PSA: What Drive Modes Lock the Center Diff (True 4wd), Etc?

[Expedition Dave]

What Drive Modes Lock the Center Differential (as in true 4wd) explained, etc.?

(I wish there was a manual CD lock button to match the rear locker)

YMMV

 

[BLUWAGN]

This was just covered last week here: https://www.expeditionforum.com/threads/platinum-4-wheel-drive.45768/

Great information as I didn't know, but mud/rut mode will get you a 50/50 front/rear split and essential full 4 wheel drive.

 

[LokiWolf]

4A will get you full 4WD also. Switch it and let it work. It just varies Torque split.

Unless you are off road, then Mud/Ruts makes sense.

Also, for clarity, we DO NOT have a locker like the 150 does. We have a simulated locker. It uses the ELSD clutches to simulate a locked Rear.

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[Expedition Dave]

Loki,
1. To your knowledge. how powerful are those clutches (or can high stress introduce slippage--which may be a safety valve)?

2. As I've mentioned as well, 4A works well in a WIDE variety of circumstances, but it is a temporaray on off/lock via electronic open/close clutches--which often is desirable. FI, if you are on ice, spinning 3-4 wheels you have NO EFFECTIVE TRACTION, and can slide badly due to gravity and road pitch. So hopping power in AWD wheel to wheel with power on/off can ultimately end up with more forward/rearward progress.

But doing that for extended periods/hours of slipping on a really slippery trail can wear/heat up your system.

YMMV and it can be very circumstantial, which is why we have so many nannies. Easier to click the "easy" button for most.

 

[LokiWolf]

Loki,
1. To your knowledge. how powerful are those clutches (or can high stress introduce slippage--which may be a safety valve)?

2. As I've mentioned as well, 4A works well in a WIDE variety of circumstances, but it is a temporaray on off/lock via electronic open/close clutches--which often is desirable. FI, if you are on ice, spinning 3-4 wheels you have NO EFFECTIVE TRACTION, and can slide badly due to gravity and road pitch. So hopping power in AWD wheel to wheel with power on/off can ultimately end up with more forward/rearward progress.

But doing that for extended periods/hours of slipping on a really slippery trail can wear/heat up your system.

YMMV and it can be very circumstantial, which is why we have so many nannies. Easier to click the "easy" button for most.

I believe they are decent, but high stress will induce slippage.

 

[Fozzy]

I have left my rear locked after pulling the boat out of the water and I couldn’t even get it to turn on the dry concrete. With my wide tires and the boat on it I couldn’t drag the inside tire. Pretty locked if you ask me and definitely locked enough for anyplace you would take the Expy. A pin lock like the F-150 would be nice, but I think the average person with the Esld rear and 4 auto system will get more places without having to think about it.


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[LokiWolf]

I have left my rear locked after pulling the boat out of the water and I couldn’t even get it to turn on the dry concrete. With my wide tires and the boat on it I couldn’t drag the inside tire. Pretty locked if you ask me and definitely locked enough for anyplace you would take the Expy. A pin lock like the F-150 would be nice, but I think the average person with the Esld rear and 4 auto system will get more places without having to think about it.


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@Fozzy, Wholeheartedly agree! The Combo will keep most people out of a bad situation.

I have seen it get ticked off and disengage when I was logging and doing several hard launches in row. Not the typical use of the ELSD on an Expy but a good test of it under extreme load.

 

[JExpedition07]

The clutches are very good on these BorgWarner Torque on Demand cases. It’s a hybrid of sorts as it is stiles chain driven too. Remember Ford has had this contract with BorgWarner since 1997 for these automatic transfer cases...they’ve been out a LONG time. You rarely see any failure posts on here about them even in the 1st gen section besides shift motor concerns. In fact the early models had no 2H mode and were full time 4A (1997-2000). To my knowledge the only reason 2H was added was for fuel economy benefit. I changed the fluid in my 3rd gen and there was no metal particles suspended in the fluid and it was light brown in color after many miles. As long as you change it at the recommended intervals you have nothing to worry about as far as how much it’s used.

 

[LokiWolf]

The clutches are very good on these BorgWarner Torque on Demand cases. Remember Ford has had this contract with BorgWarner since 1997 for these automatic transfer cases...they’ve been out a LONG time. You rarely see any failure posts on here about them even in the 1st gen section besides shift motor concerns. In fact the early models had no 2H mode and were full time 4A (1997-2000). To my knowledge the only reason 2H was added was for fuel economy benefit, not any big issues with the case. There is a common mod known as the brown wire mod that 1st gen owners do which allows a 2H mode. I changed the fluid in my 3rd gen and there was no metal particles suspended in the fluid and it was light brown in color. Now red and fresh. As long as you change it at the recommended intervals you have nothing to worry about as far as how much it’s used.

