Help - Centre diff lock not releasing - light going out

[EvilEd]

Been away playing in the mud for the weekend and used the center and rear diff locks in anger for the first time, rear locker is now nice and free and dropping in and out really happily. Put her back in 4h to leave yesterday and the light went out on the dash and then drove home (200+ miles) without any obvious signs. only when I went to reverse into the bay outside the house and the front tyre was skipping. Have put the centre diff lock in and out a load of times and the light comes on after a bit of driving (with 2 wheels on the verge in both high and low, but when I take it out, the light goes out but it's still engauged.

I have noticed a slight leak at the front of the transfer case, but it's not a heavy leak from the look of it. Book says only way to check level is drain and refill, not done that yet!

Any ideas ?

EE

 

[silvercruiser]

Have you tried a gravel car park reversing/turning etc or even jacking the car up?

 

[silvercruiser]

I have noticed a slight leak at the front of the transfer case, but it's not a heavy leak from the look of it. Book says only way to check level is drain and refill, not done that yet!

Any ideas ?

EE

sounds like the front output seal is leaking its an easy job with and impact gun. and you can check the level because the filler plug is also the level guage so when you undo it and try to put some in it will start to come out again if its to level if not top it up until it does.

Joe

 

[J66P]

I say try reversing and putting lever in and out of lock and not

 

[EvilEd]

had the whole side up on axle stands and that's how I know it's still in. choked the wheels and put her through the box in both forward and reverse, the yellow light goes out, but the centre is still locked. Also been for a drive up and down a local lane with a pair of wheels on the verge, any "lc" position lights up the light eventually (have to wiggle a bit off and onto the verge) and then when I put in 4h, it goes off, but it's not completely disengaging as if you jack the side up and turn the rear wheel, then the front spins as well, put the handbrake on and you cannot turn the front. The old Shoggy and Pajero both needed a few meters in reverse, but I have tried every trick in the book and she's still not having any of it...

If I take the sensor out, can you see anything of the fork mech or poke it about through there ?

Or, if the level was a bit low, could this cause it not to disengage properly ?

 

[BobMurphy]

Ed,

It sounds as though there is a problem with your Centre diff Assembly.

Have a look here:

This shows the two selector shafts and the main gear cluster in the Transfer Box.

The shaft nearest the camera is for High/Low Ratio, it shifts the drive from the input shaft (Sungear) to the Planet Gear carrier. The selector fork is fixed to the selector shaft - so you can feel the gear engaging through the Transfer Lever and engagement is carried out at very low speed only. The notches in the shaft work the detector switches on the top nearside of the Transfer Box (one on a manual, two on an automatic).

The one we are interested in is behind - the Centre Diff Lock Selector Shaft isn't directly connected to the Selector Fork. Instead, its sprung loaded (which allows us to select diff lock at any speed in any gear), It will move when the load is off the splines (coming out) and when the teeth line up (going in).

The detector switch works from a notch on the Selector Fork - therefore the dash light only works when the gear is engaged / dis-engaged, not when the Transfer Lever is moved.

Still with me ??

From what you have written, the Centre Diff Lock light is coming on / going out as expected - which means that the selector fork is moving the diff lock gear in and out of mesh with the Centre Diff's Anulus (Epicyclic Gear terminology ).

If the diff is still locked when the light is out then something else is wrong.

Earlier this year I re-built a Transfer Box for a member that had been driven on dry roads with the Centre Diff engaged. Transmission wind-up had caused one of the planet gears to burst the planet carrier and a locking pin had dropped into the teeth within the anulus, locking the diff.

A couple of pics:

A replacement Planet Carrier assembly and a tidy-up fixed the problem. Total cost of parts came to about £180 from memory, so not too desperate (my time is free )

I'm not trying to worry you unduly, but I can't think of another explanation based on your description. It sounds as though a Transfer Box stripdown and investigation is called for.

Hopefully I'm wrong.

Bob.

 

[EvilEd]

Thanks Bob, a very useful post.

