This started a few weeks ago as a slight vibration on take-off from about 5-10mph. Then it would smooth out. It'd do it everytime I took off from a stop. I parked it for maybe 4 days, and drove my lil blazer. Tried to drive it the other day and you cant go over 3mph without it trying to rattle itself apart. I propped it up on stands and had the wife drop it in gear while I looked at the rear driveshaft (thats where the vibration feels like it coming from, the back) and the center bearing looked like it was wobbling real bad. Pulled the DS and replaced the bearing. I really thought that was the problem. No such luck, still does it just as bad as it was before. Anything I should look at before I haul it to the dealer, as it is undriveable right now. I did notice that up on the stands only one tire turns when I spin the driveshaft. I have a LSD so shouldnt both turn? Maybe my rearend is jacked? Any help would be appreciated. Thanks.

 

I assume you checked the U joints good?

With a LSD, one wheel will turn if your clutches are really worn out.

It could be a lot of things...when you spun the wheel, did it spin free? Was the tranny in park? If it was in park, the other wheel should spin the opposite direction. If in neutral, either the driveshaft will turn, the other wheel will rotate opposite (or both).

I would check the u joints first...un strap them and feel them rotating...don't just try to feel them while installed, you can't tell by doing that.

Also check your pinion bearing on the rear end...see if you can move it in/out or up/down (use a pry bar)...1/4" rotational play is normal.

 

When I had the shaft out, I checked the u-joints, smooth movement, no play. No play in the pinion that I can tell. Just crawled back under, and I believe I have bigger problems. Noticed when I spun the DS by hand it was binding in one spot. Looked at the transfer case and in the binding spot it lifts the transfer case up about and inch, as I spun the shaft, it went up and down, up and down!!!!!! What in the world is wrong now? Thanks for the info, and any more that comes.

 

sounds to be a sticking u joint. change em out first and see what happens. for there price and ease of changing them. start there. my ujoints didn't look like they where binding with little play. when i pulled them apart 90% of the needle bearings where missing and the cups where almost worn through.

remember always start with the cheapest route first.

 

Removed the DS again and sure enough the lead U joint in the second shaft was seized in one direction. Smooth the other way though, guess thats why I missed it the first time. Had to order them, of course noone had them in stock here. $55 bucks each, figured Id do all 3 why im at it. I dont have a vice, and noone has a u joint tool so I started taking them out with a socket and a hammer. Got one out, then smashed my hand real good. Guess I'll get the rest out when the swelling goes down enough to hold the dang socket again! LOL! Dang South Texas rust has em in there real good. Thanks for the help.

 

Yeah, I would have said U-joints also. I have gotten 30-35,000 per u-joint on the rear portion of the shaft at the carrier bearing. I had it replaced under warranty at about 32,000 and then just replaced it at about 65,000 with a greasable model. I changed out two of the u-joints but the one at the carrier bearing was so bad that it left a big rusty spot where I was working. Part of the bearing material had event sintered itself to make up for the slop so you couldn't feel it by hand.

 

Only one of the bearing cups was seized. The other three were healthy, but the one was seized so bad you couldnt even move it with a hammer. There wasnt much bearing left in it, just rust powder. Gonna pick up the new joints today, and hope Northern or Harbor Freight is open. So I can pick up a U joint tool. Hand is still a bit sore, and i dont wanna chance smashing it again.

 

My truck had hot plastic squirted into a middle groove. Even heating it real good, I couldn't get the darn things out. Most annoying Ujoint I ever changed. Good luck with them.

 

Mine had the plastic retainer as well, cutting torch put enough heat to burn out the plastic and the new ones came with the standard c-clip, as far as i can tell and according to my dealer, the factory u-joints on my truck have to be burned out, theres no way to pop out the plastic holding them in there.

 

Mine have the clips on the rear shaft, and injected plastic on the front shaft. Couldnt find a u joint press, so I bought a bench vise. The joint were so rusted in there, It broke the friggin vise. Just the little retainer bolt inside. I had to beat the ears on the DS while squeezing it with the vise and sockets, and it would pop loose eventually. Anyways, I replaced two of them, and the third, well, it can wait a little while longer. I know I shouldve just replaced it, but Ive spent all my 4 day weekend working on it, and it was time for a break. Trucks back in action, it sure felt good to drive it again. Been driving the S10 Blazer for too long!

 

Check at carquest for your ujoints. just did my there like 21$ each plus they have grease fittings.

 

The six speed trucks and the autos, apparently have different u joints. Automatic U-joints were way cheaper than the six speed ones.