Very basic locking differential question

[dirtwinston4prez]

Many thanks to all the persons who wrote about the pros and cons of open, limited slip, and locking differentials on 4WD and 2WD vehicles. The discussions were an awesome help as I plan to replace my old 2WD F150 having open differential with a newer model 2WD possibly equipped with the 3.55 electronic locking differential paired with 2.7L engine.

But my question and concern is a lot more basic than what persons normally dive into.

With the 3.55 electronic locking differential, is it correct that it will never engage unless I decide to manually press a button or some other trigger ?

I'll only be getting the locking feature for the infrequent occasions that we go onto dirt roads which can be muddy if the weather hasn't been kind. With my current truck, I weave around were possible and hope that I avoid deep muddy spots. Someday my luck might run out.

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[JExpedition07]

Correct, you press the button and it locks

 

[Kanuck]

I just looked in my manual and it says a looking diff is only on 4 x 4's Not available on a 2 wd truck. That is for my 2021 XLT. Can you get a locking diff on that truck? You might only get a limited slip diff.

 

[parkerdog]

Many thanks to all the persons who wrote about the pros and cons of open, limited slip, and locking differentials on 4WD and 2WD vehicles. The discussions were an awesome help as I plan to replace my old 2WD F150 having open differential with a newer model 2WD possibly equipped with the 3.55 electronic locking differential paired with 2.7L engine.

But my question and concern is a lot more basic than what persons normally dive into.

With the 3.55 electronic locking differential, is it correct that it will never engage unless I decide to manually press a button or some other trigger ?

I'll only be getting the locking feature for the infrequent occasions that we go onto dirt roads which can be muddy if the weather hasn't been kind. With my current truck, I weave around were possible and hope that I avoid deep muddy spots. Someday my luck might run out.

On my "22" 3.73 locking differential you push a button to engage the locking part. 3.55/3.31 would be the same.

Above a certain speed 20 or 30 miles an hour even with it turned on it automatically unlocks. I find it handiest when in town driving to take off from stoplights in slick conditions. When you get above the 20-30 it unlocks to cut down on fishtailing and then when you slow to a stop at the next light or sign it will re-engage.

This is with 4x4 also.

 

[fordtruckman2003]

Trucks with electronic locker will also lock in certain drive modes. I do believe as above that locking differential is only an option on 4x4 trucks. 2WD would not have the drive modes that will force locking.

 

[pittman]

Hey check out getting a Torsen differential installed in the rear on your truck. They're different than an e-locker but have lots of advantages too. Likely a simpler installation and you won't have to run any electronics.

 

[SomebodyInGNV]

I just looked in my manual and it says a looking diff is only on 4 x 4's Not available on a 2 wd truck. That is for my 2021 XLT. Can you get a locking diff on that truck? You might only get a limited slip diff.

I had an E-Locker on my '16 RWD Lariat with MaxTow. I just tried building a '24 on Ford's Build-and-Price site. 5.5' SuperCrew Lariats are available only as 4WD; XLTs are available as RWD. On those, electronic locking axles are available in 3.31, 3.55 and 3.73 ratios.

On my '16, the E-locker worked only by selecting the switch. It disengaged automatically at 20 MPG. There was no drive mode selector then, of course. Whether the E-locker engages automatically with certain drive modes on the '24, I have no idea.

 

[JExpedition07]

My STX throws the rear locker on in Mud/Ruts and Deep Snow/Sand drive modes

 

[WhiteLightningnshitshadow]

Are you sure you have an open diff and not an LSD?

 

[Probity]

You can get an electric locking rear diff. on '24 and earlier 2wd F-150's. As others have noted you have to manually engage it, and it disengages at speed above 20-25 mph. My $0.02 as someone who's last 2 F-150's and an F-250 were 2wd with an e-locker:
*for your intended application - "infrequent occasions that we go onto dirt roads which can be muddy if the weather hasn't been kind" - tires are as important (maybe more so) than the e-locker to prevent bad outcomes. All-season tires and mud don't always play well.
*and the type of mud, especially if it's sticky clay/gumbo type will render even a locking rear diff. almost useless once the tires get fully coated with mud. Kind of like a skid-pan drivers training course I went on a number of years ago where we drove RWD cars with bald tires on oily tarmac, lots of tire spinning and no real traction.
*weight in the bed helps (300# or more?).
*an e-locker is a plus if you launch/recover a boat on a good condition (not super slimey or steep) boat ramp. Lots of small boaters in my area use 2wd trucks with e-lockers.
*it can give a small bump on resale value, but that's down the road a number of years

 

[dirtwinston4prez]

Thanks Probity for sharing your observations of 2WD. Very interesting and a fun read.

Looks like the e-locker money is better spent on good mudder tires - and a few bags of gravel/sand in the bed when dirt roads lie ahead.

Plus, I don't like making a truck more complicated than they already are.

 

[Samson16]

But do you want to drive around on mudders every day for the occasional off road need? How much is the e-lock upgrade? Certainly won’t hurt resale that’s for sure.

 

[dirtwinston4prez]

Much thanks again.

I wasn't expecting such practical advice, and perhaps I should have asked my question in a different way.

We won't be pulling boats on slippery slips, towing in general, nor doing major off roading. But we very much want access to the back roads/trails in our national and state parks. Many of the more remote roads and trails are limited to 4wd or other "acceptably equipped" vehicles.

We can manage and pull off the extra bucks for 4wd paired with the 2.7L Ecoboost. And that will do the trick for the parks. But we also live in California and get slammed like all get out on gas prices. So the loss of 2-3 mpg piles up the cost when we are not doing the park stuff. Especially if things go back to $ 7-8/gallon after this November.

So I was thinking 2wd with the e-locker and good rear tires would hopefully get us onto those backroads during such trips.

 

[amschind]

I would also vote for a Torsen. It's a purely mechanical system, and all of the parts are beefy. You won't break one unless you aggressively abuse it. I had front and rear torsens in my old explorer and it had milder road manners than the worn out Ford limited slip. I currently have an Elocker in the back and the Raptor Torsen in the front, and both act like open differentials most of the time.

The difference is that a torsen never locks, it just redirects torque to the wheel that is moving slower with worm gears. If a wheel attached to a torsen is spinning, it will not vector torque as it requires SOME resistance on the wheel with traction (the slower spinning wheel) to work. That is actually easily overcome as you just apply a bit of brake to simulate traction.

 

[Calson]

Manufacturers stopped providing limited slip differentials and now sell "anti-spin" control whereby the brake is applied to the faster spinning wheel. I wanted a limited slip and the only option was to go with an electronic locking rear differential and only Ford and Ram provide this for their standard trucks.

I noticed that if I am in 2WD and select "slippery" as the drive mode the truck shifts into 4WD mode and there seems to be nothing I can do about this. I am used to GM trucks that had true LSD and it could be used in 2WD mode at any speed.

With my trucks the only option is to be in 4WD for traction and the locking differential is useful only off the pavement with the Ford design.

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