Proof of Active Locking Rear Differential

[Wilco]

I have just acquired a Disco 3S TDV6 with Electronic Air Suspension/Terrain Response and Active Locking Rear Differential. My previous Landrover was a Defender 300 Tdi to which I added an ARB rear air locker (differential). This had two switches - used sequentially - one to switch on the air compressor and the other to activate the air-locked rear differential. My Discovery 3 has no obvious indication that it has a locking rear diff! How do I know it has one? Does it work automatically when the vehicle's computer senses that it is needed? Is there some indication on the compliance and/or the build plate? What is to stop someone from claiming that the Discovery 3 they are selling has an active locking rear differential when it doesn't? HELP:eek:

[langy]

I was curious, so I looked into the D3 on wikipedia: Your Nav/DVD screen should have a setting for '4WD information'. When selected, it shows ride height,angles of wheels, status of locking center diff. Given that the rear locking diff is factory fitted, it's status should also be shown.

Take the Disco to some mud and try it out. If it has a locking rear diff, you should see something on the screen.

Or, is there some extra wires or a solenoid somewhere around the rear diff housing? (It is electric after all...)

[Tote]

The indication is only available if you have a fully optioned satnav screen installed. Apart from that there is no real way of telling if it has an electronic diff unless you put 1 wheel up on a ramp that will lift the opposing wheel off the ground. A difflock equipped D3 will proceed up the ramp with only 2 wheels on the ground, one without the difflock will not. The other method that comes to mind is to put your vin into one of the online tools, that may tell you if the difflock was fitted as they are a factory only option.
Regards,
Tote

Edit: I just put my VIN through CALVIN and it only tells me it is RHD, 2008 model and auto. Maybe a phone call to the dealer with the VIN number might help.

[jik22]

Your Nav/DVD screen should have a setting for '4WD information'.

Not on an S you won't - unless you also have the HiICE and Nav options! ;)

[gghaggis]

You can visually identify the control solenoid on top of the diff. See
Land Rover Electronic Rear Differential - Cutaway Creations (http://www.cutawaycreations.com/cutaways.php?project=land-rover-electronic-rear-differential)

for an idea of what to look for.

Cheers,

Gordon

[WhiteD3]

You can visually identify the control solenoid on top of the diff. See
Land Rover Electronic Rear Differential - Cutaway Creations (http://www.cutawaycreations.com/cutaways.php?project=land-rover-electronic-rear-differential)

for an idea of what to look for.

Cheers,

Gordon

Thanks Gordon, that's an excellent site for getting to know the D3's innards!

[Wilco]

Thanks langy - you were spot on with the solenoid suggestion.

Cheers
John

[mcrover]

The indication is only available if you have a fully optioned satnav screen installed. Apart from that there is no real way of telling if it has an electronic diff unless you put 1 wheel up on a ramp that will lift the opposing wheel off the ground. A difflock equipped D3 will proceed up the ramp with only 2 wheels on the ground, one without the difflock will not. The other method that comes to mind is to put your vin into one of the online tools, that may tell you if the difflock was fitted as they are a factory only option.
Regards,
Tote

Edit: I just put my VIN through CALVIN and it only tells me it is RHD, 2008 model and auto. Maybe a phone call to the dealer with the VIN number might help.


I'd be thinking just normal TC will keep it driving up a ramp....but I could be wrong.


All I know is that when they are working they work reeeeeeealy well.

[Wilco]

Gordon you are a genius. I have viewed the images on cutaway creations and a few minutes ago I poked a torch under the back wheel arch and spied a solenoid sitting on top of my back diff!

[Tote]

I'd be thinking just normal TC will keep it driving up a ramp....but I could be wrong.


All I know is that when they are working they work reeeeeeealy well.

At a recent club day we had a RRS with a diff lock and a Disco 3 without. The Disco stopped forward progress at idle speed once both opposing wheels were off the ground, the RRS just kept on climbing until the driver stopped to avoid driving off the end of the ramp. Very impressive demonstration.

Regards,
Tote

[inside]

D3 with diff lock
YouTube - Land Rover Experience Honiton for Yeovil Land Rover 1 (http://www.youtube.com/watch?v=SWepa1vq09U&feature=related)

FL2 obviously no diff lock
YouTube - Land Rover Experience Honiton for Yeovil Land Rover 2 (http://www.youtube.com/watch?v=V1taiNf2BHs&feature=related)

[Utemad]

Inside they're great videos. Really shows off the systems.

[Wilco]

Further to Gordon's link to a site showing images of the Electronic active rear diff I have managed to take a photo of my rear diff (attached) showing the solenoid.

[WhiteD3]

Great videos Andrew.

I do have a question though, or at least an observation:

In the D3 vid the instructor talks about the need for the diff lock to engage to move forward once two wheels have left the ground. He also talks about the air suspension.

In the FL vid the instructor advises there's no diff lock or air suspension, and then demonstrates how the traction control will get the FL through.

Thing is, the D3 has traction control, so what was proven in the demo?

[djhampson]

Great videos Andrew.

I do have a question though, or at least an observation:

In the D3 vid the instructor talks about the need for the diff lock to engage to move forward once two wheels have left the ground. He also talks about the air suspension.

