Hello, I just bought my a non-running sc300, this weekend that a dumb dealership cleaning guy soaked in water for $7000. Well needless to say I got it running after getting about a gallon of water out of the engine. BUT at 65 to 70 mph the car shakes and vibrates. I got the wheels balanced. still shakes. I even went far enough to switching all four wheels out with my friends wheels. Still shaking!!!! What in the world. I did noticed though when taking off the wheels, I had to use a 4 foot breaker bar to get the lugs off. I am wondering if the rotors are warped? There is slight vibration when braking, but still why does it only vibrate at 65-70????? please help.

 

Do a search and you'll find that many others have experienced this, several possibilities exist. Have you done an alignment? Checked the driveshaft center support bearing? The driveshaft balance (weights)? You can also tighten up the rack a bit, only requires loostening a nut and tightening the fitting inside of that nut, but very little, but it will make the steering heavier, your dealer can do this for you, it's easy. As I mentioned, do a search if you need more info, this was just addressed again recently and you'll find what you need.