front diff in 4x4 high mode

[Luis696]

hi, does anyone know if diff is locked in 4x4 high mode?

 

[Aussie Explorer]

Only if it has a front diff lock installed.

The front diff is active when in 4*4 HI but is a open differential in stock form (or a Single spinner), I.E the tyre that looses traction first will take all the power and the other tyre with traction will just sit there.

 

[Luis696]

is it means that with 4x4 high set, front wheels works similar to the car having front wheel drive?

 

[dreamr]

I assume you are trying to figure out how the control trac works?

Or are you having a problem with the vehicle being stuck in 4 high?????

The control trac system has three general settings.

In auto
The transfer case is engaged in it's high gear (only has high and low)
There are a set of sensors in the T-case that report the driveshaft revolutions to the GEM module behind your dash. If there is a difference (ie rear tires slip) The Gem sends a signal to the TOD (Torque On Demand relay) this in turn sends a variable rate signal to the clutch packs in the transfer case. These engage the front driveshaft and effectively transfer as much torque as is needed to the front. There is always a small percentage of torque going to the front but it can transfer as much as is needed when it is needed. I have heard that this signal terminates at 35 leaving you effectively in 2wd. I can not substantiate that.

4hi-
Still the transfer case is left in it's high gear. However the TOD relay is switched to give a constant torque split of 50/50 front and rear.

4 lo
same as 4-hi in the 50/50. However here the shift motor is activated to place the transfer case into low range.

There's is a lot more to the system, but there is an overview.

Now if you were stuck in 4 hi (which does happen)
Try unplugging the battery for a bit to reset everything.
If that does not solve the concern and there are no flashing 4x4 lights I recommend trying to clean the Hall effect sensors in the t-case.
If still no go still, it is time to have a tranny shop read the GEM

 

[dreamr]

I just noticed that you are from across the big pond. I am not sure if Euro Spec Explorers have the exact same sytem but I believe they do.

 

[Luis696]

thanks DREAMR this did lighten up my view, re UK models, my one has export sticker, and as far as I know, it means that it is American one, but it has steering wheel on our side. My question has been related more or less to something I still can not find answer

It is just to help me better understand my car, as 4x4 one, I’ve read few articles not only over internet about differential, and it is really related to one point: is it any difference (when set up on 4x4 high) in work of a front wheel driving system from normal car which having front wheel drive, bottom line, is the differential takes some of the power from the wheel (during turn) which makes shorter way, every one knows that without this car having front wheel drive, will not be able to turn without problems.

I hope it is clear, I do know what is the question, and I’ve tried to picture one. If you dont understand I'll try better.

 

[Doubt Incarnate]

it works exactly as front wheel drive does, when its engaged. but that doesnt mean you can run it on pavement or all the time. the front and rear wheels still need to be able to turn at different rates, unless you have AWD its not going to happen. you would need a center differential or viscous coupling to run "full time 4x4"

 

[dreamr]

A front wheel drive uses an entirely different set up (transaxle).

Our vehicles are set up like any other standard rear wheel drive 4x4. Power is transferred to the transmission then through a transfer case. The transfer case then splits the power to the front and the rear as needed or indicated by your dash switch selection. the power is then sent to the axles through the front and rear driveshatfs. So no it is not like a fwd car where the axle and tranny are basically one unit.

The front end cannot be constantly engaged with a fifty fifty torque split (4hi or low) as the front and rear tires travel different distances going around a corner. This will cause the t-case to bind up and slip one of the driveshafts to relieve the tension. On ours it is typically the front that will give. Too many times though and the case will be damaged. Auto is not effected by this as much as it is a computere controlled system that knows when to disengage the front or not. Though it will always send a very small portion of the power to the front up to 35 mph.

 

[Luis696]

finally, I might say, my question has been answered, THANKS GUYS, THANKS VERY MUCH, especially to DREAMR