Confused

[LR34]

...I also have a 2002 Toyota Tacoma (part time 4WD) with push-button locking center diff and locking rear diff (factory); front diff is open...

Isn't the front diff on the LR4 open as well? It seems that if all 4 wheels are on snow with minimal traction, 3 wheels are getting power and spinning (if locking rear diff) but not all 4 (ignoring traction control braking kicking in and assisting to get power to wheels with the most traction). I have no idea, I couldn't find much info on LR4 4WD either.

 

[BznLR4]

Isn't the front diff on the LR4 open as well? ...3 wheels are getting power and spinning (if locking rear diff) but not all 4

With traction control ON, power cuts when a wheel spins to keep you on the road. With traction control OFF, you get power to all 4 wheels (snow flying from all corners).

This is the "secret sauce" that I haven't found a good explanation for. However, I can tell you that the Toyota Tacoma with center and rear diffs locked performs as you describe (3 wheels spinning) while the LR4 powers all 4 wheels.

It really is quite a trip to drive a vehicle with all 4 wheels spinning, pulling ~12,000 lbs of plow truck out of a snowdrift. You find that you swing side-to-side, sort of feels like being water skis! There was a bit of learning curve figuring out how to handle it, but we got the job done and it sure was fun! The driver of the plow truck commented that he hadn't seen anything like it, and he has been plowing here in Montana for ~20 years.

Would be great if someone could chime in with a technical explanation of what the Land Rovers are actually doing. It must be some sort of variation on a limited slip differential (LSD), but inquiring minds want details!

 

[Count Laszlo]

There was an awesome video my brother sent me a while back that I unfortunately cannot find that showed a Disco II on a snow covered lake with all four wheels spinning in unison and it was totally awesome looking... it tracked like a spider. Land Rover doesn't mess around...

 

[BznLR4]

Howdy

How can you easily tell you have the heavy duty pak?

thx

If you log into the Land Rover Topix website and enter the VIN you can expand the factory configuration for full details. Look for "LOCKING REAR AXLE - E DIFF"

I wish I had known about this when shopping! LR dealers know how to look up factory configuration details, but aftermarket dealers seem to have trouble knowing what options are installed. This could be a useful tool!

 

[Quijote]

I know that the Wrangler Rubicon and the G-Class (not GL), allow you to lock all three diffs.

Jeeps quadradrive II on GC's, (at least on the one I just sold) had a center locking diff and LSD's (limited-slim differentials) front and rear.

If you want all four wheels to spin "mechanically," you need locking diffs or at least LSD's.

What car companies have been doing for a while now is not use LSD's and instead use electronics to use the brakes and clamp on to the spinning wheel, forcing power to be sent to the other wheel.

Early on, these systems were clunky but now they are excellent (Audi quattro, MB 4-matic, etc). The downside to these systems is that they are not as robust and meant more to get you out of a mild sticky situation or provide great traction on slippery surfaces, but are not meant for serious rock-crawling.

Combine these systems with locking diffs and you get great results. That is probably why the LR4 does so well despite not locking the front wheels.

I cannot imagine a scenario where you need lockers throughout, and if you did, you probably are (or should be!) driving some seriously modified rig with huge tires, not a shiny $60k luxury SUV.

 

[LR4USN]

Cool I'll check that now now.. I have the 4 for an overnight drive

 

[Count Laszlo]

Cool I'll check that now now.. I have the 4 for an overnight drive

How is it so far? Please report back.

 

[LR4USN]

I have two locks - so rig IS fully fully loaded

Went for night time drive - wow high beams are like you have spot lights on.. very cool.

 

[AceRider]

What car companies have been doing for a while now is not use LSD's and instead use electronics to use the brakes and clamp on to the spinning wheel, forcing power to be sent to the other wheel./QUOTE]


I thought that is what the LR4 is doing, using the brakes on the spinning wheel to transmit torque to the wheel with traction? The manual says something about brakes may overheat when LSD is working, and I thought that was the reason why.

 

[Quijote]

What car companies have been doing for a while now is not use LSD's and instead use electronics to use the brakes and clamp on to the spinning wheel, forcing power to be sent to the other wheel./QUOTE]


I thought that is what the LR4 is doing, using the brakes on the spinning wheel to transmit torque to the wheel with traction? The manual says something about brakes may overheat when LSD is working, and I thought that was the reason why.

They likely do this in combination with the center locking diff (and if so equipped, the rear locker).