Electronic Locking Rear Differential Question
 

I test drove the 3.55 with the e-locking rear end and wasn't very impressed at all. I was asking myself what the point of this was and am writing this to see if anybody can answer it for me because I am sure Ford does have a reason for it. Here's my view. If you put it in lock mode it only works up to about 20 mph then goes back to regular one wheel drive. The problem I have is say when it is raining out and you are going 30 mph and you punch it, with these crazy powerful diesels you are definitely going to spin the tires in which you lose control with the e-locker. If you get just the regular limited slip differential when going 30 mph and punching it the tire will slip momentarily until the axle locks up automatically helping to gain traction. Can someone please tell me the big advantage to get the e-locking rear end? When I plow I'm in 4x4 and was thinking that you could maybe just plow in 2 wheel drive with the rear end locked but that's all I can see this being good for. Hopefully I will be signing paper work on my truck tomorrow and would like some feedback.

I use it to plow in 2wd. Works ok.

Honestly, it's probably not worth the money and to do over, I wouldn't have got it. A standard limited slip would be better, IMO.

It works well for me on the farm, but haven't had a use for it yet on the pavement, but I haven't had the truck for a winter here yet. My property has hard clay on some of the acreage and black loam on other parts of the acreage. The clay is very slippery when wet and the loam just sinks. When I am slipping from a start, typically while pulling something at a very low speed, I can pull the knob out and engage the locking rear end and it gets me going. Granted, I could probably do the same thing by engaging the 4WD, but at least I feel like I am getting value out of that option.

In a minimum traction situation such as you describe you are more likely to lose control of the vehicle if the rear axle is locked, since both wheels will break traction and then you can spin out. With the differential in the open position one wheel will spin and the other does not thus maintaining some stability. The elocker gives you a 50 - 50 split in power to the rear wheels when engaged, the LSD provides much less of a split to the wheel with traction, and potentially nothing to the wheel with traction if the other is on ice (as opposed to the elocker which can deliver 50% of available torque to the wheel with traction). It would be a rare situation where one really NEEDS the differential locked at a speed above 20 mph. I am sure the engineers do not allow it simply because of the previously mentioned stability problem if you manage to break traction wit both wheels.

Works good for turning around, when the road is too narrow to jocky around one of these long wheel base rigs. Lock and spin :)

It also works great for pulling a boat out of the water on a wet slip. You can avoid just about all spinning...

My 2010 6.4 had a limited slip axle and it wasn't worth a crap.

The limited slip axles in the Ford's is not an auto-locker. The truck I had before my 2010 was a 2003 half ton chevy and it had an auto locker in it. That worked quite well. In contrast, the limited slip in my 2010 ford was worthless.

The way the limited slip axles work is there is a clutch pack inside the diff. The clutch offers resistance to the axle shafts turning against each other, like a brake on a wheel - it doesn't lock the axle up it just resists it moving. This transmits SOME of the drive power back over to the wheel that has traction in a limited traction scenario, not all of it as a locked axle does.

That having been said, the SRW trucks have traction control (not sure about the DRW's? Is it just stability control they lack?). The traction control on my truck works well enough that I can't hardly get the tires to chirp if I stomp on it. Once the turbo kicks in the tires will spin briefly then the power is dropped and all and the tires stick. I have not tested this theory yet, but what someone explained to me a while ago is that the traction control will control the individual wheel brakes. This tells me that if one tire is spinning the traction control will brake it. On an open diff if you brake the wheel spinning that power is sent to the other side of the diff - the wheel with traction. In essence, it does the same thing as a limited slip - clutch pack in the diff = brake pads/rotor on the spinning wheel.

My opinion - the ELD is the way to go. My limited slip diff in my 2010 was so bad I had to put the truck in 4x4. With the ELD I turn it on and away I go - most of the time :D For the other times theres 4x4.

So when driving in the winter, this is the first winter with this truck, is it okay to leave the differential locked on snow covered roads and let it automatically disengage over 20 mph and then let it re-engage when the speed comes down under 20mph. Or should I just manually engage it while at a stop and then disengage it after I am up and moving?

Don't see how it'd hurt anything, mechanically, however, not sure it's really what you want. Lockers and ice aren't the best combination, unless you're just having fun. Best to leave it in four wheel drive and leave the traction control on.
Locking the rear is best reserved for off road situations, deep snow, boat ramps, etc.

Not sure if it will do any damage but I am pretty sure it was not designed for that. It will disengage above 25 mph and then will not re-engage until you drop to 19 mph.

I guess I dont understand what is to be impressed about or not. Seems like you are spending a lot of brain cells on something that you cannot change.

Either:

1) live with the 3.55 ELD

or

2) dont get snowplow or camper package, and get 3.31

If 1 or even 2 MPG is going to break the deal, then maybe the truck is not for you.

Just askin.

I can't tell you how many times I've been stuck with Limited Slip and 4x4. One front tire and one back tire spinning. Just because I backed in to hook up to a trailer and had ice or mud under one of the tires. And the opposite tire was on firm ground,

Take the example of pulling off the shoulder of the road and getting the passenger side tires into a snow bank that a plow has pushed up. One tire on pavement , one tire in snow. At least with the locker, the tire on pavement with catch.

As far as leaving it engaged all the time. I wouldn't, Every slow turn you will hear the tires chirp as you wear off excess rubber. Engage it when you need it. Your tires will last a LOT longer and I suspect your rear end will have less wear and tear

The elocker works more like a spool than a locker... it is a direct mechanical linkage between the two axle shafts, and thus the two wheels. Much different than how a traditional locker works. It is not designed to be used on pavement or hard surfaces at all because one of the tires will be forced to slip during turns and then something has to give... either the earth or the truck. In the dirt, the ground moves easily... on the pavement it's usually the tires that give (or worse case the rear end).

The LSD is a waste, in my opinion... I really wish that my 2006 had a selectable locker. I had one on my old Toyota and used it all the time; mainly at the boat ramp, or as someone else said, when I would pull into the ditch and have one tire in the mud and one on the street. It is extremely helpful for those situations. I wouldn't leave it engaged all the time though, especially on wet or ice roads as it will NEGATIVELY affect the ride/control of your truck.

I bought my truck from the dealer's stock and it has the 3:55 locker.
I don't need it now, but it's nice to know it's there if I do, such as a slippery boat ramp ect.

I really like my ELD as my 08 limited was useless,I engage it all the time whenever I see a muddy road. Works great,wished Ford would give us one for the front end on the FX4 trucks.