I have a 6.2 gasser with 3:73 gears......Since most 4x4 trucks I have owned have NOT had LSD, I was more asking if there is some engineering reason not to have a LSD? Right now, I would trade the locker for a LSD as that is what would affect 99% of my driving.

 

No, it is not an engineering reason to not include a LSD in all these trucks, but more likely it's an accounting and/or marketing reason. They're costly, so Ford won't give them away for free, and not every buyer wants to pay for one. It's an option for which one must pay to play. FWIW, I went with the e-locker on mine.

 

Fords LSD was there just in name only. Just to be on the sticker, because EVERYONE asked for it. It was shimmed lightly, and had "friction modifier" in the oil that neutered it down to the gutless open differential most of us experienced. Why, drive my Mustang Mach 1, it bangs and clanks around turns. Push the clutch in while turning over a slight drive curb and it rattles like a broken chevy. Ford get's hammered by dumb customers complaining about broken drives, when it's just the LSD being a noisey LSD. So they neutered the LSD to the point we started getting stuck everywhere with 2 wheel peel in 4wd, but yay, it's nice and quiet now.

So we shimmed it tighter and got rid of the modifier. Then it worked much better. But made the truck loose, banged, and the friction plates wore quickly.

Electronic LSD and open diffs seem to work better than any factory Ford LSD I've had in a Ford truck. And the ABS braking the spinning tire, is easier to get right every time. Best of both worlds with the e-locker and TCS setup. The loud clappy LSD in my Mach works great though. I wish Ford would add a front E-locker as well, even if it was only available in 4L.

 

In fairness, the factory LSD in my 2017 dually worked quietly and exactly the way it should. Responds quickly to spin and gets both sides spinning. No clanking or noises. Sure, if you get on the throttle hard it fades out...but by that point you're stuck anyway.

 

To my knowledge, LSD is not even an option for SRW SD trucks. I would have certainly ordered one if i could have.
The Torsen diff in my '15 Mustang GT works very well and makes no strange noises. ABS based traction control is a hazard, in my opinion as the majority of the systems cut power exactly when you need it...merging into traffic, etc.

 

This x10. one tire fire AND the truck cutting power. WHY THO? My nissan was 100000000x worse, if it was raining i had to turn off the traction control or else you couldn't merge with any acceleration.

 

Brake and throttle based traction control systems often get maligned on this forum, but I think it is unfair. The concept of using the existing ABS system to determine which wheel is spinning faster than another, and pulse the brake on that spinning wheel to force torque across the axle to the side with more...is frankly brilliant.

The throttle control part is less wonderful. There are really two reasons why the throttle is managed. One is the theoretical fact that continually spinning a wheel when you're stuck is not going to make you any less stuck...but rather is likely to get you more stuck. Careful throttle application can also sometimes provide more progress than uncontrolled spinning. The other reason is more devious...rapidly applying the brake to a spinning wheel shock loads the axle tremendously, which could cause it to wear prematurely or even break. Thus, by limiting how much you can make the wheel spin...you can help prevent breakage.

That said, it is unquestionable that traction control is effective, and vastly superior to open differentials. There are times when we as drivers prefer full throttle control because we know we need momentum to make a hill or get through a mud hole...but the vehicle doesn't agree. In this case, throttle intervention can usually be turned off by pressing the traction control button.

 

I suspect Tires for the guys having trouble merging with traffic. The Cooper STT's I had on my 2008 F250 made open diffs look good, until the truck sunk in and dragged a pumkin in snow or mud.

 

I have driven trucks from all the big 3 + Toyota (both Tundra & Tacoma) and the F250 exhibits wheel spin more often than any other I've had.

I have the OEM, 18" Goodyear "Kevlar" tires so maybe a tire swap would help traction. To turn onto my street, the main road is fairly flat but my street begins with a hill. I almost have to be coasting when I make the turn because if I apply any throttle the inside wheel spins. I understand the physics of the wheel being uloaded during the turn but no other truck I've had did this.

To be honest, the lack of a LSD was almost a deal-breaker for me. Without having the option to buy the locker, I would likely have passed on a F250. I like the truck very much but Ford not even offering a LSD option is a head-scratcher to me. To be perfectly fair, Toyota does not offer a LSD option for the Tundra either. Annoyed me so much that I installed an Auburn LSD in my last Tundra......was a night v day difference driving in the rain. May end-up doing the same with the F250.

 

GM does not offer a limited slip, either. They offer the G80 auto-locker. Being fully automatically, it can quickly lock and unlock much faster than the Ford selectable e-locker. It is also all mechanical, nothing electronic to break. The downside is that it is not as strong, and some wheel spin has to occur before locking happens. The locker also unlocks when the load is removed...say, when you're in the middle of the mud pit or trying to make it up a rock step ledge.

RAM offers an "anti-spin" differential which is an LSD. Personally, I think it does not work well (or the truck I had already had worn out the clutch packs).

The current Ford Super Duty trucks have the lightest pickup beds, so maybe they have the most unloaded rear ends and spin easiest, I dunno. Maybe its the 925lb-ft.

 

The torque limiter takes care of a lot of that. I know they are torque limited in the first three gears, but does anyone know how much?

 

The dually only limits torque in first gear; SRW trucks are the first three gears. I'm driving a SRW diesel now, and even with the limitation it spins the rear pretty effortlessly.

Ford has not said how much, but based upon the transmission input shaft rating of 1400lb-ft you can rest assured it likely cannot supply more than 700lb-ft in first gear.

 

The FX4 package was on my truck when I bought it last March. I find the skid plates come in handy when hitting road gators or nutrias while traveling at 70 mph in Louisiana! Shocks are not that bad but I don't expect to get over 50K on them. The FX4 decal is cute compared to the base 4x4 one. Just got back from a trip to Maryland and realize the 55 degrees we're having is a lot better then the 15 we had the other day in Virginia...ya'll can have the cold weather!!

 

FX4 also forces you to get 70 series A/T tires (unless you upgrade further to 20 inch), compared to the 65 series A/S tires, which are about an inch taller than the 65 series. I bring this up because it does have an effect on overall gearing (about 20 tire revs per mile difference). If I were ordering FX4, I would also opt for the 355 gears.

I have had two trucks with the FX4 package (an 03 and a 16) and learned that in itself, it offers nothing for me. As stated, the shocks are no better than stock, and the skid plates just make the truck heavier and a little harder to work on (removing fuel tank), and since I use my truck as a tow vehicle only (no off-road) its a worthless option that you have to pay for, unless you really love the FX4 decals (my 16 was a platinum that didn't have the decals).