Transfer box failure

Hector the Bad · Jan 17, 2023

1987 Landrover 90 hard top:
my transfer box seems to have failed - in the snow a couple of weeks ago, when pulling out a stuck car, it was observed that the front wheels were spinning but the back wheels were stationary. Not a good sign in a permanently four-wheel drive setup. The high/low/diff lock lever will not stay in place except in 'normal' high ratios - if low or diff lock is selected it springs out as soon as the clutch is released. With the lever 'floating' after springing out of position, would this put the vehicle into 2-wheel drive instead of 4-wheel drive, or is 2-wheel drive impossible unless the transfer box is faulty?

My local and very good garage says that all this indicates a failed transfer box. The number stamped on the transfer box is FRC5HA5, which might indicates it's an earlier type and ripe for failure. (The main gearbox is an LT77 - the serial number indicates an early version and it seems ok).

I am thinking of an exchange transfer box unit from Ashcroft transmissions - their exchange units also seem to incorporate some improvements carried out to later transfer boxes.

Does anyone have any experience in having to repair something like this or any other advice? Thank you! R

miktdish · Jan 17, 2023

Landrover Defender/90's aren't really 4 wheel drive.
I'd be surprised if your transfer box has 'failed'.

The output of the gearbox will go to the easiest path and spin that wheel. if you unwieght a front wheel, it will spin, if you unwieght a rear wheel that will spin.
If you 'lock' the transfer box it will provide drive to both the front and rear axle, therefore you will need to lift one wheel on each axle and they will both spin.

The small lever in the cab moves a dual/2 point lever to get the transfer box to 'lock' the box,.
You need to operate it regularly so it doesn't sieze up. It sounds like the small levers on the transfer box are sized.
If you can remove the middle seat/cubby and then the cover you can see what's going on as you move the levers, taking the gear tunnel off makes it really easy (see pic below).
Lots of penetrating fluid and some light oil with lots of waggling will probably cure the issue.
I took mine off, cleaned all the joints, fitted new washers and grease and it slids in and out feeling both tight and smooth.

lynall · Jan 17, 2023

I would confirm the fault first, the lt230 tfer box is super tough so long as it has oil, so I would be very sure its needs doing first.

Was the rear prop spinning or just the front wheels ie was power reaching the rear diff
You only have to have one wheel on each axle off the floor and the car will not go forwards even if the tfer box diff is locked.

Lever popping out normally means the silly plastic bushes are worn out/missing, floor and tran tunnel out for access.
Mine pops out every now and then, and I lose all drive, but not tried it with the diff locked.

I have driven a defender with front wheel drive only and it was very strange.

2nd hand tfer boxes are not expensive, and like I said above as tough units they are normally a safe used buy.
Loads of ratios available, std def is 1.4, disco is 1.2, military had some low ratios, 1.6 Iirc and thats to do with the really low powered engines they ran.

MattYorke · Jan 17, 2023

Agree with the above. I did blow a transfer box once - and you know about it!
If it's just jumping out of gear, it can easily just be the selector mechanism, shown above. I had that on mine once - it wouldn't stay in high im my case. A bolt on the selector mechanism had come loose. 10 minutes with a spanner and all was good again.

Also remember there is no 2 wheel vs 4 wheel drive. The vehicles are permanent 4 wheel drive, but just with a centre diff that locks. And again, even with a damaged box, you'd likely stilly be able to lock the centre diff.
So it all points to being a bit of adjustment and freeing up the linkages in the first instance.

tottot · Jan 17, 2023

As above, it seems like your centre diff lock is not engaging. As well as linkage issues as above the D in the cam [ next to 26 in pic above can wear ]

dag019 · Jan 18, 2023

I would agree with the above it is likely to be a selector adjustment issue. What happens if you hold the selector over for diff lock as you lift the clutch. This might stop it springing out of place and you will feel difflock engage? Same goes for low range. Hold it into position as you raise the clutch. If this works it is definitely a link age adjustment issue.

I have had my transfer-box go a couple of times but both times it has been bearings rather than a catastrophic failure and you get lots of warning that bearings are beginning to fail. I will also say that each box had done about 200k at the point the bearings went so again another note for being very tough.

payydg · Jan 18, 2023

@Hector the Bad

If the LT230 fails it's most commonly the splines on the input gear or sometimes the centre diff can explode. Both would mean you'd have no drive to any wheels. If one wheel is spinning suggests the box is functioning and as above likely a selector issue. If front wheels were spinning why didn't you have any drive? No traction? Have you tried on a surface with traction?

Hector the Bad · Jan 22, 2023

payydg said:
@Hector the Bad

If the LT230 fails it's most commonly the splines on the input gear or sometimes the centre diff can explode. Both would mean you'd have no drive to any wheels. If one wheel is spinning suggests the box is functioning and as above likely a selector issue. If front wheels were spinning why didn't you have any drive? No traction? Have you tried on a surface with traction?

