2nd Gen Non-Engine/Transmission 4x4 troubles

[THess]

Sometimes when I put the truck in 4 wheel drive it jumps. It doesn't come out of 4x4 according to the light, and the transfer case lever doesn't move or anything it just sort of jumps. I took the CAD off of the axle and one of the pads that is on the shift fork had broken off. I found it under the shift collar in the housing. Could this pad be the cause of the jumping? If it is does anyone know where to buy just that part or do I have to buy the whole thing? I need your help; we've got a lot of snow on the ground here and 4x4 is pretty much a necessity.

 

[SFPADGETT]

When my shift fork broke, the light would come on, however the 4 wheel dirve would not engage. My truck always has "jumped" when putting it into 4 wheel low, not much when in 4 wheel high

 

[THess]

I know that 4 wheel drive is engaging to some extent because when I'm stuck and put it in I can get out. The feeling is sort of like the jumping on a dry road when you go around a corner in 4x4, but it happens while going straight on a slick road, almost rythmically. My shift fork is fine, I think, but one of the little plastic pads that slide in the groove is broken.

 

[DieselDoghouse]

Have you investigated the rest of the front driveline for any out-of-balance/jump - the double cardan joint fer instance?? Also I believe the teflon feet for the yoke are still available as rebuild parts.

 

[tstephens]

I have had a similar problem for over a year now and still have not solved it. Mine will also jump, or more of a clunk or binding sound. It too does it going straight. I first though it might be the chain in my transfer case, as I had run it out of fluid, not aware that it was leaking. I rebuilt the case, with new chain and all new bearing, and a new shift fork in there that was worn. Still made the same sounds. Then I checked the vaccuum to the CAD -that was fine. Took the cover off the CAD and everything seemed fine in there too, and my 4x4 indicator light does come on and stay on in 4x4. Next I took the diff cover off and inspected the gears in there-looked ok too. I replaced the axle u-joints. Still sounds bad. Just last week I replaced the u joints in the front driveshaft - made no difference. I was also told it could be the 4x4 shift lever adjustment, so I disconnected that and put it in 4x4 manually underneath, still making same sounds and binding/jumping. Mine really sounds like it is in the transfer case, so my next move is to remove that again and take a closer look at the components inside, although at this point I do not know what it could be. That will be after this crazy snow season is over here too. Mine will still get me out of a stuck situation, but it really sounds so bad that I don't dare travel over 20 mph in 4x4.



These are all things you can check and if you figure it out, let me know please. Good Luck

 

[THess]

If it was something in the driveline like the u-joints would it jump all the time. Mine doesn't. Sometimes it does right away, but other times I can drive a few minutes and it starts then stops and starts and stops. I checked the vacuum in mine and it is fine too. The motor moves the fork fine and completely with the cover off. Could the vacuum motor be bad anyway, and be letting the two axles come apart just a little and then slip back in?

 

[HHhuntitall]

Check your vacuum vent line. It runs out of the transfer case vacuum switch on top, and up to the back of the engine. If it's stopped up, the vacuum actuater on the axle can't move with very much pressure, as it's developing a vacuum on both sides when it moves. I may move without pressure against it. My ranch hands drag the lines off all the time in the brush, and they'll get sand in them, and stop up the vent line, and sometimes the vacuum lines themselves. Check all your lines for blockage. You might check the vacuum switch, as well. I've got a '98 that clunks no matter what, and it seems to be the axle disconnet when it engages. When rolling the axle disconnect engages, suddenly spinning the center shaft, or stopping it, depending on your situation. My 4x4 light doesn't work, as the light wireloom on the axle has been ripped off for two years.

 

[tstephens]

If it was something in the driveline like the u-joints would it jump all the time. Mine doesn't. Sometimes it does right away, but other times I can drive a few minutes and it starts then stops and starts and stops. I checked the vacuum in mine and it is fine too. The motor moves the fork fine and completely with the cover off. Could the vacuum motor be bad anyway, and be letting the two axles come apart just a little and then slip back in?

I agree that your problem doesnt sound like u joints - I didn't think mine did either, but many people suggested that and I had replaced most everything else already.

I suppose the vacuum motor could still be bad, but in my case the 4x4 indicator does not flicker at all while clunking, which leads me to believe that it is staying engaged. Yours could be different though - keep us posted if you figure it out.