would cause my disco to lose drive? it may be a really blonde question to ask but i'm no mechanic but am very keen to learn - and not affraid of getting my hands dirty

thanks everyone

Simple, the drive train on discos is set up so that the power will take the easiest route. So if you have one wheel off the ground for example it will spin but the other three will stay put. The result is you get stuck. The principle is the same with standard 2WD cars and thats why they get stuck in mud with all the power going to the spinning wheel. The centre diff on the disco takes up any difference in road speed between the 2 axles. So if you lose a CV joint (ie it breaks and you lose power to that wheel) then the power will be spent to that wheel and it will be spinning away inside the axle going nowhere. If you select Diff Lock then it allows some of the power to go to the undamaged axle and hence it will drive.

I think thats right, thats my understanding of it and I'm sure theres someone who will correct me on some point!

ahh i get it.

thanks for that

Nat

revjames said:

Simple, the drive train on discos is set up so that the power will take the easiest route. So if you have one wheel off the ground for example it will spin but the other three will stay put. The result is you get stuck. The principle is the same with standard 2WD cars and thats why they get stuck in mud with all the power going to the spinning wheel. The centre diff on the disco takes up any difference in road speed between the 2 axles. So if you lose a CV joint (ie it breaks and you lose power to that wheel) then the power will be spent to that wheel and it will be spinning away inside the axle going nowhere. If you select Diff Lock then it allows some of the power to go to the undamaged axle and hence it will drive.

I think that's right, that's my understanding of it and I'm sure there's someone who will correct me on some point!

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EXACTLY!.

The centre diff lock is fitted to get round that very problem, of a Landy getting stuck just because ONE wheel is slipping. With the centre diff NOT locked, the TORQUE applied to each of the four wheels must always be the same even if a wheel slips. Both sides of any plain differential WILL receive equal torque, so if one spins, the drive to the other also fails. That torque is limited by the GRIP of the four tyres on the ground.

If any ONE wheel loses grip, it spins freely, and the torque needed by THAT wheel to make it spin is very small compared to the torque when the tyre is gripping. So, as ALL the wheels get the same low torque, the car goes nowhere, and the spinning tyre digs a nice hole.

If you lock the centre diff, then you are guaranteeing that equal torque WILL NOT be applied to front and rear axles. The front end could be over a cliff and the tyres in fresh air, but if the rear tyres are on the ground they will drive - reverse would be good in this situation!

Ideally for best grip you need limited-slip or solid-locking diffs in the axles as well. That way you could have THREE wheels over the cliff, and one wheel gripping the ground!

CharlesY