Vibrations in drivetrain? (1 Viewer)

[Chrash]

I've been searching for threads that mimic the problem I'm having and Im coming up empty. Im experiencing vibrations under load and they get worse as speed increases. At 65mph it concerning. They disappear as soon as I let off the gas and I coast smooth as glass. I got all four wheels off the ground, put it in neutral and checked out all the u joints and driveline. Visually everything looks okay to my novice eye. U joints have grease and there is no play when I try to jiggle them by hand. Does this sound familiar to anyone? I would appreciate any feedback or suggestions, maybe point me to a thread I missed on the subject. I have it off the ground now and I can crawl under and check things if anyone has any ideas.

Its a 96 LX450 with 211,000. Over the last two years Ive rebuilt the front axle with new seals and koyoto bearings, new brakes and rotors all around. New tires were balanced and put on by a shop. A bunch of baselining repairs, tune up, fluids, etc. The vibrations started about 300 miles ago. I didn't do anything high stress to cause it, just started one day while driving. It was fine in the morning, vibrations started after work one afternoon. It starts, shifts, accelerates well other than the vibrations.

 

[BILT4ME]

Did you check the U-Joint play with the driveshafts UNLOADED? Everything you describe points to a U-Joint.

 

[Chrash]

By unloaded do you mean all weight off the suspension? I have it on 4 stands on the frame rails at the moment. Axles are hanging from the suspension.
U joints are what I think too, but they look and feel fine. When the problem first arrived I pumped more grease in until it started seeping from each joint. I was completely underneath it and bench pressing each joint looking for play, everything seems tight.

 

[Dave 2000]

Did you grease the slider zirk? If yes by how much?

Regards

Dave

 

[Hack]

Find a deserted alley with buildings on each side. Slowly drive the vehicle down the alley with the window open. If you hear a 'click, click, click': You've got a bad u-joint.

If you've already done the wiggle test, have you checked your tires/wheels? You might have slung a wheel weight.

 

[Chrash]

Just crawled under to figure out what you meant by slider zerk. The zerk on each shaft? It's possible I missed those two. I definitely did the four u joints, possible I missed the zerks on the shafts. I'll pump some in now. How much should go in, should it ooze out from somewhere?

 

[Chrash]

Thanks Hack. I think Dave is onto something. I feel a bit foolish that I missed two obvious grease points. I'm going to give that a shot.

 

[retrofive]

U-joints ooze, but don't over fill he drive shaft, it needs room for compression.

 

[Dave 2000]

It is normally over greasing the sliders that can cause vibes, but of course no grease means they may be jammed. Just don't go mad while searching for problems, you do not want to add to them.

Regards

Dave

 

[Chrash]

Thanks Dave. I'm still uncertain if I greased the sliders or not. Puts me in a conundrum. Seems either way could cause my issue. Hmmm...

 

[Dave 2000]

Ok go with this, pump a load in there (both shafts), then unscrew the zirks x2 and go for a drive, if you over filled grease will be expelled as the shafts expand and contract with axle movement, messy yes but a certain method to put you right.

Regards

Dave

 

[retrofive]

Ok go with this, pump a load in there (both shafts), then unscrew the zirks x2 and go for a drive, if you over filled grease will be expelled as the shafts expand and contract with axle movement, messy yes but a certain method to put you right.

Regards

Dave

/\

 

[Chrash]

Thanks guys, that's exactly what I'll do. Test drive will have to wait till tomorrow. Labor Day off and I started day boozin about an hour ago. Been a pretty nice Sunday tinkering with the 80. I appreciate everyone's help, I'll update when I know more.

 

[BILT4ME]

By UNLOADED I mean....No booze in YOU!














No, not really!

Unloaded on the driveline does NOT mean the wheels off the ground, although that certainly helps.

It means, set the parking brake, place the transmission in NEUTRAL, chock the wheels, THEN get under it. You SHOULD be able to wiggle the DS a little bit rotationally by hand. If you get vertical or lateral movement, the U-Joint is shot.

I always try to do this AT DRIVE HEIGHT (rather than on the stands) because that way it is in the "wear point" position. This is the place where the driveline NORMALLY operates and wears. When you take the weight off the truck and let the axles hang, the splined yokes will be in a tighter place because they on the UNWORN area of the shaft. Sort of the same with the U-Joints, but not as much.

ALWAYS grease the driveline in an UNLOADED state and at normal drive height, because otherwise, the grease goes to the UNLOADED side of the splines and not to the side that is wearing.

When you grease the slip joint (Splined yoke that allows the DS to telescope), only put in 3-4 pumps when it is in its NORMALLY OPERATING POSITION.
If you do it when it is EXTENDED (such as wheels off the ground) do as @Dave 2000 has said and unscrew the zerks to allow the grease to ooze out. There IS a hole in the center plate behind the U-Joint, but that is FREQUENTLY clogged. If you over grease, it will blow out that plate and that's worse. If you don't relieve the pressure and it doesn't blow out the plate, you can still hydraulic the bearings in your T-Case because the pressure cannot relieve.

Lots of threads here about this.

 

[nukegoat]

Head gasket

 

[mudgudgeon]

U joints are what I think too, but they look and feel fine. When the problem first arrived I pumped more grease in until it started seeping from each joint. I was completely underneath it and bench pressing each joint looking for play, everything seems tight.

If your u joints are shot, grease may not make a difference. If your still chasing a vibration, remove the drive shafts so you can rotate the uni joints in every direction. They should rotate smoothly and freely in all directions, if they are excessively stiff, or notchy, they are done.
The roller bearings in u joints can be seized, and still feel and look ok while the drive shaft is bolted in.

 

[shocktower]

Head gasket

PHH

 

[Chrash]

Finally got it greased up and took it out on the highway. It's much smoother. I'm hyper focused on vibrations now, still getting a some here and there, but it's much better. Thanks to everyone, I appreciate your help.

 

[Chrash]

Compression in all cylinders is good and the phh is taken care of

 

[Burbot]

Is your front shaft in phase as it should be(here we go)sometimes it's hard to tell w out pulling the shaft and laying it on a solid surface.