1990 Range Rover Classic 3.9 V8 diff lock

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
O

out with Suzuki in with disco

New Member
Posts
43
Hi All,

I have just bought the above and rapidly fitted it with some 235 70 16 Insa Turbo Saharas in time to take it on its first outing with the ADWC last weekend.

I was a little disappointed to find that it got stuck on just about every obstacle possible and had to get pulled out no less than 6 times.

I had an SJ that easier coped with these tests so I am a little peeved.

The car doesn't have a diff lock on it which is no doubt part of the problem.

My question is around this and I am hoping that people could suggest way to make it more capable. I have looked for a diff lock but cannot see anything for it.

If anyone knows where to get one or any other solutions to make it better I would be grateful.

cheers
James
 
a classic rangy has a centre difflock, and generally its driving ability rather than vehicles ability that gets people stuck
 
thanks, however, I would consider myself relatively capable and able to read the terrain. The terrain is not new to me.

Can you elaborate on the centre diff lock please. When I was stuck only some wheels were spinning relative to how much pressure or how stuck the wheels were.
 
the centre diff works locking the front and rear shafts together, this does not lock the axles. its hard to explain really lol

when offroading do you push the lever forward into low range and then left into difflock?
 
see this is where I am puzzled. As far as I can tell it only has high or low. Naturally I have it in low when tackling an obstacle but the level only moves forward and back there is no option and certainly no instructions on it to move it left. I want to pop outside now and try it! May have to wait til tomorrow as I am sure the neighbours wouldnt be so keen to hear it starting at this time
 
out with Suzuki in with disco said:
see this is where I am puzzled. As far as I can tell it only has high or low. Naturally I have it in low when tackling an obstacle but the level only moves forward and back there is no option and certainly no instructions on it to move it left. I want to pop outside now and try it! May have to wait til tomorrow as I am sure the neighbours wouldnt be so keen to hear it starting at this time
Click to expand...

it should have difflock, forward and left, it could be siezed if it hasnt been used and there is a thread on here somewhere about freeing it
 
Ok, do you understand how a four wheel drive system works?
in road going mode every diff is open, front rear and centre (not rangey).
when one wheel either front or rear loses traction all the power will go to that wheel leaving it spinning with 100% power through it. Useless.
When you engage diff lock, or the viscous coupling on a rangey automatically locks, (which it does when it senses wheel slip front or rear, basically it works a bit like a limited slip diff) you are garuanteed power to the front and the back. But because the axle diffs are open you still only get power to one wheel but now one wheel front and rear.
The range rover is a whole different world from the suzuki. They are completelt different to drive and it will take a lot of getting used to. Driven correctly the range rover is the better vehicle for sure but will take practice.
I am an off road driving instructor and we have a suzuki that we do demos in and its really quite funny to watch it get cross axled in a small hole! whereas the old rangey just carries on hardly feeling the bump!
And yes if yours does not have diff lock then it will be a viscous transfer box. Nothing wrong with that only the wheels have to spin before it locks. A bit like getting stuck then engaging diff lock. Duh!
 
Last edited:
thanks lads.

So if it has no diff, then how do I get one? Is it something I can buy or should I get rid of the gearbox or the truck altogether an buy something more capable.

Where TIG9619 says that if it has no diff lock then it will be a viscous transfer box, I was in mud so sticky that the front wheels would not spin but the rear were so it was absolutely useless.
 
if only the front or rear were spinning then either your viscous unit in the transfer box is duff and not locking. most likely as it should do it as soon as a wheel spins.
or you have a normal lt230 transfer box fitted with the original linkage and it will not allow you to move the lever to the left to engage diff lock, hence all the drive going to front or rear.
you first need to get underneath and determine which transfer box you have and go from threre.
a standard lt230 with a centre diff will have a round plate with m10 bolts next to the handbrake drum at the rear of the unit. next to this will be the serial number and the ratio sticker.
if it does not have this plate then it is a viscous box.
you could either get a second hand one or ditch it and fit a standard one from a disco which will be cheap as chips and gives you the option of manually engaging diff lock.
A borg warner will look like this with a line of bolts around the middle of the casing across ways
bwl2.jpg

this is an lt230 with a long front output assembly and the diff lock stud on it
230a.jpg
 
Last edited:
use your momentum to carry you through the sticky stuff, that the advantage of its 2 1/2 tonne rangie+the v8 of course!
 
v8 discos wrong, the 90 model wil haved vc as stated above.Do you have drive to al four wheels?ie before getting stuck?also comparing a classic to a zuk aint clever.
 
I have been reading this thread with interest, and would just like to know something I've always wondered about my recently sold coil sprung 1993 LSE 4.2L V8.... there was an awful load of grunt in that motor, and many times when pulling away on tarmac, wet or dry, from a standstill, I spun the front wheels easily.
Should this have been able to happen? Or was there a faulty Viscous Coupling?
Forgive me if this is a stupid question, but my 2 Rangies before that were manual diff-lock Vacuum Switch models.... and I had a basic knowledge of how that actuated / worked........:confused:
 
hugechoonz said:
I have been reading this thread with interest, and would just like to know something I've always wondered about my recently sold coil sprung 1993 LSE 4.2L V8.... there was an awful load of grunt in that motor, and many times when pulling away on tarmac, wet or dry, from a standstill, I spun the front wheels easily.
Should this have been able to happen? Or was there a faulty Viscous Coupling?
Forgive me if this is a stupid question, but my 2 Rangies before that were manual diff-lock Vacuum Switch models.... and I had a basic knowledge of how that actuated / worked........:confused:
Click to expand...
Suspicous.Did you definately have drive to the rear?Ive had a v8 90 spin the front whilst towing a trailer up hill.
 
