Jrezo

Past post,

https://www.clublexus.com/forums/815379-post34.html

I felt the same thing

Amskeptic

I have a high frequency vibration at 55-75 or so, it is much faster than the rotational speed of the tires. This is after replacing the transmission mount.
Something driveshaftish . . . . I will repack the CVs in the spring and see if that has any bearing on this vibration.

My Mercedes had this, and you could see the halfshaft between the differential and the wheel hub go back and forth twice per revolution of the wheel. It was the CV ***** catching in the wear pockets in the ball grooves.
Colin

Jrezo

did you notice any positive progress from the trans mount?

How many miles and is it a vibration like a drowning noise or more of a high sound?

Amskeptic

A) Not at all, if anything, I made it more pronounced. To keep the alignment of the driveshaft correct, I should have done the engine mounts and the center bearing mount and the differential mounts as well. But I didn't.
In the spring, I will plumb-bob align the driveshaft with the recommended shims and whatnot.

B) Miles on the car? 107,015 miles. Vibration has been lurking under since I have owned it, that is 11,000 miles now.
Drowning noise? High sound?

It is not really a sound. It is a high frequency vibration under the floor, the entire body shell is involved. I would say it is around 1,5-2,000 rpm, which would be about 33 hertz. It is oblivious to load, it does not care if the engine is idling or off even, it is first noticeable in the 50mph range and it gets annoying at upper 60s lower 70s, and anything above that, it gets masked by the increase in other noises/sensations.
Colin

JimsGX

PropShaft Center Carrier Bearing is my guess...