Hey group, I wanted to leverage your knowledge to double check something I heard today.

I was at the Ford Quick Lube center getting my oil changed on my 04 150 4x4. The quick lube center is located across the street from the main service center and generally has much less knowledgeable service people.

While the truck was on the lift, I happened to spin one of the front tires. I was surprised by a) how much resistance there was and b) the other tire rotated. The reason I was surprised was I assumed the front hubs would be disengaged since the truck was not in 4x4. I looked underneath and sure enough, turning the wheels turned the axel to the transfer case.

My concern was that I didn't want my whole front transfer case turning on every day use. Every other 4x4 I have had in my life allows the front wheels to spin free when disengaged.

I went over to the main service area and asked the service manager how it worked. He didn't know so he walked me to the back to talk to his tech people. One of them immediately said that the front hubs work off vacuum. The vacuum keeps the hubs disengaged when the 4x4 is off and with the engine off, there was no vacuum and thus the hubs engage. His point was this was a safety feature in that should a vacuum line brake, you still have 4x4.

The main service center was to busy so I couldn't put it back on a lift with the engine running to test the theory.

All my other hubs were either manual or had a small electric motor to engage them (i.e.. by 93 ranger) so this was new to me. What he said made sense and fit the profile of what I was seeing.

So my question is simple, anyone out there know the system and agree or have a different understanding of how this system works?

Thanks in advance.

 

I'm not sure how the other systems work, but Ford did the same thing on the 97-2003 F150. Only difference was a vacuum was required to put into 2wd. Vacuum loss meant no 4x4.

But there weren't really any problems with those years systems.

 

I just purchased a used '04 F150 SuperCrew FX4. I love the truck with on exception. There is a pulsing vibration when I hit about 65 MPH. It goes pretty much away at 70 MPH and is barely noticable at 55 MPH. The reason I am explaining this in this thread is that it feels and sounds similar to the way a 4x4 feels on dry pavement when the front hubs are locked. I also noticed two days ago, when rotating the tires, that like Aubry found, when I would spin one of the front tires the exposed axel shaft would also spin.

I too was not expecting this. Where does the front axel disconnect? Right at the hub or up in the front axel housing. I wish I would have paid more attention when I had the truck on the jack stands. I never looked to see if the other front wheel was spinning the opposite direction (suggesting the front end was locked).

Also, although I appriciate 92Merc's reply, it does not tell me for sure how the 04 F150s front hubs disconnect and if they are locked in a vacumless state (opposite the way he explains the '97 - '03 to have been).

~BCrooks

 

The 97-03 did not have front hubs, they had CV joints at the wheel. All locking was done at the diff. The 04 locks at the wheel with the vacuum operated hubs. I believe it also locks at the diff, similar to the 97-03. Default for the 04, no vacuum is locked.

 

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There was a thread about this same issue a week or so ago (don't have time to find it for you now) but that was the general consencus on that one. when the vehicle is running vacuum keeps everything unlocked, so... no vacuum... no free wheel. the locking and unlocking takes place in the diff. so regardless if the tire turns so will the axle!

 

The TSB for the vibration problem that plaqued some of the 04s wanted to check that the hubs were releasing. In the instructions it stated that the vehicle had to be running, in 2WD and to raise the front wheels and rotate. If the axels rotated check the hubs. I took that to mean that the hubs were locked if the vehicle was off, which it appears from this post.

 

Im gonna try this when I get some time i think it should work. Jack the front of the truck up and start it up. See if the resistance changes maybe someone with a lift can try it and see what happens when you put the truck in the air and shift it into 4x4
jbs