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MountaineerGreen's Selectable Front Diff Swap

MountaineerGreen

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I covered this some in my front end rebuild thread, but I think its worth its own thread.

Its a great mod, helps with fuel mileage, allows for the use of a locker or having 2wd low. I do not have a locker up front, so my front driveshaft no longer turns when I am driving down the road, much like an F150 or any older truck with hubs.

EDIT: Please note I do not have the AWD Tcase anymore, I have a selectable "true" 4x4 BW4406

For the V6 guys, I *suspect* this will be a bolt in deal. That is not confirmed, but the 96 v6 Explorer I pulled my front diff from had the oil pan clear of the knot on the passenger side of the differential. The v8's may run into oil pan clearance issues, but that will be covered.

This is mostly a bolt in deal, with a little bit of wiring needed. The CV axles are the same, as is all other drivetrain parts.

I got this from a 1996 Eddie Bauer Explorer with 4.10 Gears- Notice the vac globe in the picture. It has an extra port for the valves to pull vacuum from.

vacdiscodiff_001_Medium_.jpg


The "knot" on the passenger side of the differential

vacdiscodiff_002_Medium_.jpg


This is a standard front diff- the only thing different is the disconnect isn't there. All the mounting points are the same as is the driveshaft yoke.

frontendwork_018_Medium_.jpg


Its a drop out, bolt in deal- remove the half shafts, disconnect the driveshaft. Put the "new" diff in and bolt it back up.

I got the valves from another 96 as well as the wiring harness from Karl to install on my truck.

Mine is a V8, and I don't believe this is a bolt in deal for a stock V8 truck. I have a drop bracket lift, so my differential being lowered helps greatly.

frontendwork_026_Medium_.jpg


This picture is from the bottom, looking straight up-

frontendwork_031_Medium_.jpg


See how close it is to the oil pan?

I got it all bolted in, of course I made sure the vac motor and shift fork were in good shape before that.

I got the "vacuum control" valves mounted to my header panel, sorry no pictures. There are two wires and two hoses that connect to the diff, then run to the valves. The two wires are just for the indicator, a signal source down, then back up when the diff is engaged.

A power wire goes to the valve, +12v at all times.

Then, two wires, one for disconnected, one for engaged. All they need is a ground signal to activate the valve.

I got all this info from this very useful thread:

http://www.explorerforum.com/forums/showthread.php?t=88718

So, I ran 5 wires from the connector on the harness under the hood to the dash.

I wired the switch using a relay and painstakingly drilled a hole in my radio bezel for the switch.

Here it is off:

diffswitch_009_Medium_.jpg


On:

diffswitch_007_Medium_.jpg


The light is an indicator light for the differential position. Switch position has no effect on the light.

Here, the light is on even though the switch is in the off position. That is because I put the Tcase in 4hi engaged the front axle and turned enough to bind the front axle. Turn the switch off, the light won't change until the differential disconnect releases.

diffswitch_008_Medium_.jpg


I am getting 1-2 MPG better fuel mileage consistently with this axle disconnected.
 


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AMMO_HOOAH

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I love this idea my only question is what years/ configuration had this axle? Also when I start calling yards what am I asking for as far as the vacuum stuff?
 




MountaineerGreen

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The selectable axles came from 95's and 96's, I believe.

I have concerns about running the selectable diff with 37's though. The disconnect may not hold up to em.

You need the diff, the wiring/hose harness that goes to the valves, the valves themselves and the vac globe from the same truck.

If anyone ends up needing it, I will post a wiring diagram.
 




95exploderboy

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The selectable axles came from 95's and 96's, I believe.

That is correct. I ended up locking mine in the locked position after I stopped trusting it to work when I wanted it to.
 




Hokie

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The v8's may run into oil pan clearance issues, but that will be covered.

See how close it is to the oil pan?

Pretty certain it wouldn't work for us non diff dropped V8 guys?

I am getting 1-2 MPG better fuel mileage consistently with this axle disconnected.

Exactly why I'm considering it. That and I could lock my front end and still use 4x4 (well, technically 3x4 ;)) when driving to/from the ski resorts.
 








Hokie

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Ok-
Now another thing I have to do--geez will you guys ever quit?:D

Well, no one has tried on a V8 with the diff in the stock height... so we don't know if it can be done.

Ford never put a vacuum disco front axle with a V8 as they were AWD and didn't need it.
 




MountaineerGreen

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Pretty certain it wouldn't work for us non diff dropped V8 guys?

I am not really sure- it'd be tight for sure. You could possibly clearance your oil pan a bit. But the only way to tell would be to hang one under there.

