viscous locking differential

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Thread: viscous locking differential

  1. #1

    viscous locking differential

    I was shocked to learn that the Range Rover does not lock its center differential when it is put into low range (for some reason I thought it had a center lock), my question is how much power can the "viscous locking differential" supply? Will it supply as much as a true locker?

    Also can we discuss various lockers we have on the rears and fronts?



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  3. #2
    Join Date
    April 28th, 2004
    Coolum, QLD - Australia
    Yep, shocking but true.

    While a proper locking centre diff (solid gear) may be desirable for outright and definative power distribution, I don't think there any conversions available.
    However, the BW viscous transfer fitted to my p38a rangies doesn't seem too bad.
    Upon fitment of my rear ARB locker, I was warned that excessive slip may be experienced - all the power re-transmitted to the front axle. This advice came from a chap with a 93' and had video evidence of all power be sent to front once the rear locker was activated. But this was a much earlier model, maybe with a few more k's on it?

    Having tried my locker out a few times since, I've had no problems.
    Even with car going no-where see-sawing diagonally on one front and one rear wheel and ETC working overtime, the rear locker (once activated) allowed forward progress - on many other occasions, in differing terrain. Proof that the viscous centre diff may be up to sensible power distribution?
    I posed this question to Maxi-Drive, they were un-aware of any problems.

  4. #3
    Join Date
    April 21st, 2004
    Dubai, UAE
    Hmmm, lockers, lockers, lockers

    I have been looking at these for a long time now, trying to work out what the best option is for my Rangie, and as yet I still haven't made any definite decisions.

    The problem is that there are several different types of locker to choose from, and all provoke either love or hate from all sorts of people sitting carefully on each side of the fence.

    Firstly, no, the centre viscous coupling does not lock, and no one I know of has ever done this conversion. With this in mind, it does seem like any sort of difflock is a waste of time, because this coupling will just transfer the power away from the stuck/locked up axle.

    But, as Hardy says, there seems to be some clever work afoot here, because this is not what happens, the coupling does sense wheel traction/spin, I know because I get mine stuck regularly, and it does feed power to both ends of the car.

    So what sort of locker to buy, the most popular is the ARB one, but equally well used are the Detroit, Maxi-drive, KAM and McNamara all have their plus and minus points, btu this is where I get confused !

    The ARB's seem to be the favourite for P38's, tried and tested, very strong, but also quite expensive, and I have to admit I do worry about the airlines.
    Detroit Locker and TruTrac LSD have a great reputation for strength and simplicity, not a lot of things to go wrong, seem to be very reliable, people swear by the "magic" combo of a Detroit locker on the back and the TruTrac LSD on the front.
    Maxi-drive also have a good reputation, very strong, choice of compressed air or cable operated, but less people seem to use these than the other two.
    KAM have a great reputation for this type of stuff, although don't seem to be as well known as some of the others, they do a whole host of strengthened stuff, including the elusive 3.80:1 R & P gearing that no else seems to supply !
    Mcnamara also have a good reputation within Oz for making difflocks and strengthened bits and pieces, but don't seem to do too much internationally.

    You've also got loads of smaller companies like Ashcroft transmissions in the UK who supply a combination of their own built bits and supply of other brands.

    One day I will make my mind up, but if I had to choose one system now, it would be either the KAM system or the Detroit Locker and the TruTrac LSD, both of these are tried and tested, but are a lot more simple and with less things to go wrong than the ARB setup.

    Sorry for the long post, didn't seem that long when I wrote it !

  5. #4
    Join Date
    April 28th, 2004
    Coolum, QLD - Australia
    I was on a steepish, wet grassy slope the other day - going nowhere, except backwards. All 4 wheels were turning uniformly, ETC action was barely present.
    The viscous centre does transmit power pretty evenly, given the chance.
    With rear locker in, ETC seemed to quieten down a bit - as though the rear channel is no longer needed.

    Chris - ARB may be the go as the installation/operation is more straight forward. Initially cheaper, too. If you break an axle THEN you can still always buy MD upgrades. That's my plan of attack.
    I'm not sure your '98 has ETC all round? This would have a big impact on whether you'd want a front locker. I don't think I'll need one, I'm satisfied with the current combo - ETC front, ARB rear.

    However, I feel the trend in lockers will head the way of ETC or hydraulic brake/diff manipulation. More sophisticated versions will offer better, progressive operation plus by nature being less punishing to driveline.
    This is already evident in the new LR3.
    Maybe it's this type of development (in the past) that allows the P38's centre diff to behave better than that of a Classic?


  6. #5
    Join Date
    April 21st, 2004
    Dubai, UAE
    Sorry Hardy, forgot to mention, mine doesn't have ETC, it's a '98 model and the ETC only became standard from '99 onwards, back in '98 it was an option which the guy I bought mine from didn't specify.

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