Ok. I have just about had it with my four wheel drive. I have spent countless hours on the thing and more on new parts than I would like to admit. At this point, I need some input because I am out of ideas.

Symptom: Clunking in front end when in 4hi or 4low, forward or backward, usually under torque (turning or going up a hill). I am reasonably sure this is caused by the shift collar in the CAD slipping off the end of the intermediate axle shaft, since the splines are buggered on the one I pulled out of there yesterday.

Actions: I started by replacing the pads on the CAD shift fork, then the fork, then the intermediate shaft, then the collar and finally the entire actuator assembly. I also tested the vacuum. I don't have a vacuum tester, but I held my finger on the lines coming from the t-case switch and the suction seems as strong as it is right at the vacuum pump. Oh yeah, the t-case switch is also new. I tested the actuator and the fork will move as it is supposed to when I move the t-case shift lever. It is strong enough that I can't budge the fork from the 4wd position by hand.

Theory: There seems to be some longitudinal play in the intermediate shaft, and I'm wondering if that is allowing the collar to slide off under high torque. I can use a screw driver and force the intermediate and inner passenger axle shafts apart about 1/8-3/16" where the CAD collar spans them. The only thing I can think of is that the bearing is worn in the differential and it is allowing the shaft to move in toward the diff just enough for the CAD collar to slip off.

I'm getting way too good at pulling Dodge hubs (anti-seize is a miracle). I don't know what else to do, and I really need to figure it out because winter is coming. I don't want to ruin the new intermediate shaft ($$$), and I can already see wear on the splines just from testing it once gently last night. I should also say that I have replaced the u-joints, ball joints, entire steering linkage, track bar, and rebuilt the transfer case. There isn't much left at this point.

I'm also wondering whether anyone knows if the passenger side inner axle shaft from a 2002 Dodge D60 will fit in my 95. I have heard that the 02 had a traditional solid long side shaft right before Dodge went to AAM's in03. I'm fed up with CAD.

Finally, I don't believe that a posi-lock cable alone will fix my problem. I agree that it is a superior system to the vacuum acuator and I think I'm going to install one while I'm at it (if I don't simply stuff a solid shaft in there), but something is moving in that tube and I'm not convinced it is the shift fork that is causing all this.

Sorry for the long post. This is but a small glimpse into my frustration. Despite all this, I should note that I haven't had a bit of trouble with the engine and I love my truck. The worst part is that the cost of replacement parts for the 4wd is destroying my performance mod budget!!

Thanks.

 

Update: I have a plan to eliminate an important variable. Since I have and extra actuator assembly, I will lock the shift fork in the 4wd position and then test it out. That should tell me whether vacuum is a culprit. I'm still wondering if the space between my axle shafts is normal. Has anyone else experienced that? Thanks.

 

I have thought about replacing the CAD/split axle with a solid axle. I know it is done in Jeeps. The front end would spin all the time, but it does in the new trucks, so no issues there.
Have you checked other things like engine mounts and transmission mounts? Drivetrain windup stresses alot of stuff, and I agree that the shaft could be a a culprit. What do the splines on the inside of the collar look like?

 

The splines on the inside of the collar fared better than the outside of the intermediate shaft, but there is some wear. That is why I replaced it with a new one. I am going to try to test out my version of a perma-lok tonight if I can sneak out to the garage. I think that will answer some important questions.

Based on the research I've done, the only problem with a one piece passenger axle shaft would be the fact that the front driveline would turn all the time. If it is out of balance, which could be the case since they weren't designed to run that way, I might have some vibration to deal with. Believe me, at this point I can deal with that. There are some smart guys with the means to fix that for not much money. I need 4wd that works.

The problem is that I'm having trouble finding the correct shaft...for under $500. If I knew what other truck models had the same length shaft with the same splines and the same yoke size, I would be off the bone yard. I have considered welding the shift collar to the axle shafts, but I thought better of that once I realized I wouldn't be able to get the axle out of there without grinding the welds. I suppose I could weld the shafts themselves together and then perma-lok the collar in place, since I doubt a weld would hold up to the torque of a mildly altered 6bt on its own.

In the end, this is why I figured I might as well replace the factory parts and run a stock setup or throw a posi-lok in there. I would have gone straight to the posi-lok, but the friendly neighborhood auto recycler had the entire shift assembly for $40 and it looks almost new. Silly me, I thought it would also save me time!

