P38A Center diff lock issue

Hi all.

So, I am looking for a best way to throw Borg Warner's viscous coupling to trash bin and make normal diff lock system - which is fully locked or unlocked when I want it, not when "Liquid inside coupling disturbed" and all that Parquet Rover stuff.
I have two major variants, how to solve this problem (Of course I can also weld that viscous coupling and install front wheel hubs, but this way I will loose Full-time 4WD - this variant is better, than viscous coupling, but not so good, as I wish):

1) LT230 swap. This variant looks realy good, because LT230 is the best transfer box for Land Rover - no chain, different aspect ratios, factory diff lock etc. But the problem is, that how to install it upside down? Someone did it? I found few threads about it, but without specific descriptions

2) All new locking mechanism to Borg Warner transfer box, for the viscous coupling place. This variants looks easier, and I heard about people, who made it - anybody knows something about them?

Thanks in advance for replies

Nothing wrong with viscous coupling if working correctly. If yours is seized fit a new one if it has become to free fit a new one. Not a lot else to be said.

I don't want viscous coupling, which works correctly, I want mech diff lock, which will never overheat and leave me alone with open diff in mud, and will not bring a shame for it in off-road discussions.

Really, I don't need advices about "advantages" of viscous coupling, I hate it. And I will change it anyway, but first I want to collect information, from people, who already made this swap)

He clearly knows best...

Bexer said:

... but first I want to collect information, from people, who already made this swap)

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You may have quite a long wait.

eightinavee said:

He clearly knows best...

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This seems so, only answer i can think of is if he does not like viscous coupling is, tough shit.

Bexer said:

I don't want viscous coupling, which works correctly, I want mech diff lock, which will never overheat and leave me alone with open diff in mud, and will not bring a shame for it in off-road discussions.

Really, I don't need advices about "advantages" of viscous coupling, I hate it. And I will change it anyway, but first I want to collect information, from people, who already made this swap)

Click to expand...

I doubt you’ll find much info out. It really isn’t a question that has ever needed asking before and arguably still doesn’t need asking.

In the Land Rover off road competition world, the Borg Warner is generally the preferred setup and has proven to be robust. And is probably why Range Rovers have used them for decades.

Bexer said:

Hi all.

So, I am looking for a best way to throw Borg Warner's viscous coupling to trash bin and make normal diff lock system - which is fully locked or unlocked when I want it, not when "Liquid inside coupling disturbed" and all that Parquet Rover stuff.
I have two major variants, how to solve this problem (Of course I can also weld that viscous coupling and install front wheel hubs, but this way I will loose Full-time 4WD - this variant is better, than viscous coupling, but not so good, as I wish):

1) LT230 swap. This variant looks realy good, because LT230 is the best transfer box for Land Rover - no chain, different aspect ratios, factory diff lock etc. But the problem is, that how to install it upside down? Someone did it? I found few threads about it, but without specific descriptions

2) All new locking mechanism to Borg Warner transfer box, for the viscous coupling place. This variants looks easier, and I heard about people, who made it - anybody knows something about them?

Thanks in advance for replies

Click to expand...

Cars after 1999 have the 4 wheel traction control and that makes a big difference. When we went laning round Rutland the only car not to get stuck was a P38 with 4W TC!

Look at Ashcrofts and their Airlockers. That will lock the front and rear axles but not front to rear. Remember to peg the diff. Could be worth a call to Ashcrofts. I cannot remember the guy's first name but he's very knowledgeable and helpful, although you may have to wait for him to call back as he's very busy. might have been Paul Ashcroft but I've got a terrible memory for names.

@jamesmartin know these gearboxes inside although I'm not sure he'll approve of your plans! Most of us on here tend to keep our cars original so snorkels and the like are in the other forums.

Grrrrrr said:

Cars after 1999 have the 4 wheel traction control and that makes a big difference. When we went laning round Rutland the only car not to get stuck was a P38 with 4W TC!

Look at Ashcrofts and their Airlockers. That will lock the front and rear axles but not front to rear. Remember to peg the diff. Could be worth a call to Ashcrofts. I cannot remember the guy's first name but he's very knowledgeable and helpful, although you may have to wait for him to call back as he's very busy. might have been Paul Ashcroft but I've got a terrible memory for names.

@jamesmartin know these gearboxes inside although I'm not sure he'll approve of your plans! Most of us on here tend to keep our cars original so snorkels and the like are in the other forums.

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If I could find a P38 snorkel that didnt look like drain pipe, I'd have one!!!

Bexer said:

I don't want viscous coupling, which works correctly, I want mech diff lock, which will never overheat and leave me alone with open diff in mud, and will not bring a shame for it in off-road discussions.

Really, I don't need advices about "advantages" of viscous coupling, I hate it. And I will change it anyway, but first I want to collect information, from people, who already made this swap)

Click to expand...

IMO the viscous coupling was just a bean counters cheap alternative to a proper diff lock.

