Forum Discussion

4x4ord's avatar
4x4ord
Explorer III
Dec 04, 2021

4x4 front hub

I'm familiar with Ford's vacuum actuated front hubs on their 4x4s and was able to add an EGR solenoid into the system that can be energized to prevent the hubs from engaging on rare occasions when I want 2wd low range. Not that it is a big deal but I thought it was kind of a neat mod and it only cost $15. Anyway it got me wondering how GM and Ram hubs work .... I think GM hubs are engaged 100% of the time? Does Ram have auto hubs?

Edit: For those interested in performing this mod on the 2017+ Fords here are some pics that might help:
The factory solenoid is left untouched:





This vacuum line is unplugged from the the vacuum manifold located by the windshield washer reservoir and plugged onto the output of the solenoid being added:



New solenoid being added:




Additional piece of vacuum line going from the input of the added solenoid to vacuum manifold:





This is a filter that I removed from what I'm calling the output port of the added solenoid and transplanted to the shown location:


Link All though this solenoid seems to work fine it has slightly smaller ports than what would be ideal ... I'm sure someone could spec a better choice.
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  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Dec 04, 2021
    My 1978 Chevrolet had full time four wheel drive (locked and unlocked/low and high) but the 2020 does not.
  • MFL's avatar
    MFL
    Nomad II
    Dec 04, 2021
    So this solenoid just releases the vacuum, to keep hubs from locking? Is this operated remotely? Sounds easy, do you have a link to purchase, and maybe pic of install in vacuum line?

    Jerry
  • BarabooBob's avatar
    BarabooBob
    Explorer III
    Dec 04, 2021
    Ford's IWE system works off of engine vacuum. For this design, the vacuum is placed on the system unlocking the hubs while the truck runs in 2-wheel drive mode. When shifting to 4-wheel drive, vacuum is released, which locks the hubs. This leaves the front axle locked for fail-safe operation. This quote is from gears magazine.
    The front hubs are unlocked when the vacuum is applied. If the vacuum is released,, the front hubs lock in four wheel drive.
  • MFL's avatar
    MFL
    Nomad II
    Dec 04, 2021
    Mine has auto and lock. While I've not had a failure, such as damage to vacuum line, I thought that with vacuum disrupted, I'd need to manually turn hubs to LOCK, if I wanted 4x4.

    Jerry
  • cummins2014's avatar
    cummins2014
    Explorer
    Dec 04, 2021
    MFL wrote:
    So this solenoid just releases the vacuum, to keep hubs from locking? Is this operated remotely? Sounds easy, do you have a link to purchase, and maybe pic of install in vacuum line?

    Jerry


    Had one of those hubs go bad on my old Superduty , instead of replacing ,it was cheaper to go manual hubs ,and I plugged off the vacuum lines . Although that mod is much cheaper , I got the same results , I had two low.

    I would like to do the mod I have read about on my Ram to have two low.
  • cummins2014's avatar
    cummins2014
    Explorer
    Dec 04, 2021
    MFL wrote:
    Mine has auto and lock. While I've not had a failure, such as damage to vacuum line, I thought that with vacuum disrupted, I'd need to manually turn hubs to LOCK, if I wanted 4x4.

    Jerry



    I could manually lock my hubs on my 99 Superduty ,and they were also auto .
  • MFL's avatar
    MFL
    Nomad II
    Dec 04, 2021
    cummins2014 wrote:
    MFL wrote:
    Mine has auto and lock. While I've not had a failure, such as damage to vacuum line, I thought that with vacuum disrupted, I'd need to manually turn hubs to LOCK, if I wanted 4x4.

    Jerry



    I could manually lock my hubs on my 99 Superduty ,and they were also auto .


    I could be wrong on my thought above? I don't remember reading about auto failure in the owners manual?

    There are times 2 low would be nice, if a really simple fix. Maybe the OP will add more info.

    Jerry
  • MFL's avatar
    MFL
    Nomad II
    Dec 05, 2021
    I've been doing some reading, and it appears my understanding of Ford's SOTF 4x4 is correct, as of 2013. If I have no vacuum to LOCK my hubs, I will have to get out, turn my hub setting from auto, to lock, and 4x4 will work. It seems sometime around 2015 Ford changed to the opposite, using vacuum to maintain 2wd, and no vacuum moves to 4wd.

    Here is a quote from FTE in 2013 "The auto hubs use the vacuum pump. If ever your vacuum pump dies or gets a leak in it. (which I've had happen several times over the years). You will not have any 4x4. By turning to Lock, You can have 4x even though the vacuum pump is lost."

    If this is correct then the solenoid that OP is using, likely won't work for my truck.

    Jerry
  • Grit_dog's avatar
    Grit_dog
    Navigator
    Dec 05, 2021
    Lwiddis wrote:
    My 1978 Chevrolet had full time four wheel drive (locked and unlocked/low and high) but the 2020 does not.


    Thanks for that tidbit of completely unrelated information.
  • Grit_dog's avatar
    Grit_dog
    Navigator
    Dec 05, 2021
    The bigger question I have, is why has Ford spent the money on redundant hub locks for over 20 years now?
    Is it any more than a selling point to see a tough new truck with manual hubs?

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