Thanks to all that post before hand. I have a 96 Cummins with a stockish motor and manual transmission. The problem is that the truck jumbs or catches when you drive at all in either 4 hi or low. It felt like it was in the front end, but its hard to say.I recently went through the whole front end, new wheel hubs, seals, and cad actuator. Even after this it still jumps and clunks when you drive it. My question is where do I need to investigate more to find the problem. The vaccum lines all looked ok and the four wheel drive shifter is in proper adjustment. Any help would be great.

 

Sounds like you could have a bad u joint thats binding as the axleshaft rotates, thats where I'd start looking anyways.

 

What he said

 

ya replace both sides at hub units and check the front driveshaft ones two

 

Bad u joint, while you're at it, id check the actuator and make sure that it is working properly. I'd consider upgrading to the Posi-Lok system, much better than the CAD i hear!

 

Don't mean to jack the thread but my shift fork keeps jumping off the collar. First the little plastic pieces broke off so we replaced them but when they did again we put a screw in it and it worked for a while but is doing it again. Any ideas?

 

Ya I bought the posi lock system and I love it. If you say that all ujoints are good, front end good meanings bearings, seals etc....then I would have to say that it sounds like your transfer case chain is slipping. Its not uncommon at all to have the chain stretch in these t-cases and skip teeth as it rolls. And no, it will not do it in 2wd but only in 4wd either hi or low, it dont matter. I helped my buddy swap out his t-case for the exact same reason. I hope its not in your case, but it may be something to look into. Good luck.

 

Thanks, to all that posted. The ball joints are only a year or two old, and the same for all the U joints in the front end. I like to think that its not the transfer case because you can feel the clunking coming from the front of the truck. I'm going to have a dedicated 4x4 shop look at it because it doesn't make sense. The front end is basically all new now and shouldn't be giving me problems.

 

Trust me they can still be bad... I have done them twice in one year before!

 

theres a ball in between the u-joints on the back end of the driveline they go bad quite often that can cause the u-joint to freeze up/lock up. i had the same problem