The Diesel Garage banner

1 - 13 of 13 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
It seems that with winter coming to most of us, there have been a lot of questions about the functionality of the vacuum-operated hubs many have on their ESOF 4x4s. It also seems that if they don’t work when you flip the ESOF switch, people call them POSs or worse. I’d like to set the record straight and show a bit about how they work and how to perform simple maintenance on them that should keep them operating whenever they are called upon. If others have more info or more detailed knowledge of their operation or modification, please post in this thread. Hopefully from here out when someone posts and says their hubs didn’t work we can just link this thread and answer the questions. Pics are linked at the bottom of the post.

This is all based off my experience and may not work on all vehicles. Perform at your own risk!

BASIC OPERATION:
When you select 4HI on the ESOF switch, two main things happen. A motor on the transfer case engages the front drive shaft, and the hub vacuum solenoid applies vacuum to both front hubs. 4LO is the same except the transfer case motor engages the low range gears and front drive shaft. (Note you have to be in neutral or park with a foot on the brake to engage 4LO)
The vacuum solenoid stays energized for about 45 seconds. This pulse operates the auto hub, which is similar to a clicker-style ball point pen. The pulse is applied and released much like pushing the top of a pen – the tip stays out/the hubs stay locked. When you disengage, vacuum is applied again, the hubs unlock (push the pen top, the tip goes in). When you rotate the Auto-Lock selector to Lock, it is like holding down the button on a pen – it forces the hub to lock (pen tip out) continuously.

OPERATING TIPS
The key to getting the hub to engage is motion. While the transfer case will shift into 4 while stopped, the front wheels have to move in order to engage the hubs. If you are already stuck, the front wheels can’t spin, and the hubs can’t engage. If you need 4wd, engage it via the ESOF switch while the truck is in motion. If you are already stuck, rotate the Auto-Lock selector to Lock to force the hubs into Lock and you’re good to go.
A note about the Lock position: It IS NOT bad to drive around in 2HI with the front hubs locked. It causes the front differential and front drive shaft to spin, but the drive shaft is disconnected in the transfer case. You may see a little drop in fuel economy, and may hear the gear noise when turning, but it will not damage your rig. If it is snowy out or you anticipate needing 4wd, just lock the hubs before you leave. Then you don’t have to worry about any of this. Of course, leave them unlocked for a cross-country highway trip, but many people up north simply lock their hubs in the fall and unlock them again in the spring.

VERIFICATION PROCEDURES
To verify if your hubs are locked there are several things you can do. The easiest is to verify that they are unlocked (2WD, hub in auto). Reach around the wheel and grab the U-joint in the steering knuckle. You should be able to rotate it by hand. Either the opposite side knuckle or the front drive shaft should also spin. Note the opposite knuckle will spin in the opposite direction. As a test, lock one of the hubs manually and then rotate the front drive shaft by hand. The unlocked side should spin freely (open differential). Once you are done using 4wd, go back to 2wd (motion is required again) and try to spin the knuckle. My hubs typically do not unlock automatically when going from 4wd to 2wd. After using 4, and when I no longer need it, I have to manually unlock the hubs (reset the ball-point pen). Rotate the selector to Lock and back to Auto once or twice and spin the knuckle again. They should now spin freely. You can play with the setup by safely jacking the front axle off the ground and with the key on (not running), put the tranny in neutral and select 4x4. Spin each of the front tires through a revolution or two within the 45 seconds of solenoid activation. You should feel each wheel engage and see the front drive shaft spin. Select 2wd, feel the hubs unlock once they are rotated.

MAINTENANCE PROCEDURES
You hear a lot about hub selectors that are too stiff to turn. If you maintain them properly (like any piece of equipment) a ten year old should be able to move them back and forth. Here’s what I do with every oil change. It takes all of ten minutes and requires no tools, and is virtually risk free (no bearings will fall out, etc).
Pictures are linked at the end of this post.
1. Remove the plasti-chrome lug nut cover/hubcap
2. look at the hub – there is a retaining ring with two prongs sticking out. Squeeze the prongs with your fingers and pull out the ring. If they are dirty, you may need some needle nose to get it out.
3. Now just pull the hub straight out. It may need a little wiggle, and really dirty ones may need a few gentle taps from a rubber mallet.
4. Clean the inside of the hub. Remove any grease. Inspect the O-ring seating surface and lock-ring groove
5. Clean the hub. Now is the time to soak it in penetrating oil if the selector is too stiff to move. Select the Auto and the Lock positions and spin the inner shaft – see how it works?
6. If you start removing the small lock rings on the hubs themselves you expose bearings – I personally don’t go any further.
7. Inspect the O-ring. This is what keeps the vacuum while locking.
8. I apply a light coat of waterproof synthetic grease to the metal surfaces and O-ring. Some say it is not necessary, so you’ll have to decide for yourself.
9. Now reassemble. Push the hub all the way back in and give it a little extra push at the end to make sure the O-ring is seated. Put the retaining ring back in – MAKE SURE it seats in the groove (so your hubs don’t pop off)
10. Verify they are back in Auto, and check to make sure the knuckles move freely

