Tow package for extra 4x4 worth it?

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Deadman

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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.

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

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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.

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.
 

shane_th_ee

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A lot of mis-information or at the least mis-understanding here of what LSD, locking differentials, transfer cases, and how they all work!!!
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.

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JExpedition07

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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

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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.)
 

Plati

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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.)
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

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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.

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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