Dear Tom and Ray:

My 1991 Toyota Camry is an excellent car in most every way. However, about three months ago, I had driven a short distance from home, when all of a sudden the car developed a shimmy very much like driving on a flat tire. I pulled over and stopped to inspect the tires, but found no flat. When I started up again, there was no shimmy. A few days ago the exact same thing happened in the same location. Again I pulled over and stopped. This time, when I started up, the shimmy continued for several miles until I reached the Toyota dealership. I left the car to be checked. They called me later to say that they found no problem, and couldn't get it to shimmy. I insisted they keep the car overnight and try again in the morning. Again, they found no problem. Do you have any idea what might cause this?
Arthur

RAY: Arthur, I KNOW what's causing it.

TOM: Whoa! Do tell, Oh Great Piston Puss!

RAY: Your parking brake is hanging up. When you release the parking brake and leave your house, one of the shoes isn't releasing. So as you drive, this shoe is rubbing on the drum and heating up.

TOM: And we all know what happens to things when they heat up, right? They expand! And after a certain amount of heat builds up (which explains why it happened at the same distance from your house both times), the brakes expand enough to start catching a wheel as it comes around. And that feels a lot like a flat tire.

RAY: The first time you pulled over, the brake became un-stuck before you started up again. Maybe using the brakes to pull over did the trick? Maybe the brakes just cooled down enough while you were looking around for a phantom flat tire.

TOM: The second time this happened, the brakes didn't un-stick until the car sat at the dealership for a few hours. By the time they looked at it, the brakes had cooled off and was fine again. And of course, since mechanics don't use parking brakes (it's in the by-laws), the next morning, the parking brake didn't stick.

RAY: Take it back to the dealership, Arthur, and ask them to take the drums off and operate the the parking brake. Make sure it's really working. My guess is it's working, but it's not un-working. Good luck, Arthur.