Understanding diff lock in the P38

Diff Lock Article

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Originally Posted by PhilipA

If your rear traction control does not overheat then I guess that a front locker could help but on a gnarly climb you still have the possibility of an overheat , and then the front locker will not help much.
In a non TC car IMHO it is very clear cut that it should be rear.
In a TC car it is not so clear cut but I personally would still go for back, as these fancy traction aids always seem to give up when you most need them. I have seen it happen on a club trip on Mt Airlie when a member got the 38A version of three amigos just before the most difficult step.

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Excuse my thickness Philip, what's the "38A version of three amigos"?

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Originally Posted by Remy

Diff Lock Article

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Good read - and quite enlightening.

ARB have quoted me approx $1600 to supply and fit a front air-locker to my Rangie.

In terms of cost and priority, it is now right behind the transmission replacement and purchase of a Faultmate.

cheers, Paul.

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Excuse my thickness Philip, what's the "38A version of three amigos"?

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Discovery 2 has 3 lights that light up when the ABS and traction control fails.

I do not know the light show variant for 38s .

The car in question simultaneously blew a heater hose (known early 38 problem) and coincidentally (ie not connected) had the traction control failure lights come on. LOL. Luckily we had a Rover dealer mechanic on hand, but he had to be snatched up the obstacle.

It can be caused by a sensor getting wet, wheel bearings failing/slop or just plain cussedness.
Regards Philip A

I do.....

The message centre says "TRACTION CONTROL FAILURE" and you hear a warning beep.

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Originally Posted by adm333

I do.....

The message centre says "TRACTION CONTROL FAILURE" and you hear a warning beep.

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I'll add that to the list of things I don't ever want to see on the Message Centre of my P38A. Thanks for the heads-up.

Cheers, Paul.

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Originally Posted by adm333

I do.....

The message centre says "TRACTION CONTROL FAILURE" and you hear a warning beep.

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Well that's a nice one to add to the list.. :( This has recently come up on mine after some medium rocky action out west.

It originally came up as "TRACTION CONTROL OVERHEAT" and i guessed that it just had a big work out and might cool down and sort itself out. Guess not :eek:

Booking in with Graeme Cooper next week for a service and a smoothing of my new Haltech (very happy with that!)

Cheers,

Dave

the vc center in the transfercase is like sort of like a open diff center not a locker.

if you lose traction to the front wheels ( both or one) it will send nearly all of the power to them as its the easy way for it to go, like a open center. think of it as your car just went from 4wd to 2wd. with a center diff lock (tcase) it makes both front and back drive shafts turn at the same speed no matter what.

then diff locks on in the axles come into play and keep the wheels turning at the same time.

if you have axle lockers and a vc t/case you will still only get drive to the front or back wheels when one has less grip, you will just be turning both wheels insted of the one thatsin the air.

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Originally Posted by 2door grover

the vc center in the transfercase is like sort of like a open diff center not a locker.

if you lose traction to the front wheels ( both or one) it will send nearly all of the power to them as its the easy way for it to go, like a open center. think of it as your car just went from 4wd to 2wd. with a center diff lock (tcase) it makes both front and back drive shafts turn at the same speed no matter what.

then diff locks on in the axles come into play and keep the wheels turning at the same time.

if you have axle lockers and a vc t/case you will still only get drive to the front or back wheels when one has less grip, you will just be turning both wheels insted of the one thatsin the air.

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But the VC locks up when it detects slippage, resulting in a locked centre diff.

There are no locks as such on the axles, just traction control on the rear or front + rear (depending on model).

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Originally Posted by Scouse

But the VC locks up when it detects slippage, resulting in a locked centre diff.

There are no locks as such on the axles, just traction control on the rear or front + rear (depending on model).

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ok i didn't know that, i was told that a vc will never lock up and will slip sort of like a toque converter and that is why they are replaced with a locking center diff in rrc and disco's

is that right?

The viscous coupling is designed to be an "automatic" locking centre diff, I guess to alleviate the Range Rover driver from having to make those decisions.

A viscous gel substance floats between fins of the front and rear output shafts.

When the speed differential becomes two great the gel heats up and causes the fins to lock together. It is all meant to happen quite quickly, such that front or rear wheel spin should "activate" the locking mechanism.

In my experience with my RRC '94 and my current P38 both of which have the VC, it doesn't quite work fast enough and if I had a choice, I think I would rather be able to choose myself whne I locked in the centre.

http://www.aulro.com/afvb/attachment...s-coupling.jpg