Deadman
Full Access Members
Exactly. There's many Platinum's running around without a locker, and tow pack.
Tow package for extra 4x4 worth it?
- Thread starter carymccarr
- Start date
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Gumby
Full Access Members
*Waves*
So, I think I'm starting to understand how my 2014EL works. If I have it in AWD power will be delivered to front and rear wheels. If rear starts to slip then the computer will send more power to front wheels to try to keep them turning at same rate. I have a LSD in the rear so if one rear wheel starts to slip the computer will apply brakes to that wheel and the LSD will give more power to the other rear wheel. If I didn't have LSD in rear and one wheel started to slip then it would spin and I'd lose all traction in the rear. If I had a locker in the rear both rear wheels would turn at same speed and if one started to slip the other one would keep driving. Do I have this right? Oh .. and LSD's kind of stop working after 100K miles or so.
Wait … my 2014EL has non-limited-slip rear diff.
Just figured that out with axle code 16.
Wait … my 2014EL has non-limited-slip rear diff.
Just figured that out with axle code 16.
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JExpedition07
That One Member
Exactly, the 2007-2014 Expeditions with the Control Trac 4WD system have 4 wheel traction control with an off-road mode according to the manual. This applies brake pressure to wheels that are slipping via brake application and sends power to a traction wheel. They did away with the LSD in 2007 because the two would fight and in testing they found the 4 wheel traction control to be more effective than a single lsd. The traction control on mine is a totally different animal if in 2WD or 4WD. According to the manual off road mode is automatically engaged in the 4L selection which alters the braking bias.
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I would have thought a Locker locks it and runs that way … not kicks in when needed?
Its too complicated for my tiny little brain. Its like 5 dimensional chess. You have to know what year Expy you have and what (2WD AWD 4WD) drive it has and whether it has LSD or what traction control mode you're running in or if you installed an aftermarket product or whatever. I think I'll just leave it stock and run it in AWD and hope I'm ok!
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duneslider
Full Access Members
The LSD has nothing to do with brakes. An LSD is inside the rear differential and can be either electronic or mechanical. It is possible that the LSD has stopped working but it usually takes a lot of miles and a lot of use for that to happen on the mechanical ones. I don't know what ford used. On the mechanical one there are clutch packs in there and they can wear out. Usually they can be rebuilt. Also, if you have an lsd they usually require special fluid or additives to work correctly, so if you replaced the rear fluid and didn't use the right stuff it will not work correctly. If it is electronic and isn't working it could just be a simple electrical issue that is preventing the clutches from engaging. Traction control if well designed in a 4x4 mode can simulate an LSD function by applying brake to the slipping wheel to the point the wheel with traction will get power transferred to it. This can work really well if done right, sometimes it is totally worthless. I don't have enough experience with ford's to know how well they did with it.
Ford does use a center multi disc differential lock which is actually a really nice feature and when in 4A will balance power front to back depending on traction. I believe it can even send 100% to the front wheels. If you have a 4H setting the center is locked and provides 50/50 bias as well as 4L which is a 50/50 bias but lower gearing. It actually is a really nice system. The 2018+ with the terrain management or whatever its called just uses different profiles in how it engages the center differential and how it used traction control. The terrain management systems can do a really good job if they are designed well.
My understanding of the 2018+ rear locker is that it is an electronic locker and when not engaged a limited slip or LSD. So under normal use if a rear tire begins to slip the clutch packs engage providing varied amounts of power to both wheels, probably never a full 50/50 bias but I don't know for sure. When activated a solenoid is going to push the clutch packs together and it should have a near 50/50 bias. I don't know for certain this to be the case but I do not believe it has a true mechanical lock like an ARB air locker would have, those types typically don't have LSD capability.
Probably the biggest down side to LSD's is that they require wheel speed to activate. A true locker doesn't require wheel speed. For normal day to day driving an LSD is nice to have and works pretty well and has nice street manners. They aren't great offroad for slow stuff but seem okay for mud in my experience. Full lockers are not street friendly at all and are a recipe to get you sideways and off the road really quick.
duneslider
Full Access Members
Generally if a locker is activate the traction control is turned off and if the locker is activated the rear wheels are turning at the SAME rate and traction control will see they are turning at the same rate and not activate any braking there anyway.
If we are talking LSD...maybe. Not sure how they are on the newer ford. If they are electronic and tied to the TCS then the TCS might activate the LSD rather than apply brakes.
PC Rob
Member
I've had the heavy duty package in both my current and last (2006) Expeditions. while the need for it now regarding snow for me is minimal (Florida) I used to live in the Pocono mountains and certainly drove my share in heavy snow conditions! Came in handy though, dragging other sorry souls out of the ditches. When I do really appreciate it, is pulling a 5500 lb boat and trailer up those steep and slimy boat ramps here in the sunshine state! Some of these ramps are more slippery than the snowy roads up north.
scottdm
Full Access Members
The Silverado Trailboss uses the Eaton G80 mechanical locker in the rear end. From the videos I've seen, it needs quite a bit of wheel spin before it abruptly engages. I prefer the Expy's setup where you can activate the locker BEFORE wheel spin occurs.
https://www.eaton.com/us/en-us/catalog/differentials/mlocker.html
https://www.eaton.com/us/en-us/catalog/differentials/mlocker.html
Deadman
Full Access Members
I believe the traction control defaults to ON every time its started, so I rarely think to shut it off ahead of time. So then the traction control tries to kick in as or before the locker tries to kick in, so I'm not sure which one kicks in first. Old school with no traction control, then the locker just did the work and you could actually spin your way thru stuff if needed.