You could drop your diff about 1" and it may help. It'd help your CV angle with a TT as well.
 




Hokie

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I am not really sure- it'd be tight for sure. You could possibly clearance your oil pan a bit. But the only way to tell would be to hang one under there.

You could drop your diff about 1" and it may help. It'd help your CV angle with a TT as well.

I've made a promise to myself to never TT a vehicle again ~ after driving an '07 Toyota 4Runner around in the New Mexican oil/gas service roads I've come to appreciate a nice, smooth ride.

Oh well, I'd love to do this but I don't have the time/money/shop to mess with shaping or custom oil pans
 




AMMO_HOOAH

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I know this thread is kinda old but how do has it been holding up for you mountaineergreen? I picked up (literally) a couple of selectable axles and the stuff to go with them this weekend. Not to mention a moonroof, and a new hood.

Edit: I'd also like to know how you wired the light to the indicator leads.
 




MountaineerGreen

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Check my first post, it explains the wiring thing pretty well, once you get all the factory harness in hand it will make more sense. I don't really know how to explain it better.

I love the selectable differential. It eliminates any vibrations from my non balanced double cardan driveshaft since it doesn't spin. I occasionally click it on just to keep it all moving, I can tell a huge difference when accelerating. Since I drive mostly on road, this is perfect for me. Also, if I am in a place where I need low range but not all four wheels griping, I can put my case in 4 low but not click on the differential for what works out to be 2 low.
 




ProjectAviator

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I have the vacuum valves, and all the vacuum stuff, but the globe. if someone needs them. I went to 4:10s and a 97 front diff. ( Thanks Hokie the 4:10 rear and install help on both) I will be using the vacuum globe for a reservoir on my wifes Lincoln, though.

Tim
 




AMMO_HOOAH

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Actually I'm just a little confused on how you used the relay in there.
 




MountaineerGreen

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Honestly, its been nearly a year since I did the swap and I can't remember how I wired the relay in. I used a standard 5 prong automotive relay though :scratch: Next time I have my stuff apart, I will diagram what I did.
 




410Fortune

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Did you ever take any pictures of the inside of the vacuum disco bubble?
I'm wondering how much can be shaved off :)
 




ProjectAviator

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From what I have seen it is wired like a 5 wire door lock system. there is a diagram I saw once on here.

Tim
 




MountaineerGreen

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The explanation in the thread I linked in the first post is very helpful-

The main connector for the system is shown on the left of the picture. The two solenoids are in the center of the picture. On the main connector, there are 5 wires. 2 of these are sensor wires (Brown and Black Wires), and the other 3 control the solenoids. The Purple/Orange wire is a constant +12VDC. This is fed to one of the pins on each solenoid. The other two important wires are the Green/Pink wire and the Blue/Yellow wire. When the Green/Pink wire is pulled to ground and the Blue/Yellow wire is floating, the solenoid shifts to unlock the front axle (2WD Mode). When the Blue/Yellow wire is pulled to ground, and the Green/Pink wire is floating, the solenoid shifts to lock the front axle (4WD)mode. All this is automatically accomplished when you rotate the switch on the dash from 2WD to 4WD.



I thought about this more today and here is what I got- The 12v positive went to one of the side posts on the relay, switched by the lighted switch. A ground was run to one the main "input" post on the relay, the green/pink wire connects to the post nearest the input. The blue/yellow wire goes to the furthest post on the relay. Tie the brown wire to a ground and the black wire to the ground post on the switch. Make sense?
 




AMMO_HOOAH

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Actually I ended up figuring it out today, except I had to get a different relay. I used one that had a N.O. and a N.C. circuit, so it would switch from one solenoid to the other.

Edit: Also not every toggle switch is setup to be able to work with the light still on when the switch is off. Some the light can only be on when the switch is no matter where you have the ground and hot.

Edit 2: So I spent like 45 minutes today trying to find another (I burnt the LED out of the first one on accident) toggle that works with the light on in either direction, alas I couldn't find another so I just wired in non-lighted switch with a indicator light. Thanks for doing the legwork on this mountainneergreen!
 




MountaineerGreen

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I had the Mounty out for some fairly serious 4x4ing this weekend and used the heck out of this disconnect. I ran in 4x4 low most of the day, just clicked off the diff to make tight turns or faster sections of the trail. It saves wear and tear on the CV axles, helps with tight turns and makes my truck more capable than ever.
 


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V8BoatBuilder

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I love my selectable axle too, for the same reasons Evan posted above. I really like having 2wd Low Range.

But I need the electrical plug that connects to the axle to monitor the lock/unlock position, anyone have an extra?
 




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