Moonfish

Are the end joints right or is this out of phase?

'97 t100 4wd

Moonfish

Maybe this picture is better

Moonfish

It rumbles going 35-55mph. I jacked the back end up and it is definitely coming from the back end somewhere. A deep rumble. My mirrors vibrate. I have push/pulled on the U-joints and none of them seem loose or have any play in them that I can tell.

Thanks guys. J

MudHippy

If it ain't right, it ain't off by much. It looks dead-nuts in the top pic.

While you've got it jacked up, grab each wheel with both hands and push/pull. If they have any in/out play it's probably the wheel bearings.

MudHippy

EDIT: 90° out. Sorry. My bad!

Moonfish

Yeah it is harder to see but the ends are not parallel with each other. I'm just makin sure there wasn't some reason or exception. And I totally need to check those bearings also.

I'm gonna spray penetrant on the bolts and tackle that tomorrow. I hope it is that easy. The big noise you can't find the cause of is really irritating.

4Crawler

iTrader: (3)

Looks like a CV/double cardan joint on the top, so phasing is not a big issue like on a single cardan shaft:
- http://www.4crawler.com/4x4/CheapTri....shtml#Phasing

Check the pinion flange and shaft angles:
- http://www.4crawler.com/4x4/CheapTri...n-Measurements

MudHippy

Oh that's no biggie. Just unbolt the driveshaft from the pinion companion flange. Pull the slip yoke out, rotate 90°, re-insert. Bolt the shaft back up, pump the slip yoke full of grease, and you're good to go.

What's with the pinion seal leaking there though? And why are you asking about the driveshaft being out of phase in the first place? Are they related? Or are you already ahead of me on all of this? Don't answer if you are, I lose track of who's doing what these days. I mean what, there's gotta be more than a couple dozen of us fixing our trucks on this site...

Moonfish

I hope it is wrong because something shakes the whole truck.... At least it should have been balanced when aligned correctly? The truck is stock so I haven't been worrying about angles.

Yes the seal is leaking. I'm hoping the wobble took out just the seal. I just changed the oil in the diff and the oil looked great and the plug was clean so, I'll try and see. I have something to try at least. thanks

MudHippy

If the seal is leaking because of the wobble, then there's some loosenes at the pinion/companion flange that's causing it. Either the pinion nut is backed-off and needs retightened, or the outer pinion bearing is shot. There's not supposed to be ANY freeplay in the pinion, so no amount of wobbling it is going to make it oscillate and wear on the seal excessively(other than if there's a pre-existing condition allowing it).

Moonfish

One would think so but I can't feel any play in it. Maybe 238,000 miles made the seal wear out, we'll find out soon. Oh, just moved the shaft 90 degrees and no more huge rumble. I didn't realize the 1/2 of the shaft next to the pinion was so short. I can see how it would fall out if someone was doing some work on the driveline. I think my tranny was redone at some point, there is orange FIPG visible so maybe it happened then. Sometimes the new guy does your repairs:> Anyway, it is a relief to find the cause of this. My mirrors were vibrating at highway speed.

MudHippy

That many miles would. More or less. Usually less.