Hello!~it's getting close to that time that I might be needing to put my Jeep into 4 wheel drive. By the way, I guess I have Command Trac Axle Shift Motor.
It seems to be having a problem, the last time I put into 4 wheel drive it seemed like it didn't catch right away.
Then when it was in 4 wheel drive it made some noises.
It appears to work on vacuum?
And one of my friends said that it is built into the front right axil housing.
I never took it apart yet, but it appears (according to the Chilton manual) that it has a shift motor.

Is there any way to check that shift motor to see if it is working correctly?
John

 

99% chance it's trashed, dump it;
https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/

 

I've got the same problem and read the article but still unsure how to keep it locked in, I'm kinda slow lol.

 

Ok!~I read the post at the site.

So does that mean that if you remove the drive motor and put it into 4 wheel drive that it will stay in 4x4 all the time?

How much could that drive motor cost...any how?

I like 4 wheel drive, but don't like it full time.

I have another Laredo on my land that is 4 wheel drive...might take the parts out of that one.

Also the local junk yard has at least 4 Jeeps there.

So it is the drive motor that is bad?

Thank you!~very much, John

 

No, it will not be in 4wd all the time.

That thing on the axle, all it does it turn the passenger side axle from 2 pieces to one. It was thought to keep fuel mileage from being hurt from the extra drive line power loss. But in later years they just put in a one piece axle. That axle disconnect is just not needed.

Flip the collar over, which locks it into a one piece axle. The tcase is what switches it from 2wd to 4wd.

 

Just do this:

https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/

 

I am still wondering how the Jeep 4 wheel drive (Command Track) works?

Is the axil still turning on the left side when your driving down the road, not in 4 wheel drive?

So I understand that the t-case has to be put into 4 wheel drive to get the drive shaft turning in the front.

So if you lock the axil on the right side (then it would be like a solid axil as on the 1991) can the wheel turn without the axil turning?

Maybe I'm really slow at grasping how this works!!!

I have a 1967 Dodge 4x4 and it has locking hubs.
So to be in 4 wheel drive... I have to lock in the hubs and put it into 4 high or low. Other wise the axil are not turning in the front....right?

Thanks!~John

 

By doing the cAD mod, you are making your front axle operate just like your Dodge with the hubs engaged. It's what Chrysler did in late 91, but no hubs.

 

I understand what you saying about the cad mod and I am not trying to be difficult, but I'd like to know what goes wrong with the original equiptment?
How does it work? I know it works off vacuum, but what goes bad?
Where does the vacuum come from on the engine?
Could it be something as simple as a vacuum line falling off?
Is it a loss of vacuum or does the drive motor wear out and can you see something damaged or warn out?
Any one ever figgure these out? I have a parts Jeep that has the same drive motor how can I tell if it's good or bad?
John
I live on top of a hill (300 feet higher than our town) and need 4 wheel for the winter in Mt.

 

It's unreliable. Here's why:

There are numerous places for vacuum to be lost due to old rubber hoses.
The vacuum diaphragm in the vac motor can fail.
The vacuum harness doesn't fit securely on the vac motor and can be pulled of by driving over small plants.

The vac motor shaft can seize.
The shift forks can bend slightly. They went through 2 revisions of the forks to address the problem.

 

I'm one of the few here who doesn't having it work as designed. The line that comes off your intake, back across the firewall, then forward down to the vacuum ball behind the right front bumper, that line has a "Y" sort of hidden there down near the trans dip-stick. That vacuum goes to the vacuum switch on your transfer case.

The vac-disco is sort of neat. In 2WD it holds the shift fork on the slip collar one way. Then when you select 4WD the switch on the case provides vacuum to the other side if the diaphragm to pull the collar over. ONCE IT IS ACTUALLY OVER, vacuum is diverted to the switch that turns on the light on the dash.

The vacuum lines on the disco can be knocked off really easily by brush, maybe even snow. You can secure them with a large zip-tie, (sort of just snug, not tight)

Was just thinkn'. I bet those of you that have hacked yours could find a vacuum line from the case that you could rout to the switch for the light.

 

Well I guess I have one more question.
Can you install Warn locking hubs on a 89 Cherokee Laredo?
I did on my 67 Dodge.
Don't know much about these Jeeps, but learning more and more each day.
Thanks!~John

 

One more thing (I hope) can you start up the vehicle with the drive motor off the axle and then have someone switch the vehicle into 4 wheel drive and see if the drive motor is working?

I am not trying to drive you guys crazy.
Thank you!~John

 

Even though the motor is working, it doesn't mean the "system" is working. The shift fork can be tweaked, the slider gear can be stuck on the axle etc. Just eliminate it.

 

Yes, you can. (assuming you mean the vac-disconnect on the right axle). Last century I had the fork break on my 84. Comen up on 300K on my 90, only issue has been the lines gettn knocked off. I was a little surprised how nice the front diff looked when I had the cover off a couple months ago.