Bent belly skid and driveline vibrations

I adjusted the pinion angle. Best I can measure it's about 0.8*.

View attachment 258267

Vibes are the same. I rotated the tires and no change there.

Vibes are definitely more pronounced under load. Going up hill the vibes are much worse than coasting down hill at the same speed.

In 4wd the vibes are less. Not sure what to make of that. May be reduced load on the rear driveshaft.

I guess next step is the pull the rear driveshaft to confirm that's the problem and inspect as best I can.
You mentioned that you rotated the tires but did you have the tires balanced also?

I'm interested in what you find here as I'm dealing with a similar situation.
 
You mentioned that you rotated the tires but did you have the tires balanced also?

I'm interested in what you find here as I'm dealing with a similar situation.
no just swapped front to back, flipping l/r on the rear. Idea is that if the unbalanced tire is in the front I'd feel it in the steering wheel, but I never did. Also a good thing to do to keep tire wear even, so I figured it was worth doing either way.
 
I took the driveshaft off and went for a drive, and the vibes were gone.

The driveshaft seemed tight and I couldn't feel any slop in the joints, but when I spun the caps (that went to the pinion) they felt just a little gritty, so I'm thinking I should replace at least that one and see if that fixes the vibes.

It makes sense that it would be worn as the pinion-driveshaft angle was off 6-7 degrees.

Do you think I can keep the double joint u-joints? I'm thinking/hoping that they should wear less as they weren't out of alignment.

All the joints are greaseable. The pinion u joint measured 1.063 x 3.618, I take it that's a 1330 series. Which one should I get? I'm thinking spicer sealed/non-greasable. What's the best source? Last time I rebuilt a driveshaft it had to hunt to find spicer joints.
 
Just to be clear, you're talking about the REAR driveshaft, right?

If it were me, I'd replace all three U-joints at the same time. Unless, you really enjoy doing the work and just want to tear the shaft apart again in the near future. lol

Correct, that sounds like a 1330. Here's a source I've used before for good prices on Spicer joints. Denny's Driveshaft in Kentucky. The shipping to Oregon may be a different story though...
https://www.dennysdriveshaft.com/p9...x_greaseable_universal_joint_1330_series.html
I really like the greaseable joints because I'm a fan of maintenance. Other's prefer to not have to worry about it and use sealed joints. It's really personal preference.
 
Measured as best I could with the joints still in the driveshaft and they're defiantly not all 1330. 1310 makes more sense as those are the factory sizes.

I have a rear Dana 44 and it looks like the rubicons used a 793x, but that's 1.125, while mine measured at 1.063, which would be a 5-134x.

Is it possible they installed the wrong ujoint? Seems like the vibration would be terrible right away if they did that.

Guess I need to crawl back under and try to measure the yoke at the axle.
 
You are smart to get in there and measure them, that's probably the best way. A shop could have made just about anything work so there's no guarantee the stock replacements will be the correct ones. There's no way you could have the wrong joints installed, I think they wouldn't fit at all.
 
p.s. Local there's only MOOG and SKF versions of the 793X. It'd be nice to support local and have the option for quick buy and possible return if it's the wrong size, but I've always heard to stick with spicer.
 
Personally it's only the front axle u-joints I'd worry about with respect to strength but everybody has different needs. I ran Moog in the front and they wore out quick but for the driveshaft I wouldn't worry.
 
Personally it's only the front axle u-joints I'd worry about with respect to strength but everybody has different needs. I ran Moog in the front and they wore out quick but for the driveshaft I wouldn't worry.

OK thanks. Makes sense there's less stress on the driveshaft and much easier access too.

I checked the pinion and confirmed that the u joint is sized correctly, so I guess it's a 134x. That wasn't listed in the chart of TJ u joints so I wonder what's up with that. It sure looks like a TJ Dana 44. I sure hope the chromo shafts I just bought for them fit.
 
It took a month + 1 week to get the centering ball from summit, so I FINALLY tore into the double joint.
1st joint was sooth and looked good.
Centering ball looked good and was smooth too.
I was starting to lose hope and thinking I was barking up the wrong tree, then I pulled the last joint.

