the salesman says you can turn the **** on the dash to 4wd and not lock the hubs and the truck is in 4wd or lock the hubs to get true 4wd like the older trucks is this right.
are the front diff internals turning all the time ?

 

Yes if you have esof, turn the **** to get 4wd and you don't have to get out and lock the hubs, a vacuum inside the hub bearings pulls the hubs into lock.

 

I think I read on a thread where someone took delivery on a truck with the manual locker in the "lock" position. You may want to make sure they are unlocked.

In another thread someone indicated they suggest driving with the manual locker in the "lock" position occasionally to distribute grease and keep inner pasts lubricated.

The manual locks can be used as a back-up if the ESOF does not work. As brickman indicated it is a vacuum system. But, I think the vacuum opens the system when you start your engine. When you hit the ESOF to 4WD, it kills the vacuum and allows the actuators in the hub to engage. If this is not correct please hammer me. This is exactly how the F150 system works as well (except they have no manual lock for backup).

 

When you're in 4WD there's no difference between "automatic" and "lock" on the hubs. "Lock" is there in case "automatic" fails to engage.

 

Also it takes a certain amount of revolution to get the auto hubs to react, so if you've backed up into a snowbank and can't get any movement that's when you get the privelage of getting out in the blinding snowstorm and lock them.

 

that makes more sense then what the salesman said thanks for the info
i just assume to use it like the older system and lock them when needed

 

I think you've misunderstood. You leave them in auto and do NOT have to engage the lock for 4x4. The only reason they have lock is in case you get in a bind or there is mechanical or electronic failure with the autolocking hubs. Your salesman was correct. Welcome to the modern world!

 

When you turn the **** on the dash, and the hubs are in "auto"; they will automatically lock. When you are in 2WD, they unlock and the internals stop turning. With the hubs in "lock" the internals are spinning all the time, whether in 4WD or 2WD. Either way, you have a true 4 wheel drive. I hope I made this as clear as mud for you.

 

So this is my 1st 4wd. About a month ago I engaged 4wd not sure what to expect. I noticed the following:

1. The trucks gearing seemed shorter as the truck felt like it had tons more torque especially in 4L
2. The trucks steering felt like it was binding as I turned driving about 5mp. I was driving on gravel.
3. It took more brake pedal pressure to stop the truck..related to #1

All of these things surprised me and I'm still not sure if that is normal 4wd operation

 

1. Torque and gear ratios are the same in 4H as 2H.
2. This is normal. There is no differential built into the transfer case, so the tires have to slip a little, especially when the truck is turning.
3. In 4H the transfer case has ratio of 1:1. In 4L it's around 2.5:1. (I'd have to look it up to find the exact number :-)) You have a lot more torque due to the lower gearing, so it definitely takes more pedal pressure to come to a stop.

 

1. 4Lo is geared very low and you can get a lot more oomph to the wheels.
2. In 4Lo the universal joints attaching the front wheels to the axle shafts are "engaged" meaning that there is power being applied to them. They don't like turning when under power and there is too much angle (steering angle) applied to them. When in 4Lo - and sometimes 4Hi as well - you should avoid sharp turns.
3. Yep. 4Lo will really move a lot of weight. There was a thread recently here in the 2017 forum where a 2017 Superduty pulled a loaded semi truck using 4Lo. It's not something you should do but it's incredible to see that these trucks can do it.

4Hi and 4Lo should not be engaged on dry pavement. It can cause the drivetrain to bind which puts stress on it. It's not the end of the world if you do it for a little ways but it's not something you want to do for miles.

 

1. Both front hubs must be locked in order for power to reach the front wheels. If the hubs are left in the "Auto" position they will lock automatically when you move the dashboard dial to 4H or 4L. They will unlock automatically when you move the dash dial back to 2H. Otherwise, you can still manually lock the front hubs by moving them to the "lock" position. You will still be in 2WD until you move the dashboard dial to 4H or 4L.

2. Having the hubs lock automatically or doing so manually does not change the way the 4x4 operates. The front differential is an open type, meaning power will go to whichever wheel has less traction.

3. For the purposes of keeping the axle u-joints moving freely, along with keeping the top half of the differential ring gear and axle half shafts coated with oil, it is a good thing to engage 4x4 Hi while driving in a straight line on dry pavement. The engagement can be short...just moving forward a few hundred feet would do the trick. Make sure to disengage 4x4 before making and turns. If you do not wish to drive with 4x4 engaged, you can also manually lock the front hubs but leave the dashboard dial in 2H. This will cause all the front 4x4 driveline components to spin and lubricate, but will not engage 4x4.

4. There is no difference in torque or gear reduction between 2H and 4H. 4L uses a 2.64:1 low range gear reduction. The truck will feel like it is pulling at the leash when operating in 4L and you will need more braking effort...but it will also shift through the gears very quickly despite your overall speed being much slower. Aside from the additional gearing reduction, there is no increased traction to be had from using 4L. It is just for pulling heavy loads or for crawling up steep slopes off road.