In the FL vid the instructor advises there's no diff lock or air suspension, and then demonstrates how the traction control will get the FL through.

Thing is, the D3 has traction control, so what was proven in the demo?

I wondered the same thing. I've seen videos of the D3 doing the same thing the FL2 rear wheel did (stop start stop start etc).

Lets look for somewhere tomorrow Mark and do a little
experiment - I'm guessing you don't have the active rear diff?

[WhiteD3]

I'm guessing you don't have the active rear diff?

An oversight on my part:redface:

[gghaggis]

RichardK and I have taken our (almost identical) D3's over the same ground - mine with the locking diff, his without, and you struggle to find any difference in the cars' performances on all but the most extreme rock-climbs. The std traction control is (in most situations) just as competent at controlling a spinning wheel as is the locking diff. In "rock-crawl" it's much more effective than the FL2.

Cheers,

Gordon

[inside]

RichardK and I have taken our (almost identical) D3's over the same ground - mine with the locking diff, his without, and you struggle to find any difference in the cars' performances on all but the most extreme rock-climbs.
This confirms what I have read elsewhere. The active rear diff's benefits are rarely noticed in the D3 due to the traction control.


The std traction control is (in most situations) just as competent at controlling a spinning wheel as is the locking diff. In "rock-crawl" it's much more effective than the FL2.
I would think the advantage in rock crawl is purely down to the air suspension (clearance) and low range of the D3 and not related to traction control at all?

Keeping in mind that this is the D3 Zone is it reasonable to come to the conclusion that the traction control and comparable performances of the D3 and FL2 is equal when you compare traction alone regardless of active diff locks?

[gghaggis]

The system response times vary in the different TR settings. The TC is at its most aggressive settings in "rock-crawl", least aggressive in "sand".

As the FL doesn't have "rock-crawl", it wouldn't lock up as fast. And of course, not having low-range, as you said!

Cheers,

Gordon

[Redback]

Anyone know why they don't have this for the front as well:confused:

Baz.

[ChawtonD3]

Yep, if you have a front locker you seriously compromise steering on slippery surfaces and add a lot of stress to front drive shafts, particularly to CVJ's. With a rear and a centre locker the traction control on the D3 still operates across the front wheels but at the same time you get to keep pretty good steering, especially in deep sand or mud(Turn of DSC). The compromise would only be on steep hard surfaces that some HP would be lost to the brake action of traction control.

If you put your D3 in the position of the video example it only stay like that at idle, as soon as you add any significant throttle the traction control activates and starts braking the airborne wheel to drive the grounded one.

[Desert Traveller]

A number of Mags did some comparisions between a fully locked Patrol and a D3 with the eDiff. The D3 killed the fulled locked Patrol in ability to get up slippery slopes. As previously noted the front diff lock compromises steering and cvs.

[Kobe]

Hi Thinking of buying a Disco 3 V8 HSE. Can any body tell me if this was standard on the HSE or an optional extra??

[rocmic]

Sorry to say it was an option on all models. But don't panic about it, they are damn good even if they don't have the ediff.
Cheers
Mike

[Grentarc]

Hi Thinking of buying a Disco 3 V8 HSE. Can any body tell me if this was standard on the HSE or an optional extra??

I think the only vehicles with it standard is the supercharged RRS and RRV

[rar110]

Gordon you are a genius. I have viewed the images on cutaway creations and a few minutes ago I poked a torch under the back wheel arch and spied a solenoid sitting on top of my back diff!

Wilco,
You are pretty fortunate. Do you have terrain response? It's just that D3S with an electronic rear diff lock and without TR would have been quite unique. Maybe it activates when traction control detects slippage.

[winaje]

Hi Thinking of buying a Disco 3 V8 HSE. Can any body tell me if this was standard on the HSE or an optional extra??

PM me the VIN and I'll run it through TOPIX and check for you.

[Nicky]

Wilco,
You are pretty fortunate. Do you have terrain response? It's just that D3S with an electronic rear diff lock and without TR would have been quite unique. Maybe it activates when traction control detects slippage.

So unique that this set-up could not exist. The e-diff depends on TR for input.

[rar110]

So unique that this set-up could not exist. The e-diff depends on TR for input.

That's what I thought, but it's an S which didn't get TR or EAS (unless MY09 or a special order), like the SE.

Even if an MY09 it would still be a special order and unusual for the lower spec S D3, when they were running out the D3 in anticipation of the D4.

[gghaggis]

There were quite a few D3 S models optioned with TR and EAS, from 2005 on. No reason why they couldn't have an eLocker as well.

Cheers

Gordon

[rar110]

There were quite a few D3 S models optioned with TR and EAS, from 2005 on. No reason why they couldn't have an eLocker as well. Cheers Gordon

True. I was thinking more wouldn't, rather than couldn't, option up an S with TR/EAS due to cost comparison with an SE which got that and other nice stuff standard. I assumed the S was more for customers who specifically wanted coils, cloth seats & halogens.

[gghaggis]

Back then, an optioned S was cheaper than an SE - no leather, sat nav etc. Quite a few buyers got a decent spec for a lower price.

Cheers,

Gordon