Hi All,
Have been searching all over the place for help with this problem and really need some good advice, I’m stumped.
We have a 2006 XC90 V8 with 95k miles on it. It’s my Fiance’s car and she drives it daily…I’ll give you a little background…
A couple of months ago while doing routine maintenance, I found the RR wheel bearing had too much play, so I changed it and in doing so had to change the RR axle (Used one) since it was seized into the hub. Around that time I also replace both lower control arm bushings on both sides up front (they were split and separated).
Shortly thereafter, my fiance said the car developed a HORRIBLE VIBRATION while driving normally. I took it out for a test drive and sure enough, once we hit 20mph there was a terrible vibration throughout the entire car. It is definitely NOT a tire vibration, but will rattle your teeth out.
Here’s the kicker…while driving straight down the road, if I JERK the steering wheel to the left, the vibration completely stops then returns once going straight again. If I jerk the wheel to the right it has no effect on the vibration.
I was originally thinking LF wheel bearing possibly and with almost 100k on it, I decided to change the wheel bearing just in case…NO CHANGE!
Then I thought, maybe that used RR axle In put it was bent, so I got another one under warranty from my supplier and changed that out again…STILL NO CHANGE!
I am stumped here…been a DIY mechanic my whole life but this one really has me scratching my head.
I have read some possibilities on here…maybe one of the front axles, or possibly an engine mount…I don’t know where to look next.
Does anyone have any thoughts, experience or ideas about this???
Sorry for writing a novel…thanks for any help!
Rob
P.S. Updates…
I have since replaced the RR wheel bearing AGAIN just to be safe, along with the RR control arm that was bent. Repacked the front CV joint in the drive shaft (which was fine)…
LOOSING MY MIND HERE!!! 
Have you checked the other CV or U-joints in the driveshaft? These can seize up and cause bad vibrations like you are experiencing.
Did you get it aligned after the control arm bushings? It needs to be.
I would also worry about either strut bearings or ball joints binding up. If so, these things should *probably" be giving some noise, but not necessarily so.
But until you say otherwise, I’m going with it needing an alignments after those bushings.