4 wheel drive puzzle

[ruralandalone]

I apologize  for what might be a really strange post.   Any help or suggestions would be appreciated.

I am continuing my restoration project on my 1986 Commanche  2.5l gas  pickup.   Four wheel drive.  I know it is 4 wheel - from underneath - but:

I am in the process of starting on the interior,  and I was looking at the high-low lever and the  shift lever.  What has become rather obvious is that there is no "select-trac" lever on the plastic surrounding the stick shift.  Nor is there any place for one.  So either  the surround is not original, or it is not a ":selec-trac" transfer.. 

Further investigation shows that the transfer case is a New Process Gear 207AM3. 

So here are my (admittedly odd) questions:

1) What kind of control did (does) this  transfer case have?  Is it a mechanical lever, an electrical switch, a vacuum switch, or what?

2)Is this the right transfer for an 86?

3)What parts am I missing?

 

My previous experience is only with military 4wd vehicles.  This jeep is the youngest vehicle I have ever worked on, and I admit I am out of my depth.  Levers I can figure out....

[Eagle]

For 1986, Selec-Trac referred to an NP 228 or NP229 transfer case that used both a lever and a separate vacuum switch to engage 4WD. The NP207 was what was called Command-Trac. It's the predecessor to the NP 231 transfer case that was used from 1987 through the end of production in the XJ and MJ. No full-time position, only 2WD-High, Neutral (which wasn't a true neutral), 4WD-High, and 4WD-Low. Shifting was done by the lever to the left of the console,

 

Please post a photo showing the shift bezel and lever(s) on your console.

[ruralandalone]

Thanks for taking the time to help me out. No need for a picture - You are clearly correct.  The truck has "command-trac" and only one lever.  Now to see if I can get it to work (after re-reading the manual a few times).

Upon reflection, it was rather a stupid question.  More research on my part would likely have found the link between the transfer case model and the type of drive.

[ruralandalone]

SO, the command trac control works.  At least as far as the front drive shaft.  Unfortunately  the  front wheels don't spin in 4wd.  So there is likely a problem - maybe with the vacuum actuator?  I am open to suggestions as to how to diagnose this further...

[Pete M]

the vacuum actuator (CAD: central axle disconnect) is a super common failure point.  see the link in my sig for a couple writeups on how to bypass it and never have that problem again.   

[ruralandalone]

That is wonderful!!!!!!  Nice clear instructions and I should have no trouble doing it.  I took the vacuum lines off at the actuator this morning and 2 of the 3 are completely full of rust. It does not look like mine has worked for a LONG time.

Does it matter if I plug the 3 lines or not? OR just hook them back up even though they are not going to do anything?

 

BTW, the whole concept of a disconnect seems like a needless complication to me.  More to break for a minor reduction in parts wear and a (perhaps) minor increase in mileage...

[Pete M]

Jeep did away with it in the early 90s.  I would follow the lines back to the t-case and plug them there so you don't have a vacuum leak in the future.    

[ruralandalone]

I pulled the CAD off, cleaned it up, moved the sleeve over, and tried it by hand.  If I turn the driveshaft by hand the wheels turn.  Looks good.   Also discovered that, while the vacuum unit itself looks good, the vacuum lines are rotted to the point that they leak.   So the vacuum lever is not going to work.  Since the fork stayed where I put it, I figured I would simply reinstall it without removing the c clip, and see what happens.

I started the engine, put it into 4wd, and looked at the results.  The front wheels turn. Sort of.  Certainly not at the speed of the rear wheels.  In fact I could stop them with my foot.  Odd.

Took the CAD off and the fork had not moved.

I moved the sleeve to the disengaged position.  I discovered that if I put a  screwdriver on the   drive gear (on the left) I could turn the driveshaft by hand and the gear would not move.  So it seems that there is major slippage somewhere between the driveshaft and that gear.  Any suggestions how/where to proceed?

[Pete M]

might be time to verify the gear ratios.   

 

the fork won't stay put forever.  you need to either flip the housing or use a hose clamp on the shaft to keep the collar in place.    

[ruralandalone]

I agree. I just wanted to see if it would work.

Am I correct in thinking that the gear on the left should be directly and firmly coupled to the driveshaft?

[Pete M]

"gear on the left"? 

[Eagle]

1 hour ago, ruralandalone said:

I agree. I just wanted to see if it would work.

Am I correct in thinking that the gear on the left should be directly and firmly coupled to the driveshaft?

 

Yes ... and no.

 

I assume you're referring to the inner axle shaft on the passenger side of the front axle. The central axle disconnect (CAD) basically works like a transmission synchronizer -- the slider is always engaged on one shaft, and the vacuum motor moves it over to engage or disengage the other shaft. But -- the front axle has an open differential, so even with the CAD engaged the front wheels won't be locked together.

 

That said, your explanation could be a bit clearer -- there are no gears in the CAD, just two axle shafts, a sliding collar, and the vacuum motor.

 

Let's see if this will come in:

 

[ruralandalone]

I was indeed referring to the inner axle shaft on the passenger side of the front axle .  The shaft onto which the slider goes when it engages via the cad.  By "gear" I was referring to the teeth cut on the end of the shaft. 

The way I see it, I should not be able to turn the driveshaft by hand with the inner shaft (at the cad) locked in place with a screwdriver.

And what I certainly don't understand is how the driver side wheel is connected and disconnected via the cad.   The passengers side would seem to be self evident.  I looked at the drawing you provided (I have the parts cd) but I confess I don't see the connection.  

 

[Eagle]

Do you understand what a differential is, and how it works? The inner axle shaft on the passenger side does NOT connect rigidly to the wheel on the driver's side. It goes through the differential -- which is not locked.

[Pete M]

if the CAD is unlocked, the ring gear spins, the spider gears do their thing and all the force from the driveshaft is transmitted to the inner half of the pass axle shaft which spins furiously but the power goes no where.   

[ruralandalone]

Thanks for all of the information.  My mechanic buddy had a look and feels that everything is working as it should. Live and learn!!