Dear Tom and Ray:

We have a 1995 Jeep Grand Cherokee. Whenever we hit a big bump in the road or a pothole, the Jeep starts shaking uncontrollably, and the steering wheel is next to impossible to hold straight. We have to slow down, pull over to the shoulder of the road and come to a complete stop before starting back up again. Then it's fine. This doesn't happen all the time, but it's becoming more and more frequent. Can you please help us determine what might be the problem so we don't become a flaming ball of wreckage?

-- Tracy

TOM: Well, if you're reading this from the burn unit, Tracy, you can ignore the following advice. But if you're still pre-inferno, we suggest you take this car to your mechanic immediately.

RAY: Right. We understand the appeal of free advice. But when you're having trouble controlling your car, don't drive around and wait for us to answer your question in the paper. Remember, cars are dangerous, and we're extremely slow and lazy.

TOM: You could have a bad ball joint, Tracy, or a failing tie-rod end. If either of those broke, the results would be disastrous, even for an experienced heap navigator like yourself.

RAY: If it's not a ball joint or a tie-rod end, then it's probably the steering damper. This vehicle has a suspension system that's sort of -- uh, what's the word for it?

TOM: Barbaric.

RAY: That's it. It's old technology, it's cheap technology and it's further compromised by having to perform both on the road and off the road. The result is that the handling is only marginally acceptable, even when all the parts are working perfectly.

TOM: So to improve the steering, they added something called a steering damper. What does a steering damper do? It's basically a shock absorber for the wheels that steer the car. It damps the oscillations of those wheels to keep the steering wheel from going back and forth in ever-larger gyrations until it's shaking uncontrollably. Sound familiar, Tracy?

RAY: And of course, worn-out or overinflated tires, or bad shock absorbers will only exacerbate the problem.

TOM: In any case, you can't drive like this. So take your car to a mechanic you trust, and have him check out the entire front end. If all the basic suspension and steering components look OK, then I'd strongly suspect it's the steering damper. And don't wait, Tracy.