Confused about LSD/locking diff vs 4WD

[wannaexpy]

Hi all,

Long time open diff 4wd owner, just researching to see if I can get away with a true locking diff ( like GM G80) in a 2WD Expy instead of the traditional 4WD with open diffs or ineffective LSD. Watching the Eaton company video on UTube it is apparent that even a 4x4, no matter what brand with LSD doesn't pull like a locking diff. Hard to argue with the video.

I want an Expy, 2008-09 due to the independent suspension ride and 3rd seat folding ease but don't want the mpg penalty of 4x4 if it will just spin out. My old 4x4 1977 GMC non locking 1 ton just spun and was an embarrassment in the mud or snow, the 1982 Jeep with Quadrant Trac did fantastic and the 1977 F250 4x spun a lot...

So, who out there gave up 4 wheel drive and has a locking diff Expy that they are happy with in winter??? Des ford even make a locking diff or do I have to buy aftermarket to stay 2 wheel? (It's really hard to find a 4x4 in Phoenix with Limited trim).

Thanks

 

[Big White]

My 04 2wd has 3.73 LSD rear. Pulls my 6000 pound boat out of the water fine.
Limited slip is not the same as a locking however.

 

[wannaexpy]

Ever lost traction to the point you cussed it? I don't drive hard but my old non-locking trucks really were embarrassing in low traction. Why pay the mileage and maintenance costs for something marginal?

 

[sgtowing]

To get true locking abilities you have to go after market. What is it spinning in?

Sent from my Galaxy SIII Using Tapatalk2

 

[Big White]

Don't forget, in marginal conditions like a wet boat ramp, LIGHTLY apply the parking brake and the slipping wheel will stop and both will work. Try it. Simple and effective.

 

[tonydiv]

You also need to factor in that most newer 4 wheel drive trucks and suvs need to have open diffs to effectively use their electronic traction control systems. These systems apply brake force to an individual wheel as it loses traction, thus sending power to the wheels with traction. If you introduce a mechanical lsd or locker to this equation, the system no longer works.

 

[wannaexpy]

Good point on the new computer software issue. So what you are saying is that I am "stuck" with the non-locking setup for the software to work. But how does GM get away with it in their newer G80 readrdiffs then?

 

[sgtowing]

In the Hummer H3 we had,(front and rear locking diffs) when you pressed the button to lock them, the traction control shut off.

Sent from my Galaxy SIII Using Tapatalk2

 

[mazdaparts]

The LSD in most fords are set up for a 70/30. You can change the way the clutch pack is stacked for a 50/50 if you want to go through the trouble of tear the carrier out and rebuilding it. From what I have read they are only good for 100k or so anyways.

 

[mindgame]

Long time open diff 4wd owner, just researching to see if I can get away with a true locking diff ( like GM G80) in a 2WD Expy instead of the traditional 4WD with open diffs or ineffective LSD.

Quick answer? Yup.. I dont see why you think you can't.

When the Easton is not engauged, it behaves like your stock open diff.. When you need to lock the rear.. flip the switch, and you are locked..

Albeit, I think you will enjoy more getting a 4x4 instead of 2x4 with lockers..

This is on my list also

 

[wannaexpy]

Thanks for the replies. I always liked using low range for when I backed a heavy travel trailer but we don't TT any longer and I don't pull a thing anymore except maybe the lever on the La-Z-Boy recliner.

Reason I asked is that I am having trouble finding an 08-09 Limited in Arizona that's a 4x4. There's a few 4x4 XLT's but nothing much else that's not a 2x4. Course, what's a guy in Phoenix use a 4x4 anyway, it's not Buffalo NY here in January. I can go to snow country and find one but that's a hassle.

 

[alaskanexpy]

if i remember correct flagstaff gets a good amount of snow right?

i think you would kick yourself forever if you get a 2wd.

keep an eye out for Lincoln navigators. the prices are pretty close between the two.

 

[Dib52]

Expand your search to include Eddie Bauer packages. Unless you have your mind set to certain options, almost everything comes in the EB or can be had if you can find them.
Back to the original question... The AdvanceTrac of the Expy will have a tough time interfacing with a mechanical locker. Sensors, sensors, and more sensors between the traction control, ABS, roll stability will throw the system out of whack if you throw a locker out back.

 

[splintrcel]

Every diff has its pros and cons. Since none of our trucks are really just for off road only the stock limited slip is awesome. The issue with locking a diff is ur turning sucks. Its just what happens with a straight axle set up. The diff makes a huge difference. Not having to mess with the diff while driving is prob the best option for me i guess. I have never ever had an issue in any snow storm in WI. If you want hard core off road stuff look into Detroit Lockers. They stay locked until you turn then open up. This is only for off road use and can not be turned off. Its prob useless for most of us lol, but great if you only do off road. I like my limited slip however. Ford really has a nice setup on these trucks (1st gen that is).

 

[wannaexpy]

Did the 2nd gens all have traction control? I'd go down to a 2005 to keep the higher HP unless people think that chips are worth it.

