OK, so I already know I need shocks & struts and I discovered recently that my upper engine mount is broken (bushing is seperated). I got a new engine mount today and plan to replaceit tonight. The shocks/struts are more money than I have unfortunately. I need to know if the horrible vibrationsare related to these issues or if there is an additional problem(s) that need to be addressed as well.

Somewhere between 45-70 mph (not always, just random) the car will start a violent vibration that feels more like an almost flat tire than anything else (no - my tires are fine). It will go away completely if I let off the gas but as soon as I press the gas pedal again it starts back up. After a while it will just go away. It rarely happens if I'm in the car by myself but if I have1 or morepassengers it's guaranteed to happen.

I'm scared to death I'm going to lose a wheel or something but this car is my only transportation right now. Please any and all suggestions are welcome.

 

I had something like that happen to me, turns out I had a bent rim.

 

99 Volvo S80 T6 100k miles

Same issue and took it to the dealer for a look.

New tires, balancing, 4 wheel alignment and still there. Dealer looker further and said the CV joints have some play in them. Just bought the replacment passenger side one from www.eeuroparts.com for about $100. You can find some good directions for DIY job inside the S80 posts.

I'm going to tackle later this week and I'll post an update

 

Easy as pie. Just check the passenger side for that Visco clutch option. Mine had it and I did order the right one. The tell tale sign is another item behind the 2nd CV joint before the axle enters the transmission.

Dumbly put, it looks like there are 3 CV joints instead of two. If you have this, you have the Visco clutch.

Directions were excellent here http://www.matthewsvolvosite.com/for...ic.php?p=63174 just some bolt sizes being 1 size off. Otherwise an easy job that took 1 1/2 with 2 guys

Vibration all gone. Runs so good I may do the drivers side now!

 

To the OP. What did you end up finding ou about your car? I have the same vibration issues, occurance/speed/passengers/etc. I am thinking I need to replace the passenger side axle but wanted to see if that was your case before I order one up.

 

Sorry for not updating.

I replaced the upper engine mount and most of the vibration went away. Now it only vibrates under hard acceleration. I will be checking the CV joints next.