I have a question, the manual that came with our 1998 Land Rover Discovery says that the vehicle is always in four wheel drive but seems to contradict itself saying we can unlock the four wheel drive. I live in Alaska and in the winter 4 wheel drive is needed most of the time. If all Land Rovers are always in four wheel drive is that four wheel drive good enough for driving in snow or should I lock in the four wheel drive? Thanks

 

it is always in 4 wheel drive - your differential can be locked and it can be in either 4wheel high or low - normal is 4high no diff lock engaged - if you were going off road and need significantly more traction capability you could engage the diff lock (it will lock the center diff so all the wheels get the same amt. of power regardless of traction situation) - low range either locked or not locked will reduce the max speed considerably - is really only need to say get up a very steep hill - normal snow driving 4high no diff lock handles 99% of the situation - hope that helps

 

There are three differentials on your truck (and mine too). Front, center, and rear.
In normal operation (aka: Unlocked - Hi.... which would be 'down-right' on your differential lever on the center console) all three diffs are 'open' and power will be directed to the wheel that meets the least resistance. In this case if you have one wheel in the air (or on ice), that wheel would spin while the others are on solid ground.

When you lock the center differential you are sending equal power to the front and rear differentials. This means there is always power going to at least two wheels. The front and rear diffs are still unlocked and will send power to the wheel that slips. The hope is that if a rear wheel is slipping, the front wheels are in a position such that they will have traction and 'pull' the car out. Same, but reverse the logic, if a front wheel is slipping...the rears will 'push' you out.

On a stock Disco there is no time when all four wheels have equal power if one or more is slipping. (if they are all on solid ground and not slipping you should NOT have your center differential locked because you will 'wind up' your transmission and/or axels). Again, the center diff should be locked only when the wheels can slip such as sand, gravel, or snow.

Some owners change their front and/or rear differentials to locking units. In this case you can send power to all four wheels if all three diffs are locked.

So yes, the Disco is 'all time four wheel drive' meaning that at any given moment power can be send to any of the four corners. That is not to interpreted as all four wheels having power at all times.

How a diff works...



...and another helpful thread about these issues

https://landroverforums.com/forum/di...01/#post246145