Ahhhh, so you are saying that it is binding up front to rear, not left to right?

 

Yes front to rear

 

No, it binds up side to side, too. Unlike the rear, the fronts have two shafts connected by u-joints that want to stay nice and straight under tension from torque with the hubs locked. Same thing you experience in 4WD on high traction surfaces (notice it doesn't seem as bad on loose dirt for example) is what you experience with 4WD in a vehicle with a locked differential even on low traction surfaces.

 

Not to start an argument here, but the information above stated isn't completely correct. Yes the wheels will naturally want to go straight when under load the front hubs being locked have NO impact on binding what-so-ever. The only thing that would play any part in binding is if the front differential has a full locker installed. The correct term to be used here is "drivetrain binding."

With that said the front wheels will spin at different speeds and no binding will occur there due to the front axle alone. It's no different than a stock rear axle really and each wheel will spin independently of the other. Drivetrain binding occurs, in 4wd, because the front tires are traveling further than the rear (different speeds) and this causes the front driveline to spin faster than the rear driveline. This front/rear speed variation causes making turns difficult because the transfer cases (part time 4wd tcase) in our trucks is designed to do one thing provide "EQUAL" power to both front and rear axle, on a part time basis, for maximum traction which means it spins both drive shafts at the same speed.

When on slippery or loose surfaces (the intended use for 4wd) the road conditions will allow the faster axle to slip the wheels and the drivetrain binding isn't felt. When on the hardball in 4wd the road conditions don't allow for the faster axle to slip and the drivetrain binding is felt. It is felt because the transfer case can't accommodate for the difference in driveline speeds. If the Transfer case was a fulltime 4wd case or an AWD type it would have an internal "differential" to compensate the different driveline speeds and drivetrain binding wouldn't be an issue.

Think back to the trucks in the 70s/80s (Ford/Dodge) that came stock as full-time 4wd. Those had full time 4wd tcases and there was no drivetrain binding felt.

 

Yeah, I believe you are correct.

PS Full-time AWD is different than part-time 4x4 engaged. I don't know enough about the trucks you reference or their intended use, but a simple example is the Jeep Cherokee that came with either the same NP231 as the Wrangler (part-time) or NP242 with a full-time option. Usually full-time AWD is managed by clutch packs and such and are designed to allow some degree of slippage.

 

Chevy also uses clutch packs, which is why their 4x4 system sucks and needs to be replaced every 20k miles.

 

I have the 3.31 gearing with locking dif. i camp almost every weekend and have used the locking feature when pulling the camper out of my yard and again when pulling into camp. if it is soft i will throw it into 4wd and use the lock as well. i have not spun a tire yet. My older 4x4 would shave a tendency to spin the tires slightly if the ground was soft and would throw mud up onto my camper. i like the feature...and it work well getting into my driveway during the ice storm....

 

Digging up an old thread, but I had to because so many people don't have nearly the appreciation for this feature that they should. There are many reasons to love this system, but here are my top two:

1. GM only offers an "auto locking" rear diff which requires wheelspin in order to work, disengages when it feels like it, is not nearly as durable, and does not allow the driver to command the axle locked or unlocked. RAM trucks are even worse, offering a useless "limited slip" differential which might not even be installed (excepting Power Wagon, but that is specialty and most are not used for plowing or towing).

2. The option cost of $390 is the bargain of the century. Anyone who has done off-road driving in Jeeps, Land Rovers, etc knows the cost of installing a selectable locker such as an ARB. On my old Range Rover, it was about $1300 not including install. I find the air systems not as good, because air lines can freeze or be damaged more easily than the electric systems.

People can use Ford's locker as they please, but in my years of off-road driving, the order of operations should be engage 4x4 first, rear locker second. An unloaded pickup has really, very little traction over the rear wheels. You're far more likely to spin the rears uselessly and possibly throw rocks and gravel all over your rear bed panels.

Here is a thought about traction control vs a locker: I don't have experience with previous-gen Super Duties in this area, but the 2011-2016 single-rear wheel models feature 4-wheel electronic, throttle and brake-based traction control. Traction control works at all times. Because these trucks all have "AdvanceTrac" stability control, the ABS system is 4-channels. The throttle portion of traction control is primarily annoying and can mostly be turned off. The brake portion is actually very useful: the ABS ECU (for traction control purposes) is constantly comparing the speed of each wheel on one axle to the speed of the opposite wheel on the same axle. Only a slight variance of wheel speed is allowed (to allow for cornering speed differences, etc) before the brake will pulse on the wheel spinning faster. Obviously, on a 2WD truck or a 4x4 truck operating in 2WD mode, the front wheels will never experience any traction control events. However, in 4x4 mode, the traction control will also brake a spinning wheel on the front axle, transferring some power and possibly getting you moving. This system works quite well, really. However, the rear locker works better. Of course, when engaged, it prevents any difference in wheel speed across the rear axle and by default there will be no traction control events. However, it can still work on the front axle.

 

From my experience with AdvanceTrac disabled and the ELD engaged the truck overrides the AdvanceTrac system and the traction control dash light will blink and cut engine power if you get sideways with the ELD engaged. This was on a snowy surface.

 

AdvanceTrac can still cut engine power, but it won't be able to brake selective wheels to correct a spin, since both rear wheels would be locked together.

 

There were several trucks I passed up when making my purchase due to the gear ratio and ELD. I bought my truck in 2012 and I couldn't wrap my brain around the higher gear ratios. The service manager cleared things up as I was not wanting any gear higher than 3:73. He really didn't understand the ELD as he told me it would "automatically" engage. I was smart enough to know a Electronic Locker needed a switch to engage and also realized how this option separates Ford from their competition. Just as aluminum body trucks will be normal in a few years, so will the Electronic Locking Differential.

 

No way will ELD become standard equipment. GM will not change away from their auto-locking diff, and who knows what RAM will do. It's a great feature, but most will have no use for it.

 

Going in out of the sand washes at Glamis the sand can get deep and many get stuck constantly. I have been stuck there.

Its slow going, under 25mph there for sure.
When towing my 13,000+gvw TH, the rear truck tires/axle will sometimes get into a rapid hopping type syndrome in 4wd. I've watched a new Chevy in the washes that hopping broke his u-joints.
Letting up will stop the hop, but might/will get you stuck.

In the sand when almost getting stuck and starting the hopping, pulling out the ELD switch stops 90-100% of the hop. I just try to automatically pull out the ELD switch as soon as I engage 4wheel when going slow in the sand washes... And don't hardly ever get even a little hop,,, unless I forget to use ELD.

I like the ELD.

jmo

 

I notice the hopping while driving in deeper snow. For me, engaging the ELD does not eliminate the hopping. The hopping is entirely the fault of the rear axle being located by leaf springs. A RAM with rear coils or air would not do this. Nevertheless, I prefer the leafs for their simplicity.

 

Many times I fly out to Phx and rent a truck to pull my TH to the dunes. This last thanksgiving I got a Ram 2500 with 2500 miles on it. It either didn't have ELD, or I couldn't find it. It hopped like a mad rabbit in the sand. Didn't get stuck though. Not sure if it has leafs or coils, never looked under it. it did tow good though, nice truck.

I assure you with first hand knowledge, a new RAM 2500 diesel cc, has axle hop in the sand, bad. Just like all the new diesel 3/4-1 ton PU trucks.

Fords ELD is the only thing that I've found to stop the majority of axle hop. Not sure why, just know it works to greatly reduce hop in the sand.

jmo