I'm looking at a 01 Expy which has the AWD. I was suprised to see it!
Does anyone have it and any problems or complaints on the system?

 

I work for a Ford dealer and I personally wouldn't recommend one to my worse enemy.

 

AWD is an interesting concept. If it is done with a differential in a two-speed transfer case, then you'd still have low range -- a plus. If it's merely a differential (single-speed), then the benefit of AWD would likely be mediocre IF there was no differential lock to ensure that you don't merely spin one tire (like if it's on ice, or if it's off the ground).

It's too bad mxracer514 didn't post something just a bit informative rather than editorial, since he probably has something to say that we could find useful.

 

I have a 99 EB 4X4. I have no complaints with the AWD, have been in snow and ice in the mountains, seems to have worked well. I don't recall reading much in the way of complaints on this board regarding the AWD. Unless the 01 AWD is different than the 99, I wouldn't hesitate to buy another.

 

We just sold our '97 Expy. The AWD system worked perfectly during the 5 years we owned it.

 

If you want more info: There are a couple different types of awds that Ford uses. One uses a vicious clutch and has no 4l, it actually doesn't work to bad and we've had very few problems with them but it was available on the older explorers (a vicious clutch works like a fan clutch) The other awd is an electronic this is the one to stay away from. I have worked on this type transfer case more than any other type. It uses front and rear speed sensers to determine wheel slipage. They have had quite a few problems with engagement and speed sensers if your oil gets a little dirty it can even cause it not to shift properly. Those of you that have not had problems with awd you ad better start knocking on some wood. I think Ford made a big mistake producing an awd, they are not very good 4x4s and not very good 2x4s, and they eat more gas just my opinion for what its worth

 

Now, THAT was useful. Thank you for the post.

What kind of problems do you find? Are they "Hot-Dog-Cowboy" related, or crappy-design/material related?

Do they look like they are intended for serious tow-vehicle use? Snow plow?

Can you contrast the viscous version with the Suburu version?

Do you have any opinion as to which 4x4's (mfr) are good?

Do you have any experience with the current round of Ford 4x4s so you can contrast the performance/durability between the electic shift on the fly vs the manual shift versions?

Thank you in advance -- and in anticipation of your post.

 

I think the problems are more design/material related. I think they were produced more for people living in areas with ice and snow. I really don't know anything about the suburu so I can't really comparethe two. The transfer case with the viscous clutch I believe only came in the explorer for a year or two. I think that they called it control trac. You can tell its got the viscous clutch design because there is no switches on the dash or shift levers. If I remember correctly when I went to school on it a few years ago under normal driving conditions the power that is applied to the front wheels is about 20% and has the wheels begin to spin the clutch heats up and more power is applied to the front wheels, the design has I said this design has been pretty bulletproof and I think it would probally work pretty good in a climate like the one you live in.
Stay away from the electronic shift awd, Fords current round of shift on the fly cases seem to be pretty good the only repeat problems I 've seen are with people who continually drive in deep water, the shift motor eventually gets water in it. If I had a choice I would by a manual shift transfer case. I own a shift on the fly 4x4 and wouldn't hesitate to recommend it but I wouldn't recommend an awd, especially with the electronic transfer case.
I really can't speak for other manufactuers (dodge and chevy) because I have always owned Fords and my parents have always owned Fords, most manufactuers don't build the transfer case anyway, they buy them from outside vendors like borg-warner or new process so its possible that some fords and chevys for example could have the same transfer case

 

You might want to research the systems that have been used on the Expedition (not Explorer). As far as I know- having participated in a lot of Expedition related forum discussions & e-mail lists, the systems used on Expys have worked well. At least not a lot of people complaining about it- and believe me, they would complain. Plus, the viscous coupling system used by '97 & '98 Expys had 2WD, AWD, 4Hi and 4Lo settings. And although the newer Expeditions are a little different in that they don't have a 2WD setting, they do have 4Lo with AWD.

 

Nomo, your correct the explorer viscous clutch system did work good, they may have worked so good that I've never seen one that had 4l. The only viscous clutch transfer case I've ever seen was on an explorer and it was full time 4x4 and had no 4l. It was only made a couple years. If Ford made another transfer case that also used the viscous clutch I've never seen it. You maybe correct in saying Ford made a viscous clutch transfer case that had 4L other settings, I'am in the service business and don't pay much attention to what vehicles are equiped with from the factory, I can only speak for what I've seen and repaired. When I went to Ford training on the control trac 4x4 the only case they offered was a full time 4x4 with no low gear. Regardless of who's right or wrong in my opinion awd does nothing more than burn more gas. I would say probally 75% of the transfer cases that I've had to repair were expeditions with electronic shift awd.