MODIFICATIONS
2LO:
Some want the ability to use 2LO in certain circumstances (backing a trailer is one big one). There are a few ways to do it. One is to disable the vacuum function altogether (see next section)(least preferred method). The other is electronically (preferred method), All you have to do is wire a switch that prevents the hub vacuum solenoid from energizing when 4WD is selected (see pics at end of post) FOR MY TRUCK this worked: Cut the red wire going into the hub solenoid far enough down to splice into both sides of the wire. Run a new wire from one side of the cut to a switch on your dash, and then back to the other side of the cut wire. I mounted my switch so it is closed (on) in the down position. Thus, when it is down, everything acts like normal. When it is up (open), the hub solenoid does not engage, and the hubs do not lock. Now when you want 2LO, start in 2Hi with the hubs unlocked. Flip the switch up, place the ESOF switch in 4LO (remember, neutral, foot on brake), and viola! Now, to get 4WD back, either lock the hubs manually, or take the ESOF switch back to 2HI and your hub bypass switch back to off.

VACUUM REMOVAL:
Some like to just remove the vacuum feature all together, and treat the hub like a conventional manual one. (not sure why, but more power to ya) If you want to do this it is not difficult. Look at the bottom o the vacuum solenoid – there is a red line that runs to the hubs and a black line that tees into the vacuum reservoir and then goes to the HVAC system. Plug the red one at the elbow further down the line and you’re set.


Please add to the thread if you have more info or if I am all backwards. Again, these work for me – no guarantees! Check out the pics – they should explain most of this.

Steve

http://community.webshots.com/album/524525758VHLVFc
 

·
Registered
Joined
·
4 Posts
Good write up, I'm doin the 2-LO mod tonight:rock
 

·
Senior Member
Joined
·
5,365 Posts

·
Member
Joined
·
864 Posts
It seems that with winter coming to most of us, there have been a lot of questions about the functionality of the vacuum-operated hubs many have on their ESOF 4x4s.
Steve

http://community.webshots.com/album/524525758VHLVFc
Excellent write up steve. I know about the vaccuum leaks as i have one, so i just lock it in manually. Now though my 4x4 stopped working all together. The 4x4/4x4 low light would light up from time to time for no reason while just driving now nothing, silanoid on transfer case doesnt kick in, lights on dash doesnt light up at all, nothing happens at all. Now i checked all the fuses but found none bad. i dont know how to check a relay if that is what it maybe, are the 2 next to the brake fluid reservor the only ones, or are they in that bigger box right next to it? Not sure what to do with this whole thing, figured cant just be transfer silanoid since nothing lights up anymore. am i missing fuse or relay somewhere, or should i just replace the 2 i mentioned? anything will help as im pulling hair out on this one :bang :bang
 

·
Member
Joined
·
154 Posts
Ok I will ask the question on what the true benefits are for 2Lo? I know you mentioned one would be for backing a trailer in but for what reason? If you could give me some reasons then I might just do the mod but haven't really found a reason to use it.

International350 have you checked the harness on the transfer case to make sure it is actually plugged in? The reason I ask is this past summer had my tourque converter replaced, tranny rebuilt and transfer case gone through (a freaking expensive bill) and we were up at camp sitting on a beach like we have done many times before and I ended up getting stuck getting off the beach going up a hill. Well no matter what I did could not get the front hubs to lock and ended up going off the beach sideways. Well after getting back to camp crawled underneath and found the harness to the transfer case not in all the way. Didn't notice at that my 4x4 light on the dash didn't light up just because I was freaking pissed off but then after we got back and I calmed down I was able to go through it and start figuring out what was wrong. Well the harness was never plugged in all the way after it was put back together. Just an idea. If someone has a schematic of the wiring from the switch to the transfer case we can see what wires need to be energized and you could start testing to see what has power and what doesn't.. Good luck on your troubles though. Been there and done that will a big hole in my pocket.
 

·
Member
Joined
·
864 Posts
Hey thanks bro, yeah all is working now, I basically took everything apart and cleaned it and now alls well. Heres the kicker though, the vaccuum tank/bottle was actually full of water and wasnt sending any vaccuum. It was hard to dump out that little tiny hole but i got it all out. Now it locks in every time. Did it all at once so not sure if taking electrical apart or hubs or everything else or what but it now works. Excellent write up and thanks for all the help.
 

·
Member
Joined
·
864 Posts
how many of you guys have gone to manual hubs and just ditched the auto hubs? My auto hubs have gone out on me they keep trying to engage and grinding. Trying to figure out if i should just get warns manual hubs or get another good used set of hubs
 

·
Junior Member
Joined
·
16 Posts
Great write up.

Thanks for the great write up on the Hubs. From here on I will be sure to pull my hubs everytime I change my oil.
You missed your calling as a Technical Writer.
Have you posted anyother Threads similar to this?
 

·
Junior Member
Joined
·
1 Posts
I realize this is an older post but am hoping someone responds to it. I've got a 97 F250 4X4 PSD. I am in the process of changing over to manual hubs. I can't find a decent blow up of the process for my year. I'm switching to Warn. I really need some pictures or a decent step by step. If anyone can help I'd really appreciate it. Thanks!
 
1 - 13 of 13 Posts
Top