 

I have eliminated vacuum as a possible problem. With the shift fork locked in the 4wd position, the collar still slips. Furthermore, when turning to the right, I can hear what I think is the intermediate shaft clicking against the collar. That tells me that the intermediate shaft is sliding into the differential at least 1/4" and allowing the collar to slip off. That has to be what's going on, right?

So, what is the next step? It seems that I have no choice but to take the differential apart and figure out what was supposed to hold the axle shaft from sliding inward. Does anyone know where I can get a some photos/diagrams of the carrier? Thanks.

 

This thread is starting to look like a monologue...

Anyway, it looks like Dodge discontinued the CAD in the second half of 2002 (after 8 years of nonsense, imho), but changed from 30 to 32 splined inner shafts in2000. Therefore, unless I change out the side gear in my differential to a 32 spline, I wouldn't be able to use the stock inner shaft from a 2002 truck.

At this point in my research, I'm wondering about two things:

1) Could the inner needle bearing at the CAD be worn to the point that it allows excessive space between the inner and intermediate shafts, thereby causing the shift collar to slide off?

2) Do these symptoms indicate a worn or damaged side/inner pinion gear in the differential?

I am vexed by the fact that I have visible wear on the end of the new intermediate shaft after driving less than two blocks.

Also, Quad4x4 sells a bushing that fits in between the inner and intermediate shafts. I have not seen one of those in the rigs I have dealt with. Is that bushing supposed to be there from the factory? Will that help my problem? Thanks again.

 

I had issues with the CAD at one point. found the shaft on the vacuum selector had been bent somehow.
If you have 28"hg vacuum or so you probably dont have leaks or a bad pump. are you sure the shift fork is moving the coupler into the right spot?
try prying against the shafts and see if something is out of line or has play in it.
the stubs should line up evenly and stay that way. its possible they arent lining up like you said. Ive never seen it happen but its possible.
the collar should slip over the two shafts and not allow the splines to slip. If it is slipping something is really worn and/or theres a big gap between the shafts.

 

I'm also wondering if it is the gap. I have about 1/8-3/16" of play between the shafts. I can move the intermediate shaft back and forth that much with my fingers. Is that normal?

 

Both sides move, or just the inner shaft?

 

Just the inner. Outer is tight.

 

I have additional information to add to the confusion. I pulled my diff cover off (I created an impressive stain in the driveway in the process when I forgot how to do it correctly) and everything is fine in there except for one thing: the intermediate shaft has slid into the carrier so far that it is actually hitting the carrier cross pin. The driver side inner axle shaft is flush with the end of the side gear, like it's supposed to be. I'm not a mechanic, but that doesn't seem right to me. Some where, some how, whatever is supposed to hold that intermediate shaft in place is no longer doing its job. I'll post pics when I get them off my phone in the morning. It is quite a sight.

Has anyone seen this before? I have looked pretty hard in the threads and I haven't been able to find an answer.

I think my next step will be pulling my passenger side hub again and removing the axle shafts so I can get a good look at the needle bearing in the axle housing at the CAD opening. I really don't know what else it could be.

 

Here are a couple of shots I took of the carrier last night. I tried to push the end of the intermediate shaft out with my finger right before I took these pics, and that is why there is a small gap between the end of the axle shaft and the side of the carrier shaft. It was pressed right against it at first and I was only able to move it an eighth or less.

I did confirm that the new intermediate shaft was the same length as the old one before I put it in there.

 

I spoke with Dan the Gear Man from Quad 4x4 yesterday. He said that my carrier condition was perfectly normal and that my problem was unlikely CAD related. I took a very close look at the roller bearing at the CAD and it looks fine. Actually, the splines on the new intermediate didn't look bad either the closer I looked at them so I re-installed my posi-lok and solicited some help from my neighbor. We put the truck through a series of tests to try to narrow down exactly where the sound was coming from, and I think we may have come up with some possible answers. As the drivetrain builds up strain when the front wheels are turned, the front driveline will actually start shaking and then the loud popping noise occurs--somewhere in the middle of the truck. Up to that point, I had never had someone else drive and put my head under there to pinpoint the noise. There is only one joint I haven't yet replaced: the double cardan. I can't get any movement out of the thing while it is in the truck, but I can see that the cups on the u-joints have been leaking. Who knows what condition that ball is in. I ordered rebuild parts and will update when I have them replaced.

Interestingly, this has happened to another DTR member, so I may be on to something.

https://www.dieseltruckresource.com/...t=cardan+joint