I have a 97 Explorer with automatic 4wd. How does the 4x4 system engage/disengage? Is it at at the transfer case and hubs or transfer case only?

Thanks,
Dave

 

Not sure if 97 had a full time 4wd option. If this is what you have, there is no driver input to be in 4wd, unless you go to 4 H or 4 L. If it's normal rear wheel drive with 4wd H/L switch, operation is the same.

Ford says you san switch from 2wd to 4wd H from 0 to 55 MPH. Anyone that's tried this at anything over 5 MPH knows it cluncks so hard feels like you just dropped your suspension. Caution to either stop or go very slow when engageing an automatic transmission. A 5 sp can slip the clutch in a little so the speed doesn't really matter.

Operation:

At 0 or slow speed, press 4wd H button. This tells the controller to activate the shift motor on the trasfercase. The motor turns a worm gear that rotates a shaft that goes into the T-case. The front driveshaft is now being drive. So as you move forward, or backward, the automatic hubs are driven to lock. You're now in 4WD high. This means output shafts of t-case run the same speed as the output shaft of the transmission. Don't operate a normal 2WD car in 4WD on the dry street as you lock your front and rear wheels with no viscous coupling to absorbe the tire speed variations. A full time 4WD vehicle has such a coupling. 4H is typicall for ice/snow on the road or for cruising down dirt/logging roads...

To go to 4WD Low, you have to stop. The controller gets a signal from the vehicle speed sensor that won't let it go into low if the vehicle is moving. You also have to put it in nuetral, manual or auto. And with a manual you have to push in the clutch. Ford safety at work for us. Now hit the 4L button. If all above conditions are met, the controller turns the little shift motor again so the shaft goes to 4L position. Depending on your case the ratio can vary, but you are now dividing the transmission output shaft speed by some amount and reducing the t-case output shafts speed while simultaneously and proportionaly increasing the out put torque. the operation of the auto hubs is the same wether 4H or 4L. You use 4L for off road fun, basically. I always off road in 4L because you are always going slow. No reason to have to work hard while having fun. Put it in low and let the engine torque do the work.

Now when you are all done having fun, take out of 4WD in reverse order of above - need to stop, nuetral, clutch to get out of 4L. Then when back to 2WD, travel for 10 feet in the opposite direction of that which you were going just prior to stopping and taking the truck out of 4WD. This will unlock your autohubs. Failure to do this and the wheels will then drive the drive shafts into the front diff and cause preamature wear/failure.

have fun!

 

Thank you for the information, I guess I should have been a little more clear.

I have a 97 explorer with 4wd that automatically engages based on wheel speed sensors. I also have the option of selecting 4wd H and L.

I would like to know if this system uses auto locking hubs. Based on your response I am guessing that it does. I ask this question because when I jack up my truck and rotate the front tires by hand, the front axle shafts turn. I was assuming that there are no locking hubs in this model but I just wanted to make sure. I don't want my front drive train to be rotating if it doesn't have to.

If there are locking hubs in this truck then I suppose its time for me to rebuild them, or at least re lubricate them. I did this on my F150 and it wasn't fun. Greasy split rings are hard to handle!

 

Well my 2002 Durango is set up like this but since its so new an still under warranty, I've not researched and learned exactly how it works. But I know it is in contnual 4WD but not locked front to back. it uses a viscous coupler within th t-case to distribut most of the power to the rear and then mor up front if slip is detected. I think yours is set up the same. Here's what I found on the Atuozone web site:

There are 2 possible t-cases, Borg Warner 44-05 or an All Wheel Drive unit.

The Borg Warner 44-05 transfer case operates in the same manner as the 13-54, except that it also houses a transfer case clutch. This clutch, which is controlled by the Generic Control Module (GEM), enables the vehicle to be driven in 4-wheel drive on dry pavement by cycling the clutch to compensate for different front and rear driveshaft speeds (as in turning). The system has a dealer installable Neutral (N) position mode.

The All Wheel Drive (AWD) transfer case is a 2-piece aluminum, chain driven, viscous clutch type unit. The AWD transfer case is always active in 4-wheel drive, thus producing a full-time engagement. The viscous clutch automatically distributes power to both the front and rear wheels, depending on need.

Front axel:

The Mountaineer, 1995-99 Explorer and 1998-99 Rangers use a centrally mounted front differential with unequal length upper and lower control arms and front axle halfshafts. Also, these axle assemblies do not use hub-locks at the wheel ends. Instead, they use a vacuum operated disconnect system mounted to the axle housing, which locks and unlocks the axles. See Vacuum Disconnect Axle Lock later in this section for service procedures.

The vacuum disconnect axle locking system was used on the Mountaineer, 1995-99 Explorer and 1998-99 Ranger models only. The axle locking controls are mounted to the axle housing. All other models use manual or automatic locking hubs at the wheel ends.

There is a picture and directions for hob disassembly at this link. (Does not look fun)

http://www.autozone.com/servlet/UiBr...3d800baf64.jsp

I could not find the theory of operation so I'm not sure what signals to engage the hubs. Not sure how ofter they actuate. Also could not find a recommended service/lubrication schedule for the hubs. The owner's manual would tell you or you can contact a dealer.

 

the info you just recieved was incorrect, the 97 control track front end runs all the time, When the dash control is in auto, the front end signal is sent to the electric clutch in the TC and engages 4h as long as there is a difference in rotational speed between the front and rear driveshafts. When you select 4H at the switch the power is applied to the electric clutch in the TC, you are in 4H regardles of shaft speed differencial, to engage 4L you must stop, place shift lever in N, apply the brake and turn control switch to 4L, this activated the electric shift motor on the TC and maintains elecrical power on the front drive clutch...you do not have any wheel activating mechanism (hubs).. note well:... do not drive on dry roads in any position than auto or 2xW

 

yes the front of these are like a fwd car no way of unlocking hub from axel... in theroy when driving down a dry black top road your rear is getting 98% front 2% power when the back wheel slips it send more power to the front (auto mode) but when lock in 4 hi power is split just like a normal 4x4...

 

Well I have never looked at one of these assemblies. I found the info on Autozone and as you can see, it clearly states it is for this car. And it appears that the data there was pulled out of a Haynes or Chilton type manual. I'd have a hard time believing that Autozone or the publisher of the info would error here - don't you think someone should check this?

I'm not saying either is right - just a nuetral party. Did anyone chek out the pictures on that web site? Looks like a pretty complicated method of locking the axles. So your saying ther is no such axel locking mechanism or controller mounted on the top of the exel housing? The axels are directely connected to the diff and the only slippage is the electrically controlled clutch? So then the wheels will constantly drive the axles when the car is in motion? This was Dave's initial question.

Your description matches my AWD Durango.

 

Jharger, you may have looked at the picture, but I have now rebuilt 4 of these TC's.

(We use these trucks with the Fire Recue dive Unit, so they get lots of abuse)

So "yes" my original posting is correct.
The only time there is slippage in the clutchpack is when the TC is in the Auto mode, other than that it is either locked in or locked out.

Dave to answer you original Question, Yes your front wheels will drive the front diff and axles up to the front output shaft of the TC, all the time. There is no way to freewheel the front end.
This will be my last input on this subject. One sometimes has to go to the mountain, not just look at the topo map!

 

yep the hubs are splined just like a fwd car... so the axel always turns (like most ford gm and dodge trucks)... not like the old 80's lock out or the 1st gen explorer's.... waiting for them to make a kit to put lock out on one I seen in peterson 4wd magizne they mad a set up for a dodge 3/4 ton had to change everthing from the axle to a-arms..