Dear Car Talk:

I'm trying to find out if I need to replace the control arm "bushing" or the control arm "ball joints" on my Mazda6. When my car is moving and I'm turning or braking, there are banging, popping, creaking sounds in the front left (driver's side). I had a mechanic take a look at it, and he said it was the control arm ball joints, and it would be about $550, which seems reasonable. However, I found out there's also a bushing in there, which is rubber and can dry-rot. Can the bushing make a noise (doesn't seem likely, since it's rubber), or is there something else I might take into consideration? Thank you in advance! I love the show and column, and everyone there is super knowledgeable!

-- Pam

I'll give you the bad news first, Pam. If you're already hearing those noises, and it is coming from a ball joint, that ball joint could be getting ready to break. And if it does break, the wheel will partially detach and fold under the car. How does that sound for exciting?

Normally, people report that this happens at low speed, like when they're pulling out of a parking space. But that's just because we never get reports from the people to whom this happens at high speed. They're usually dead.

As you can imagine, once one of your wheels is lying flat on the road surface, the car really is not good for much of anything -- other than long-term parking.

Now, a banging noise could be coming from a worn-out or detached control arm bushing, too. That would allow the metal control arm to bang up against the car's subframe.

But here's the good news: You don't have to figure out which part is making noise. That's because on your particular car, the control arm bushing and one ball joint come as a set. Your car is unusual in that it has two lower ball joints for each front wheel. So if your guy says you need two ball joints on the driver's side, you'll be getting two new ball joints, two new control arms and two new bushings -- you have no choice.

Typically, when a customer at our shop complains of banging or other noises from the front end, we'll put the car up on the lift, grab the tire and try to move the wheel around. We'll push it and pull it and pry at it. And while we do that, we'll watch all of the key front-end components to see if any of those parts have excessive play in them.

For instance, if we see the "ball" part of a ball joint moving around inside its socket, we'll know the ball joint is bad, because there should be zero play in there.

If the ball joint's good, we'll check the control arm bushings and other components, looking for inappropriate movement. We usually can figure out pretty quickly what's causing the noise.

But you don't need to bother doing that, Pam. Because the only way you can get a new ball joint is by purchasing a new control arm, bushing included. So if you're buying two ball joints on the driver's side, you'll automatically be the proud owner of two new bushings, too.

And $550 is the right price. Just consider yourself lucky that you don't need the passenger side as well.

So go back today and get it taken care of. I really hate to see people play ball joint roulette.