Viscous Coupling?

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RangeRoverJoe

RangeRoverJoe

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What dose a viscous coupling do in transfer case?

Will my range rover classic have one?
How dose it work?
How can you tell if it still works?
 
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Depends on Year....

Works by locking up when one axle is turning faster than the other (indicating a loss of traction) Works on the same or similar principal to the Viscous unit on the engine fan or the Torque convertor...one axle is drving a rotor disc, the viscous fluid flows through a stator plate to the other axle which has a rotor disc....if one rotor disc travels faster than the other, the viscous fluid gets churned up up and this flows through the stator plate and starts draging the other disc round...if the speed of rotation is large enough the fluid starts thickening and turning faster, this in turn turns the other rotor disc faster to match it....until both axles are turning at the same speed....

Testing is carried out by putting main box in neutral, jack up ONE wheel, Handbrake off, and trying to turn that wheel....it should be stiff and may need a breaker bar on the wheel nuts to rotate.....this is good.

If it is locked solid, this is bad....

If the wheel rotates freely, this indicates a broken Diff, Half Shaft or Prop Shaft....

IIRC - the VCU was introduced in 1991 for tha classic, but can't be 100%....

To see if yours has it - the ratio transfer lever will have a 'Diff Lock' position i.e. you have to move the lever to the left to engage Diff Lock...and to the right to dis-engage...

Don't engage Diff Lock on a hard surface, it should be done on loose surfaces only, as with it locked up you potentially are making both axles turn at the same speed when going round corners, and on hard roads, you could wind up the gearbox ,and couse issues....
 
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yes, and to work properly your transfer box from this year should have ATF fluid in it and NOT EP90 gear oil.....I am shocked at the number of garages that fill these later ones up with EP90 :(
 
When mine went on a classic rr ..It was like,,, Say i would be driving down a duel carriageway, come to an island slow down,And as i turned the steering wheel to go round there was a massive amount of juddering from steering wheel and from underneath.Got a second hand fitted one and all was ok.
 
I recently had mine on a brake tester and I insisted that the tester put the rear wheels on rollers.

I was most surprised to see that when the front wheels were driven the rear wheels didn't turn at all.

Yet, when I engage difflock all wheels are driven.

Is this normal?
 
shoppinit said:
I recently had mine on a brake tester and I insisted that the tester put the rear wheels on rollers.

I was most surprised to see that when the front wheels were driven the rear wheels didn't turn at all.

Yet, when I engage difflock all wheels are driven.

Is this normal?
Click to expand...

Yes if you have a manually engaged diff lock.
 
Phew, thanks. Yes, I do have a manual difflock, I think. To select difflock, I move the lever to the left (where I can select hi or lo also).

This has been bugging me for a while. I was thinking I had a 2x4. :)

Just out of interest, how does the difflock with with the viscous coupling?
 
shoppinit said:
Phew, thanks. Yes, I do have a manual difflock, I think. To select difflock, I move the lever to the left (where I can select hi or lo also).

This has been bugging me for a while. I was thinking I had a 2x4. :)

Just out of interest, how does the difflock with with the viscous coupling?
Click to expand...
It was explained above, but basically it reacts to different speeds betmeen the front and rear axles and progressively locks the centre diff automatically.
 
I got how the viscous coupling works, I was just interested in how the difflock locks it up since there doesn't appear to be anything external on the viscous coupling.
 
Thanks, that's incredibly helpful.
whatever.gif
 
You would think that someone with almost 12000 posts would have understood that sometimes it better, for the sake of conviviality of the forum, to say something like "there's a plate inside that is gripped with a solenoid" rather than "You don't know sh1t. Google it".

Maybe you've been here too long.

/Edit: there's no mention of how difflock works in this thread. Maybe *you* should read it.
 
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shoppinit said:
You would think that someone with almost 12000 posts would have understood that sometimes it better, for the sake of conviviality of the forum, to say something like "there's a plate inside that is gripped with a solenoid" rather than "You don't know sh1t. Google it".

Maybe you've been here too long.

/Edit: there's no mention of how difflock works in this thread. Maybe *you* should read it.
Click to expand...

Another dummy spitting noob!! Read post 2, seems pretty clear to me or as suggested :search:
 
Sterling contribution there, classic kev. It appears you also have reading problems.

Where is the difflock explained in the 2nd post? I see an explanation of a viscous coupling, I don't see any explanation of a difflock.
 
shoppinit said:
Sterling contribution there, classic kev. It appears you also have reading problems.

Where is the difflock explained in the 2nd post? I see an explanation of a viscous coupling, I don't see any explanation of a difflock.
Click to expand...

Stop being a knob.
 
Tell you what, I'll happily concede to being a knob when you tell me where the difflock is explained in the 2nd post.
 
shoppinit said:
Tell you what, I'll happily concede to being a knob when you tell me where the difflock is explained in the 2nd post.
Click to expand...

Never sed it was but you are being a knob. That sort of thing isnt appriciated. Unless you have a few more posts. You aint got a vc dont worry about it. Or google it.
 
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