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Vibes - Still

rmoorex

NAXJA Forum User
Location
Indiana
Starting point: 1991 XJ. 4.0, 4WD, 5 speed AX15. 1996 Dana 30. 1987 Dana 44. Geared to 3.55. NP231 t-case. 3 Inch lift front and rear.

All was OK. No vibes.

Installed a reman t-Case and a Tom Wood's double cardigan propeller shaft.

Vibes VERY BAD @ 45 mph +. Didn't subside no matter the speed; 45 - max.

Re-geared to 4.10 (Thanks to macgyvr and Seth, two exceptional people. Super friendly, down to Earth. Seth is a mastermind that Dana should be very thankful for.).

Same, bad vibes @ 45 mph +.

Removed rear propeller shaft.

Smooth as silk.

Installed front propeller shaft in the rear.

Same vibes.

1" Transfer case drop.

Same.

Back to the OEM cross member and 4 degree shims.

Same.

7 Degree shims (don't ask. My father's son was stupid).

Same.

3 Degree shims.

Same.

What must be one of the world's worst 4 X 4 shops fixed their screw up. They didn't tighten down the axle retainer on the rear passenger side drive shaft. Leaking fluid. New bearing and seal.

Same.

New tires and wheels.

Same.

Swapped the yoke on the slip yoke kit.

Same.

Found that the transmission mount was cracked. Installed Stinky Fab transmission mount.

Worse. Very bad vibes at 35 mph +. Did not subside at higher speeds.

Once again, removed rear propeller shaft.

Once again, smooth as glass.

Flipped rear drive shaft 180 degrees (NO, not front to back, its a double cardigan, not possible [well I guess somebody could accomplish the feat :variety: ], rotated it).

Vibes 80% less. No lie. Not my imagination.

Current state: 1 Degree shim (based on input from Tom Woods). Brand new Tom Wood's drive shaft.

Vibes slightly less.

Throughout the entire situation, when coasting to a stop, with clutch disengaged (clutch pedal to the floor) from 35 MPH +, vibes like crazy until I hit 2 MPH.

I have a .45 side arm, a 12 gauge pump, 12 gauge OU that will accept 3 1/2" shells, a bow, and a 22 magnum. I think I would pick the 22 magnum. The pain of being tagged by that about 10 times would feel the same as this situation, but I would be done and wouldn't have to worry about the damn XJ anymore :yelclap:

I guess I am down to asking for a new t-case???

PLEASE ADVISE, or just volunteer to finish me off with the 22, please.
 
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Have you tried putting it on a lift or both axles on jack stands and running it in place, observing what is going on?
The axles need to have full weight on them to keep the driveshaft angles the same as when on the ground.

Rotate the wheels from front to back and see if that has an effect.
 
I have seen this when there was insufficient spline engagement in the drive shaft. This happens when for one reason or another the spacing from the tcase to the diff is longer than usual. Then you get a similar issue when you move the front to the back.
 
From your descriptions, the vibes are in the rear t-case half, or the rear driveline.

If the transfer case or the SYE is from OmixAda, I would suspect that as the root cause of the vibes.
 
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I have seen this when there was insufficient spline engagement in the drive shaft. This happens when for one reason or another the spacing from the tcase to the diff is longer than usual. Then you get a similar issue when you move the front to the back.

According to a Woods tech, if the drive shaft is the "perfect" length, at rest the the exposed spline length should be 2 1/16". Current state is at 2 3/16".
 
Have you tried putting it on a lift or both axles on jack stands and running it in place, observing what is going on?
The axles need to have full weight on them to keep the driveshaft angles the same as when on the ground.

Rotate the wheels from front to back and see if that has an effect.

https://youtu.be/JYZ4MRtlP64 . This video is at 45 MPH.

https://youtu.be/lY8oAdrP258 . This is a video at slow speed.

Changed since that video however. 3 Degree shim to 1 degree. And a brand spanking new drive shaft. Vibes are 10 - 15% less now. Not much difference.

Thanks for the input.
 
Is there a flexplate on standard setup?

Motor mounts good? Trans mount?

Sent from my SM-G975U using Tapatalk
 
Starting point: 1991 XJ. 4.0, 4WD, 5 speed AX15. 1996 Dana 30. 1987 Dana 44. Geared to 3.55. NP231 t-case. 3 Inch lift front and rear...

Installed a reman t-Case and a Tom Wood's double cardigan propeller shaft.

Vibes VERY BAD @ 45 mph +. Didn't subside no matter the speed; 45 - max.

Totally by happen-chance, it is not the diff angle or anything to do with it.

Ugggghhh

:banghead:

Output shaft on the AX 15 is wobbling. Transmission has failed.

Time to seek out recommendations on acquiring an AX 15.

Hats off to any of you folks that have restored one of these vehicles. You have my respect. Not for the faint of heard, or weak in resolve.
 
Totally by happen-chance, it is not the diff angle or anything to do with it. Ugggghhh :banghead: Output shaft on the AX 15 is wobbling. Transmission has failed.Time to seek out recommendations on acquiring an AX 15.Hats off to any of you folks that have restored one of these vehicles. You have my respect. Not for the faint of heard, or weak in resolve.

I'm a little sceptical about your determination. First the TC is the final support for the transmission output shaft. Second unless it was really "f-ed up" it should not carry thru the TC.
 
I'm a little sceptical about your determination. First the TC is the final support for the transmission output shaft. Second unless it was really "f-ed up" it should not carry thru the TC.

I am probably looking at the diagram from the parts catalog wrong.

The shaft on the front of the transmission is sloppy. Very loose.

Is that the input shaft, and not the output shaft? That would make more sense.
 
You would be talking about the shaft that has the clutch(transmission input shaft). The transmission output shaft feeds the transfer case input gear thus feeding the transfer case input shaft. From there it goes thru the transfer case output shaft(s) and yoke.
 
Original post said the vibes started after the rebuilt TC was replaced and new drive shaft. Replacing the DS resulted in only slightly better but still vibes.

Removing the rear DS smooth as silk. Was that driving with front DS only or on jack stands?

Have you tested and ruled out the rebuilt TC?
https://youtu.be/yQqhI3njjrM

Seems as if it was smooth without the rear DS the transmission shouldn't be the cause of the vibes.
 
Original post said the vibes started after the rebuilt TC was replaced and new drive shaft. Replacing the DS resulted in only slightly better but still vibes.

Removing the rear DS smooth as silk. Was that driving with front DS only or on jack stands?

Have you tested and ruled out the rebuilt TC?
https://youtu.be/yQqhI3njjrM

Seems as if it was smooth without the rear DS the transmission shouldn't be the cause of the vibes.

Driving with front drive shaft only. Not on jack stands.

I am not certain how to test the t-case. The t-case rear output shaft (not sure what to call it?) is solid when attempting to move (wiggle) by hand.

Here is a video on the transmission input shaft:

https://youtu.be/fpN3Mo5-2gQ

Also, the internal clutch cylinder was definitely loose. It was rattling for sure.
 
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