The RR classic is a very capable vehicle and on those tyres should be pretty unstoppable! I have done a lot of off road use in the same motor and can vouch for its capability. As others have said you have a centre vicous diif lock which is fully automatic and is free until it senses loss of drive at one end at which point it locks up to ensure drive goes to both front and rear. It could be that the diff lock is knackered, its not unknown for that to happen.
As a rough test Jack up the offside back wheel on sturdy trolley jack so that you can see it out the drivers window. Start it up and very gently try to drive off. If the lifted wheel just spins and you dont start to move off the diff is knackered. If you move forward this will show that drive is being split to the front wheels and diff is working.
Its also worth noting that these cars should not be MOT brake tested on a two wheel roller test despite what the tester may tell you. This can cause failure of the centre diff lock. They should be done on a full 4 wheel rig or on a road test with a taply tester.
Hope that helps
 
goonarmy said:
Suspicous.Did you definately have drive to the rear?
Click to expand...

Thanks Goonarmy,

I'm not sure, I bought a 2nd hand transfer box, cos the original one died.... there was definitely a problem with that even before it died, I used to get the old "front wheels skitting" sketch when on full lock.... but it never occurred to me that the "new" box might only be driving the front wheels.... interesting.... I may put that to the new owner..... he's a friend of mine...(at the moment....haha lol):)
 
Tig9619 said:
Ok, do you understand how a four wheel drive system works?
in road going mode every diff is open, front rear and centre (not rangey).
when one wheel either front or rear loses traction all the power will go to that wheel leaving it spinning with 100% power through it. Useless.
When you engage diff lock, or the viscous coupling on a rangey automatically locks, (which it does when it senses wheel slip front or rear, basically it works a bit like a limited slip diff) you are garuanteed power to the front and the back. But because the axle diffs are open you still only get power to one wheel but now one wheel front and rear.
The range rover is a whole different world from the suzuki. They are completelt different to drive and it will take a lot of getting used to. Driven correctly the range rover is the better vehicle for sure but will take practice.
I am an off road driving instructor and we have a suzuki that we do demos in and its really quite funny to watch it get cross axled in a small hole! whereas the old rangey just carries on hardly feeling the bump!
And yes if yours does not have diff lock then it will be a viscous transfer box. Nothing wrong with that only the wheels have to spin before it locks. A bit like getting stuck then engaging diff lock. Duh!
Click to expand...

Don't really want to argue with an instructor but I often read put downs of the VC and sometimes it needs to be put straight. Yes the VC needs some slip to lock up fully but its no way like getting stuck before locking up an open diff. The VC limited slip diff does exactly as its says on the tin, its always stiff but allows a limited amount of slip before it locks up fully which is the opposite of hows its often described as an open diff which then starts to lock.
The disco or landcruiser etc which have truly open centre diffs will always spin out torque through the wheel with the least traction loosing momentum with every spin until you lock them up. This is not the case with the rangie, even when you get spin at one wheel it is still sending torque to the other axle which is not the case with an open diff. The more it happens the hotter the silicon gets and the quicker it locks up.
Obviously a locked diff offers an advantage in some extreme situations but the VC offers an advantage in turning without axle wind up/spinning wheels. It offers significant advantages in ice and snow over a normal diff lock. All in all it is a good compromise.
 
I was not putting the viscous box down in any way i think they are an excellent box with very smooth power delivery.
I was however giving a simplified explanation to make understanding easier. if you bombard people with technicalities they tend not to take anything in!
Yes you are right a vc will never be truly open like a mechanical diff would.
 
wow, thanks everyone for your input. It is appreciated. I have a lot to go on now and will try and reply over the next couple of days.

What I can say though is that prior to getting stuck 4wd is definitely working. In terms of using momentum to get through the sticky mud, I was concerned I might drown it by making water fly up through the engine into the electrics. I must find out what the problem is as I cant have my mate who still has an SJ laughing at me from the other side of the terrain that I cant get through!!!

:)
 
You must log in or register to reply here.

Similar threads

C
Range Rover 1990 Transfer Case Viscous Coupling Seized
2
Replies
22
Views
2K
cljcars
C
Paj90
Diff lock won't engage
Replies
3
Views
802
dag019
dag019
RobV8Defender
1990 Range Rover Classic Dashboard Scratches
Replies
4
Views
855
RobV8Defender
RobV8Defender
RobV8Defender
Range Rover Classic 1990 Air Vents
Replies
7
Views
1K
norseman
norseman
M
1990 Range Classic 3.9 Petrol Cooling Fan Permanently On
Replies
4
Views
931
kermit_rr
kermit_rr
Back
Top