Member Since: 16 Jan 2006
Location: Melbourne
Posts: 123
OK - and hopefully there are some tech heads somewhere reading this forum especially if they have LR UK connections. I am a very very long time user of LSD's on road cars and diff locks on other vehicles and they are terrific. When I get delivery of my new TDV6 I am sure that I will play however I suspect that at least initially there will be very few situations where the large tires and 4x4 and standard programming cause the rear diff to lock up.
Two questions.
1) How do I override the programming so as to ensure that on road the rear locker diff acts as a normal LSD and continues to apply power rather than reduce power in the event of wheel slip like most ASC + T type systems (BMW for example) do ?
2) How off road can I install a switch so that I can manually over ride even a LSD type appication and make sure that it locks and stays locked or at worst continues to apply power ?
Obviously it is software controlled and is lockable so it must be possible to over ride the programming and lock it on demand. I suppose that the only issue is that doing so might send the rest of the electronics into spastic mode.
18th Jan 2006 12:29 pm
disco4x4au
Member Since: 19 Jan 2006
Location: Perth
Posts: 409
Hi all,
I'm new here, but will hopefully be a D3 owner in the next few weeks .
With regard to Smarticus' scenario, I would have thought that if the ETC activates prior to the locker, but fails to control the difference in wheelspin between the left and right wheel, then the locker will activate. At that point there is no longer any difference in wheelspin rates, so the ETC disengages. Is that right?
And of course, if the locker activates first, the ETC would never be called, other than on the front wheels. So why the concern that something would break?
Cheers,
Gordon
19th Jan 2006 7:15 am
Smarticus
Member Since: 01 Jan 2005
Location: Northumberland
Posts: 655
Gordon, I guess my concern is that I think of diff locks as being essentially mechanical things and ETC as essentially an electronic thing. Clearly as you say these 2 systems need to co-ordinate their actions very carefully to avoid a conflict. Both must also be dependent on sensors concerning vehicle movement and wheel rotation. We all have seen the evidence of sensors on these vehicles failing, or giving rogue messages (in most cases suspension related but in others transmission related). Just imagine if the sensors on the rear axle failed and the diff lock and ETC worked against each other - ouch. And what would the cost be ? If a headlight costs £400 to replace when it gets a small crack in it, what must a diff or half shaft cost Disco 4 TDV6HSE
Defender 200TDi CSW
RR Evoque
19th Jan 2006 9:43 am
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
Hopefully this will help...
Excerpts from Landrover documentation
"The multi-plate clutch assembly for both centre (transfer box) and electronic rear differentials act in a similar way. The aim of the multi-plate clutch assembly is to prevent excessive differential slip and therefore maximise the traction performance of the vehicle. This is fundamentally different from the 'braked' traction control, which can only counter act differential slip when it occurs.
A certain amount of differential slip is required to allow the vehicle to turn corners and to remain stable under control of the Anti-lock Braking System (ABS). The transfer box control module monitors the driver's demands through primary vehicle controls and automatically sets the slip torque at the rear differential via the electronic rear differential control module. The system is completely automatic and does not require any special driver input.
The multi-plate clutch assembly actively controls the torque flow through the rear differential and optimises the torque distribution in the driveline. The clutch assembly biases the torque from the differential to the wheels with the higher grip and prevents the wheels with the lower grip from spinning
The electronic rear differential control module is connected on the CAN bus, via the transfer box control module, and controls differential operation using CAN messages from other control units on the network. Wheel speed, steering angle, automatic transmission speed, temperature information, car configuration, axle ratios and mode inputs, are some of the main signals received by the control module.
The control module also sends messages via the CAN bus to tell other control modules on the network, the status of the electronic rear differential. The clutch torque and default mode status are some of the main signals sent out by the control module.
The Terrain Responseâ„¢ system allows the driver to select a program, which will provide the optimum settings for traction and performance for the prevailing terrain conditions.
The system is controlled by a rotary control located on the centre console.
The system uses a combination of vehicle subsystems to achieve the required vehicle characteristics for the terrain selected. The following subsystems form the Terrain Responseâ„¢ system:
· Engine management system
· Automatic transmission (if fitted)
· Transfer box
· Brake system
· Air suspension.
