Now that you mention it maybe they don't turn. I think I'm incorrect, sorry. I don't understand how you can switch to 4x4 at 70mph if they are stopped though, lol! My curiosity is peaked. Hopefully someone smarter than me can explain it to us

 

You really shouldn't be going 70 and going into 4x4? Is that mph or km per hour? And if you are driving 70 in 4x4 the roads must be pretty good. I believe on this system you can engage from 2h into 4h at about 50-55 mph? And you should be at a crawl or in stopped to engage to 4L.

I had warn hubs before and they were great. They were just locking and free wheeling though and did not have the auto feature at the time. Not sure if Warn hubs now have that feature but they are THE name for hubs.

And try to go straight if engaging into 4x4, especially on hard pack. If in a slippery situation it doesn't matter so much. I also am undecided on the e-locker vs a limited slip on the rear. I think the e-locker may be better for getting going and going slow but the limited slip on my other 4x4's worked well too! Ford's e-locker won't work over 20 mph anyway.

On the ATV's it is solid drive on the rear and the front usually have either an electrical or manual type of locker on it for true 4x4. Some don't have it though and just have the open-ended differential, meaning the standard where the tire with the least traction spins and the other tire that could have traction just sits there with no power. You can not usually get limited slip or lockers on the front as they can dangerous at speed or in certain situations, like going up a very steep, slippery grade. The old Bronco tried it but it was too dangerous and had some problems. For most people the locking rear and open end front are good enough. Serious off roaders get the switch for lockers front and rear.

 

The f150 owners manual states you can enter 4x4 at any speed, I haven't read the f350 manual. I assume they are the same but I do not know for sure. I live in north dakota and sometimes in a snowstorm on a 4 Lane road one Lane will be clear and one Lane with have 4 inches of powder so I pop it in just in case to pass the douche nozzles from texas and Florida and every other state who doesn't know how to drive in the winter who are going 40 in the plowed dry clear Lane when the speed limit is 65. I'll also use it if icy. Not to sound cocky but to ward off the inevitable lectures from non drivers I'll just say that I don't care what you think. Im a very experienced driver who drives in extreme conditions as often as possible for fun and I drive better sideways than most people can forwards. I love no travel advised conditions, that's when I go play. But please understand I'm not doing it in high traffic populated areas, I live in a very rural area and I would never put anyone's lives at risk with my extreme driving shenanigans.

 

I put it in 4x4 on the highway a lot, make sure im off the throttle, keep my speed down. I get a little thump now and then if my hubs aren't locked.

 

I switched in and out of 4x4 a few times with hubs manually locked to try it out and it didn't shift any faster but it never clunked once.

 

With the hubs in AUTO and 4x2H selected, you can turn the front drive shaft by hand. If the front axles are not coupled to the wheels, and the front drive shaft is not engaged in the transfer case, what is turning the front drive assembly as you mention above? Further, what brings the front drive assembly up to speed to synchronize and engage the front hubs and the drive shaft in the transfer case when you select 4x4H at 70 mph?

 

Read my next post after that. And I have the exact same question.

 

I'll assure you if you lock the hubs manually vs using auto hubs it will definitely be faster. You may not notice it at speed but going very slow it will happen every time. This is because when the hubs are locked all your actually doing is turning on the front driveshaft when you engage 4x4. Everything else is already done. The disadvantage is that your fuel mileage may suffer a little on the highway.

If you still don't believe me try a little test. You need to get your vehicle in a slightly stuck situation like turning into a sharp back when on a slippery surface or putting the front end in a small ditch were you can't go forward. So pull up to a sharp bank or into a ditch and verify you can't move forward. Now with hubs in auto try 4x4. There is 90% or higher chance you will not actually go into 4x4. This is because the front wheels need to turn at least some to engage the hubs. If everything lines up perfectly they might engage but this would be very unlikely. Now try the same thing with the hubs manually locked. 4x4 will engage instantly and will do it every time. This is one of the advantages of any vehicle with lockable hubs. Just wanted everyone to know as its a great asset to our trucks. In most cases the auto option is great as it offers ease of use, better fuel economy etc. But if you ever get stuck before engaging 4x4 and can't move, or have a vacuum leak etc then this little feature is worth its weight in gold. Anyway, hope this clears things up a bit. As for bringing the front drive shaft up to speed I have no idea but would love to find this out as well.

