I have a '98 XC70 wagon. I had a rebuilt transmission put in less than a year ago. Recently I noticed the car was shaking when I made a turn. It only lasted a few seconds, and seemed to happen when switching gears (it's an automatic). The last few days the shaking is getting worse, and happens whenever I accelerate, especially from a stopped position. It could also be my imagination, but when driving I hear a "rumbling" noise louder than before; it seems to increase and decrease with my speed. Anyone have any ideas what this might be?

 

Check the bushing on the transmission mount, they have a tendency to go out, along with the upper motor mount. The sway bar end links are also prone to failure, as well as the ball joints. To check those, just raise the front end and try to shake the wheel up and down and left to right. If you get wobble up and down it's the ball joint, left and right is the end link. For the mounts just look for any kind of play or cracking in the bushing. Any of these could cause the vibration, and if you're getting it during acceleration and turning, it may be a combination of any of them. All the parts are pretty cheap from IPD and are easy to install.

 

Check your driveshaft. My 98 V70XC AWD was doing the same. More thumping and vibration from take off but would smooth out. It was my carrier bearing support in the center of the drive shaft. Got a rebuilt one from Colorado Driveshaft.com , $475, Vovlo doesn't service them, only sell new ones $1100. Good luck.