I have a stupid question. How do the hubs work on '97 F-150? Are the hubs engaged all of the time or are they automatic and engage when 4X4 is engaged. The reason I ask is because I have been noticing a whine in the front end lately so I jacked up the truck this weekend to check the wheel bearings and noticed that the front drive shafts turn when I rotate the tires. If this is normal or are my hubs not diengageing?

Thanks,
CSD

 

Thats normal. The CVs turn all the time. The F150s all came with auto hubs, can't get a manual hub yet. Maybe now that the FX4 package is coming out they might. I think the Ranger FX4 is getting manual hubs.

 

I'm not sure what design the 97 is, I believe all 97s and up are the same, so it would be the same as my 2000 4x4. I tend to follow a literal interpretation of auto hubs, in the sense that is through a driver-engaged mechanism the hubs "lock" and through the use of one-way or overrunning clutches unlock when driving in the opposite direction (i.e. reverse)

In that sense, I believe there really are no "auto hubs" on any modern 4x4 truck, Ford or otherwise. The axle shafts are always turning, and the only thing keeping the differential from operating as normal is that the right axle is disconnected from the right side gear in the front until you hit that 4x4 lever (so the left side gear spins the right in reverse via pinion shaft gears). Contrast that with auto hubs, where the axle shafts are only turned when auto hubs are engaged. Also, 4x4 works in reverse too. Contrast that with auto hubs that disengage in reverse...

 

there are a set of half shaft's that are always turning, and there is a automatic locking hub that attaches to the transfer case. In order to disengage it you have to go at least 6' in the oppisite direction.

However, mile marker ( http://www.milemarker.com )may make a 4wd replacement manual hub that can be used. I'd also check warn's web site ( http://www.warn.com ).

 

there are no hubs, the axle is disconnected on the right side, so in 2wd, the side gears and spider gears turn, but not the ring and pinion. the right side output shaft of the front axle actually turns backwards going down the road in 2wd, and the sliding coupler the puts the right side axle shaft together is operated by a vacuum actuator. when you have a manual shift xfer case, a switch tells the gem that its been shifted to 4wd, and it powers up the soleniod that applies vacuum to the actuator that couples the shaft. On a elec shift, once the gem sees the 4wd motor plates reach the 4wd position, it does the same thing to connect the axle.

 

lariat4by4

Glad you stopped by. First off, your pictures aren't coming through, at least I'm not seeing them...

I was having this discussion with some others awhile back and it kind of drifted off to nowhere. Basically, we were trying to figure out whether there are really ANY differences between what the shift lever and the shift **** do on the 4x4. I do understand shifting INTO 4x4, and that they both activate a solenoid. The question then became what about when you shift to 4x4 LOW, does the manual shifter and **** also activate solenoids (i.e. perform the same exact function), or does the manual shifter actually physically hit a shift fork and move a sliding clutch to engage the reduction gear, while the **** uses a solenoid for that. It does seem like you go through a lot of extra movement with the manual shifter to get to that 4x4 LOW. It would be a shame if all that does is click a little solenoid just like the ****.

Also, you didn't elaborate on how the front draft shaft is driven up to road speed and the chain sprocket is locked...It's always good to have a complete description of how the 97+ 4x4s work in one thread so you can refer people back to it when the same question gets asked again...Since you seem to know more than me, I'll give you the floor...

 

ok, the manual x-fer case shifter that comes up through the floor physically moves the shift forks and a pin type switch that lets the gem module know that you moved it into whatever position, the elec shift has a motor that kinda looks like a windshield wiper motor, but has plates in it to feedback to the gem so it always knows what position its in and it can stop at the right place. Thats kinda like the difference between manual windows and power windows. As far as the driveshaft spinning up, theres a magnetic clutch that brings it up to speed, and when it gets spinning the same, it slides the coupler on, locking it. then, the vacuum soleniod comes on and the actuator moves the coupler over the right axle disconnect, since the ring and pinion are now turning and the axle stub on the right isnt going backwards anymore. So no matter what type of 4wd shift you have, (manual or elec.) , the front axle engagemant is the same, as soon as the gem module sees the xfer case in 4wd, it applies power to the front axle disconnect solenoid.

 

lariat4by4,

Thanks for that info. That's exactly the way I understood it, except for the 4x4 LO function. So IMHO, the shift stick and **** perform the same function re/HIGH, but for LO with my shift stick I am physically putting that transfer case into reduction gear engagement, as opposed to a electronic device doing it for me like with the ****. It may seem like splitting hairs, but dammit I want to be doing something with that stick, that's why I got it (and because it looks cooler)....

Another question, when did Ford move to the center disconnect (isn't it 97 and up)? Also, do any other truck makers have auto hubs still (not that I would every buy from them, just curious). And what is your opinion, are you happy with the CD system or would you prefer the old auto hubs back, and why?

 

chivy uses an electric actuator that does the same thing--not sure about dodge but I think it is vacum.

 

yea, the chevy has a electric actuator that actually is a heating coil that when it heats up, it pushes a piston out, i hear they dont work real well in sub-zero places, there is a aftermarket one for chevy that is a electric/physically moved actuator. I think the dodge half tons have a solid front axle??? not sure though, as i really only work on fords.

 

First of all thank you all for an explanation I have been trying to get out of my dealer. You have cleared up a lot of my confusion.

Now for my questions.

1) Do you still need one complete wheel revolution for the front drive axles to "lock" with the front differential or will they lock with the wheels stationary?

2) I have a 97 F150 with 85K miles and electronic 4x4 shift. This past weekend, I could not get the front drive axles to the wheels to lock-up. The rear wheels spun and the fronts sat there. I could hear the solenoid doing something on the transfer and the vehicle jerk slightly as the front drive shaft came alive. Where do I start looking.

Thanks again for all the help. This is a great site.

Mike

 

mrnpn

1) No, it will lock stationary.

2) Vacuum leak is my guess, since they are vacuum acuated, if there's a leak it might be slow to engage.