 

Even though the hubs allow the the wheels to spin free of the drivetrain, it does not mean that the axles and driveshaft do not turn at all. There is still some friction that turns the drivetrain a minimal amount. As far as bringing things up to speed at 70 mph, I think you are a good candidate to re-read your owners manual or maybe even read it for the first time. High speed engagement is not recommended. The auto hub system is a luxury compromise and is not well suited for engagement at high speed. Basically waiting until you absolutely need it to engage 4wd is a bad idea. It should be engaged long before you actually get stuck or you risk damage to the system. These are heavy duty pickups, not luxury crossover SUVs with AWD systems.

 

Why do f350s not lock on auto if front wheels are stopped? F150 still do. The rest of the drive train turns until it matches whatever position the front is in and then clunk, locked and you're moving! Anyone know why f350s are not that way?

 

Just read the 4x4 section of the manual which can be found here. No mention of any speed limit restrictions on shifting but does mention the clunk is a result of the driveline coming up to speed so there must be a clutch of some sort in there.

https://owner.ford.com/servlet/mobil...0&results=true

 

Unless Ford and other automakers are doing something different on the new 1/2ton trucks I would think they are the same but don't know for sure. I can tell you that I've had 2 F150's a 2000 model and 05 model and both had standard auto hubs thus had the delay. Now considering they had somewhat smaller diameter tires and a much lighter front end than a diesel super duty they did engage somewhat easier. However, I still received the occasional clunk from the front end in less slippery conditions. Both trucks though would not engage immediately "every time" and surely wouldn't engage easily at a stand still. That being said if I first put the drivetrain in neutral it definitely engage quicker. Anyway, maybe the newer trucks have an improved system but not sure.

Here's funny story I had with a friend. He had a new 1999 Chevy Z71 with less than 10,000 miles. One day we were crossing a field in 2wd. The field was dry and hard so no need for 4x4 or at least we thought. So he was driving across and all the sudden the front end went down into a low spot. Naturally when it went down he let off the gas and the truck stopped. Then he tried to continue and the rear wheels started spinning. Reverse offered the same outcome. For at least 5 minuets he tries to get the 4x4 to engage but to no avail. Its about this time I look over at him and say "man chevy's don't do well off road do they". If you could have seen the look on his face…. Priceless! He was so dang mad I thought he would explode. At the time I wasn't aware that this was a common issue but I soon learned it with my 2000 Ford a year or two later. It sure was fun picking on him that day though with his new Chevy. LOL

By the way after 5-10 minutes of rocking the truck back and forth he finally got it to engage. Once it did he pulled right out.

 

I've been in that situation multiple times in my f150. Front wheels won't move but when the back ones turn far enough so it matches up then it clunks and locks in. I don't understand why people say this isn't true on super duty. Maybe I just got lucky every time with my f150, lol!

 

The modern F150 does not have locking hubs per se. Integrated Wheel End (IWE) is what they call it. It works pretty much like a locking hub, but it is not an external hub and it is spring loaded to the engaged position. The vacuum holds it to the disengaged position so that is why many people say that they can't turn their front shafts in 2wd because the truck isn't running when they try it.

I don't have any experience with this system, but I'm guessing that the force of the spring is much greater than that of the vacuum used to activate the superduty hubs. If you spin the rear wheels on a Superduty ever so gently when trying to engage 4wd while stuck, the hubs usually lock, but it is a less than ideal situation. That is why it is nice to have the option to lock them manually in dire situations. Additionally, it is possible over time for the vacuum system to develop leaks that can affect how well the hubs engage.

 

I got ya. I've never been in that situation with the super duty yet but I don't see why they wouldn't lock the same way in auto as the 150s do. Turning manually is def a better option in that situation and a good backup to have if the vacuum function is reverse that of the f150s.