4WD - How does it work on the Explorer???

[jetmaker]

Hi all,

I've got a 2000 XLT Explorer, and I am curious about how the 4X4 system works. My truck is factory equiped with a limited slip rear diff, and what I want to know is the following:

1) in 2x4 mode, what wheels are powered (I know it it shte rear, but do I actually have power to both rear wheels)?

2) when I put it in 4x4 HIGH, what wheels are powered? Are the 2 rear + 1 of the fronts?

3) when in 4x4 LO, what wheels are powered? Does the front and rear diff lock electronically to drive all 4 wheels?

Thanks for the help.

jetmaker

 

[JDraper]

First off, I would guess you have an "auto" mode instead of a 2WD mode.

In "Auto", the rear end is powered(The front is always powered slightly..If I remember correctly it's 4% under ideal traction conditions) until the sensors detect slip, and then it begins to route more power to the front.

In 4x4 high, both axles receive full power, but since the front is an open differential, only one wheel is really powered.

4x4 low is just a gear ratio reduction, no electronic lockup on either axle.

 

[jetmaker]

Thanks JDraper.

You confirmed what I already thought. So in reality, I have a 3x4.

BTW... I knew about the AUTO position, and it is a feature that I would rather forget about. But thanks for improving the accuracy of the post.

jetmaker

 

[V8BoatBuilder]

Just to add,
-4Auto is what you should use on the street, it's mostly rear wheel drive, but if the rear starts to lose traction in rain, on ice, in snow...... then it will send power to the front. Very cool, very safe.
-4Hi just locks the front and back driveshafts together, 1/2 your power goes to the front, 1/2 to the back. On each axle, power will go to the wheel that has the least resistance on it. This is less so in the back, due to the limited slip differential. Use this setting for deeper snow, on dirt and sand offroad, etc. Don't use it on dry pavement.
-4low: same as 4x4hi, but reduces your overall gear ratio by 2.4. You will go slower, but have much more torque. Excellent for offroad, pulling a boat up a launch ramp, but its hard to turn on dry surfaces, and you can break parts. Be careful with its use.

There are lots of posts on this subject, feel free to search. Welcome to the site!

 

[jetmaker]

Thanks for the welcome.

Read in anohor post that the Automatic Hubs are a real POS. Now, how do the autohubs know when to engage? Is there some kind of electronic signal or sequence in which the system works?

It is hard to tell whether my hub/4x4 system is engaging. Is there any audible clues as to the engagement?

Thanks.

 

[JDraper]

Your truck doesn't have autohubs. Your hubs are permanantly bolted to the axle shafts and everything always rotates. That's one reason you don't have a 2WD setting on your switch. The autohubs were discontinued in the Explorer starting with the introduction of Control-Trac in 1995. If you pop one of your center caps off on the front you can see the end of the axle and the bolt that holds it to the hub.

In auto mode, there is some slip between the front and rear. When you turn the switch from Auto to 4WD Hi, all you are doing is locking up the transfer case so there is no slip.

There are really no audible clues when you switch between Auto and 4WD since everything is already rotating. All that happens is the clutches in the xfer case lock up.

 

[jetmaker]

JDraper,

Thanks for the info. This would explain why the steering feels the same whether in Auto or 4x4 mode.

jetmaker

 

[antogt]

Hi, Im new here.I was just lurking around and I read this post.
To say that in an open dif. only one wheel gets power is not quite accurate. tourque is applied to both wheels.
The amount of tourqe available is the most tourque that can be applied without spinning a wheel or losing traction. In an open diff the first wheel to spin determines available tourque. If conditions are very slippery or the wheel has lost virtually all traction then very little tourque is going to the wheel that still has traction. If the tourqe is not strong enough to overcome that traction then that wheel stops.Then you would effectively have only one driven wheel. But this is only in very low to no traction situations.

 

[JDraper]

 

[jetmaker]

autogt,

Correct me if my understanding is wrong here, but as I see it, an open diff transfers power to the wheel that offers the least resistance. The internal friction in the system is not enough to distributed the torque at the same time. Rather, the torque is alternated from wheel to wheel in very rapid intervals. The theory being that as soon as one wheel is gets the torque, the other wheel is offering less resistance, and hence now gets the torque. And it cycles like so. When driving straight, this effect is unnoticable due to the speed at which it is happening.

Let me know if you disagree. It is worth understanding this correctly, so your input is appreciated.

jetmaker

 

[antogt]

Hi jet,
I don't disagree with your understanding of an open dif.
as a matter of fact, your explanation offers a better practical description of what is actually occuring than mine. I'm not an expert, I was merely pointing out that to say only ONE wheel gets power is not entirely accurate. Your explanation seems to indicate that torque is only present at one wheel at any given time. I hadn't ever considered it this way. I always thought of it as torque being present at both wheels but limited to only the amount nessesary to turn the one with least resistance.
I don't think our descriptions are to far off from each other. I do know one thing. I'm gonna look into this a little further cuz now you've really got me thinking. You're explanation leans really heavy on practical application.Which is something I failed to take into account and is afterall important.

Take care,
Antogt

 

[jetmaker]

Antogt,

Agreed. I think our descriptions are basically the same, but it is really irrelevant in that the real world situation is that when one wheel looses traction, we go nowhere. Until that happens, it really does not matter how the system works..

JDraper mentioned that on the 2000 XLT 4x4, the hubs are not auto style, rather a fixed link. Now this would explain why I do not find hub conversion kits for the 2000 year models. My dealer said the other day that the hubs were automatic. So, not to question JDraper's knowledge, I'd just like confirmation from some other members on this. Thanks all.

jetmaker.

 

[JDraper]

I guarantee they aren't auto hubs. I own an '01 which is the same as the '00, and I've worked on MANY explorers. Gen II Explorers (1995-2001, not including the Sport Trac) that are either 4 wheel drive or all wheel drive do not have auto hubs, they have the Control Trac system which has the CV stub shafts splined into the hub assembly and then a bolt holds the shaft into the hub. The Gen I Explorers (1991-1994) came with either fully manual hubs or auto hubs, with the autohubs being in the overwhelming majority.

Take the bolt cover off one of the front wheels and you will see the end of the axleshaft bolted firmly through the hub.

Your dealer needs to be a little more knowledgeable....

 

[jetmaker]

JDraper,

That's the problem I have with dealers. They often do not know enough about the vehicles they service. However, it is my nature to question conflicting information, even when I place more credibility on one than the other. In this case, your credibility was weighed higher. I appreciate the reply.

Thanks.