Datatek said:

IMO the viscous coupling was just a bean counters cheap alternative to a proper diff lock.

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Not sure that can be true. The cheaper and in production at the same time Discovery 1 had the LT230 with centre difflock. Really can’t see it being a cost thing.

I dont intend changing mine as I believe in keeping it original as possible, but I reckon the viscous coupling sucks. Give me a wee yellow knob to lock the diff every time that goes "CLUNK" to tell you it is engaged

300bhp/ton said:

In the Land Rover off road competition world, the Borg Warner is generally the preferred setup and has proven to be robust. And is probably why Range Rovers have used them for decades.

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Ah, and that's interesting, if this Borg Warner is allegedly so good, why there's only discoveries with LT230 there?

Grrrrrr said:

Cars after 1999 have the 4 wheel traction control and that makes a big difference. When we went laning round Rutland the only car not to get stuck was a P38 with 4W TC

Click to expand...

I used to drive a 2001 model year P38 with traction in deep snow - TC wasn't very helpfull, when it was engaged, but after 10 minutes of slip I saw "Traction failure" on dashboard and it was disabled, until car reached asphalt. It's not a replace for three normal diff locks, as on G-classe

Grrrrrr said:

Look at Ashcrofts and their Airlockers. That will lock the front and rear axles but not front to rear. Remember to peg the diff. Could be worth a call to Ashcrofts. I cannot remember the guy's first name but he's very knowledgeable and helpful, although you may have to wait for him to call back as he's very busy. might have been Paul Ashcroft but I've got a terrible memory for names..

Click to expand...

I asked them about center diff lock, they said that don't have anything for it.

Grrrrrr said:

Most of us on here tend to keep our cars original so snorkels and the like are in the other forums.

Click to expand...

My car is more original, than a better part of P38, which are in operation now - but there are two things, which I will not accept in P38 - viscous coupling and windshield heater (but windshield is easy to change). I don't have snorkel (It's usefull, but I don't need it, because I drive only through mud, not through rivers - and don't want to see a pipe in front of me), I only want normal diff lock - and I'll get it.

300bhp/ton said:

Not sure that can be true. The cheaper and in production at the same time Discovery 1 had the LT230 with centre difflock. Really can’t see it being a cost thing.

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Yes, for example kickback for chief engineer from Borg Warner - because they suddenly changed normal LT230 on Range Rover Classic to this Borg Warner *** in 1993, without any advantages for customer

Bexer said:

Ah, and that's interesting, if this Borg Warner is allegedly so good, why there's only discoveries with LT230 there?


I used to drive a 2001 model year P38 with traction in deep snow - TC wasn't very helpfull, when it was engaged, but after 10 minutes of slip I saw "Traction failure" on dashboard and it was disabled, until car reached asphalt. It's not a replace for three normal diff locks, as on G-classe


I asked them about center diff lock, they said that don't have anything for it.


My car is more original, than a better part of P38, which are in operation now - but there are two things, which I will not accept in P38 - viscous coupling and windshield heater (but windshield is easy to change). I don't have snorkel (It's usefull, but I don't need it, because I drive only through mud, not through rivers - and don't want to see a pipe in front of me), I only want normal diff lock - and I'll get it.


Yes, for example kickback for chief engineer from Borg Warner - because they suddenly changed normal LT230 on Range Rover Classic to this Borg Warner *** in 1993, without any advantages for customer

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discovery wasnt the luxury model so had to be inferior,borg warner is a better box
the viscous gives the same effect as diff lock but has advantages in that it can engage for brief moments when an operator might not have thought about selecting,
buy a disco or a defender or fit a fake button saying engage viscous it will work

Bexer, it would help if you knew what you were on about...
"I used to drive a 2001 model year P38 with traction in deep snow - TC wasn't very helpfull, when it was engaged, but after 10 minutes of slip I saw "Traction failure" on dashboard and it was disabled, until car reached asphalt. It's not a replace for three normal diff locks, as on G-classe"
The "Traction Failure was nothing to do with the viscous coupling,it is a stand alone unit and is not monitored. Traction failure is reporting an ABS or gearbox fault,its often low battery voltage that puts it up.

eightinavee said:

Bexer, it would help if you knew what you were on about...
"I used to drive a 2001 model year P38 with traction in deep snow - TC wasn't very helpfull, when it was engaged, but after 10 minutes of slip I saw "Traction failure" on dashboard and it was disabled, until car reached asphalt. It's not a replace for three normal diff locks, as on G-classe"
The "Traction Failure was nothing to do with the viscous coupling,it is a stand alone unit and is not monitored. Traction failure is reporting an ABS or gearbox fault,its often low battery voltage that puts it up.

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TC only works for short periods otherwise the brakes overheat. Again it's a cheap alternative to a LSD or difflock using the ABS system.

jamesmartin said:

discovery wasnt the luxury model so had to be inferior,borg warner is a better box
the viscous gives the same effect as diff lock but has advantages in that it can engage for brief moments when an operator might not have thought about selecting,
buy a disco or a defender or fit a fake button saying engage viscous it will work

Click to expand...

