Driveshaft vibration caused by I'm balance or worn center bearing?

[Morritse]

Recently replaced my driveshaft because the center bearing support was completely gone.

I bought a used one which appeared to be in good condition, but still have some vibration starting at 80mph and getting worse faster I go.

Any one experienced these issues?

Confusing part is that the vibrations feel almost identical to the ones I had after I repaired my broken center bearing carrier with window weld, leading me to believe it's caused by a worn carrier again... But on visual inspection it looked fine in the new one.

[LYKUNO]

The problem with buying a used prop shaft is that while it may look to be in good condition, you really can't be certain how much wear and tear it has been through, whether it was ever apart and reassembled improperly, or if the donor car was in an accident. There's a lot that can go wrong with the reassembly of a prop shaft (in the event it had ever been worked on by someone prior to you), as evident in this document. Have you checked all the other rotating parts (e.g., axles) and associated suspension components for slop/wear? From the Blauparts.com website:

Wondering If You Have A Worn Audi Driveshaft Or Audi Center Support Bearing?

This troubleshooting guide can help to determine if you have an Audi quattro driveshaft (a.k.a. Audi propeller shaft) or center support bearing problem and if it's in need of removal and replacement.

Symptom: A high pitch whining coming from the center underside of the car. The high pitch noise varies with vehicle speed. Lower pitched at slow speeds and higher pitched at fast speeds. It may even begin to make a screeching noise; especially when driven in cold conditions.

Repair Solution:To determine the cause of the noise put the vehicle up on a repair shop post lift with all four wheels off the ground. Driving the vehicle on lift and using a stethoscope, confirm that the noise is coming from the Audi center support bearing area (see image below). If it is, replace the Audi center support bearing.

Symptom: Quattro driveshaft vibration is felt from the center underside of the car, especially when straight line accelerating. Much of the shudder is felt through the shift lever upon acceleration. The shudder worsens when taking off from a stop sign and smoothes out somewhat when the car gains speed and/or when you let off the gas pedal.

Repair Solution: 1) Make sure the vehicle is turned off and in park. Inspect the Audi center support bearing. Has the rubber that surrounds the middle of the bearing separated from the bearing bracket? If the rubber has separated from the bracket, replacement of the center support bearing in needed. 2) At the driveshaft yoke in the middle of the driveshaft you'll see the universal joint. Grab the front half and the rear half of the driveshaft with your hands. Twisting from side to side, see if there is any play in the Audi universal joint. If there is, replacement of the Audi universal joint is necessary.

Symptom: Quattro driveshaft vibration is felt from the center underside of the car, especially when turning a corner from a stop sign. This shudder can also be felt through the shift lever when first taking off from the stop sign.

Repair Solution: Make sure the vehicle is turned off and in park. Inspect the front driveshaft CV joint (located on the end of the driveshaft where it connects to the tailshaft of the transmission - see picture below). Grab the driveshaft with one hand and the outer cage of the front CV joint in the other, twisting from side to side to see if there is any play. If you detect any play in the CV joint, replacement is necessary. Due to the close proximity of the front driveshaft CV joint to the catalytic converters, the grease in the CV joint cage hardens and looses its ability to lubricate. This lack of lubrication accelerates wear on the driveshaft CV joint. When lubrication is lacking, the joint will begin to bind during acceleration when engine torque flex occurs. This driveshaft torque flex is magnified when turning your Audi left or right.

Symptom: Quattro driveshaft clanks near the hand e-brake area. This occurs on acceleration or deceleration.

Repair Solution: Make sure the vehicle is turned off and in park. Inspect the Audi center support bearing. Has the rubber that surrounds the middle of the bearing separated from the bearing bracket? If the rubber has separated from the bracket, replacement of the center support bearing is needed.

Symptom: Quattro driveshaft has loose rattling noise coming from the underside of the car. This noise sounds like loose pocket change that would be jiggling around in your pockets. You'll hear this noise as you transverse the gears, upshifting between 1st and 3rd gear. This noise also occurs at deceleration when you let off the gas pedal and slow down.

Repair Solution: Make sure the vehicle is turned off and in park. Inspect the front driveshaft CV joint (located on the end of the driveshaft where it connects to the tailshaft of the transmission - see picture below). Grab the driveshaft with one hand and the outer cage of the front CV joint in the other, twisting from side to side to see if there is any play. If you detect any play in the CV joint, replacement is necessary. Due to the close proximity of the front driveshaft CV joint to the catalytic converters, the grease in the CV joint cage hardens and looses its ability to lubricate. This lack of lubrication accelerates wear on the driveshaft CV joint. When lubrication is lacking, the joint will begin to bind during acceleration when engine torque flex occurs. This driveshaft torque flex is magnified when turning your Audi left or right.