Another darn vibration question

Flivver250

Flivver250

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Jun 3, 2018
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Dubai/Florida
My sled has a 3" frame lift, 1" body lift and 1" TC drop. SYE and Tom Woods drive shaft. New upper and lower adjustable control arms. New 4.56 ring and pinion in the rear (properly broken in), all new carrier bearings front and rear, new front U-joints shaft and axles.

I have tried removing the TC case drop and adjusting the angles, re-lowering the TC and adjusting the pinion angle and still get a seat of the pants vibration. I can get it where it is only noticeable 60 mph and higher, or get it worse, 50 mph and higher. Ripping my hair out. I need an old priest and a young priest. Could I have bad rear axles or am I just a knuckle dragger on the adjustment. I ready to replace axles because, well, in for a penny, in for a pound. Thoughts?
 
If angle changes are not changing the vibration then something else is in play. If it is a balance issue it will be rpm range dependent meaning if it shows up at 50 it will diminish at 60. Loose components will most of the time continue to worsen as rpms increase. Do not rule tires either as I have fixed several driveline issues with a good tire balance.

First thing I would do is to leave the front shaft out, remove the belly spacer and adjust the rear so the the pinion centerline is one degree lower than the centerline of the driveshaft. This will be a good place to start driving and see what is going on. From there you only want to make one change at a time and see what happens. That way you are not trying to guess what is going on you can create a result good or bad and go from there.
 
Flivver250 said:
Re-balanced the new tires once already, does not mean it was done right.
Click to expand...

Well to see if tires are the issue take it for a drive, note when and what the vibration is like and then rotate the tires and try to recreate the vibration. If the tires are the problem the vibration will have changed as you have moved it to a different location on the Jeep.
 
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