May be Borg Warners advertised their transfer box like this, but in fact it isn't true and enough to make a cat laugh, that for person on framed 4x4 with axles will be better, to loose control of center differential - I already mentioned G-classe, which was more expensive and luxury than RR in 1990s, and still do it now - there are all three diff locks in all versions (Front, rear, center), and nobody said "Bitte, install viscous coupling, it's too hard for me to control diff lock". At least, they should have given the buyer a choice - like on Grand Cherokee, which had three transfer box - part time, normal 4WD and stripped down 4WD with same viscous coupling on p38 (All jeep owners don't like it, of course)

PS I don't want to buy Disco, Defender, G-classe or something else, I like p38 - but I want to fix mistakes of factory, to make it better.
PPS The button for diff lock isn't problem - I'm going to take original low gear button from P38 with manual gearbox - it's original and there is a picture of gear with letter "L" on it, the best variant of diff lock button, only P38 guru will understand, that it's not original diff lock system

eightinavee said:

Bexer, it would help if you knew what you were on about...
"I used to drive a 2001 model year P38 with traction in deep snow - TC wasn't very helpfull, when it was engaged, but after 10 minutes of slip I saw "Traction failure" on dashboard and it was disabled, until car reached asphalt. It's not a replace for three normal diff locks, as on G-classe"
The "Traction Failure was nothing to do with the viscous coupling,it is a stand alone unit and is not monitored. Traction failure is reporting an ABS or gearbox fault,its often low battery voltage that puts it up.

Click to expand...

Yes, I know, that traction is part of ABS and not connected to viscous coupling, I just told, that this system is useless, than the car slips for long time, unlike diff locks. The traction failure on that 2001 P38 wasn't because of mechanical problem, it was a result of long time slip.

Bexer said:

Ah, and that's interesting, if this Borg Warner is allegedly so good, why there's only discoveries with LT230 there?

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The Range rover cost more. The Discovery uses the same setup as the also cheaper Defender.

The LT230 is a good transfer box, but so is the Borg Warner. Maybe you could find some more info of other people having issues with the Borg Warner?

Bexer said:

I used to drive a 2001 model year P38 with traction in deep snow - TC wasn't very helpfull, when it was engaged, but after 10 minutes of slip I saw "Traction failure" on dashboard and it was disabled, until car reached asphalt. It's not a replace for three normal diff locks, as on G-classe

Click to expand...

TC is indeed very helpful. However it works the brakes quite hard. The p38 will disable the TCS when it detects the brakes are getting hot, to allow cool down and will then work again. The big thing to consider here is, no Land Rovers with solid axles have ever been supplied with diff lockers or LSD's. With the TCS disable the p38 is equal to all other Land Rovers of the same or earlier era in terms of driven wheels. With it working it is far more capable.

Bexer said:

I asked them about center diff lock, they said that don't have anything for it.

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And maybe that should be a hint that nobody else finds it a problem

I daresay Ashcroft can offer axle lockers or ATB's. The ATB's would complement the TCS perfectly.

Bexer said:

My car is more original, than a better part of P38, which are in operation now - but there are two things, which I will not accept in P38 - viscous coupling and windshield heater (but windshield is easy to change). I don't have snorkel (It's usefull, but I don't need it, because I drive only through mud, not through rivers - and don't want to see a pipe in front of me), I only want normal diff lock - and I'll get it.

Click to expand...

Are you in the USA?

Bexer said:

Yes, for example kickback for chief engineer from Borg Warner - because they suddenly changed normal LT230 on Range Rover Classic to this Borg Warner *** in 1993, without any advantages for customer

Click to expand...

Plenty of advantages. It requires no user interaction to operate. And allows seamless transition between different surfaces and grip levels, where with an LT230 you'd have to keep putting the difflock in and out.

Yes, you cannot beat the 3 diff locks. The viscous coupling requires different driving as it needs to lock up. That means booting the damn thing to get it to lock up. That will work the brakes hard if the TC kicks in though so understand where you are coming from. It certainly burns the brake fluid if you do a lot of it so you need a complete flush out of the fluid if you do it a lot.

The Disco 2 still had centre diff locks, didn't they? That'd be my starting point.

Grrrrrr said:

Yes, you cannot beat the 3 diff locks. The viscous coupling requires different driving as it needs to lock up. That means booting the damn thing to get it to lock up. That will work the brakes hard if the TC kicks in though so understand where you are coming from. It certainly burns the brake fluid if you do a lot of it so you need a complete flush out of the fluid if you do it a lot.

The Disco 2 still had centre diff locks, didn't they? That'd be my starting point.

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The viscous is, supposedly, progressive, try turning a jacked front wheel by hand, there is a small amount of lock between front and back at all times, until the batard fails and seizes completely. It's the differential rotational speed between front and rear drive lines that causes lock up, so no need to "boot it" as you put it, all it needs is one end to lose traction.