 

In '97 & '98, the Expeditions had a front center-axle disconnect for part-time 4x4 with a two-speed viscous-coupled transfer case. In '99, Ford changed the Expedition to a "live" axle setup with full-time 4x4 but still with a two-speed transfer case. It looks like now the Expedition uses the same 4WD system called Control-Trac. This appears to be the same system they use in the new 4-door Explorers which also have a two-speed transfer case. I'm not sure about the systems used in older Explorers- but it doesn't matter anyway because the question was about the Expedition's AWD system which, AFAIK, has been good through all the model years. From both our experiences, I'm guessing Ford changed the Explorer to use the same system as the Expedition.

The Escape has the Control Trac II setup which uses the type of transfer case that you describe having been trained on. Maybe this is the system you've been working on so much? This 4x4 system is a lot different than the one used on the Expedition.

 

Nomo, I don't want to insult you but the expedition doesn't have a viscous clutch design it uses a coil much like the clutch on a a/c compressor. The 2002 explorer does have a viscous clutch design case available but it is full time 4x4 with no low range. Lets not argue about what comes in a vehicle it does no one any good. If you like I would be happy to cut and paste the descriptions of transfer case operation from our Ford shop manual to settle the argument. I just want people to know the correct info, so they can make an informed decision.

 

I'm sorry. My information must be wrong.

on edit: I actually mis-read the information I have. Again, sorry for the confusion and subsequent erroneous info.

 

Nomo,
I'am going to post the shop manual decription to clear the air about the operation of these cases once again I'am not doing this to insult you in any way.

From the 2002 Explorer shop manual:
The constantly activated, automatic, all-wheel drive transfer case has no external controls. A two-piece aluminum case houses the assembly. The unit is chain driven. A non-repairable viscous coupling provides torque distribution to the front and rear transfer case outputs. The viscous coupling contains slotted alternating plates through which a high viscosity fluid flows. The resistance of the fluid shear causes the plates to transmit torque at the approximate ratio of 35 percent to the front output and 65 percent to the rear output.


From the 2002 expedition shop manual:
Features and Operation

The automatic four-wheel drive (A4WD) transfer case uses an electronic shift 4x4 system that allows the operator to choose between three different 4x4 modes. The operator can switch between A4WD and 4WD HIGH modes at any speed. However, to engage or disengage LOW Range, the GEM requires that the vehicle speed is less than 5 km/h (3 mph), the brake is applied, and the transmission is in NEUTRAL.

In A4WD, the generic electronic module (GEM) varies the torque split between front and rear drivelines by controlling the transfer case clutch. Under most conditions, the GEM activates the transfer case clutch at a minimum duty cycle (percentage of time the clutch is turned on) which allows for a slight speed difference between the front and rear driveshafts which normally occurs when negotiating a corner on dry pavement. When the rear wheels are overpowered, the GEM detects this slip condition, and the duty cycle to the transfer case clutch is increased until the speed difference between driveshafts is reduced. In this manner, the GEM can redirect engine torque to the front wheels when the rear wheels lose traction yet still allow operation in the A4WD mode on dry pavement.

From the 1997 expedition shop manual:

The A4WD system is an electronic shift 4x4 system that allows the operator to choose between three different 4x4 modes as well as 2-wheel drive. The operator can switch between 2WD, A4WD, and 4WD HIGH modes at speed. To engage or disengage LOW Range, the vehicle speed must be less than 5 kph, the brake depressed, and the transmission must be in NEUTRAL.


A4WD

In A4WD, the generic electronic module (GEM) varies the torque split between front and rear drivelines by controlling the transfer case clutch. Under most conditions, the GEM activates the transfer case clutch at a minimum duty cycle (percentage of time the clutch is turned on) which allows for slight speed differences between the front and rear driveshafts which normally occurs when negotiating a corner on dry pavement. When the rear wheels are overpowered, the GEM detects this slip condition, and the duty cycle to the transfer case clutch is increased until the speed difference between driveshafts is reduced. In this manner, the GEM can redirect up to 50% of engine torque to the front wheels when the rear wheels lose traction, yet still allow operation in the A4WD mode on dry pavement without driveline wind-up.

I hope this clears up any confusion and maybe helps someone understand how Awd's used by Ford work.

 

I had mis-read the information I have and got the Explorer and Expedition confused. :o

Still, I haven't heard of any issues with the Expedition's A4WD system. What problems are you seeing?