All I've been able to find is information about the notorious CAD Dana 30.

I have a stock 1991 XJ Cherokee 2 door 4wd. It has a Dana 30 High Pinion Non-Disconnect front axle.

The symptoms:
4wd on the floor engages, light on the dash displays part-time (4high and low). the drive axle from the TC to the front dif locks in but the front wheels do not turn... There is no grinding, and no noise from the front axle while in 4wd.

Diag so far
I lifted front end and spun one tire, the other spun the opposite direction, again without grinding or other noises. The U-joints are intact. When spinning the tire with 4wd engaged the front passenger tire felt like it locked up for a moment but then gave without resistance.

I'm at a loss with what the hell could be going on in that dif, I haven't had time to open it up yet. I want to know what i'm looking for and do any possible diag before tearing into it.

The dilemma:

I have a spare parts jeep with a Dana 30 CAD axle that has already had the PosiLock (branded cable, vacuum bypass) installed ready to swap in. I would prefer having the High pinion if feasible. It's a weekend rig, not a daily, and I don't want to dump money into her just yet.

The Questions:

1. What steps would I take to diagnose which component of the front driveline has failed.

2. Is it worth it to repair the high pinion non-disconnect? or should I save the time and just swap out the axles?

 

I would say it sounds like an issue in the transfer case internals, might want to look into that, could be the chain is slipping some how or the shift fork isn't engaging. Have you had the front end off the ground in 4wd with the rear driveline disconnected? Because when you turn one wheel by hand with the case in 4 it will still turn because it is an open differential, same reason the other wheel spins opposite when you turn it by hand in 2wd.

 

Disconnect front drive shaft from differential. Put transmission in neutral. Take a pipe wrench and turn the yoke on the front diff. If the jeep rolls, your problem is between the yoke and the tranny, which points to the transfer case.

 

x2! Start from one end and work your way upstream.

 

So I got out this morning and took a look. With the driveshaft up front connected and the TC disengaged I can freely spin the Front Drive shaft.

This would point to a diff issue correct? since my axle is a non disconnect? The front drive shaft should spin the tires but should not spin independently is my understanding.

 

If you able to freely spin the front driveshaft while it's connected to the front differential yoke and removed from the tcase, your problem is definitely in your differential. The front diff is constantly engaged from the front tires to the driveshaft. The mechanical connection/disconnect is made at the transfercase. I would simply pop the cover off and have a look inside. I'm sure it's going to be very obvious what the problem is. I'm interested in seeing what's going on inside this thing, post some pics!

 

If your front wheels were on the ground and you could spin the front drive shaft without the jeep rolling you definitely have a problem in the differential or with one of your axle shafts. I'm having a hard time picturing what could cause what you are describing in the differential without you hearing some hellish noise.

The DS connects to the yoke, and the yoke is splined to the pinion. If the pinion turns the ring gear has to turn unless there are no teeth on either the the ring or the pinion. If the ring gear turns and both wheels are on the ground the vehicle has to move unless the axle shaft on the ring gear side is broken.

I would think that if you had a broken shaft you would most definitely know it. If all the teeth were broken on either your ring or pinion I would think that would be obvious also. You just need to jack the front up and pull the diff cover and see what gremlins are lurking in there.

 

The ring gear could be missing somehow

 

That would be a kick in the nadds.

 

That's why I want pics lol. If the ring gear is gone, hilarious....