 

[wannaexpy]

Thanks all you who replied. Guess I will just shop for a 2nd or 3rd gen Expy with open diffs and not care about if it has LSD or not. I have read a lot bad about the SUV's with AWD that are simply computer coltrolled braking of the spinning wheel, hopefully the weight of the Expy combined with the more robust 4WD vs. car based AWD will be good enough for drives in mid-winter to Oklahoma and Colorado to see family.

Next mission is researching chips to see if anything is really worth it. Anyone care to discuss? I am aware that many threads can be searched with tuner or chips as the words...

Thanks,

WannaExpy

 

[LocDoc]

The four-wheel electronic traction control (ETC) used on newer Ford Expeditions is nothing to laugh at. It is far-and-away better than any of the Traction-Lok limited-slip differentials offered by Ford.

The Expedition’s electronic traction control is calibrated for off road use; it uses additional software logic to determine if the four-wheel four-sensor four-channel anti-lock braking system (ABS) should "brake lock" the differentials.

If, after a couple of squeezes of the disc brakes, the slipping wheel or wheels continue to slip (spin), ETC will tell the ABS to apply full brake pressure to the slipping wheel or wheels, brake locking them. Even with two drive wheels (one front, one rear) airborne - completely off the ground, an Expedition four-wheel drive can still keep moving forward.

When ETC "brake locks" either the front or rear differentials, it can force more torque (up to 100 percent) to the non-slipping wheels by "over driving" or "over torquing" them.

This amateur video (below) shows the ETC "brake locking" the airborne left rear wheel. The right front wheel is also airborne and is also being brake locked.

http://www.youtube.com/watch?v=cIv6L52LkFE

Note that two-wheel drive Expeditions get two-wheel electronic traction control (ETC). Only four-wheel drives get four-wheel ETC.



As for the four-wheel drive system itself?

Expedition is available with automatic ControlTrac four-wheel drive which was designed and developed at BorgWarner. It features an intelligent locking center multi-disc differential.

The center multi-disc differential (computer controlled electromagnetic multi-disc clutch) is locked in Four High and Four Low modes, giving a locked front 50:50 rear torque split.

In Auto mode, the center multi-disc differential is unlocked and provides "torque biasing", varying the torque split from front 0:100 rear, to front 100:0 rear, or anywhere in-between.

Only the BorgWarner 4416 and 4417 transfer cases can "torque bias".

The BorgWarner 4406 transfer case can vary the torque slip from front 0:100 rear, to front 50:50 rear, or anywhere in-between those two parameters in Auto mode. It cannot torque bias, thus it cannot send 100 percent of torque to the front wheels.

 

[jasonlmarsh]

Awesome post LocDoc, Thanks! I had been wondering how Ford handled the 4WD-AUTO mode. Question... How do we know if we have the BorgWarner 4416/4417 transfer cases with "torque bias", or the 4406 without?

edit: oh another question. Would you recommend running in AUTO mode all of the time, or would that likely decrease fuel mileage, or the life expectancy of the components?

 

[LocDoc]

The BorgWarner 4406 unit was used from 1997 to 2002 on the first generation Expedition (UN93). It is somewhat intelligent, using basic artificially intelligent control logic to work out how much torque should be sent to the front wheels, and for how long.


The front:rear torque split in Auto mode is variable from (rear-wheel drive) 0:100, 10:90, 20:80, 30:70, 40:60, to 50:50 (all-wheel drive).

Auto mode also allows the center multi-disc differential to let the front and rear propeller-shafts slip as needed, so that "torque windup" and "driveline binding" do not occur while on dry pavement.

Note that 1997 and 1998 models have a Two High mode, but it was later discontinued for the 1999 model year, leaving Auto, Four High, and Four Low modes.




The BorgWarner 4416 unit was used from 2003 to 2006 on the second generation Expedition (U222).

4416 is similar to the 4406 it replaced, but has more advanced software added to its artificial intelligence, allowing it to predict traction loss before it happens, so that the center multi-disc differential can transfer torque before its ever needed. This is helped along by the systems ability to work out what type of terrain or surface its being driven on. Two High mode was reintroduced and remained ever since.


There was also the addition of "torque biasing" capability (Auto mode only), which allows the center multi-disc differential to bias all 100 percent of the engine’s torque to the front wheels, for temporary front-wheel drive.

Torque biasing occurs when the system detects both rear-wheels have encountered severe traction loss (i.e. both rear wheels are on ice, etcetera), and are no longer able to help move the vehicle. So all of the engine’s torque is rerouted to the front-wheels.

The front:rear torque split in Auto mode was now unlimited, completely variable from (rear-wheel drive) 0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, to 100:0 (front-wheel drive).

Of course the center multi-disc differential can still be locked in Four High and Four Low for a permanently locked 50:50 torque split.



The 4417 unit was used from 2007-present on the third generation Expedition (U324), Expedition EL – Expedition Max for Canada/Mexico (U354)

It is pretty much the same as the 4416, but includes a default off road program that is automatically selected when Four Low mode is engaged.

 

[jasonlmarsh]

Thanks for that info, very informative!!!

Do you see any detriment to running 4WD-Auto mode all of the time? and do you know how long it takes the system to recognize and engage the front wheels? In my previous vehicle, 4-Auto would hurt gas mileage, so it was only turned on in poor weather, but even then, the engagement of the front wheels was so slow to react that I rarely used it, and just popped in 4-High most of the time.