Dear Car Talk:

I have owned my 1983 Datsun (Nissan) 280ZX Turbo since it was 6 months old. It has only 125,000 miles. It has never been in an accident. Recently I had it repainted, got new tires, muffler, suspension, struts, tie rods, calipers, new bearings, brakes, new air conditioning unit ... pretty much everything on it is new, including the reupholstered bucket seats.

The problem I have is that the front end now sways, or "floats," back and forth on the highway; it almost feels like I'm driving on ice or hydroplaning. Two separate mechanics have looked at it and can't figure out what is causing this. Any ideas? Please don't tell me to get rid of it -- it was a birthday present from my husband 33 years ago. Thank you so much! -- Elizabeth

I can tell that this car has great sentimental value to you, Elizabeth. So, look at the bright side: This steering problem will keep you from racking up too many miles on this beauty in the future. You'll never have to upholster the seats again.

Actually, it sounds like a classic case of a car that's out of alignment. For instance, if you have one front wheel that's pointing straight, and the other front wheel is even slightly pointing in or out, it'll feel like you're driving on roller skates. It's hard to imagine that two different mechanics would have failed to check that, but I guess it's possible.

So the first thing you should do is take it to a good alignment shop and ask them to align it. And don't forget to check the rear wheels, too. That's something they may have missed.

If it can't be aligned, then you've got a deeper problem. It's hard to believe that a wrong suspension part was used -- usually the wrong parts just won't fit -- but I suppose that's possible.

The other thing that can make a car impossible to align is an accident -- something that distorted the shape of the frame or a front-end component. Maybe that time you lent it to your cousin Leo and he hit that 7-foot-wide pothole, he bent a control arm or something.

Or something could have happened in the shop. I once dropped a car off my lift. In fact, it was a Nissan Z! That car was never to be aligned again. Actually, it was aligned right to the junkyard after the insurance company declared it a total loss.

But it doesn't take falling on its side from 6 feet in the air to bend a key component, and it's possible that something happened to your car that you're not aware of.

The other thing that could possibly cause this is bad tires. I know your tires are new, but if there's some tread separation or some other defect, that could cause squirming. Bad tires are more likely to squirm at lower speeds and create a wobble at high speeds, but I wouldn't rule out a bad tire.

An easy test is to ask your mechanic to try swapping the front tires and rear tires to see if that makes any difference. If it's better, that suggests you've got a bad tire up front right now.

But start with the alignment. Your symptoms are classic, and if it hasn't been properly aligned, an alignment could fix everything. Good luck.