Vibration over 50 mph after driveshaft u-joint change

Lifted straight six

Lifted straight six

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Oct 26, 2020
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arizona
To start off, my tj is a 2002 4.0 with an ax15 and NP231(swapped ax15 when my nv3550 blew up) with a tom woods rear drive shaft and a SYE kit. I decided to change the rear u joints in my driveshaft after feeling some play, i replaced 2/3 of them, the 2 i replaced were the outsides, not the one inside of the centering ball because it looked okay. After reinstalled it felt way better, no movement of the u joints. I took it for a test drive and above 50mph it starts getting a vibration that i can feel through my seat. What could have caused this? It is a double cardon tom woods driveshaft.
 
Is it possible that the shaft was out of balance before you replaced the joints? Now, with tighter joints, the vibes are transferring into the cabin instead of being absorbed by worn joints? Just a theory, I don't have solid proof of this.
 
Did you by some chance remove the slider assembly from the shaft"
Did you ensure the double cardan joint bolts are tightened to the output yoke and the straps are properly tightened to the pinion yoke ?
Did you check the centering ball of the dbl cardan joint for unusual play ?
 
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It's also possible, and definitely not impossible, to not have gotten the u-joint's bearing cup seated between the tabs in the yoke. Or it unseated while the strap was being installed. That will cause it to sit off-center and to vibrate.

u-joint.jpg
 
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Jerry Bransford said:
It's also possible, and definitely not impossible, to not have gotten the u-joint's bearing cup seated between the tabs in the yoke. Or it unseated while the strap was being installed. That will cause it to sit off-center and to vibrate.

View attachment 275904
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I have had this happen before, although it caused a squeal and severe vibration, this isn’t as bad but definitely noticeable. checked for this and all seating looks normal to me.
 
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CharlesHS said:
Did you by some chance remove the slider assembly from the shaft"
Did you ensure the double cardan joint bolts are tightened to the output yoke and the clamps are properly tightened to the pinion yoke ?
Did you check the centering ball of the dbl cardan joint for unusual play ?
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slider assembly was not removed from shaft, I am going to check the centering ball tomorrow on my day off… clamps are also properly tightened
 
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SvtLdr said:
Is it possible that the shaft was out of balance before you replaced the joints? Now, with tighter joints, the vibes are transferring into the cabin instead of being absorbed by worn joints? Just a theory, I don't have solid proof of this.
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this would make sense and it’s definitely in my line of things to check out… but there was never any severe vibration like i have now. do you think this would cause vibrations only starting at 50mph?
 
Yes, definitely possible. In my experience, subtle driveline vibes tend to be more noticeable at certain speeds, then seem to fade as speed changes.
 
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SvtLdr said:
Yes, definitely possible. In my experience, subtke driveline vibes tend to be more noticeable at certain speeds, then seem to fade as speed changes.
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will check that out ! gonna pull the DS tomorrow and see if i can’t find something obvious before I go get it balanced for 200 dollars. ugh, thousands of dollars spent in the last year on this thing. but damn i love it
 
Lifted straight six said:
To start off, my tj is a 2002 4.0 with an ax15 and NP231(swapped ax15 when my nv3550 blew up) with a tom woods rear drive shaft and a SYE kit. I decided to change the rear u joints in my driveshaft after feeling some play, i replaced 2/3 of them, the 2 i replaced were the outsides, not the one inside of the centering ball because it looked okay. After reinstalled it felt way better, no movement of the u joints. I took it for a test drive and above 50mph it starts getting a vibration that i can feel through my seat. What could have caused this? It is a double cardon tom woods driveshaft.
Click to expand...
I have the same problem, and the only thing I could find wrong is my right front U-joint is all rust. Possible source of vibration?
 
Richard1958 said:
I have the same problem, and the only thing I could find wrong is my right front U-joint is all rust. Possible source of vibration?
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if you can feel it through your seat, it’s most likely an issue from the rear/behind trans, I have a driveshaft shop inspecting mine now… will let you know if it’s that 3rd u joint I didn’t replace. Check your centering ball in the DS, along w all 3 u joints if you have the same issue, will respond back after i get my jeep back on monday or tuesday
 
Lifted straight six said:
if you can feel it through your seat, it’s most likely an issue from the rear/behind trans, I have a driveshaft shop inspecting mine now… will let you know if it’s that 3rd u joint I didn’t replace. Check your centering ball in the DS, along w all 3 u joints if you have the same issue, will respond back after i get my jeep back on monday or tuesday.
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You’re referencing the front DS, yeh? I have always suspected something was up with it
 
No, the OP has a double-cardan rear driveshaft due to the slip yoke eliminator, which is very similar to the front shaft.
 
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JPHikr said:
Like Jerry said if the Joint is not completely seated it will vibrate.

Use a C clamped to hold the cups on tight while seating into yoke.
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got word from the shop today, told me the actual spindle where the caps of my u joints sit had been grinded out which caused my u joints to not sit in as tight as they’re supposed to… haven’t gotten to test drive yet, hoping tomorrow night will be when i can get it out. but i’m assuming that’s what it is that’s causing my vibration.
 
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