Weird Vibration

[Bent77]

So here's what I have, 14ff, CV driveline, 205, 465. U joints are good and CV is fairly new. Shaft has been balanced and is not missing weights.


Here's what it does, above 5 mph it develops a vibration, similar to an out of balance driveline, only more so. But it does not do it all of the time. It goes in like 5 minute cycles of on and off. Increases intensity with speed.

Does not do it with the rear driveline removed. Does do it in either 4wd or 2wd, does it both under power or coasting. It is not engine or engine speed related, any gear.



So, fire away with your thoughts and suggestions. I have a few theories, but am choosing not to muddy the waters yet...

 

[70jimmy]

Are you twin sticked so you can put it in front wheel drive only with the rear drive shaft installed?

I think you can rule out rear axle shafts.

I would look at tranny and transfer case mounts / bushings, yokes, pinion shaft and rear T case output shaft.

Even though driveline is balanced, did it get bent?

Try putting it up on your fancy new stands with the rear axle elevated and see if the vibration can be seen with the tires turning.

My 1.24 cents, adjusted for inflation

 

[Hogback Fabrication]

Any play at the pinion or t-case output?

 

[obijuan]

is the cv socket worn out? ive done that a few times because of poor pinion angle.

 

[Bent77]

It has a new t-case mount on the side of the 205, so no tork flexing or moving of the t-case.

No go on the twin stick, but the only play I have on the rear output is about .010 front to back. Almost none up and down ie bearing looks good, oil looks good.

I haven't checked the pinion yet, and the fancy new jack stands will have to be utilized tomorrow.

The CV socket was new this summer, and the only thing that has changed is the top is now on, maybe squating it and pissing off the CV?

 

[guz71]

I would check the pinion nut too, it could be loose. What does your pinion angle look like?

 

[Bent77]

The pinion points right at the t-case output. the weird thing is that I ran this new d-shaft all summer with no issues.

Today I'm going to put my trail shaft in, and will check the p-nut when I do. I will post up if I find anything.

Thanks for all the input guys!

 

[obijuan]

is the pinion pointed down 1* for axle wrap?

 

[Bent77]

You know, it was, but my springs are so bent now it has probably changed. I will go put the angle widget on it and see.

And it still vibrates with the other driveline...

 

[Bent77]

So after messing with all of this shiat, I finally dropped the t-case on the frozen tundra and dragged it into the garage. Low and behold, the input shaft bearing is growling. So I popped a new bearing in it and will put it back in either Sunday or monday.

Any reason this should go bad? Other than slinging oil, it doesn't seem like a very easy spot to get oil to...

 

[BoondocK5]

Check t make sure all the engine to trans bolts are in and tight. don't ask, it cost me a T400.