Vibrations under load

[vtraudt]

I have been fighting this on a 2006 A4 2.0T Cabrio FWD (CVT) for a week now, and are lost.
Car has 150k miles.

The car exhibits massive vibrations under load. NO vibrations off throttle/coasting or coasting in N.
Vibrations at all speed.
Frequency changes with driving speed (wheel revolutions) not engine RPM.

Done:
front right wheel bearing has a bit of play. Changed.
found excessive engine movement. assumed snub mount. Replace with red poly snub (installed centered under dead weight of engine).
still movement on passenger side, replace motor mount (stock mount).
still movement. Particularly when going from P to R. Took video from under car, found that rear trans mount is bouncing up big time when shifting into R. Found that center bold of the mount (and a holder on the bottom?) is missing. Ghetto fixed by removing the mount, put nut on top and bolt with large washers from bottom. No more movement.

Took car to shop for test drive. Then on hoist, mechanic commented when inspecting the drive shafts that they had NO axial play (but expected them to have some play to allow of up/down motion of wheels and to avoid to put pressure on the constant velocity joints and the transmission output shafts). He lifted up the engine (weight of suspension) and then shafts showed the expected play.

a) on its own weight, are the drive shafts supposed to have some axial play?
b) if not, what might CAUSE the drive shafts to bind.

Any suggestions how to further troubleshoot?
It is NOT known if drive shafts are original or if they have changed. But vibrations were NEVER that bad prior.

[Audibot]

How about your transmission and rear differential mounts? Those do go bad over time.

[vtraudt]

How about your transmission and rear differential mounts?

I haven't found them to cause such 'hard' vibrations. They do created clonks and excessive engine movement.

Unless the wear is causing the secondary issues (for example drive shaft binding?) that in turn causes the distinct speed/load dependent vibrations.

[mtroxel]

I bought a Passatt with engine problems. Fixed that (bent valves and valve timing adjuster) then had a vibration like that. Luckily you can swap wheels/tires between my Audi and the Passat. Immediate relief. Bought new tires for the Passatt and put them on the same wheels: no vibration. As I understand it, if the tire carcass goes bad, a belt can slip around and make the tire un-ballanced.

[Tyintegra]

I have been fighting this on a 2006 A4 2.0T Cabrio FWD (CVT) for a week now, and are lost.
Car has 150k miles.

The car exhibits massive vibrations under load. NO vibrations off throttle/coasting or coasting in N.
Vibrations at all speed.
Frequency changes with driving speed (wheel revolutions) not engine RPM.

Done:
front right wheel bearing has a bit of play. Changed.
found excessive engine movement. assumed snub mount. Replace with red poly snub (installed centered under dead weight of engine).
still movement on passenger side, replace motor mount (stock mount).
still movement. Particularly when going from P to R. Took video from under car, found that rear trans mount is bouncing up big time when shifting into R. Found that center bold of the mount (and a holder on the bottom?) is missing. Ghetto fixed by removing the mount, put nut on top and bolt with large washers from bottom. No more movement.

Took car to shop for test drive. Then on hoist, mechanic commented when inspecting the drive shafts that they had NO axial play (but expected them to have some play to allow of up/down motion of wheels and to avoid to put pressure on the constant velocity joints and the transmission output shafts). He lifted up the engine (weight of suspension) and then shafts showed the expected play.

a) on its own weight, are the drive shafts supposed to have some axial play?
b) if not, what might CAUSE the drive shafts to bind.

Any suggestions how to further troubleshoot?
It is NOT known if drive shafts are original or if they have changed. But vibrations were NEVER that bad prior.

These are the same symptoms I had on my B8.5 when it was in need of fuel injectors and a carbon cleaning.