RRC viscous coupling

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chris_mack

chris_mack

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Melbourne, Australia
Apparantly the RRC, or at least some of them, have got a viscous coupling instead of a manually locking centre diff.

How reliable is this, and how well does it match up off road to a manual diff lock?

The on I am getting has this set up, along with a 4 speed autobox. Do they tend to have any gearbox/transfer box issues that I should watch out for? Thanks
 
Unless you intend doing some extreme off roading like rock climbing or log hopping then the added traction afforded by a VC during turns is probably an advantage over a locked up open diff.

Again, once you account for lack of engine braking on downhill sections, an auto offers some advatages in how you put down power.

In any case the ultimate strong/weak point in the Rangies armoury is the guy behind wheel!
 
The main advantage of a viscous coupling is that it's completely automatic and only engages when you need it to. It does require a small amount of spin before it locks up so does behave slightly differently to a lockable centre diff, but my impression is that it's a better system.

They do go wrong occasionally though and seize up eventually so you should check that it's working properly, otherwise it can trash your front diff.

Guy
 
chris_mack said:
ok does it have to be in N for that or park?
Click to expand...


Sorry Chris should have said .... Jack up front offside wheel, Handrbrake ON & Gear in Neutral ....you should be able to turn it (with some pressure) 27lbs/foot Torque..... if yer can't turn it at all ....

Then Yeah VC is Fooked!!!

If it IS Fooked ..DO NOT drive it it'll destroy yer front Diff, best way is as I have had to ...... Drop out front prop & off yer go ..until you feel like gettin REAL dirty & replacing the VC
 
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Sunday was a hung over day of not doing a lot for me! I was goin to fix some new speakers in it but went to the shop supercheap auto (like halfords) and it was shut cos of ANZAC day. so did literally nothing all day!
 
the hooded claw said:
Sorry Chris should have said .... Jack up front offside wheel, Handrbrake ON & Gear in Neutral ....you should be able to turn it (with some pressure) 27lbs/foot Torque..... if yer can't turn it at all ....
Click to expand...

I think you need a whole lot more than 27ft/lbs to turn it! Even Ashcroft quote 35 at the output shaft of the transfer box and at the wheel you're going through the diff as well.

Someone on Rangerovers.net quoted me 60ft/lbs on the wheel nut - apparently it shoud rotate 90 degress in a minute with this amount of torque applied to it, but someone else calculated that it would be approx 90ft/lbs on the wheelnut.,

It seems a bit of a black art, but as long as you can turn it at all, from what I can gather it's not seized.

Guy
 
the hooded claw said:
Sorry Chris should have said .... Jack up front offside wheel, Handrbrake ON & Gear in Neutral ....you should be able to turn it (with some pressure) 27lbs/foot Torque..... if yer can't turn it at all ....

For ''gear in neutral'' read transfer box must be in neutral. Don't forget to use chocks before jacking it up! On a new VC (personal experience with an Ashcroft recon. unit) you should be able to turn the wheel with 30 lb/ft though obviously this effort will increase with the vehicle's use /mileage. 'Around town' driving with a high percentage of cornering will reduce the life of the VC as opposed to 'straight line' mileage.
Click to expand...
 
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kooky_guy said:
I think you need a whole lot more than 27ft/lbs to turn it! Even Ashcroft quote 35 at the output shaft of the transfer box and at the wheel you're going through the diff as well.

Someone on Rangerovers.net quoted me 60ft/lbs on the wheel nut - apparently it shoud rotate 90 degress in a minute with this amount of torque applied to it, but someone else calculated that it would be approx 90ft/lbs on the wheelnut.,

It seems a bit of a black art, but as long as you can turn it at all, from what I can gather it's not seized.

Guy
Click to expand...

No No No, misquote. 90 lb feet on halfshaft retention nut. Nut at centre of hub NOT on wheel nut. 27 lb feet on output flange nut. With propshaft removed. Should of course be Nm and not lb feet sorry. If you use lb feet it should be 20 lb feet at output flange or 60 lb feet on halfshaft nut. NOT wheel nut.
 
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wammers said:
No No No, misquote. 90 lb feet on halfshaft retention nut. Nut at centre of hub NOT on wheel nut. 27 lb feet on output flange nut. With propshaft removed. Should of course be Nm and not lb feet sorry. If you use lb feet it should be 20 lb feet at output flange or 60 lb feet on halfshaft nut. NOT wheel nut.
Click to expand...

Well that's me confused then.

So have we concluded that mine is seized after all? It does move at 60lbs/ft on the wheelnut, but very slowly. Certainly not the 90 degrees in a minute that was suggested.
 
kooky_guy said:
Well that's me confused then.

So have we concluded that mine is seized after all? It does move at 60lbs/ft on the wheelnut, but very slowly. Certainly not the 90 degrees in a minute that was suggested.
Click to expand...

Read the method on the Ashcroft Transmission web site. There are two torque figures given one is 27 Nm one is 20 Nm. 20 lb feet and 15 lb feet in old money. You should be able to turn it easily but with some resistance at 27Nm (20 lb feet) but at 20 Nm (15 lb feet) and without going over that torque setting it should move 25 to 30 degrees in a minute. That is on drive flange with prop removed. Do not use a wheel nut apply torque to halfshaft nut and just multiply settings by 3.54. (Diff ratio) to get same results.
 
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