Thank you everyone for the advice on lubricating, bush checking and other precautionary measures before taking the expensive step of replacing the transfer box. The wheel spinning situation explained: I was pulling a small saloon car back onto the road in the recent snow. A friend who was with me, who was outside the vehicles at the time, watching the fun and games, observed that at one point for maybe ten seconds my front wheels were spinning in the snow but that the back wheels were stationary - and the vehicle wasn't moving. At some point, the Landy got some sort of grip and started pulling the stuck car back onto the road. That's all I know. It just gave the impression that the front wheels were the only ones with any power and that the back ones were inert. At no point were any wheels 'off the ground'. It seemed to me that eventually the General Grabber tyres on the front wheels churned away the snow and the gripped the road, and off we went... If there had been any power to the back wheels, surely they would have either spun or pulled the vehicle forward?

On the lubricating advice - I presume I can do all this by accessing the transfer box from the top by removing the cubby box (easily done) and then the clip-down metal cover between the front seats? Can the bushes be replaced using the same access route? Or does any of any of this need to be done by jacking the vehicle onto axle stands and going in from underneath?

lynall · Jan 22, 2023

Maybe what you have is a rear diff or drive member failure, and unknown to you the tfer box is in difflock so the power out from the tfer box is 50/50 but as the rear has a kanckered diff/drive member then no rear wheels will turn?

tottot · Jan 22, 2023

Most likely because the diff lock in the transferbox was not engaged [ does the light on the dash come on?] with the front wheels on a very slippery surface then all the power tends to go that way. Then as you suggest as the front tyres found some grip some power then went to the rear wheels as well and off you went.
To check if diff lock is working. First chock vehicle and with hand brake off jack one wheel off the ground. [any wheel] With diff lock out [normal position] you will be able to spin that wheel.
Then have someone hold the diff lock lever over in engage in position [ the lever itself does not put the lock in, it just allows the bits in the box to engage the lock when things line up. Turn the jacked wheel now and lock will engage [ light on ] and you will not be able to rotate wheel more. [ you will be able to move it a bit back and fore only] If wheel keeps turning most likely selector issue as above.
It is a good thing on any 90/110 to exercise the high/low diff lock mechanism now and then to keep them usable when needed.

miktdish · Jan 23, 2023

@Hector the Bad Lets go through this again.

The engine provides drive to the LT230 (The Transfer Box) inside the LT230 is a mechanicaly lockable differential.
The 'lock' is controlled by moving the small gear lever from side to side. Towards the driver - unlocked - away from the driver - locked.
In 'unlocked' mode drive is sent to both axles but will take the route of least resistance. If a wheel (any wheel, front or back) is unwieghted, that wheel will will spin.
By unwieghted I mean 'easier to spin than any other'.
If a front wheel is on ice and all the other 3 are on snow the wheel on ice will spin.

If the LT230 is 'locked' drive will be sent to both front and back axles.
The front wheel on the ice will still spin but the back wheels will get equal drive and probably push the car forward.

If one of the back wheels was 'unwieghted' it would spin and you'd go nowhere.
You can get 'cross-axled', this happens when the axle articultes away from the car and nears it's end stops and 'unwieghts' the wheel on the high side, if the other axle articulates the other way and unwieghts a wheel, both of these wheels rotate and the car goes nowhere.
The only way to stop this happening is fit a 'diff lock' or 'limited slip diff' to either or both of the axles.
These devices mean that both wheels on an axle will get drive, the diff lock gives it all the time where the LSD only applies power when it detects one wheel is spinning to the other wheel.

So. Is a Defender a 4 wheel drive vehicle ?
Yes and No . Drive is present on all 4 wheels, unless 1 can spin easier than the other 3.
If you had a diff lock on both axles (or an LSD) and the LT230 was 'locked' then you have a true 'all wheel drive' car.

https://www.arbil.co.uk/4x4/shop/arb-air-lockers-accessories/
https://www.lrparts.net/da9011-auto...fender-discovery-1-2-range-rover-classic.html

//On the lubricating advice - I presume I can do all this by accessing the transfer box from the top by removing the cubby box (easily done) and then the clip-down metal cover between the front seats?\\

Yes

ER1C · Jan 23, 2023

miktdish said:
@Hector the Bad Lets go through this again.

The engine provides drive to the LT230 (The Transfer Box) inside the LT230 is a mechanicaly lockable differential.
The 'lock' is controlled by moving the small gear lever from side to side. Towards the driver - unlocked - away from the driver - locked.
In 'unlocked' mode drive is sent to both axles but will take the route of least resistance. If a wheel (any wheel, front or back) is unwieghted, that wheel will will spin.
By unwieghted I mean 'easier to spin than any other'.
If a front wheel is on ice and all the other 3 are on snow the wheel on ice will spin.

If the LT230 is 'locked' drive will be sent to both front and back axles.
The front wheel on the ice will still spin but the back wheels will get equal drive and probably push the car forward.

If one of the back wheels was 'unwieghted' it would spin and you'd go nowhere.
You can get 'cross-axled', this happens when the axle articultes away from the car and nears it's end stops and 'unwieghts' the wheel on the high side, if the other axle articulates the other way and unwieghts a wheel, both of these wheels rotate and the car goes nowhere.
The only way to stop this happening is fit a 'diff lock' or 'limited slip diff' to either or both of the axles.
These devices mean that both wheels on an axle will get drive, the diff lock gives it all the time where the LSD only applies power when it detects one wheel is spinning to the other wheel.

