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2001 with CAD and vacuum actuator, has anyone replaced this with a factory or store part and what would you recommend? No, I don't want to the cable, just replace what's broken. Rock Auto has a standard motors unit,a dana unit where the part numbers don't match anything online...

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The CAD system is very simple in function and action.  Here's a link to help you diagnose... http://dodgeram.org/tech/repair/4X4/4x4_engagment.htm

 

I think the most common problem causing CAD issues is there's a vacuum problem or vacuum line problem or the axle collar inside the CAD is worn and wont slide properly.

 

One thing I think worth mentioning is that even though the trucks owners manual may state that the CAD 4wd is shift on the fly..... doing so at speed above 5-10 mph can be damaging to the synchro ring inside the transfer case.  Shoving it into 4wd at higher road speeds can wear out the synchro which will in turn wear out the slide collar in the CAD.

 

Unlike the full time non-CAD systems, the CAD system is a "part time" 4wd which means the front driveshaft is not spinning at road speeds while in 2wd.  So to engage 4wd the transfer case has a synchro ring which acts like a clutch that speeds up the driveshaft to whatever speed the rear driveshaft is spinning.  Then when the two driveshafts are speed matched, the left and right front axle shafts are speed matched as well allowing the passenger side split shafts inside the CAD to be connected via the sliding collar. :thumbup2:

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Don't forget mechanical damage of the CAD vacuum motor. Like mine was struck by debris and bent the rod in the vacuum motor causing it to hang up and stick. Still to this day that truck hangs up on the release you need to stop back up 5 feet and the CAD will release. Been several times to have issues with vacuum lines, under heavy throttle vacuum low have the CAD unlock, list goes on. MoparMom even owned a Chevy S10 with a similar system and had the same issues with vacuum and loss of 4WD truck was sold within a few years it didn't survive Idaho winters at all.

 

Non-CAD system doesn't have these issues. Even with a driveshaft that spins 100% of the time when you engage its lock. When you push that lever back to 2WD it's instantly unlocked. No CAD collar to hang up or vacuum issues. A much simpler system with no failures.

 

Being I own one of both system the 1996 Dodge is CAD axle and my 2002 Dodge is NON-CAD axle. 

On 4/23/2018 at 11:43 AM, CTcummins24V said:

2001 with CAD and vacuum actuator, has anyone replaced this with a factory or store part and what would you recommend? No, I don't want to the cable, just replace what's broken. Rock Auto has a standard motors unit,a dana unit where the part numbers don't match anything online...

 

I've had to replace the one on my 1996 and its a NAP unit. Still having issues with hanging CAD ring on release. It'll engage fine but you must stop and back up to release this on. It was doing this before the change and after as well.

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I have been thinking of going to the cable actuator on mine. My vacuum stystem has been working after trouble shooting the vacuum lines some years ago. I know that there are a ton of the vacuum operated systems on the road, but it still makes me nervous. Would hate to lose 4x4 at an inopertune time. 

 

The real problem with mine is the 4X4 light on the east stays on all the time. 4x4 engages and disengages properly, but the light never goes off. Replaces the switch with no luck. 

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The 4wd indicator switch for the bulb is nothing but a contact switch, nothing complicated.  If there's trouble with the light not working correctly then make sure the wiring is fine and there no corrosion.  If the switch and wiring check out with a tester then its likely something worn in the CAD housing itself.  Lots of people like to place blame on the vacuum part of the CAD system but they overlook the fact that if the collar or axle bushing wears out then engagement and disengagement will be a problem.  Converting to a cable system only masks this. :thumbup2:

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My 1/2 ton Dodge has the CAD. Has never worked since I owned the truck. I have the 4x4 PosiLok sitting under the seat. Of course I haven't driven the truck in nearly three years. It's kind of a beauty queen with only 74k on it. LOL!

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3 hours ago, KATOOM said:

Lots of people like to place blame on the vacuum part of the CAD system but they overlook the fact that if the collar or axle bushing wears out then engagement and disengagement will be a problem.

 

Might be worth looking into on the 96 Dodge and seeing if I can resolve that issue a bit more. (Sticking on release time).

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On ‎5‎/‎9‎/‎2018 at 6:42 AM, KATOOM said:

One thing I think worth mentioning is that even though the trucks owners manual may state that the CAD 4wd is shift on the fly..... doing so at speed above 5-10 mph can be damaging to the synchro ring inside the transfer case.  Shoving it into 4wd at higher road speeds can wear out the synchro which will in turn wear out the slide collar in the CAD.

 

I agree.  It was partly for this reason, and also to gain the option of having two wheel drive in low range, that I disconnected the vacuum controls at the transfer case and installed a manual vacuum control valve in the cab to engage the CAD.  When roads are expected to be snowpacked, I will engage the CAD before I move the truck so that I can go in and out of 4wd on the fly as needed without harming the syncrho in the transfer case or harming  the CAD unit.

 

The vacuum control valve is a heater control valve from a Pontiac in a salvage yard.  The cost was $2.00 and with a slight modification it has been in use for over 200,000 miles.  The truck has 292,000 miles currently with no CAD problems yet.

 

- John

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