At least I know what I am up against. Though I think that is way past my technical ability for how long I can have the truck off the road for.

At the very least, if something is a little sticky (ie shaft is moving just enough to turn the sensor off but not to disengage properly) then I will not be adding to the worst case scenario.

Can I ask where you got the parts from (Mr T, Ian or 3rd party) ?

Thanks

EE

 

[BobMurphy]

Can I ask where you got the parts from (Mr T, Ian or 3rd party) ?

I ordered the parts from Ian Rubie. A great service, but they did take a couple of weeks to arrive.

I did wonder if it was possible for the selector fork to move enough to trigger the detector switch, but not enough to free the diff. There is a detent ball on the selector shaft, but nothing that positively locks the selector fork.

Give the box an oil change and then see how it gets on. There is an oil pump in there so you are not just relying on 'splash' to reach the bearings.

Hopefully it will free-off with use, but if you've driven a long way with it locked I think that's unlikely.

Proper little ray of sunshine, me

I'm happy to help if you need the box looking at - but I'm a long way from you and that won't be a quick process .

Bob.

 

[andrewlowe13]

Hi everyone.
This is my first post, so please bear with me.
I've arrived here after a few years of 4x4 ownership; and I hope that J.Wildsmith and P.Humphries might remember me???
I'm not quite a 'Land cruiser owner' yet, just doing some more research to narrow my searches through the 'for sale' listings.....

I've been looking at a few things around here, trying to gain some information about LC90 transmission / transfer design, and this looks like an excellent post! Love the photgraphs and the write up (Thanks Bob). Hope no one minds me high jacking the topic?
I was wondering if someone could put me right on the different options / modes that the transfer box gives you please?
By that I mean the different ways that the transmission can be selected, for different circumstances, ie high / low / diff locked / diff unlocked.
I currently have a Mk2 Shogun, which I think it getting near to wanting to get replaced, and before this, I had a Mk1 LR Discovery.
The Disco had 4 options on the transfer box:
High / Diff unlocked
High / Diff locked
Low / Diff unlocked
Low / Diff locked
The Shogun is quite different (maybe partly at least because of the 2wd option), and there is no option to have low range without the diff being locked. This has a 'sequential' selector, and runs:
High / Diff unlocked
High / Diff locked
Low / Diff locked

These are all just the center diff functions, and not to do with any axle diff locks obviously.

I don't know if there are any differences in the age of these, but I was wondering about a 1998 and onwards ish?!
I would be very greatful if someone could enlighten me on this please.

Cheers,
Andy.

 

[BobMurphy]

I was wondering if someone could put me right on the different options / modes that the transfer box gives you please?
The Shogun is quite different (maybe partly at least because of the 2wd option), and there is no option to have low range without the diff being locked. This has a 'sequential' selector, and runs:
High / Diff unlocked
High / Diff locked
Low / Diff locked

Andy.

Andy,

Welcome to the site.

As you are doubtless aware, the UK '90-Series' Landcruisers have permanent four-wheel drive with separate gearboxes and transfer boxes, like the LR Defender, Discovery & Range Rovers.

They have a solid beam rear axle on control arms, panhard rod and coils. The fronts are independent with a double wishbone, knuckle swivel and coils (no Radius Arms and 'A-frames' with ball joints here ).

The Transfer box works as you have described for the Shogun . .

Transfer lever over to the left:

Back = 'H' - that is high ratio, centre diff unlocked.

Forward = 'HL' - that is high ratio, centre diff locked.

From the forward position the lever can be moved to the right:

Forward = 'N' - That is a neutral position (useful as a security measure )

Forward again = 'LL' - That is Low Ratio with Centre Diff Locked.

