As I mentioned in an earlier post, today I drove a 4WD F250.

Many, many years ago (mid 70s) I had a 4WD and it involved throwing a bar on the floor to engage/disengage 4 wheel drive. That was it.

My normal daily driver (Honda RidgeLine) also engages the 4 wheels, when necessary, but all automatically.

This tested buggy had a three position selector switch on the dash AND I noticed - hubs? on the front wheels.

OK, so how do I properly use all this? Also, how to test and if purchased, how do I maintain them? Chances are very good I'll never need it but still need to know.

 

First do you have auto hubs, most do, there should be a auto and locked position. With auto hubs you can shift from 2wd to 4wd any time but it won't engage until all four wheels are going the same speed. The best way to shift in to 4low is to stop, shift to N and while holding the brake switch into or out of 4low. True manual hubs are rare and as long as they are locked I think the 4x4 shifting is the same.

 

From what I have read about this on the newer trucks, the ability to lock the hubs manually is a back-up/redundancy in case the automatic (vacuum system) fails.

Here is an older post with someone asking about the locking hubs (the first couple of replies cover it pretty well):

https://www.ford-trucks.com/forums/1...-4wd-hubs.html


Good luck,



-Kaw-Liga.

 

Yup, this is the Electronic Shift-On-The-Fly (ESOF) system. Seems like the majority of Super Duties were built with this system. Just like Kaw-Liga said, the hubs are either set to automatic or lock. The purpose is to be able to manually lock the hubs in the event of a failure in the locking mechanism.

An easy way to test this is engage 4-hi on the switch and turn the wheel at idle speed in drive. If it engages the driveline will bind up and the truck will come to a stop. If it keeps on going like nothing happened it's not engaging.

 

An easy way to test this is engage 4-hi on the switch and turn the wheel at idle speed in drive. If it engages the driveline will bind up and the truck will come to a stop. If it keeps on going like nothing happened it's not engaging.


Please further explain Ford 101 for Dummies test of 4wd system. Would that only test one front side and need to be repeated in the other direction?

Additionally can I actually shift on the fly (as name implies)? or stop and engage first?
Are there any max speeds while in 4wd? Are there any required PM services which need to be periodically done here?

 

Nope. When you turn the front wheels basic geometry dictates that the front wheels have to spin faster than the rears because they are covering more ground as the truck moves forward. To better understand the concept, imagine the front wheels turned 90° so they were perpendicular with the frame. The front wheels would both move forward and the rear axle would be stationary as it pivoted around.

If one of the hubs isn't locked in you will get no binding because the front has an open differential. The shaft that's connected to the hub that doesn't lock in will travel at a different speed than the wheel and there will be no binding.

Yes you can, the book on older models says you can shift at any speed. Newer models say you should be going 55 MPH or slower to engage 4-hi, but you can go faster than that after shifting. To engage 4-low the truck must be in neutral, going 3 MPH or less, and your foot has to be on the brake pedal.

 

I'm still left wondering ... is there any maintenance involved with these?

 

Yes there is. The factory maintenance schedule lists nothing but a transfer case fluid change every 100,000 miles or so. But fifteen years' experience with this system has shown that the hubs can't be ignored. You want to rotate the ***** to lock and back once a month to avoid them being frozen up, and every year or two you want to take them apart and service them.

Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page

I had the system on my '00 Excursion and I had no trouble after the dealer replaced the rotted vacuum lines. They still use the same system on the brand-new trucks as well, my '11 F350 had it and never gave me trouble.

 

Thank you; y'all have been helpful.