Each subsystem control module provides a feedback for the selected program so that the Terrain Responseâ„¢ control module can check that all systems are controlling the system correctly. The exception to this is the electronic rear differential control module which does not provide feedback to the Terrain Responseâ„¢ system as it is a slave to the transfer box control module"
19th Jan 2006 10:53 am
Smarticus
Member Since: 01 Jan 2005
Location: Northumberland
Posts: 655
Norah, I didn't follow much of that - but I think it says that my worries are groundless (sic). Interesting that the diff lock isn't actually a locker, just a limited slip diff arrangement.Disco 4 TDV6HSE
Defender 200TDi CSW
RR Evoque
19th Jan 2006 11:17 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
it will progessively 'lock' up to 100%, but it is the last item in the chain so will only kick in at full chat once every other option has been tried. Should a sensor fail or give a improbable signal, the various systems will attempt a workaround based upon other inputs. worst case is you'll need BN's porker to pull you out
19th Jan 2006 11:48 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
Norah?
19th Jan 2006 11:49 pm
carl
Member Since: 21 Dec 2005
Location: US
Posts: 28
lock
the only concern I would have with the rear locker "waiting" to lock is that like traction control, you lose momentum "before" you get the lock. I am surprised that there is no method for creating the rear locked, which would signal less traction control braking, which would keep momentum?
All this aside, I am sure that for 99% of the use, based on tires, clearance, etc... that this is really fine. Obviously we're all obsessed with these things and have nothing else to do!
I've got 2200 miles, gas milage up, last trip to 17.5, not a single fault with vehicle. Very solid, quiet, stable.
20th Jan 2006 1:16 am
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
Carl,
depending on the program(me) selected, the diffs. will be pre-loaded in the expectance of slip, the sensor input will indicate that traction and forward motion is being lost and the various ECU's will generate the best 'firing solution' taking sensor information and terrain program(me) selected into account to help prevent loss of momentum, switching off DSC can also help in some circumstances
I agree though.... it is an obsession
20th Jan 2006 8:47 am
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
Smarticus wrote:
Norah, I didn't follow much of that - but I think it says that my worries are groundless (sic). Interesting that the diff lock isn't actually a locker, just a limited slip diff arrangement.
Smarticus, it is a limited slip type, but continuously variable and is able to fully lock when needed. There's loads more info but I don't want to suffer the wrath of LR by posting complete documents
20th Jan 2006 8:51 am
BryanW
Member Since: 23 Jan 2006
Location: South Africa
Posts: 1
Quote:
I remember that the TD5 disco didn't even have a centre diff lock because of this. It was only replaced under presure from the US market where a diff lock is an important phallic symbol.
What kind of offroading do you do here? Cant be more than pavement climbing, the Disco2 without centre difflock was disaster in South Africa, rav4's were going where the disco could not over here. The D3, luckily has this incorporated else it might aswell be a X5.
The rear difflock works in extreme situations where you cant wait for the traction control to decide when to kick in. Provides for easier rock crawling with less spinning wheels and is far more controlled and gentle. (to avoid breaking it) I would think that it disables the TC in the rear axle and enables the rear locker, TC is then limited to the front axle. Fairly potent as you still have good steering control.
Rather sad we have all this cr@p on our vehicles these days, how about the days with manual lockers allround.
23rd Jan 2006 8:04 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26699
Have a look in the galleries, we do plenty of decent off-roading. If its manual locking diffs you want, save a fortune and buy a second hand D1
I have driven my old S2a, and all versions of the Disco since it was originaly launched in many off-road situations, and can honestly say that the D3 is as good in most situations as any of the others. It is better at some also. The only limiting factor is the shiny paint, and risk of damage, but thats only limiting because I want it to be. There are some people on here that would not agree with that I'm sure!
The one situation where the D3 beats any other 4x4 totally comprehensively is in the snow and ice. It is awesome, especially the hill descent control.
23rd Jan 2006 8:30 pm
simon
Member Since: 11 Jan 2005
Location: Shropshire
Posts: 18296
Bryan... buy a D3 and prove yourself wrong mate.
We can take our D3's places you can only dream of... manual lockers or not.
If you drive a Porsche pig I could understand your post, but if you drive a real 4x4 then you'd know that the D3 is the business....
24th Jan 2006 3:11 am
Penguin
Member Since: 02 Dec 2005
Location: A fun place
Posts: 485
hahaha Bryan, you need to check out some european site more often
If you look at the galleries here or look at some pictures on my site, you'll think different In a time of chimpanzees, I was a penguin. www.m-release.com
24th Jan 2006 5:51 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
simon wrote:
Bryan... buy a D3 and prove yourself wrong mate.
We can take our D3's places you can only dream of... manual lockers or not.
If you drive a Porsche pig I could understand your post, but if you drive a real 4x4 then you'd know that the D3 is the business....
you don't like Porche 's do you? saw one at Northampton services on the M1 (was it 's ? we'll never know for sure ) nearly peed meself laughing when the woman driver returned to it (it had to be the driver, no-one would want to steal one) and immediately went bright red when she saw little 5 pointing at it and laughing whilst giving the thumbs-down signal
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