Have just bought a 2022 Land Rover 110 with the rear diff added as an extra. In viewing the pivi pro app which shows the activity on the diffs (both central and rear) the rear diff seems to be permanently on, except when I am freewheeling down a hill. Is this normal? Freely admit that I haven’t got a clue on how the diffs work but I thought that it would be a aide to off roading when necessary rather than something permanently on. Any insight or thoughts much appreciated

 

Unless I'm mistaken, my Defender has mechanical locking rear and center diffs, and an electronic fake locking front diff. Here's what MT has to say about them:

I'm usually the first to hate on automatic-locking differentials. Our old long-term Chevrolet Colorado Z71 Duramax had an auto-locking rear, and I found it slow to actually lock up under moderate off-road obstacles, making the actual act of off-roading harder than it needed to be. So, I was a bit skeptical of the Defender's auto-locking center and rear-differentials when hitting the trails in Namibia. Turns out there was no reason for such skepticism; the Defender's two diffs are capable of acting as both limited-slip and locking-differentials, and they frequently (and more importantly, quickly) lock and unlock while driving. They actually lock and unlock so quickly that you end up using them far more than you would with manual lockers, which could be a minor inconvenience to toggle on and off.

The Defender is missing a locking front differential and instead relies on a brake-based electronic "differential" that automatically grabs the brake of a spinning wheel to force power to the wheel with traction. The system works quickly and effectively, but I wouldn't mind a real mechanical differential for added peace of mind.

 

As NoGaBiker notes, the center and rear electronic differentials are mechanically "clutched" (easiest way to think of it - with a special differential fluid necessary) -- which is to say they are infinitely variable and extremely quick (milliseconds) to mechanically engage. This technology was developed in German suppliers and pioneered over the past 15 years in the Discovery and RR lines, and for 5 years (to the current perfected generation) in the JLR Evoque and other European hi-end vehicles. The lifecycles and capabilities are thoroughly tested out and they lose no effectiveness as compared to an old style, mechanical locker. Yes, for those used to having that clear lock up engagement sound and feel of an on/off locker (as NoGaBiker notes), it is a signficant change. So, is the fact that the technology cannot be effectively used with a manual transmission vehicle.

Since the Discovery 2 was developed, JLR (and Jeep and others -- Scandanavian off-road racer producers, especially) have continued to develop and perfect the use of fast-acting braking on each wheel (which requires a special brake fluid), as well as the necessary sensors and software to decide how to apply the brakes and integrate their use with the clutched differentials. Terrain Response 2 adds the ability for the driver to tune the use of the lockers to one's individual preference.

The on-road and off-road impact is remarkable. Torque vectoring on-road can greatly reduce understeer and nose diving (but it wears out the rear brakes much faster than previously), while off-road it enables each wheel to provide as much grip as possible / needed without spinning, slipping or dragging (the last happens as a matter of course with on/off mechanical lockers). The creation of yaw induced by over / under driving individual wheels is markedly reduced.

Enjoy!

 

Many thanks for the posts and by your replies I assume that I shouldn’t be surprised that the rear diff lock appears to be on most of the time including on normal road use? Thanks

 

Yes, correct. All these you should see occur when in AUTO mode:

While turning the rear locker moves to more open, than when going straight.

When free wheeling, both lockers generally return to fully open (all green).

The center locker is more engaged when climbing a hill than when on flat ground.

When you are towing from a full-stop, the rear locker will be fully locked as the car begins to move.

 

Thanks and really appreciate the info