Shimmy & Shake

My 93 Olds Cutlas Ciera 6 cyl sedan increasingly shakes in the steering wheel the faster I go over 65 mph. I have had 3 sets of tires and 2 sets of wheels, all with the same problem. Mechanics say my front end is tight. Someone suggested axles but I don’t want to keep throwing money at the car. However, it is in excellent shape and is only driven in the winters when I am in Arizona. Since the speed limit is 75, I hate to go 70 and hold up traffic. Any ideas?

On a car that old there are whole number of possibilities. All I can suggest is a good chassis shop.