Ok guys this is driving me crazy. On my 99 F150 I see the vac actuator which pulls on a lever on the front diff, that moves the internal shift fork to.... Lock? the front diff? Maybe? (what does this actually do when it moves this lever?)

I am seeing kits like this below but am wondering what it replaces. Does this go directly into the front diff to replace the external shift fork or does this mount into the stock location of the vac canister to pull on the external shift arm?

http://www.alloyusa.com/alloy-usa-450750.html



My second question is how do the Navigator and Expedition 4x4 (AWD) systems work? I have a front diff from my Navigator I wanted to use on my 150, but there is no external shift fork to hook up my 4x4. It's plugged. So one, how does this even work with the Navigator if it can't lock the 4x4, and two how can I make this work on my F150?

 

Lets get some firm footing here first.
Is your 4X4 not working?
If no, it's cheaper to service it rather than trying an aftermarket cure looking for easy way out.
As to the NAV, a different design, so no you can't just bolt it on.
The gear ratio must be the same. Is it?
Doing these things becomes more hassle that fixing the original system.
You really need to find the issue first then make the decision on what to do.
We will help if you will do some work on the system to find the fault area.
Good luck.

 

My 4x4 works fine. I'm upgrading the gears and have to get the Navi front diff in my truck in order to work with my new 3.73 rear. Upgrading my 8.8 drum to a 9.75 disk with 373's. I happen to have a Navi front 3.73 diff so to avoid buying one I was going to use this one since it's low miles and in perfect shape.

 

Well ok. I can't help you much other than to say your getting into a can of worms with the conversion.
The brake system will even be an issue because there is front to rear balance (bias) upset your needing to deal with changing from drum to disc. as well as the Emg cables etc.
Good luck.

 

It's really not that hard. Swap in the master cylinder and abs pump from a disk brake truck (which I have in my Navigator), run new ebrake cables and brake lines all of which I can buy brand new for a disk brake truck. Swap axles, change the driveshafts to fit the new stuff and away she goes.

 

Yeah I decided to look at your thread and steal some insight from you because I am curious myself. I have a 97 F-150 lariat 4x4 with a bad GEM and instead of payin 150.00 at the least for a new one I am just hard wiring everything effected through toggle switches, I am now at my last step of hookin up my auto shifter for the transfer case and thought maybe i could find some useful info here but like my own experiences on this sight some of these guys just want to tell you that what you are doin is a waste of time and we are idiots for trying (new things) well I have to say that poor people have their own ways to solve problems without buying new exact fit replacement equipment. Sorry you have yet to get any helpful info for yourself, and good luck, let me know how that drum to disc conversion works for you cause im considering doing the same thing on my 2004 Ranger

 

"not that hard" famous last words! Sounds like a big deal to me.. I changed the brakes on my Mach I to 4 wheel disk. Never again.

 

I'm doing a 4.6 to a fully forged 5.4 DOHC Navigator/GT500 engine swap, with a 4R70W to 4R100 trans swap in my 99. If I can find the stinking parts at a reasonable cost it will be getting a TVS or Whipple 2.3 blower this year too. Worst case it will take me a couple years to save the money for the blower setup. But an axle swap is peanuts. Trust me.

This stuff really isn't as scary as everyone thinks. The problem is no one knows how it works or what they have to do, so are always scared to do it. READDD, look, break things... LEARN. As said above poor people figure things out, which is how I've done it my whole life. The first time is always hard. If life were easy and swaps like this were simple, life would be oh so boring.

I love that people are wimpy, makes my unique setups that much cooler

 

The f-150 and the Navi front axles are similar. The Navi has AWD so the front axle shaft is never unlocked. This doesn't require the locking system of the f-150so it is removed. You can safely replace the front axles but your mpg will suffer as you are spinning the front drive shaft all the time.

 

Just so you know; The GEM, when it sees a request for 4x4, engages the electromagnetic clutch in the t-case. This spins up the front driveshaft to eliminate clash when shifting from 4x2 to 4x4. Make sure you hot wire that clutch to your toggles. This is why the Navi with AWD doesn't use a front axle disconnect. The front axle is always turning.

 

Awesome info thanks. That clears up a lot.

One other question. Any idea if I can slap in the Navigator T-case too and basically have my truck run AWD like the Navi and Expo's?

 

You will need the Navi GEM and PCM. Based on front to back wheel speed differences the 4x4 kicks in and out. I cannot guarantee that the PCM and GEM will work with your 98 cluster.

 

Yeah I had thought about that but decided that due to the kind of use my truck will mostly be used for, im not going to worry about going through the headache of that, I figure when i need 4x4 locked in i will just stop and then lock it in. Im just gonna use it mostly for farm use so if i end up gettin stuck because i had to stop and lock it in then i reckon i will just have to go fetch a tractor to pull it out........By the way Im the poor farm hand not the rich farmer lol

 

My truck is a 99, and you bring up a point that makes me kind of worried. I'm doing this swap into my 99 150, but using the Navigator PCM to control the 4r100 and 5.4 dohc thats being swapped from the Navi. Will I even be able to make my 150's 4x4 that I currently have work? Or will the GEM in my 150 not work with the Navi PCM? Or will it work but lose the on the fly type engagement?

 

I wish you well on this but my reply #4 is coming around now that your beginning to see all the issues and questions for which I was criticized for bringing up under the term 'hassle'.
Back yard engineering takes a lot of research and understanding and even then it may not all work out.
You have to look up the differences between transmission control, harness etc.
The Gem may be different. It has nothing directly to do with the PCM in an F150.
What about 4L? That's another issue that takes special handling by the GEM .
And the GEM does control a lot of other things. Is there going to be compatibility on that as well if changed out?
You have to know both systems to have any chance of knowing what can crossover and work.
It took dozens of engineers to work out the systems and your only one person going to try and cross breed two versions yet?

Good luck. I wish you the very best.