I have an 89 civic si, and every time I'm on the freeway, the steering wheel/car shakes pretty badly between 90-120 km/h. I'm thinking that's probably due to out of balance wheels, but it gets terrible when I let off the gas. I know my motor mounts need to be replaced - is it possible the out of balance tires with worn motor mounts will cumulatively cause the vibration to be so bad? I've had out of balance tires before, and this feels much worse. Could wheel alignment have anything to do with it? I know it's not the wheel bearings or brakes. Anyone encounter this problem and have any solutions?

 

it could be a number of things. certainly wheels out of balance can cause some shaking, and if the alignment is off thats just going to add to the shaking. you could take a look around in your front end and make sure everything looks snug and that nothing obvious to the eye would cause such terrible shaking. also are all your lug nuts tightened down good in the front. i know a friend of mine had a intermittent shaking and upon decceleration it shook real bad. looked it over once we stopped and realized the lug nuts on the front right tire were all about ready to fall off !

 

i would:tighten lug nuts,balance tires again and if that doesn't work get it aligned.