Dear Tom and Ray:

My husband and I disagree about whether the button on the parking brake should be pressed down prior to engaging and lifting it. If you don't, it makes a grinding sound, and I think that can't be a good thing. My husband contends that it makes no difference. Please settle this for us. Thanks.

-- Carolyn

RAY: I'm so glad people are finally writing to us with questions worthy of this illustrious column!

TOM: It makes no difference, Carolyn. The button is there to release the parking brake. That's why it's called the parking brake release button.

RAY: The clicking you're hearing is a ratcheting mechanism that holds the parking brake in place once you apply it so it doesn't release on its own and let your car roll away.

TOM: There's a metal wheel at the base of the hand brake handle. That wheel, which is called a "ratchet," has a bunch of teeth in it. Then there's a metal spike called a "pawl," which sticks into those teeth as they go by. The pawl allows the handle to go in one direction (up) but not the other (down). So all you're hearing as you pull up the brake handle is that pawl clicking into each successive tooth.

RAY: When you push in the button, you're pulling the pawl back, out of the way of the teeth. That's why it doesn't click. And that's why pushing the button allows you to move the handle in both directions.

TOM: But it's not necessary to hold in the button while you're applying the brake. On the other hand, it does absolutely no harm. That ratcheting mechanism will last for the life of the car whether you let it click or not.

RAY: So, it's an aesthetic decision, Carolyn, not a mechanical one. If you find the clicking sound pleasing, or reassuring -- which I do -- then just pull up on the parking brake handle and let it clack away.

TOM: But if it causes you distress and heartache, then feel free to eliminate that sound from your life by pushing in the button when you engage the parking brake. It doesn't matter to the car.