So I just repaired one of vac lines to the cad, and got the 4wd working on my truck again. It still takes a while for it kick in when you shift on the fly, and it clunks when disengaging due to its lack of speed. At a stop it goes in fine once you roll back and forth a bit.

I was thinking about possibly hooking this up backwards, and running it off pressure instead of vacuum, and have a manifold with switches up in the cab much like someone with air suspension would. You'd obviously need a tank somewhere, but wouldn't this be a quicker more guaranteed way of engaging 4wd?

Please share your input, as I'm debating this idea.

 

get the posi-lok from summit, it makes it so it engages 4wd everytime...read about it and you'll know

 

what he said ^

 

You can't pressurize the vacuum motor and have it work properly. The Posi-Lok is the best solution (I have it). The vacuum design is a POS.

 

+3 on posilok.

 

Why not? Its just the reverse of vacuum. When I took that vac motor out last fall to unseize it, I cleaned/tested it out with a compressed air nozzle, and it shot back and forth with no hesitation.

I agree that it probably wouldn't work without a pressure regulator, but with one set moderately low, but still high enough to power that motor, you'd be set no?

Perhaps that vacuum motor is only designed to work under negative pressure, so repeated blasts of pressure on it would cause leaks, esp. in an older one?

 

if your motor is moving freely you might want to try to clean up the axle shafts and the slip ring as well, mine failed to work when i was stuck because of carelessness on my part when replacing the wheel bearing. what happened was that when i put the axle back in, it got some dirt on it, and that dirt got stuck in the splines and thus causing the ring to get stuck, and not engage.

 

i worked on my cad several times before i gave up. it was always something. first the shaft was sticky. then the light switch malfunctioned. then the vacuum line got torn off a couple of times. each time it screwed up was when i really needed it and i ended up stuck, walking, and pissed off. **** all that mysterious and unreliable vacuum operated crap.

there's nothing more satisfying than the solid feel of the t-case shifting and the solid feel of the posilok cabling pulling the collar in.

 

I AGREE... though i have yet to invest into the posilock, though that is in the near future, along with a back up camera since i now have some serious light back there.

 

For one, the design is vacuum actuation for engaging anf disengaging, there is no pressurized supply. The vacuum switch on top of the transfer case determines which side of the supply line has suction or not. It does not switch between suction and pressure. You would have to find a way to provide pressurized air, not an easy task on thse trucks.

But that all pales next to my real meaning. Read DVaughn's comments, because he's right on the money. As I said, the system sucks (no pun intended), not for any one reason, but for a multitude of reasons. It is poorly designed and easily compromised. Think about it, The CAD does not switch you from 2X4 to 4X4, it switches you from 3X4 to 4X4. When you shift into 4HI or 4LO you are connecting the transfer case output directly to the left front wheel. The CAD simply connects the right front wheel to the system, it does not have anything to do with anything else. It doesn't stop front axle parts from moving because those are already connected via the left front axle shaft. The CAD was a brain fart on the part of Chrysler engineers as was the idea of using 25 feet of damage or failure prone vacuum tubing to control it. The cable system is much more practical.