I found the smoking gun:

1626755807585.png
 
After all this time I've FINALLY fixed the vibes! 5 weeks waiting on the centering ball, only to find I ordered the WRONG PART like an idiot. Sent it back and the right one came in and NO VIBES! Hallelujah!


The slip spines are missing the grease nipple:
1627503447348.png


Looks like it got torn off. I put a new one on but it wouldn't hold. Seems like this is a job for JB weld. Any other ideas?
 
Little clarity plz..

One of the ujoints was shite, did you replaced bad one and discovered that you still had vibes, thus you went further to replace center ball?

Or did you replaced ujoint, vibe went away, and then you decided to refresh entire double joint, thus the 5 week wait and center ball has nothing to do with the vibe?
 
Little clarity plz..

One of the ujoints was shite, did you replaced bad one and discovered that you still had vibes, thus you went further to replace center ball?

Or did you replaced ujoint, vibe went away, and then you decided to refresh entire double joint, thus the 5 week wait and center ball has nothing to do with the vibe?

I decided to do them all at once as I didn't want to disassemble/reassemble the CV joint multiple times. So I waited until I had the center ball to take it apart and that's when I found the bad u joint, and that I had ordered the wrong ball.
 
After all this time I've FINALLY fixed the vibes! 5 weeks waiting on the centering ball, only to find I ordered the WRONG PART like an idiot. Sent it back and the right one came in and NO VIBES! Hallelujah!


The slip spines are missing the grease nipple:
View attachment 267916

Looks like it got torn off. I put a new one on but it wouldn't hold. Seems like this is a job for JB weld. Any other ideas?
I'm not sure JB Weld would do the trick given the greasy environment you're dealing with? Were you able to recover any remnants of a grease fitting from the hole? Did the fitting snap off leaving the threaded portion inside? If there's any remains of a fitting left behind you should be able to extract it and install a new fitting. Judging by the dent in the photo, it looks like the shaft took a hit dead center on where that grease fitting once lived. It's possible that threaded hole has been distorted now rendering the threads useless. Does the splined end still travel freely? If so you can always just pull the shaft apart and apply grease by hand, then reassemble. The grease fitting isn't essential, it just makes it easier to add grease and keep dirt out. Your main focus is allowing the splines to travel freely so there's more than one way to keep it greased. If you're able to salvage the threaded hole I'd recommend switching to the flatter needle-style fitting. Good luck to ya, I say RUN IT!
 
I'm not sure JB Weld would do the trick given the greasy environment you're dealing with? Were you able to recover any remnants of a grease fitting from the hole? Did the fitting snap off leaving the threaded portion inside? If there's any remains of a fitting left behind you should be able to extract it and install a new fitting. Judging by the dent in the photo, it looks like the shaft took a hit dead center on where that grease fitting once lived. It's possible that threaded hole has been distorted now rendering the threads useless. Does the splined end still travel freely? If so you can always just pull the shaft apart and apply grease by hand, then reassemble. The grease fitting isn't essential, it just makes it easier to add grease and keep dirt out. Your main focus is allowing the splines to travel freely so there's more than one way to keep it greased. If you're able to salvage the threaded hole I'd recommend switching to the flatter needle-style fitting. Good luck to ya, I say RUN IT!

I tried it this morning and it held 1 pump but cracked on the 2nd. Shoot.

No bits of the old fitting, just a dent and wallered out hole. The splines are hard to move but do move if I put my weight on it. Hanging from it the shafts don't come apart are they supposed to?
 
Finished this up a couple weeks ago, just thought I'd update in case anyone's watching.

Attached an 8mm low-profile grease fitting from mcmaster. Would have gong w/ 5/16 but couldn't find that in low-pro. Made a tape with an 8x1 10.9 bolt. Didn't even have to drill it out as that metal is super soft.

No more vibes and all greased up!

I've order a skid from barnes4wd and new nutserts from blane as I noticed 2 of them are stripped. It never ends lol
 
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