I have a 2014 F150 Platinum absolutely stock with about 37,000 miles. I have experienced a shutter or slight grinding in the front end during deceleration pretty much since new. I have taking the truck to 4 dealerships and the last one finally agreed that there was a problem. After two weeks in the shop they are telling me there are some bearings that are being replaced in the front end. I have thought this to be the result of a problem for a long time. Now here is my REAL ISSUE - I have the auto 4WD and all the front gear turns all the time while in 2H. I have asked all 4 dealerships and they all tell me this is common. I believe this is a flaw in the design of the auto 4WD Xcase. I mounted a go-pro under the truck and while in 2H the front drive shaft is constantly spinning. The owners manual defines the selections of the Xcase like this - "2H Provides optimum smoothness and fuel economy at high speed." How can you provide optimum smoothness and fuel economy while unnecessarily pushing all the front end gear? There is essentially no mechanical difference in 2H and 4A. If it had not been for the bearings that have gone out I would have never found this issue and would have just accepted the crapy fuel economy I get. I do have a heavy foot, so I have always attributed it to that. All of my driving is highway miles at a moderate (45-65 mph) and I get 15.9 mpg all the time with very little stop and go. I bet I could remove the front drive shaft and get a couple Mpg better and be close to what I should be getting if the transfer case operated as I would guess it was intended to. I would love to hear the thoughts of the forum members. Thanks in advance for your input and thoughts.

Chance

 

I don't have any personal experience with that particular tcase, but I would try to determine if the transfer case or hubs are engaged. With the truck in 2wd, disconnect the front driveshaft and try to turn the front output. If it will turn, then the transfer case is truly in 2wd.

Then with the driveshaft removed and the truck running, spin each front tire and see if the axle shaft spins.

 

The transfer case is always engaged, it's the wheel hubs that engage and disengage with the dash switch.

 

This is how it should work. My 2012 plat works this way.

2H unlocks the hubs via vacuum and disconnects the front shaft in the xFer box
4A locks hubs, engages the transfer box to ratio power front to back (torsen)
4H locks hubs, locks xFer box front to back (old fashion 4WD)

In 2H, your hubs are unlocked and your front shaft does NOT spin. Your problem sounds like the hubs were locked most of the time or weakly unlocked. You probably had a vacuum leak somewhere in the hub locking circuit. This is more common than you think and the grinding sound is a hub trying to lock....not enough vacuum to keep the gears (actually dogs) separated.

 

I have tried this and it is the tcase that is "engaged". I am told by the dealerships the clutches in the tcase are not fully disengaging and that is why the front gear spins. And this is normal.

 

So you are saying the front driveshaft and axels spin while in 2H and that is the way it is supposed to work? So shifting the tcase switch only tells the hubs when to lock and shifts the tcase to low range? I don't agree with that. Shifting the tcase to 2H should not engage the front driveshaft. The propose of locking hubs and a shiftable tcase is to keep the front axel and driveshaft from spinning while in 2H and optimizing fuel economy and smoothness.

 

I totally agree with you that the front driveshaft should NOT spin in 2H. I am convinced the hubs are not locked while in 2H. The service guys are telling me the auto tcase allows the front driveshaft to spin while in 2H and this is what I can't believe is right. They have told me that they pulled a truck off the lot and the same thing occurs. If this is true all of you with an Auto Tcase is allowing your front drive shaft to spin while in 2H. If you doubt it, put a zip tie on the front driveshaft and drive the truck in 2H and listen for the zip tie slapping the bottom of the truck. I would be very interested in what happens with your truck. Thanks again for all the replies. I am not a master mechanic but I have turned a few wrenches and have a few early Broncos so I understand the basic mechanics of a four wheel drive system.

I should clarify that when I say the tcase is allowing the front driveshaft to spin I mean that the tcase is actually spinning the shaft. I know that if the hubs are locked then the tcase will "allow" the shaft to spin even though the tcase may not be engaged.

 

I have a 2014 5.0 platinum and can definitely tell the difference between 2H and 4A. I really never thought to look at the driveshafts or axleshafts to see if they are spinning in 2H. I'm not saying that your information is wrong but that doesn't sound right.

I have always had Jeeps CJ7's, a Bronco, and 2 JK's so, who knows? Honestly I miss my locking hubs.

I think I would put it on jackstands and run it to see what's really spinning.

 

This is why I have an FX4 this time.

 

Jack up one front tire, try to spin it by hand and watch the front drive shaft. Start the truck and do the same thing.