locking rear diff

[wayne]

I have a couple of initial questions regarding a new 2012 LR4; I'm sure there will be many more as I try to figure out this thing:

1. The LR4 came with an optional locking rear differential. No where in the owners manual does it say anything about how this is engaged (cannot be engaged on pavement) or if it is engaged with a particular terrain setting. Anyone know anything about this?

2. Are official shop manuals available for this vehicle?

Thanks!

Wayne

 

[umbertob]

Lucky you, I looked all over for a new LR4 with rear lockers and couldn't find a single one anywhere (California.) Had to special order my MY13 from the UK, it's almost here.

1. The operation of the electronic locking rear differential is fully automatic, regardless of terrain response mode you are in. You have no control over it. You can view its activation / deactivation on the 4x4 screen (the padlock icon between the rear axle turns red or green depending on the "condition" of the locking differential, locked or open.)

2. You can visit TOPIx to view + print shop manuals for any 2005+ LR vehicle, including the LR4. Registration is free, but you need to pay a time-based fee to view documents such as shop manuals, electrical diagrams, TSBs, etc: www.landrovertechinfo.com

 

[NASdiesel]

I've noticed that with a locking rear diff, when in the "rock" mode, it stays on nearly full time, as opposed to other modes where it seems to take more right foot to engage.

 

[wayne]

Thanks guys, this is really helpful! I will register on TOPIx and see if I can get a workshop manual.

On the 4x4 screen, it also indicated a locking central differential. I thought this had a viscous coupling unit, no? If not, then I guess it is not a true all-time 4x4 until the central diff is locked. Is this also fully automatic?

Wayne

 

[umbertob]

It's a full blown differential, also electronically controlled. Here is a brief excerpt off a technical manual I have (applies to MY06-09 LR3/RRS models, but nothing has changed in regards to how the standard center and optional rear differentials work on MY10+ LR4 and RRS as far as I can tell):

The 4x4 driveline on the T5 platform consists of a transfer box with high and low ratio, which includes an electronically controlled centre differential. Drive line torque will normally be split 50-50 but locking the differential allows this to change.
An electronically controlled rear differential is an option. The rear axle differential is controlled via the centre differential ECU, and its control is thus also optimised.
The basic requirement for the electronically controlled differentials is to offer locking torque levels across the centre differential and rear differential, as appropriate to the active T.R. Special Program.
The locking torque levels will be based on many dynamic vehicle parameters, which determine an amount of pre-emptive lock as well as any appropriate locking or unlocking response to a change in dynamic conditions (e.g. cornering). Any change in locking torque because of a change in TR program, is applied gradually, to limit any effects on vehicle handling.

 

[wayne]

Wow, this is better than I hoped for! This is more serious capability than my 1999 P38 Range Rover.

As I understand it, I can down load material from the TOPIx site. Since I am after the service manuals, I guess I just need to pay for a relatively short period of time (enough to download). I plan on signing up for a year at $84 US.

thanks again

Wayne

 

[LR4LandRover]

Quick question on an 2010 LR4 HSE HD. As this vehicle already has the locking rear diff and center, does it make sense to also install an ARB Locker for the front diff? Or is this simply overkill?

 

[RBA]

That really depends on whether you offroad certain terrain/conditions where you need to increase your momentum to the point of potentially damaging your truck. A front locker will in some cases walk up obstacles where you may have needed a bit more momentum. I would say for 97% of terrain that the LR4 was designed for a center and rear diff is enough. If you're trying to get to the next level and rock crawling with armor, lift, larger tires then yes, it would sound like the extra performance the locker gives you may be worth it but for me, I would consider a different vehicle at that point. Just my 2 cents.

 

[LR4LandRover]

Thanks very much! Will take your advice and keep the front Diff stock.

Best,
Stephen