As pentapop did, I will probably get the 4.30 electronic locking axle because I think I want the 4.30 for towing. I just wish it was LSD when not electronically locked rather than an open differential... But when I may really need the 4WD, locking will be nice to have...

 

Put a Detroit locker in the front axle, and get the E-locker in the rear. You'll be able to do anything you want in loose gravel with the Detroit up front. That's why I love autolockers. They work in gravel, and you can still turn. When ever you aren't turning, lock the rear locker. I can't wait to put an auto locker in the front. I miss it.

Pine needles on wet pavement? Lolz. Get some good tires that'll laugh at such things.

 

Glad you caught the joke, just an expression we use living in the pacnorwest... we really only need the 4WD when the banana slugs invade.

 

detroit in front is horrible idea for most people. arb would be much wiser decision

 

If you want a limited slip differential, you should get the truck with an open rear differential and install a Detroit TruTrac. No fussy clutch packs to wear out or friction modifiers to screw up.

 

I used to think that as well. I agree with "most people". But are we "most people" anymore? Most people would be better off with selectable front and rear for sure. But auto front, selectable rear seems to outperform greatly.

I can't even begin to explain how much crow, I am, or we are, eating on the subject. We were doing it wrong for years.

The ARB won't help when maneuvering trailers in dry, but soft conditions. Open is too open, locked is too locked. The Detroit might be , just right. I tried the auto front, selectable rear, in someone elses truck. Assuming the correct tires and technique, it's a very hot setup right now that's trickling down from racing.


For the longest time, we thought the front diff was the one ruining our steering in tight sections. But we were wrong. It was the rear, all of this time. as long as a ratcheting auto locker was used up front. A selectable up front still kills steering, we just automatically assumed that a selectable fronts bad steering, applied to auto locker fronts as well. And we were wrong about that.

 

This is totally incorrect when it comes to a limited slip differential fitted to a truck. They are very lightly biased and any amount of substantial throttle input will quickly overpower the limited slip and cause just one wheel to spin. The limited slips fitted to most trucks and SUVs, but certainly these Super Dutys, is only effective at low speeds, and I mean quite low. Now, I high-performance car like a Mustang or Focus RS will have a limited slip tuned to improve cornering. Two different purposes. I drove a 2017 Ford dually for a year and I ordered it with the optional limited slip rear end. Although it worked better than previous Ford limited slips I had used, it still only functioned with light throttle input at low speed. More throttle overpowers it and causes just one wheel to spin.

Your first statement is correct. Dually trucks can only get a limited slip, and single rear wheel trucks can only have a locker. Your preferences are partially possible. The factory locker can only be used at speeds up to 25mph at which point is automatically disengages. However, although you "prefer" limited slip for high speed, the limited slip Ford offers in these trucks also only functions at low speeds (see above).

Locking the rear axle on pavement causes severe stress on the drivetrain and causes heavy binding. The limited slip would function as best it could during slow speed backing of a trailer. BUT...two notes I would like to make:
-If your rear wheels are slipping during a backing maneuver, engage 4x4! If the rear wheels can slip, there won't be much stress on the truck from being in 4x4. If you feel some binding, that is OK and won't harm the truck. Engaging 4x4 gives you far more traction capability than a limited slip ever could hope to provide.
-Electronic traction control (standard on all trucks) performs basically the exact same task as a limited slip and does it just as well. Many people malign traction control, but all a limited slip does is try to transfer some of the power (it cannot transfer all the power) from a spinning wheel to the opposite wheel on the same axle which *might* have more grip. Traction control does the exact same thing. My conclusion from lots of experience off road and driving in snow is that if electronic traction control cannot get you moving, a limited slip isn't going to either.

To conclude, I respectfully submit most people have no idea how the functions of traction control, limited slip, and lockers differ. There are absolutely times that a limited slip is more beneficial than a locker. Slippery on-road conditions when you need to just get moving and particularly when making a turn...a limited slip is much better than Ford's locker. For continuous slower-speed forward movement, such as in snow or driving off-road...the locker is much better. Traction control is valuable in most conditions, but throttle limiting can be frustrating. Typically this can be shut off if it prevents progress.

The locker does not engage and disengage quickly, which is the nature of any mechanical electric or air locker. That can be frustrating as well when the truck doesn't steer well and binds. Locker use needs to be planned in advance.

Another thing to consider is that without significant weight in the bed, there is very little available traction to the rear wheels when backing up, and many times neither a limited slip or locker will be effective here.

