Member Since: 11 Oct 2006
Location: Melbourne, Australia
Posts: 57
What is the Center Differential mechanism in the Disco 3
Is it similar to the Discovery Series II, where it is a hard locking differential with no slip at all, or is it one of those electronically controlled limited slip Torsen systems?
I'm wondering whether the CDL on the D3 can be manually locked via one of the settings in the Active Terrain Response system.
The reason why I ask is because some situations require very slow driving, far too slow for the wheel speed sensors to work, and so the traction control system effectively is inoperational.
13th Feb 2007 4:33 am
LeighW D3 Decade
Member Since: 31 Jan 2006
Location: Brisbane, AUS
Posts: 920
Hi tempestv8. Whilst I can't immediately answer your question regarding the centre diff, I believe that even at very low speeds, if a wheel loses traction the ABS will apply pulsed braking to it until it has traction again.
Regarding Terrain Response there are several modes that may determine that the centre diff is locked. But I think that the traction control will recognise the wheels that are slipping and adjust the diff locking accordingly.
My response is not based on an intimate knowledge of the D3 transmission but will suffice until someone else with factual knowledge can respond. I have a PDF file in my gallery that gives a little more information about the Terrain response modes here.
HTH, LeighLeighW
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* first ran a bearing (design failure in original engine)
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13th Feb 2007 8:11 am
tempestv8
Member Since: 11 Oct 2006
Location: Melbourne, Australia
Posts: 57
Hi Leigh,
You will find that below a certain speed threshold, ABS no longer works, because the speed sensors rely on the ability to count the notches on the hub, and when rotational speeds drop below a certain speed, it's no longer possible for the computer to work out what RPM the wheels are travelling at.
It's at those speeds that electronic traction control no longer works, and cannot substitute a hard locking differential.
So I guess, being a diehard offroader, I am curious to find out whether the D3's center differential can be locked hard or whether it's a fancy limited slip differential with electronic intervention.
Lawrance Lee
13th Feb 2007 1:26 pm
catweasel
Member Since: 05 May 2006
Location: Bundaleer
Posts: 4805
AFAIK both centre and rear are progressive and not on or off. even at low speeds if a wheel spins it should show a difference in wheel rotation .
13th Feb 2007 2:04 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
How slow are you trying to go?
A manual D3 at tickover in first gear, low box still sends rotation speed signals to the ABS controller and TC will work at this speed...
rock crawl has the differential lowest lock-up threshold of all the TR modes, both electronic differentials are continously variable types
Lawrance, it's a good question that you asked, but you need to start thinking 'outside the box'.
A car like the D3 cannot be viewed in the same manner as a D2 or a tojo or nissan. The systems employed are far more sophisticated.Have a nice day!
2010 Cayenne Diesel with PASM & Off Road Pkg
2005 HSE D3 (Sold)
14th Feb 2007 2:58 am
nwoods
Member Since: 03 Apr 2006
Location: Southern California
Posts: 563
I have been in very very slow (1mph or less it seems) conditions crawling over and down rocks and all systems seemed to work excellently. Jamo is right, this thing is like nothing else on the market.
Member Since: 11 Oct 2006
Location: Melbourne, Australia
Posts: 57
Jamo wrote:
Lawrance, it's a good question that you asked, but you need to start thinking 'outside the box'.
A car like the D3 cannot be viewed in the same manner as a D2 or a tojo or nissan. The systems employed are far more sophisticated.
Hi Guys,
I am very much doubtful that electronic traction control, no matter how speed sensitive it is, cannot replace hard locking differentials. Can anyone seriously say that the ETC system on the D3 can better a D3 equipped with front and rear differential locks as well as centre diff lock?
Anyway, I guess I have the answer that I was looking for - the Center Differential Lock is not hard locking.
The good thing is that LR have an optional factory rear locker. But not sure if they have one for the front.
14th Feb 2007 3:35 am
Desert Traveller
Member Since: 06 Aug 2006
Location: The Gabba - QLD
Posts: 420
Having had a D1 and a D2 with a centre diff lock I can honestly say that the D3 is just that much better.
I have also followed Parados and Patrols with full diff locks and had less wheel spin climbing rocky and shale covered slopes. I do have the rear locking diff. No need for a front one, they can only help in a straight line.06 TDV6 SE with many LR and after-market extras. Used only on weekends and trips out west.
Audi TT Roadster (Daily and around town drive)
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Previously 01 TD5 and 94 TDI
The D3 diff locks do 'hard lock' when the system decides it's necessary.Have a nice day!
2010 Cayenne Diesel with PASM & Off Road Pkg
2005 HSE D3 (Sold)
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