@JExpedition07 We were talking about the ELSD clutches in the Rear End not the Center diff. It is a bit of an unknown. The 150 has an electric locker that is pin driven. Our simulated lock mode in the 4th gens is just the Clutches in the ELSD engaged.

 

[JExpedition07]

@JExpedition07 We were talking about the ELSD clutches in the Rear End not the Center diff. It is a bit of an unknown. The 150 has an electric locker that is pin driven. Our simulated lock mode in the 4th gens is just the Clutches in the ELSD engaged.

Ah. It sounded like Expedition Dave was concerned about using 4A on slippery roads or trails over long periods due to excessive heat in the clutches. I assumed he was referring to the T-case because he mentioned AWD vectoring torque.

 

[Soliyou]

The clutches are very good on these BorgWarner Torque on Demand cases. It’s a hybrid of sorts as it is stiles chain driven too. Remember Ford has had this contract with BorgWarner since 1997 for these automatic transfer cases...they’ve been out a LONG time. You rarely see any failure posts on here about them even in the 1st gen section besides shift motor concerns. In fact the early models had no 2H mode and were full time 4A (1997-2000). To my knowledge the only reason 2H was added was for fuel economy benefit. I changed the fluid in my 3rd gen and there was no metal particles suspended in the fluid and it was light brown in color after many miles. As long as you change it at the recommended intervals you have nothing to worry about as far as how much it’s used.

Mine has a clutch whine @2000 rpm right before it disengages the clutches.

 

[Expedition Dave]

Was not worried so much, but wanted to make known the proper way for doing heavy terrain utilizing 4wd properly and not overly taxing by on/offing the system.

 

[LokiWolf]

Was not worried so much, but wanted to make known the proper way for doing heavy terrain utilizing 4wd properly and not overly taxing by on/offing the system.

I am not a serious off roader, a little overlanding in the past when I owned the 250, but that has been years. My experience with this system has been some muddy country roads, gravel, grass, and hard 0-60 launches. My 2017 did AMAZING in the Snow, and I expect this 2020 to do the same. Honestly I would leave it in 4A, and save the simulated locker and 4L for when it got really rough or I was stuck. It is the friend that gets you out of the sticky situation like others have said. I will be putting some better tires on it next Fall, but I will see how these OEM 22's do this year.

 

[Fozzy]

Not to mention the adverse handling of a locked rear. If you don’t have a lot of experience counter steering and drifting in slick and snowy conditions the open diff is your friend. Rock crawling or a steep gravely climb. I would lock it first. Everything else I would probably let it do it’s own thing.


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[carymccarr]

I am not a serious off roader, a little overlanding in the past when I owned the 250, but that has been years. My experience with this system has been some muddy country roads, gravel, grass, and hard 0-60 launches. My 2017 did AMAZING in the Snow, and I expect this 2020 to do the same. Honestly I would leave it in 4A, and save the simulated locker and 4L for when it got really rough or I was stuck. It is the friend that gets you out of the sticky situation like others have said. I will be putting some better tires on it next Fall, but I will see how these OEM 22's do this year.

OEM’s on my Navi were atrocious in the snow. I was shocked. Immediately went and got it outfitted with Michelin XIce’s


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[Wayne Decker]

I wish there was a list of all the parameters that change in the different modes. In pssing they mention that various things change, but I'd like specifics.

 

[LokiWolf]

I wish there was a list of all the parameters that change in the different modes. In pssing they mention that various things change, but I'd like specifics.

What specifics do you need. Pretty good description in the manual.


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[Wayne Decker]

What specifics do you need. Pretty good description in the manual.


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Steering response, ride settings.

 

[LokiWolf]

Steering response, ride settings.

Steering response is not affected. Weighting is, but ratio is not.

If you have CCD, Sport increases dampening, eco lessons. Sport is a stiffer ride, Eco is softer.


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[JExpedition07]

Not to mention the adverse handling of a locked rear. If you don’t have a lot of experience counter steering and drifting in slick and snowy conditions the open diff is your friend. Rock crawling or a steep gravely climb. I would lock it first. Everything else I would probably let it do it’s own thing.


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I learned this the hard way when I had my dads truck last winter. I had to turn around and decided to drive into what I thought was a small unplowed “parking lot” in the city. Had stones around it. Nope, empty muddy lot. Locked the rear thinking it would help (wheel turned hard) truck started flinging mud and went nowhere. 4WD, moving slow but still flinging mud and not going anywhere. Unlocked the locker and she pulled right out in 2 seconds. That’s when my friend explained to me you only use a locker in straight line maneuvers...locked when turning the wheel and it’s no longer an ally. Lesson learned. Said it was funny to watch from his truck though.