Rancidlunchmeat
2019 XLT FX4
What do you mean by the locker tries to kick in? You have to manually activate the locker, so the question is if activating the locker automatically deactivates traction control - right? Maybe I can test that after work or somebody can test before then.. should be as simple as engaging the rear locker and seeing if the traction control off light comes on.
do tell
shane_th_ee
Full Access Members
I like all the confusion resulting from the assumption that the rear differentials installed on older Expeditions are in any way related to the eLSD with locking mode installed in the 3.73 rear found on 4th gen Expeditions.
"Is the performance boost of a solid state hard drive worth the extra cost over a magnetic drive?"
"I used a computer once and they're d@mn near useless once you get the punch cards out of order. Maybe you guys are more OCD than I am, but once I take into account the extra time wasted due to re-sorting the punch cards, just using a paper and a calculator is far faster."
JExpedition07
That One Member
No assumption they are the same, I was referring the old mechanical style limited slip found in the gen 2 Expedition and why they did away with it in favor of software/ tc. They now use an electric lsd that doesn’t try and fight the traction control systems. Also a much better solution than the old mechanical style that wears out.
shane_th_ee
Full Access Members
The rear differential in question is an electronically controlled limited slip differential with locking mode. The electronics control a hydraulically actuated clutch pack which divides the torque between the rear axle driveshafts. This is very, very different from a traditional locking differential (which has two modes: open and locked). It is also very different than a limited slip differential (LSD) which mechanically limits on the difference in rotational speed between the axle driveshafts (and which has the speed differential is defined by the physical design of the components of the differential). It is also very, very different from an electronic limited slip differential (or pseudo-LSD) which uses the ABS components and software to apply a braking force to a slipping wheel.
A rear differential with an electronically controlled, hydraulically actuated clutch pack with locking mode (like that in the 3.73 rear axle installed on 4th generation Expeditions) is designed to give one the best of all possible worlds. Like a locking differential, you can force the axle drive shafts to rotate at the same speed no matter how much traction each tire has. Like a traditional LSD, you can the rotational speed differential between the two rear drive shafts. And like a pseudo-LSD, you can respond to vehicle sensor data and vary the torque between the axle drive shafts. But unlike a locking differential, you can allow some (but not infinite) speed differential between the two axle driveshafts. And unlike an LSD, you can choose whatever speed differential you want. And unlike a pseudo-LSD, you can actually lock the rear differential.
So, in the 4th Gen Expedition, how does the rear differential actually operate? Well, that's what the drive modes are telling the system to prioritize. Set it in 4A, and it's going to assume you're driving down a highway and it's going to act like a lot like a traditional LSD or pseudo LSD. Choose "snow" and it'll likely do really cute things, like act like a locking LSD when you're stopped but also watch your speed and yaw sensor* to keep from putting you in the ditch....
The downsides are cost, complexity, and heat build up in limited slip mode.
*Note that the center transfer case in these fords is also a hyrdaulic clutch pack. So "icy/slippery road" mode is also going to be varying the center transfer case clutch pack to keep you from spinning round and round should you hit a patch of black ice, which was the bane of 4H 4x4 systems.)
JExpedition07
That One Member
No misinformation posted here. Here is a great read on the ControlTrac 4WD system. ControlTrac was used on 2nd and 3rd gens, but shares much with the system in the 4th gen (still BorgWarner TOD):
https://www.ford-trucks.com/forums/928481-controltrac-4-wheel-drive-and-how-it-works.html
https://www.ford-trucks.com/forums/928481-controltrac-4-wheel-drive-and-how-it-works.html
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wow, nice even I can understand that!!
I just found out today my 2014EL has non-LSD but maybe apparently (I RTFM) it has Traction Control which sounds like the pseudo-LSD mentioned above. Just when I thought I understood it, the manual says turn it off if stuck in snow. OK. Not sure why though.
I have seen the TCS light come on in winter, now I know what its doing!
Calidad
Full Access Members
I think people fail to realize just how advanced the vehicle is regarding stability systems and what systems play into it.
Have any of you driven a super techie advanced vehicle in a bad snow storm? And not in flat country? Talking the modern Subarus, Mercedes etc. The amount of logic that goes into vectoring power or braking individual wheels is impressive.
The more electric systems that play into traction, vehicle direction and control. The more capable the car and be with computer input. Or more like 1000’s of computer inputs.
The E locker no doubt has some play in the vehicle dynamics and stability control.
The on/off button on traction control only does one thing. When you “turn it off” your just turning on a higher tolerance to wheel spin and probably more tolerance to directional vs G loads. But you better believe the nanny is still there!!! Its just giving you more leeway.
Traction control on is just full Nanny mode there to keep you pointed in the correct direction using all various systems brakes at each corner, power, steering, possibly even rear diff.
You get these really advanced systems on slick hilly mountain roads you start to see how much they can do. Its pretty wild.
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