 

Although the catch 22 is: Sharp gravel, especially sharp gravel stuck inside ice, heavy trailer, tight turns........

That gravel can cut a tire up in record setting time, with a limited slip or the traction control. Rare situation, but I've wrecked tires backing trailers on a remote construction site. When the wheel slipped, and I knew I needed to try a different line, it was already too late.

If you can sneak in 4wd or the rear E-locker without binding up too much, go for it. You can often feel the drivetrain start to bind if you hold the steering wheel gently. The wheel might even try to snap back. I let it. I use a very gentle grip on the steering when in 4wd and tight turns. It could save a universal.

I've had excellent success eliminating one wheel peel on sharp right turns on slippery roads with just quality tires, correct pressure settings, and gentle throttle application. I don't see any practical need for a rear LS anymore. Could an LS pull out faster? Absolutely. Do I need to go faster than an open diff and quality tires? Nope. Now the stock tires at 80 psi do stink, but it's unfair to judge a truck based on it's grandpa pleasing OEM tires.

The traction control works better than the previous generation LS's anyways. I'd love to spend more time testing the traction control, with a Detroit Truetrac. I'd bet that the TC will lock a Truetrac up nicely. Nice enough to be pleasing off road, heck no, but I'll bet it'll be great for more practical situations.

 

Right out of the 2018 Owners Manual.


ELECTRONIC LOCKING DIFFERENTIAL (If Equipped)

Note: The electronic locking differential is for off-road use only and is not for use on dry pavement. Using the electronic locking differential on dry pavement will result in increased tire wear, noise and vibration.

The electronic locking differential is a device housed in the rear axle that allows both rear wheels to turn at the same speed. The electronic locking differential can provide additional traction should your vehicle become stuck. You can activate the differential electronically and shift it on the fly within the differential operating speed range. The differential is for use in mud, rocks, sand, or any off-road condition where you need maximum traction. It is not for use on dry pavement.

The following conditions will affect the electronic locking differential:

• The electronic locking differential will not engage if your vehicle speed is above 20 mph (32 km/h) in 4x2 or 4x4 High modes.
  
• The electronic locking differential will not engage if your vehicle speed is above or 56 mph (90 km/h) in 4X4 Low.
  

• The electronic locking differential may not engage if you press your accelerator pedal during an engagement attempt. A message may display in the instrument display guiding you to release the accelerator pedal.
  
• In 4x2 or 4x4 High modes, the electronic locking differential will automatically disengage at speeds above 25 mph (41 km/h) and will automatically reengage at speeds below 20 mph (32 km/h).
  
• In 4L (4X4 low), the electronic locking differential will automatically disengage at speeds above 62 mph (100 km/h) and will automatically reengage at speeds below 56 mph (90 km/h).
  
• The AdvanceTrac system has the ability to take over control of the electronic locking differential and disable it during driving maneuvers when necessary.
  
  When you switch the system on, if you do not meet the required conditions for electronic locking differential activation, the instrument cluster will display the appropriate information guiding you through the proper activation process.
  

 

Traction control absolutely sucks when you get into a slick situation like mud or snow because it is applying the brakes which slows your wheel speed and momentum. I would rather have a good limited slip than traction control any day. I drive a 2012 E-series work van with traction control and an open differential and anytime I get into the mud or snow I have to turn it off or it won't go anywhere. I was trying to go up a snowy hill the other day and the traction control kicked in an stopped me, I had to turn it off and give it another run to get up the hill.

 

Yes.
You can't rock your way out of a problem without disengaging.
I learned the hard way my first winter!

 

The 12's aren't as good as the '17+.

Although the TCS is fairly weak in 2wd, lots of throttle control. It's never hampered my truck in 4wd in normal practical situations. In fact, it's ability to brake the spinning front tire, is priceless.

 

Holy cow, what's the engine rpm's with say the 4.30 gears @ 62 mph in 4L? It's gotta be about 12,000! But at least your rear diff will unlock....

 

Traction control only comes on because your wheels are already spinning. In some instances if you only need to make it a relatively short distance forward, spinning hard to maintain some momentum might get you through, but if you're headed uphill or have a long way to go...good luck with spinning. The wheel is spinning because there is not enough traction...

Press and hold the traction control button for ten seconds. It will shut off all intervention except stability and rollover. Throttle will not be limited.

 

For the previous generation trucks with the locker, Ford simply said the locker would remain engaged at all speeds. I really don't think its possible to go 62mph in low range.