It is not possible to have Low Ratio with the centre diff open as it is all mechanical and the selectors only work in this sequence. On the '80-Series' Amazons the Centre Difflock is electrically operated and it is possible to modify the wiring to fool the ECUs and run with the centre difflock open in Low Box

The Workshop Manual we all use is from "Max Ellery" - which is Australian. That shows a part-time four wheel drive variant, so the UK Colorados are not necessarily the same as the 'rest of world's' Prados. I'm afraid I'm not enough of a Toyota Geek to give you chapter and verse on all the variants out there

The UK 'Colorados' have an electrically-operated rear difflock (the electric actuator is prone to corrosion from road salt ) whereas the 'Prados' have a Limited-slip rear diff.

WHEN you come to buy one ( ), check that it has all the functions you expect and ask here for advice as necessary as there can be 'mixes and matches' going on.

I produced an explanation of how the Transfer Box works here - http://www.tlocuk.co.uk/forums/viewtopic.php?t=7927&highlight=transfer+box If you want to see all the gory detail

Bob.

 

[andrewlowe13]

Thanks Bob.
What a great respose. Lots of knowledge for me to try and absorb.

Also, the link to the descripition of the transfer box is very good. Emmensly valuable.
Whilst I think that understand the thinking behind the way this system works, I still think that it would be useful to sometimes be able to use the low gear range, but not have the differential locked. I seem to remember doing this in my discovery a fair amount.
Maybe an 80 series would be a better choice then, (Don't want to start another big debate here...) - an electrical mod to prevent the automatic lock from acting when low is selected sounds interesting. ??

Something tells me that I am not the only one to ponder such things.

Thanks again.
Andy.

 

[Gary Stockton]

The higher-end 120's (LC4 and LC5) both have the centre-diff actuated electronically, so that may be an option for you ...

 

[andrewlowe13]

The higher-end 120's (LC4 and LC5) both have the centre-diff actuated electronically, so that may be an option for you ...

I think that could take a while for the price to come down to my level!

I'm sure they would grow on you, but I don't think I like the general styling of the newer ones as much though either?

 

[BobMurphy]

I still think that it would be useful to sometimes be able to use the low gear range, but not have the differential locked. I seem to remember doing this in my discovery a fair amount.
Andy.

I suppose it might be feasible to produce a different turret for the transfer box with two levers in it and work the two selectors independently

There is a detent billet in the rear of the box that prevents low being engaged until the diff is locked. That would have to come out (an easy mod).

Maybe the selector forks would clash ; I'd need to think about that

I suspect that the torque in low ratio would destroy the centre diff - hence the need to lock it up first. You have probably seen my picture of a burst centre diff planet carrier that was caused by transmission wind-up in high ratio on a dry road .

When I had a LR Series III ('ere we go ) I hated the fact that you couldn't de-select four wheel drive on the move. One had to go into low box to re-set it, which seemed daft given that the ideas behind the early LRs came from the wartime Willys Jeep - which had separate levers for 4-wheel drive and high/low ratio.

It is possible to get a 'Series-LR' modification that gives independent selection - maybe someone should do the same for the Toyotas

(mind you . . I had five levers to play with on the Series III, so maybe that isn't such a good idea . . Transmission brake, Gear lever, Overdrive, 4-wheel drive select & High/Low ratio).

Bob.

 

[fast but dim]

this is a great, informative, thread, thanks

my lc 120, like the defender i had before it, has the option of an open diff in low box, which i regularly use for manoevering in reverse when towing, and when laning 90% of the time. this is an invaluable function, so why no open diff in low on some full time 4x4 landcruisers? i just sold my offroader, a mk 2 pajero, and really missed being able to use low on road.

 

[adrianr]

You can pull a plug on centre diff on the 80's to gain low range without diff lock so presume you can do something similar on the others to achieve same result?

 

[BobMurphy]

You can pull a plug on centre diff on the 80's to gain low range without diff lock so presume you can do something similar on the others to achieve same result?

Only on those with electrically-operated centre difflocks.

Those with manual centre lockers (Colorados, Prados and so on) can't (without some serious re-engineering of the Transfer box).

Bob.

 

[adrianr]

Hmm, you have a good point!!