Hello everyone, Im new to the super duty trucks and have never had anything higher than a F150. Question, I noticed today while turning all the way in one direction I heard a slight popping/clicking noise coming from the wheel area. I went out to inspect and found that the front locking hub switches were both in the "lock" position. I suspect that the factory put them in the lock position to test the system before shipping it out? My truck only has 100 miles on it. Anyway, I turned the hubs so the little grooved arrow pointed towards the "auto" position to see if that eliminated the noise, which it seemed to have stopped the noise.

So, again, being new to the SD trucks, can someone explain the hubs, how to use them, when to use them? I have ESOF and I thought thats what you would use if you wanted to use 4x4, at least that is the way all of my F150's have been. Sorry if this is a complete newbie question, but Im confused. thanks fellas. I tried running a search in the forums for this topic and the "newest" one that I could find is from 2011 and Im sure things have changed with these new trucks.

 

Basically, when in 'Auto', the hubs (wheels) are disengaged from the axleshafts so they are not turning the front driveline all the time. When you engage 4WD from the dial or floor shifter, the truck will automatically engage the hubs with the transfercase and you will be in 4WD.

When in 'Lock', the hubs (wheels) are locked to the axleshafts so the front driveline is turning all the time with the wheels. When you engage 4WD, the transfercase engages and you are in 4WD. Basically this is a bypass for the auto system.

 

What he said ^. When in auto, they are locked in with vacuum when you engage 4x4. The lock option is a backup in case you loose vacuum/have issues with the system.

 

The auto hubs are actuated by vacuum. If you get a vacuum leak, 4x4 no worky. That is when you manually lock the hubs. On my truck which is fully manual, the hubs can only be locked by turning the **** and 4x4 can only be engaged by manually shifting into four wheel drive.

 

I have heard that it is good to occasionally lock the hubs and drive around enough to warm up the front axle. This serves to distribute oil to all the surfaces and to drive off any moisture that might have condensed in the axle through the vent. Just another potential use for the manual hub locks.

 

On the F-150...... a similar vacuum system operates the actuators with a similar switch on the dash. When you turn the ignition switch off and shut the engine down, you then have no vacuum and basically you are in 4WD. When you turn the key, start the engine and create vacuum the actuators pull away from the hubs/wheels and disengage into to 2WD. Then when you hit the 4WD switch on the dash, you are effectively killing the vacuum to the actuators allowing them move and engage the wheels for 4WD.

So...... is this vacuum/actuator system operating basically the same way on the SDs???

And if for some reason the vacuum system fails and/or the actuators fail to engage you can manually lock the hubs???

This is how I thought it worked and how you seem to be describing. Just trying to verify.

 

I love 4x4 questions.

The "popping" noise the OP heard / felt when turning on full lock is indeed the hubs being in the locked position. When they are manually locked, or when 4x4 is engaged and they are in "auto," a full-lock turn is actually slightly beyond the capability of the axle u-joints to turn smoothly. For the sake of the best turning radius, Ford lets the wheel angle be slightly beyond what the axle joint can smoothly handle. The result is that you can feel / hear a slight binding during a full lock turn. Its fairly subtle but its noticeable. When the hub is in 2WD / Auto and not locked, the axle u-joint does not turn, and thus there is no binding on a full-lock turn.

By the way, things have not changed since 2011. The hubs operation and most components are identical to the 2011 system. In reality, the way it works is pretty much the same all the way back to at least 1999.

ATC Crazy, on a Super Duty if you engage 4x4 from the floor shifter, that means you also have fully manual hubs. Nothing engages automatically. For 4x4, you would have to manually move both front hubs from the "free" to "lock" position. Only the F-150 could have automatic hubs with a manual 4x4 shifter.

Wfedwar, what you say is good advice. You could absolutely put the front hubs in "lock" and leave the truck in 2WD and drive that way for awhile. Nothing is harmed in the least...it just spins up the axle u-joints, front axle half-shafts, front differential, and front driveshaft. This will keep things lubed and free. However, you can accomplish the same thing by simply by clicking the truck into 4x4 when you are on a reasonably long straight stretch of pavement (disengage 4x4 before a corner) or by using 4x4 on any dirt road. You don't need to lock the hubs or use 4x4 for very long to get everything lubed and free.

duckduke, you've basically got it. The F-150 hub system essentially works exactly opposite how the Super Duty system does. Engine off, or with a vacuum leak...the F-150 hubs are locked and the front end spins. 4x4 will still work just fine. Engine on and no vacuum leak and 2WD selected...the vacuum supplied will disengage the hubs from the front driveline. I think its a great system, and its definitely different than how RAM and GM engage 4x4 (they use a center axle disconnect system which cannot disengage all of the front driveline).

The Super Duty without vacuum being supplied or with a vacuum leak cannot automatically lock its hubs. This is an older design...it requires vacuum to lock the hubs. The reason you can still manually lock the hubs is for the purpose of failsafe.

 

Thanks!! I already feel better!!

On the F150 system what happened to many (not me) is they would be driving down the road 60-75 mph and hear this obnoxious sound that made them think the engine was about to fall out or blow. It was the actuators .... due to a slight loss in vacuum or blockage from the solenoid etc........ the actuators would drift and start to engage the hubs. Teeth meeting teeth and they would grind and easily damage the actuators. I learned how the system worked after I backed a boat into an unimproved launch and couldn't get out (no 4wd). The 4wd was not engaging. I tested and determined bad actuator. I replaced both actuators and the solenoid and never had another problem. Kept the old solenoid hanging against the firewall (caps on vacuum connectors) next to the old one as an emergency spare. The old solenoid was tested an worked fine.

I like the sound (even if older design) of what is on F250. Working like you stated we should not worry about tearing up actuators. They will always be disengaged.... unless intentionally engaged either with vacuum or manually. To me this appears to be a much more fail safe system.

Thanks again for the info!!

 

Yes. OP said he had ESOF, so I was going on that info.

 

I think the F-150 system is perhaps the better design, but I know they have failures. The problem with the Super Duty failsafe is that the auto hub can fail to disengage and there is no way to manually disengage the hub. So one hub can be disengaged and the other can be stuck still engaged, or partially engaged. Many a mechanic has cursed out Ford's auto hub design, be it on an F-150 with the IWE system or the Super Duty with the auto / lock system. At least with the Super Duty if you end up in a partial disengage system you can manually lock both front hubs.

 

The only times I will lock my hubs in manually is if I am out hunting etc. and know that I will probably need 4x4 and do not want to get into a situation where I get stuck and then not be able to get it into 4 wheel drive after the fact and be dead in the water... or mud, or snow etc.
Other than that with normal winter driving I just switch the **** on the dash to 4wd high and drive. But, the minute I head off the beaten path and know I will be needing 4x4 at some point in the journey, the manual hubs get locked in.