4WD Change for 2017?

[star-art]

I noticed in the sales brochures that 2017 EL 4WD trucks come with a limited-slip rear axle. As far as I know, that was not available on older models. According to the Ford sales brochures, it was not available on any Expedition in 2015 or 2016. That is why I was narrowing my search to just 2017 trucks.

When I posted this in another thread, someone asked a very good question:

Did 2017 lose the braking bias assisted 4WD? That’s what kept the limited slip out of the expedition was the two systems would be fighting back and forth. Expeditions equipped with advancetrac didn’t get a limited slip rear but it could be optioned on them without before.

That's a very good question! I sure hope the addition of this option is an improvement and not an attempt to cut corners in order to save money. I may be about to pull the trigger on a 2017 so I'd sure like to know. Any thoughts?

Thanks!

 

[JExpedition07]

Stole this from the other thread I had posted it in:

Either way I’m sure you’ll be fine. Both systems are there to achieve the same thing..... the only reason I raise this question is if that’s the case you’d only have that “limited slip” effect on the rear vs on both front and rear with the braking bias.

The limited slip is designed to start sending a percentage of power to the wheel with traction when slip starts

The braking bias senses slippage and applies friction to the slipping wheel forcing the conventional open diff to throw a percentage power to the wheel with traction, this has been one of the signatures of the control trac II system. Both are achieving the same thing in the end.... you can now see why these two systems don’t play nicely together.


Let me ask you this, what is the axle code on the door (on VIN sticker)? If you can tell me that Ill be able tell you exactly what axle ratio and diff you have.

 

[Black]

Looks like starting in 2016 the EL 4x4 started coming standard with the limited slip differential and 3.73 gear set.

Here is the 2016 brochure stating as such.
https://www.ford.com/services/assets/Brochure?make=Ford&model=Expedition&year=2016&postalCode=65613

The 2015 brochure lists all rears being non limited slip but the EL coming standard with 3.73
https://www.ford.com/services/assets/Brochure?make=Ford&model=Expedition&year=2015&postalCode=65613

Personal preference I prefer a limited slip setup over brake bias.

 

[AllBoostNoEco]

All 15-17 use the AdvanceTrac with RSC, which is the brake-bias system being referenced. In my 2015, it’s proven plenty reliable at dividing power between the wheels.
While I can get a one-wheel spin effect during cornering if it’s hard enough to unload the inside rear wheel, if I stay on the gas it always transitions into a nice little power-slide with both tires spinning.
In dirt or mud situations where a limited-slip wouldn’t have the internal bias to overcome the traction disparity, this system consistently works well.

That being said, you can have both. They really don’t fight each other at all and could even be considered complementary. As all the AdvanceTrac does is brake a spinning wheel to more evenly split the torque, that function is not changed by presence of a limited slip or even a locker. It means it doesn’t have to brake as hard to achieve that even torque split, as the limited-slip does most of the work, and the computer will be supplementing that. In situations where the traction disparity is great enough to overcome the bias of a limited-slip (one wheel in mud or on ice, the other on pavement), the brake bias system will kick in, gently brake the traction-limited wheel, limited-slip bias is reduced and the limited-slip functions as designed.

The F-150 offers both a locking differential and limited-slip, and they use the same AdvanceTrac system.

 

[JExpedition07]

Advance Trac is not exactly the braking bias I mention although it’s sesnors are what make the magic happen. The Super Duty and F-150 are equipped with advance trac RSC but do not receive braking bias assisted 4WD. Only vehicles with ControlTrac II receive this (Expedition, Explorer, F-150 Limited). Ford isn’t stupid so some how some way they make everything mesh in the EL.

 

[AllBoostNoEco]

Advance Trac is not exactly the braking bias I mention although it’s sesnors are what make the magic happen. The Super Duty and F-150 are equipped with advance trac RSC but do not receive braking bias assisted 4WD. Only vehicles with ControlTrac II receive this (Expedition, Explorer, F-150 Limited). Ford isn’t stupid so some how some way they make everything mesh in the EL.

Thanks for the clarification. I knew about the ControlTrac in the older Expeditions, but didn’t realize they continued it when they did away with the viscous coupling and replaced it with the computer-controlled clutch pack in the transfer case. Further research hasn’t proven that not to be the case.
I made the mistake of assuming since my 2013 F-150 had an open diff and I could never get that thing to spin just one tire the systems were the same.

Didn’t the guy who built his 07 or 08 Expedition with the custom Icon coilovers and custom bumpers (Aspen?) add air lockers to his without issue? I haven’t looked in a while, so I can’t recall if he ever actually gave feedback on his or not.

 

[JExpedition07]

Thanks for the clarification. I knew about the ControlTrac in the older Expeditions, but didn’t realize they continued it when they did away with the viscous coupling and replaced it with the computer-controlled clutch pack in the transfer case. Further research hasn’t proven that not to be the case.
I made the mistake of assuming since my 2013 F-150 had an open diff and I could never get that thing to spin just one tire the systems were the same.

Didn’t the guy who built his 07 or 08 Expedition with the custom Icon coilovers and custom bumpers (Aspen?) add air lockers to his without issue? I haven’t looked in a while, so I can’t recall if he ever actually gave feedback on his or not.

He may have I’m not sure, but a locker shouldn’t negatively effect anything because that is forcing both wheels to lock together in motion so I’d think the brakes just wouldn’t have to kick in all together when it’s locked. You may be correct on the limited slip and advance trac being able to compliment each other..... The difference is a locker is locked by us as the driver in advance, whereas a limited slip is reacting to the situation just as the brakes are.... so the effects are less predictable. As far as control trac it’s still used.

 

[deweysmith]

Only vehicles with ControlTrac II receive this (Expedition, Explorer, F-150 Limited).

The only vehicles that had ControlTrac II were Explorer and Escape. It's been replaced with Intelligent 4WD. It used a viscous coupling and wasn't nearly as great as plain ol' ControlTrac, which is still used on the 2018 Expedition (albeit updated a bit.)

 

[JExpedition07]

The only vehicles that had ControlTrac II were Explorer and Escape. It's been replaced with Intelligent 4WD. It used a viscous coupling and wasn't nearly as great as plain ol' ControlTrac, which is still used on the 2018 Expedition (albeit updated a bit.)

The 18’ system was downgraded a tad. No more 4High mode and only optional 4 Low mode. Looks like you are correct on the terminology, they updated the control trac a ew times but didn’t rename it, just calling the front wheel drive based one II.

 

[star-art]

According to the owner's manual, 2018 Expeditions apparently do have a "4H" option, but there's no button for it and it's not clear how it's activated. 2018 Expeditions with 4WD that don't have the Heavy-Duty Tow package get "2H" and "4A" buttons on the console. HD Tow comes with an "electronic limited-slip" rear axle and adds "4L" and rear locking differential buttons around the "Drive Mode" knob.

4H (4X4 HIGH) Provides electronically locked four-wheel drive power to front and rear wheels. The information display will display 4H when this mode is selected. This mode is not recommended for use on dry pavement. This mode is only intended for severe winter or off-road conditions, such as deep snow, ice or shallow sand.

Note: 4H may turn on or off automatically based on Drive Mode selection. In certain configurations, 4H-like functionality is contained within specific off-road Drive Modes even when the indicator lamp shows 4A. See Drive Control (page 252).