Jon442

I drove my Cutlass on the highway today for the first time. It's great up until about 65 mph. Then the whole car starts to shake and shimmy. It doesn't feel like tire balance. It has a whole different feel, like it's the core of the car that's shaking. You can feel it in the floorboard and seat. You don't feel anything in the steering wheel. And it's not consistent. It fades in and out. It's like a grocery cart with a bad wheel. It's OK for a few feet than the whole cart starts to shake and wobble. I'm confident it's not tire balance, since it has a whole different feel. Plus, tire balance would come into play at 55 and it's very smooth at 55. It seems like it's speed-dependent. The car is fine at lower speeds, regardless of RPM. But if it's speed-dependent and not tire balance, what else is there? Drive shaft? U-joints? Any ideas welcome.

don71

You probably know the wheels and tires are the number one thing that can create vibrations. If you're sure its not tire and wheel related...By all means look at the drive shaft and u joints as being a possible cause.

And..what was the last thing that was repaired or replaced on your car. Any clues there that might affect that?