I was nosing down a sandy river bank last week and felt my front wheels drop into some super soft sand. The rear wheels were still on firm clay covered in a dusting of sand. When I put it into reverse to get out, the front wheels were the only ones driving, nothing was happening in the rear. It didn't matter what program I selected. The only way I saved myself was to let most of the air out of the tyres. Is my car's 4wd busted or is this normal behaviour? Does anyone have an easy way of checking if the 4wd system is operating correctly without actually finding out the hard way?

should work in reverse too once the front wheels spin.....

I know you have to get some pretty serious wheel spin first before the Haldex kicks power around the corners.

So none of the programs will lock the centre and provide 50/50 drive? I didn't want to spin the front up too much because I was digging a hole to China.

When moving off from rest the Haldex should always engage to give 4WD, specifically to avoid initial 2WD wheelspin. So from rest no slippage should be required to engage the Haldex. (N.B. Lock up depends to some extent on TR mode and steering angle, but in the circumstances you describe I'd expect the Haldex to have been locked.) I can't find any specific reference to whether or not this works in reverse, but nothing I've found suggests it shouldn't.

Quote:

When negotiating very low friction surfaces such as wet grass, snow or ice; initial wheel-spin can cut into the surface and reduce grip. With a re-active on-demand coupling, almost 60 degrees of wheel rotation would occur before torque could be transmitted through the coupling.

On Generation 3 couplings, to counteract this Land Rover developed a unique high-pressure pre-charge facility which energizes the hydraulic circuit as soon as the engine is started. Essentially an electrically operated hydraulic pump was designed to maintain a potential of 500 Nm (369 lb ft) of torque pressure within the coupling. (This pre-charge torque capacity has been increased to 1500Nm (1106 lb ft) for the Generation 4 coupling.)

Vehicles fitted with Terrain Response also add further benefits by varying the level of pre-charge to deliver optimum traction over a range of different terrain surfaces. The level of pre-charge is varied depending on the particular terrain response mode, for example:

* Terrain response in 'Special Programs Off' mode as common with vehicles without terrain response, the coupling is programmed to transmit 500 Nm 369 lb ft of torque on Generation 3 couplings and 1500 Nm (1106 lb ft) of torque on Generation 4 couplings to the rear axle when the vehicle moves from rest in a straight line. This strategy minimizes traction loss from a standing-start regardless of the terrain. When the vehicle accelerates the pressure in the coupling is decreased to improve fuel economy.

*The ability to sense the steering angle allows the coupling to be programmed to provide no torque transfer through the coupling. This prevents the coupling locking when the vehicle is maneuvring at low speeds and acute steering angles.

* In 'Grass / Gravel / Snow' mode the coupling is programmed to maintain its pre-charge state until much higher speeds are obtained. The same applies even if the vehicle is traveling at low speeds and acute steering angles, as traction takes precedence over coupling lock-up on low-friction surfaces.

One thought occurs - an 08 FL2 will have the Gen 3 haldex (09 on has the Gen 4). The Gen 3 uses 2 hydraulic pumps - an electric pump which gives the pre-charge for lock-up from rest, and a mechanical pump which provides hydraulic pressure once slippage starts to occur. If the electric pump wasn't working there would be no pre-charge and thus no lock-up from rest. (But the mechanical pump should still have cut-in once slippage started to occur.)

I also note that the Gen 3 and Gen 4 couplings have different pre-charge torque transfer capabilities (500Nm for Gen 3 and 1500 Nm for Gen 4) but what effect that would have in practice I don't know. Maybe it simply wasn't enough to overcome the huge difference in grip between front and rear?

Also, even with the Haldex locked you might still experience diagonal wheelspin until the traction control started to work by braking the spinning wheels.

Mine is an MY09 so hopefully the Gen 4. I think the big question is does it work in reverse?

i am sure it should work in reverse

Could it be the rev's were not high enough to engage 4x4 converter? Former Mod/Member, with the most post & Chicken George Arch nemesis

mikehzz wrote:

So none of the programs will lock the centre and provide 50/50 drive? I didn't want to spin the front up too much because I was digging a hole to China.

The first rule when you are stuck in soft sand is not to let the wheels go on spinning or you end up sitting on your diffs with nothing under the wheels. I did let them spin for as long as I dared. Not a peep out of the rear wheels, very disappointing.

[quote="]The 'Land Rover Experience' instructor taught us to slowly apply the power and allow a reasonable amount of wheelslip and let the car electronics work it out. At first I found it went against my 'old fashioned' car control, but it worked every time, in the Discovery Sport Auto.[/quote]

Same here on the LRE day in an Evoque. Once one wheel spins for a certain amount of time, things start happening. Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.

but as Mike says, if the wheels spin too much you just dig in and sit on your axles...
the key to driving on deep stand is momentum, hence why sand setting locks in 4WD but allows higher revs and wheel spin so the ECU transfers power around continuously.
Being stuck nose down in sand the best bet may have to put some sand tracks(if available) branches, even towels down under the wheels

Sit on your shafts you mean Rog  MY14 Kahn Converted Dynamic - Fuji White Ebony/Pimento Interior
MY15 Xenon Headlight Conversion

MY17 RRS SVR - Estoril Blue Cirrus/Ebony 🪣💺’s

I know what I meant Ed... even if I was wrong

mikehzz wrote:

The first rule when you are stuck in soft sand is not to let the wheels go on spinning or you end up sitting on your diffs with nothing under the wheels. I did let them spin for as long as I dared. Not a peep out of the rear wheels, very disappointing.

That would be correct if the earlier FL2s were fitted with a standard Gen 3 Haldex, but LR specifically wanted the locked-from-rest functionality so they modified the Gen 3 to add an electric pump to give the pre-charge needed.

The above article is generic and doesn't address the LR version of the Gen 3.