2008 Explorer change AWD to selectable 2Hi/4Hi/4Lo? Manual hubs?

[Larryjb]

We just got a 2008 Explorer (4.6L AWD/4x4). The AWD is nice in that my wife doesn't have to think about road conditions, except on packed snow/ice where she can switch to 4Hi.

However, the AWD does us A LOT of fuel and isn't necessary for most road conditions. I have searched and found almost nothing on the fourth generation Explorers and transfer cases. My <ahem> Tahoe has Auto 4wd/2Hi/4Hi/4Lo. This is nice because I have the advantage of an AWD system in slippery conditions where I wouldn't want to be using 4Hi. I can leave it in 2Hi most of the time. Does Ford make any transfer case that would at least give the option of 2Hi for the Explorer? What about Manual hubs? This might help at least.

Larry

 

[Trac Marks]

You have something wrong. Its RWD unless slip is detected, then power is temporarily shifted to where its needed. If anything, less fuel is used as it won't allow you to needlessly spin tires.

The only AWD variations were in Sport Trac Adrenalin and, if I am recalling correctly, some V8 Mountaineers. And on those, AWD control is via the message center -- there is no 4 auto, 4X4 High and 4X4 low switches on those..

 

[Larryjb]

Um, my Explorer has the following switches: AWD, 4x4Hi, and 4x4 Lo.

This is the first I've heard of this being 100% RWD until slip is detected. I've always heard it was 30% front and 70% rear. Do you have a source I can read up further on this AWD system?

Larry

 

[MNgopher]

FWIW, the switch is labeled 4x4 Auto, not AWD.

I've seen so many descriptions of how much power is spilt to the front, I can't keep it straight anymore. The basics are some is sent up front at all times. It can increase when wheel slippage is detected (and thus the lurch many folks describe and feel when this happens...).

Even if you defeat that with the brown wire mod (or whatever wire it is on this generation), the hubs are locked with no provisions for locking or unlocking. This means everything in the front drivetrain will be spinning - front axles/CV, front driveshaft, etc... That soaks up some mileage right there. I don't believe there has been any transfer case in the 2nd, 3rd, or 4th generation that allowed straight 2WD - they were all 4x4 Auto or All Wheel Drive with no low range. Thus no factory axle disconnects or manual (or other controlled) hubs...

 

[bob60014]

Just my 2 cents. I'm in Chicago and get 17/18c and 21/22hwy with mine. If you are getting poor gas mileage I would look at another cause of this, not the AWD.

 

[Tech By Trade]

Brown wire mod, Or the orange wire mod on the 4th gen I do believe is the only way to disable the awd. Whats a manual hub? didn't they used to have those back in the olden days? Like drum brakes.

 

[Larryjb]

Brown wire mod, Or the orange wire mod on the 4th gen I do believe is the only way to disable the awd. Whats a manual hub? didn't they used to have those back in the olden days? Like drum brakes.

Everything I've heard so far, with one exception so far, is that power is always transferred to the front and rear to the ratio of 30/70, although those numbers vary. When one slips, the AWD system changes that ratio to 50:50. From what I've heard, the "brown wire mod" only stops the AWD from changing that ratio, so it is always in a 30/70, or "non-slip" ratio.

I have a lot to learn about this system, and I'm sure some of my information is incorrect. I am under the understanding that a true 2WD option is impossible without changing the transfer case. I am also suspecting that there is no transfer case that would bolt onto this generation of Explorer that would allow a 2WD option.

As for fuel economy, I will monitor it over the coming days. This weekend I'll check the fuel trims too. It would be sad if my Tahoe gets better economy than the smaller Explorer!

Larry

 

[MNgopher]

The wikipedia article (yeah, I know) on ControlTrac will give you more insight into how this system works and why the front end components are always locked (ie: no selectable locking hubs or axle disconnects). The system has to see the speed of the front and rear driveshafts, and the only way to keep the front driveshaft moving is to always have it locked. Selectable hubs or axle disconnects will definitely screw things up here, and again, there has been no true 2 speed transfer case with real 2H on the 2nd, 3rd, or 4th gen Explorers.

From going through the diagnostic testing, it certainly appears the system puts roughly 4% duty cycle minimum to the front at all times, and can send up to 98% (which would be a nearly 50/50 distribution). The nomenclature can be confusing, but remember, it is 4x4 Auto, not AWD in the Explorers (except for a small group in the last year of production as I later learned, but I don't believe that to be a large number).

Some explanation can be found here:

http://www.explorerforum.com/forums/index.php?threads/4x4-vs-awd-and-explorer-vs-mountaineer.303944/

And I hate to say it, but odds are your Tahoe will beat your Explorer on fuel mileage. Not sure where you are located, but our Explorer gets awful winter gas mileage (most due to the short tripping driving cycle my wife puts it through). Roughly 12.5-13 MPG in mostly in town. Summertime it will deliver 22 in freeway driving, but in the winter its a pig...

 

[Larryjb]

As for mileage, obtained by resetting the average fuel econ:
-on a straight highway section with no hills, fuel econ reset while at 60 mph: 29 mpg
-after a day of driving, includes hills, freezing temperatures: 13 mpg

When I looked up the mileage ratings of the 2WD explorer, it was almost the same, so there'd be little savings by any kind of mod that would give me 2Hi, even if it existed.

My 1992 Grand Marquis with the 4.6L would get better, but when I was driving it that was mixed with freeway driving.

Yeah, it's a pig on gas, BUT the 4x4 for winter driving for my wife is great. The extra mass will help prevent neck injuries etc in mild collisions. (My wife has been hit once, her mother twice)

Larry

 

[Larryjb]

Is there a specific model #, or names for the various transfer cases Ford uses on the Explorers? (e.g. Ford uses 6R60 for transmissions) I've been trying to find out more about the transfer case and just how it transfers 30% power to the front. I've got tons of other questions too, but the answers one gets on forums seem too varied.

I saw one video showing the teardown of one transfer case, but it was for the FWD based crossovers.

Larry

 

[Larryjb]

Sorry about all the posts..
I'm beginning to answer my own question. I found out tons of information from this site:
http://www.etis.ford.com/vehicleRegSelector.do
I have a 4wd 2 speed transfer case with Tod. I looked that up and it appears likely it's a BW4412 transfer case that uses electric clutches instead of a fluid couple to vary the torque transfer (F:R) from 0:100 to 50:50.

I'm still somewhat confused by Trac Marks answer, but it seems that it does indeed act as RWD when no slip is detected. As slip is detected, torque is transferred to the front. This transfer case allows 4Hi and 4Lo to be selected with pushbutton switches. This Explorer is listed as a LHD 4WD (PTD).

I wonder how long those clutches will last? I bet this will be an expensive rebuild one day.

Larry

 

[Explorer_PL]

My 06 v8 uses BW4412. Last year at 220k miles the rear output bearing went bad, was making lots of noise and was leaking the fuid. I shopped around, and rebuilding that transfer case would run 1200-1500 as far as I recall. I ended up buying a used one from a wreck with 60k miles for $ 150, and spent one Saturday swapping it. It's still good 20k later.

 

[tripplec]

So in the 4th Gen builds with V8 4.6L Is the AWD power train better than a 4WD version other than 4WD having LOW range. Is LSD used in any of the diffs.