Driveline Vibration

[06JET]

OK, I have done some searching but nothing really gets me to where I need to be with info on this. I don't drive my Yukon XL much, about 5000 miles a year. I noticed a vibration at 65-75 MPH about 2 years ago. Very small but noticeable and has not gotten any worse. This past summer I saw oil on the driveway under my transfer case and sure enough it had cracked in the area just under the electronic 4x4 switching module. I cleaned it and put JB Weld over the ares to strengthen it and to seal the leak. I will change it out this summer but I can't find the source of the vibration. I have since lifted it with keys, changed all of the steering components, and the front axle shafts. All driveshaft U-Joints front and back have been changed recently and the factory weights were still on the driveshafts. The front wheel bearings were changed about 20K miles ago and I can't feel any slack in them. When in 2WD I can't turn the front driveshaft by hand. I can with a strap wrench but not just by hand. When in 4WD hi or low it seems to be fully positive traction on all 4 corners and will bind up on hard ground or pavement. That will get your attention when it happens, makes a lot of noise. That only happened a couple of times. Vibration seems to be a little less when I run it in Auto 4WD but hard to tell. Normally goes in and out of 4WD easy with no issues. One time I had trouble getting it out of 4WD low back into 2WD but only once about 3 years ago. I rarely put it in 4WD, usually only to test and lubricate everything by letting it spin for a few miles. Any testing ideas or common problems that would help get me going in the right direction would be appreciated. I don't want to put in a new transfer case and still have this issue. Thanks

 

[SnowDrifter]

Put it in the air, 4 wheel drive, have someone hold the wheel speed at where the vibration occurs and mark the drive shaft with a tire crayon. High spots will be marked. Be ******* careful when doing this. Tie up loose clothes, hair, etc. Keep anything you want to stay attached to your body away from the spinny bits!!

Have you verified its driveline and not tire imbalance or out of round?

Was your tcase cracked or did the pump rub through?

Transmission rebuilt at any point down the line? Not all sun shells are balanced.

What about pinion angles? A differential angle between the tcase/driveshaft and differential/driveshaft will cause a vibration

 

[06JET]

Put it in the air, 4 wheel drive, have someone hold the wheel speed at where the vibration occurs and mark the drive shaft with a tire crayon. High spots will be marked. Be ******* careful when doing this. Tie up loose clothes, hair, etc. Keep anything you want to stay attached to your body away from the spinny bits!!

Have you verified its driveline and not tire imbalance or out of round?

Was your tcase cracked or did the pump rub through?

Transmission rebuilt at any point down the line? Not all sun shells are balanced.

What about pinion angles? A differential angle between the tcase/driveshaft and differential/driveshaft will cause a vibration

Thanks for the input.

Vibration did not change when I went from factory tires and rims in excellent condition to the new 20" set I have on now.
T Case was cracked at the ribs below the 4WD motor/actuator.
Trans has never been into except to change the filter.
Factory angle up front and slightly different in rear with the 2" spacers but no change in vibration.

I had it up on jacks before but was by myself. So it just ran in 3rd at a high idle and couldn't pinpoint the vibration. Didn't try a tire crayon.

 

[Doubeleive]

I don't understand this concept....
mark the driveshaft where?
how is a spinning driveshaft going to have a "high spot"
and what would that tell you

 

[swathdiver]

One thing at a time, fix the transfer case and see if that takes care of the vibration. Then go from there. While the TC is out getting repaired, you could take the driveshafts to a drive line or truck shop and have them balanced and or balance checked.

 

[Erickk120]

Does this sound more like a rumble/shudder and is it worse/more noticeable when you let off the gas? If so this seems like a common problem in a lot of our trucks. Mine does it at 70-80. I will be looking at mine this weekend. I suspect it will end up being cv or torque converter as everything in my front is new, except for cv's and leaky trans ftont seal. Will update.

 

[06JET]

Thanks for the comments.
I would like to determine where the vibration is before the new transfer case goes in so as not to crack it too if possible. I think it is the transfer case doing it but I kinda wanted to prove it so I know. Even though the weights are still on the drive shafts you think they may be out of balance?
The vibrations comes on at the same speed every time and doesn't change with being on or off the gas. Seems like if it was the torque converter I would feel it at the same RPM in each gear regardless of the speed.

 

[06JET]

Just for reference to show where the cracks were in the transfer case. Where the ribs meet the case at the machined section. I know it ain't pretty but it don't leak anymore and should be OK until I replace it.

 

[SnowDrifter]

I don't understand this concept....
mark the driveshaft where?
how is a spinning driveshaft going to have a "high spot"
and what would that tell you

You hold a tire crayon across a couple different spots on the driveshaft while it's spinning.

For the sake of a drive line vibration, a high spot(bent) and heavy spot would both be marked the same.

When the thing is spinning, the heavy side is going to have a greater centrifugal force acting on it than the light side and as such, will pull it off axis. The crayon method, due to the speed of the drive shaft, won't mark along the entire diameter. It'll kick the thing off and you'll see the high spot



If the thing's primarily out of whack in the middle, then you're likely looking at an imbalance or the thing's bent.

If you're noting a high spot primarily on one side or the other, near a u-joint, then likely you're looking at a worn bearing on the tcase or diff side, worn slip yoke, or potentially a bad u-joint that's either worn or not centered

 

[PG01]

I had a vibration on my 01, out of the blue one day, also had a clunk, i did I joints put it back together and still had vibration, yanked driveshaft again and had it balanced and vibration gone.