Hi crs12. Welcome to the forum. It sounds like none of thesed mechanics are taking your car for a test drive after completing repairs. The last step is always a test drive to confirm the repairs solved the problem.
The tires should be inspected for a broken belt. That should have been evident when they were on the wheel balancer but not everyone watches them as they spin. You can also watch the front ones if you run it in gear with the car jacked up or raised on a hoist. Most broken belts are obvious as you'll see a bulge in the tread or it will squirm sideways at one point. Some broken belts are more subtle. The tread that contacts the road will appear smooth and even, but deeper in the grooves, you'll see the carcass move up and down a little as the tire rotates.
A tire with a broken belt on the front will cause the steering wheel to move left and right a little at very low speeds, such as when driving through a parking lot. You will feel a broken belt on a rear tire as a shimmy in the seat. Either one will cause a thumping at higher speeds that feels like a tire out-of-balance.
In severe cases, a very rusted rear brake drum will cause a vibration if a chunk of it breaks off. That will cause the same vibration as an out-of-balance tire except tire balancing won't help. This is more common in states where they throw a pound of road salt on an ounce of snow.
Saturday, June 5th, 2010 AT 3:31 PM