Driveshaft wobble or optical illusion?

RD3

RD3

TJ Enthusiast
Supporting Member
Joined
Feb 8, 2017
Messages
272
Location
Tullahoma, TN, United States
What do you think? I think I found my drive line vibration

well I can't get the video to work in the post. You might be able to open the attachment and see it
 

Attachments

  • Drive shaft video.MOV
    1.2 MB · Views: 387
There does seem to be a little tiny amount of runout on the shaft. But before sending the driveshaft out for work, the rear u-joint is centered in between the nubs in the rear pinion yoke? And you've got the rear pinion angle correctly set? Have you tried varying the rear pinion angle a tad either way?

Do you have a photo that clearly shows the entire rear axle forward up to the CV to see the angular relationship between the pinion and driveshaft?
 
Jerry Bransford said:
There does seem to be a little tiny amount of runout on the shaft. But before sending the driveshaft out for work, the rear u-joint is centered in between the nubs in the rear pinion yoke? And you've got the rear pinion angle correctly set? Have you tried varying the rear pinion angle a tad either way?

Do you have a photo that clearly shows the entire rear axle forward up to the CV to see the angular relationship between the pinion and driveshaft?
Click to expand...

Yes on the u-joint if I'm understanding your question. I have set the pinion angle from dead on aligned (both angles at 18 degrees) all the way down to pinion being 4 degrees below in 1/2 degree increments. I can take a picture later and post. The pinion angle in the video is set a 1.5 degrees below
 
Jerry you have given me reason to ask another question. When setting the pinion angle to be below the drive shift angle do I measure both each time? when perfectly aligned the drive shaft and pinion angle are both at 18 degrees. When I begin to move the pinion angle down do I re-measure the driveshaft angle each time and continue until the drive shaft is 3 degrees below the ne drive shaft angle or do use the 18 as a benchmark so new setting would be 15 degrees?
 
RD3 said:
Jerry you have given me reason to ask another question. When setting the pinion angle to be below the drive shift angle do I measure both each time? when perfectly aligned the drive shaft and pinion angle are both at 18 degrees. When I begin to move the pinion angle down do I re-measure the driveshaft angle each time and continue until the drive shaft is 3 degrees below the ne drive shaft angle or do use the 18 as a benchmark so new setting would be 15 degrees?
Click to expand...
Yes, since the driveshaft angle lowers when you lower the pinion angle. No need to even test at 3 degrees below that of the driveshaft angle, that's way too low. I'd have the pinion angle maybe 1 to 1.5 degrees lower than the driveshaft but that's it. We don't need to get it lower than that since our TJs don't have much axle wrap like leaf spring Jeeps do.
 
So I spent the afternoon going back through the adjustments. Went from 4 degrees below up to 1.5 Degrees below is 1/4 turn increments. At 1.5 degrees below is my best result but I still have the mild vibration at certain speeds. It will change with different speeds like a tire that is a little out of balance will do sometimes. There are places/speeds where I don't feel it at all and speeds where it is more pronounced. The vibration is not violent or strong at all. It is more like a phone vibrating than anything I can think to compare it to. I'm attaching 2 pictures the first is at 1.5 degrees, the second is at 4 degrees below.
DS 2 degrees.jpg
DS 4 degrees.jpg
 
I'd stick with nothing more than that 1.5 degree difference. Neither a 3 nor especially a 4 degree difference is going to do anything but make vibes worse.

Have you disconnected the front of your front driveshaft to eliminate that as a possible cause of the vibes? You can support the front of it for the test by zip ties, cord, etc.. There's no need to actually remove it for this test.
 
I feel your pain brother! Do your vibes come and go like a sin wave? Worse the faster you go or same?
 
Jerry Bransford said:
I'd stick with nothing more than that 1.5 degree difference. Neither a 3 nor especially a 4 degree difference is going to do anything but make vibes worse.

Have you disconnected the front of your front driveshaft to eliminate that as a possible cause of the vibes? You can support the front of it for the test by zip ties, cord, etc.. There's no need to actually remove it for this test.
Click to expand...

I have not tried that. I will
 
What sye did you use that had the bad output? I have the same dri e shaft and vibes are violent. Wobble is a bit worse as well. Done everthing and bout to lose my mind.
 
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