So. Is a Defender a 4 wheel drive vehicle ?
Yes and No . Drive is present on all 4 wheels, unless 1 can spin easier than the other 3.
If you had a diff lock on both axles (or an LSD) and the LT230 was 'locked' then you have a true 'all wheel drive' car.

https://www.arbil.co.uk/4x4/shop/arb-air-lockers-accessories/
https://www.lrparts.net/da9011-auto...fender-discovery-1-2-range-rover-classic.html

//On the lubricating advice - I presume I can do all this by accessing the transfer box from the top by removing the cubby box (easily done) and then the clip-down metal cover between the front seats?\\

Yes

Spot on..... .4x4 is very misleading and I have had the same on the Defender when I expected all wheels to be eating terrain.
As above its power going to all 4 wheels, but physics is key. There is a lovely youtube LR video showing differential and locking etc..

PS nothing funnier than seeing a 80k Range rover cross axled on a village green with an awkward hump they tried to drive over at angle.

tottot · Jan 23, 2023

If cross axled as above dabbing the brake quite hard will momentarily slow the spinning wheel and send drive to the wheel on the ground and move one just enough to get out of bother.
On a series with a wheel in the sky one could do up the brake adjuster solid to send drive to opposite wheel.
Very often when you are stuck getting the vehicle to move a foot or two by any means will get you free.

haza88 · Jan 23, 2023

Somethings not right if it won’t stay engaged as above have already said

lynall · Jan 24, 2023

ER1C said:
Spot on..... .4x4 is very misleading and I have had the same on the Defender when I expected all wheels to be eating terrain.
As above its power going to all 4 wheels, but physics is key. There is a lovely youtube LR video showing differential and locking etc..

PS nothing funnier than seeing a 80k Range rover cross axled on a village green with an awkward hump they tried to drive over at angle.

Must have been an old range rover, as anything modern rrs/ffrr (not kin ewoks) will handle the cross locks with no issues.

payydg · Jan 25, 2023

@Hector the Bad

That is a completely normal situation for a defender if it loses traction and the centre diff isn't locked

If it won't selected diff lock - as already said - that's most likely a selector issue. There is a little grub screw that controls the pressure on the ball bearing in the selector if the external selector is moving freely back that off until it selects then sequentially tighten up again.

Hector the Bad · Mar 2, 2023

payydg said:
@Hector the Bad

That is a completely normal situation for a defender if it loses traction and the centre diff isn't locked

If it won't selected diff lock - as already said - that's most likely a selector issue. There is a little grub screw that controls the pressure on the ball bearing in the selector if the external selector is moving freely back that off until it selects then sequentially tighten up again.

Thank you everyone on the Forum who has given such good and interesting advice. I've been 'off the road' myself for a bit which is why I haven't been able to respond to the advice on this thread. I have ordered an Ashcroft refurbed transfer box which will be arriving in three weeks or so. When we remove the faulty box, we can chgeck it out off the vehicle and if it turns out to be a fairly simp0e lubrication problem or a matter of worn selector parts, Ashcroft said that I can return the (unused)b refurbed unit to them.

But one last question: how do I know for sure that I have an LT77 gearbox, rather than an R380? To select reverse, the gear lever is pushed to the far left and then upwards - so reverse gear is to the left of 1st gear. Does this alone mean that it's an LT77? I'd heard that the reverse gear selection is in a different placed oin the R380 gearbox. Also,I have an interesting clutch identity problem. Whilst the gearbox is out for the transfer box to be replaced or mended, I shall have an opportunity to replace whatever parts of the clutch need iattention - and it definitely needs it as I'm getting clutch slip and there's no sign of an oil leak underneath the vehicle (1987 Land Rover 90). I'll start a separate post for that, as I have an Isuzu 2.8 litre diesel engine, not a Landy one.... So thank you everyone and see you soon in a different thread...

tottot · Mar 2, 2023

Good you yore self on the road again. Have you done any of the checks on the external linkage suggested above ? Up left = LT77.Clutch you will only know when in there.

Hector the Bad · Mar 3, 2023

tottot said:
Good you yore self on the road again. Have you done any of the checks on the external linkage suggested above ? Up left = LT77.Clutch you will only know when in there.

Thank you tottot - I've squirted the amazing ACF-50 everywhere I can, accessing the gearbox assembly from the top, with the cubby box and cover plate removed, but we'll do it thoroughly when we get the gearbox out, in case it's a simple lube case rather than a mechanical failure.
On the matter of the clutch - would anyone who might have experience or knowledge of having the Isizu 2.8 litre diesel instead of whatever would have been standard in a 1987 Landrover 90 have any idea if the clutch would be specific to the Isuzu engine or to the standard land Rover 90 set-up? (Whatever that turns out to be when the gearbox is taken out!).

tottot · Mar 3, 2023

In the pic above by "miktdish" you can see the little arm on top of the front output that links to the shaft into the output and is what puts the gubbins into diff lock engagement position. When mine would not go into lock I found the D in the arm was worn and did not move shaft enough.

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