Chasing a vibe

[RaysK20]

I have a pretty bad vibe happen at highway speeds above 55 mph. When your on the gas it does not seem to be there, let off and it shows up bad enough to rattle the transfer case shifter like crazy. I have new wheels and tires as of last week and the vibe did not change. I changed the ujoints and that maybe helped a hair but that was not it. The vibe is high speed not like a out of balance tire. I am starting to think a bearing is going out some place. I changed the oil in the 205 case and the 14 bolt rear recently, and niether smelled burnt. there might be a little up and down play in the case output shaft but it is little and the seal does not leak. Also the mounts seem ok, Any suggestions?

[WestButteTruck]

Could be a bearing......or a bent driveshaft

[Davetopay]

Originally Posted by WestButteTruck

Could be a bearing......or a bent driveshaft

Sloppy slip joint in the driveshaft? I know my front has some wiggle in it.

[RaysK20]

The rear slip shaft does have a little twist slop in the slide shaft. Not much though. Do I just get a new yoke or have to buy the whole shaft?

[RaysK20]

I am chasing down a vibration that happens around 55 but only when you let off the gas or just on it slightly like when going down a grade. I already changed the ujoints and have new wheels and tires so thats not it. I would like to know how to check out the rear wheel bearings. Do I have to take it all apart for a visual or is there a jack it up and shake test? If it does have to come apart, will the spindle nut wrench I bought for the front work on the rear? Thanks.

[LONGHAIR]

First of all, don't fall into the trap of "it's good because it's new". That one has fooled many people. Double check the "new" parts too.
Since you just changed the u-joints, are you sure that the driveshaft is "in phase" ? Meaning that the slip-joint was reassembled correctly. and the joint caps are lined-up.
Second, vibrations around 45-55 are usually tire related. I would check them again for balance and run-out.

As far as the wheel bearings, you are going to have to remove the axles at bear minimum.....and unfortunately that spindle nut socket it probably not going to work. The fronts are usually "pin type" sockets and rears have "hex" nuts with a washer that bends over one flat.
I'm not saying to neglect your rear wheel bearings....but I doubt that it is your vibration. Have you checked your pinion for backlash/slopiness. Does it "wiggle" or move in and out?

[RaysK20]

I climbed under there with a bar and could find no in or out movments of the pinion, and the seal area is not wet. The front slide on the drive shaft has a little bit of play though. The bolt on transfer case yoke is also moving up and down a hair. Not just the yoke but the entire shaft. Maybe a 1/16 of inch and about the same for the driveline slide. The wheels and tires are new and balanced. It did the same with the last set of tires. I replaced the ujoints about 2 weeks ago and they feel fine. Yes the shaft is in correct phase. The vibe really gets going at highway speed when you let off the gas. It disappears when you get back on it. Bad enough for the transfer case lever to really start rattling good.

[LONGHAIR]

How much lift? what size tires?

[RaysK20]

No lift everything stock. Motor mounts and transfer case mounts and new shocks good. The tires are 235-85-16. About 31 inches tall. Tires are a mild tread BFG all terrain.

[LinemanL.U.47]

Sounds like a drive shaft issue to me. When you check the slip joint make sure the drive shaft is not in a bind. My drive way is on an incline if I just set the park brake and let the rear end hold the truck it puts the drive line under a little load. This can hide slip joint slop. I to was chasing a vibration and had checked the slip joint several times. It wasn't until I had both rear tires off the ground doing my rear brakes that I realized how much slop there was in the slip joint. If it's not the slip I would have it checked for straightness and balance. If it is the slip its best to have a shop replace the spline and buy a new yoke.

[LONGHAIR]

Merged, Please don't do this. It is very hard to follow and information gets lost...by you and those of us trying to help.

From the rules:

XIV. Multiple Posting - It is simply not acceptable to post your question more than once, or to post it in more than one forum. Choose the forum that your question or post best fits in, and place it there and only there. If, after posting, you feel it should be in another forum, private message the forum Moderator and ask if they would move it for you.