Ok so i left NY with my little lady in red all happy riding smooth ..... I come back Last night and when i started to drive i said wow she feels different....
So i start to cruise around 60 and the car is shaking, So i play around with acceleration i come to find that with i hit the gas at all it stop shaking and rides smooth,but when i let off(around 70mph) it begins to shake and at around 60 it really doesnt feel too good !??!?!?!

The shaking feels like the seat have massagers on them the steering wheel doesnt shake mostly the shell of the car versus the motor....

I recently had wheels balanced, Air pressure is perfect (check it weekly)

 

Loose wheel? Double check.

 

Yeah i checked that too...

I drove around slower speed didnt feel it. Around 50mph up then i can feel it

 

Maybe bad axle.

 

I hope not....

Also when i go over a speed bump i notice a sound from the front like that of a wooden floor creaking ....

 

Maybe spring bearing assembly for the noise.

 

I have the same problem with my S40 too, but then again, it is a salvage title vehicle. Now I don't feel so bad.

 

I got new tires and a wheel alignment. I noticed mines started shaking too around 60mph+. I took it back to the shop and they said 1 of the wheels were off balance. I haven't had time to drive it on a smooth surface highway. I hope my issue was resolved. Did you fix your problem yet JDSR917?