CLICK & CLACK’S CAR TALK

LITTLE ROCK — DEAR TOM AND RAY:

I need your help to settle an argument I have with my no-good brother-in-law from Illinois. At night he always drives with his fog lights on in addition to his headlights. He says he can see better with them on. I tell him, “Sure, but what about the way they blind oncoming traffic?” He says if they were too bright, then it wouldn’t be legal to have them.

I tell him, “But all that bright light up close actually reduces your long-range vision.”

He says, “How can more light be bad?”

I say, “And it makes your engine work harder, shortening the life of some components and reducing mileage.”

He says the car was designed for it, and he has done it for years with all kinds of cars and has never noticed any ill effects. I have fog lights too, but I use them only three or four times a year - essentially, on deserted county roads in the fog, when they can actually make a difference. I say he’s a feckless Bears fan. He says I’m a pansy Packers fan. Which one of us is a bigger jerk?

• Fred From Wisconsin

RAY:

Well, I think the jury’s deliberating hard on that one, Fred. But they might be leaning toward you.

TOM:

There are two kinds of supplemental lights you see on the fronts of cars. There are fog lights, which are mounted down low and illuminate the road immediately in front of the car.

RAY:

You may have noticed that when it’s foggy, the closer you get to the ground, the less dense the fog is (and in fact, using your high beams in fog makes it harder to see). So fog lights attempt to help you by lighting up the lowest, closest portion of the roadway.

TOM:

And since they’re aimed down at the road for 30 feet or so in front of the car, they shouldn’t bother oncoming drivers much, if at all.

RAY:

So, if he’s really using fog lights, you should leave the poor guy alone and get off his case, Fred.

TOM:

Sure, he’s using a tiny bit more gasoline to power the extra lights, but the difference in mileage is barely measurable. So if he prefers more light to an extra fraction of a tenth of a mile per gallon, he’s free under the U.S. Constitution to make that trade-off.

RAY:

Now, the second type of lights you see are called “driving lights.” Those essentially are an extra set of more powerful high beams.

TOM:

And like high beams, those are aimed up and far ahead, to light up as much of the road and roadside for as long a distance as possible. So driving lights will blind oncoming drivers, and they should be used just as high beams are used: on remote roads when there’s no oncoming traffic. And they need to be switched off when another vehicle approaches.

RAY:

So if he’s got high powered driving lights, and he’s leaving those on all the time (even if they’re legal and correctly aimed), then he’s putting himself and oncoming drivers in danger by making it hard for them to see. And I’d be surprised if he hasn’t been given that message by stars seeing oncoming drivers who flash their high beams at him in annoyance.

TOM:

If that’s the case, and he’s still using his driving lights all the time anyway, then he deserves to be harassed by an annoying brother-in-law. And you sound like just the guy for the job, Fred, so stay on him!

DEAR TOM AND RAY:

This morning at the gym an acquaintance (Fred) told me that he took his car to a mechanic for some brake work, and the mechanic replaced the pads and rotors. Fred said that he wanted the mechanic to replace the pads but not the rotors. I asked him if the mechanic explained why he replaced the rotors too, and Fred said no. This led to a discussion. How do you know when the pads are all that need to be replaced versus when you need to buff or replace the rotors, too? What symptoms should we typical folks look for? Thanks.

• Ed

TOM

: Well, the classic symptom of warped rotors is a pulsing in the brake pedal when stopping from high speeds. Sometimes that’s accompanied by a simultaneous wobbling of the steering wheel.

RAY:

But that only tells you when your rotors are warped, not when they’re simply worn out. And my guess is that your friend Fred’s were worn out.

TOM:

Brake pads used to be relatively soft. They were made of asbestos. And they would wear out quickly. But the hard, metal rotors would last through several sets of pads. That’s all changed.

RAY:

When we got rid of asbestos, brake pads began to be manufactured out of much harder materials - namely, metal. So now, the metal pads grind against the metal rotors, and they wear out at almost the same rate.

TOM:

So these days, 99 cars out of a hundred need to have their rotors replaced when the pads are swapped out.

TOM:

We almost always replace the rotors now rather than machine (resurface) them. When you machine a rotor, whether it’s on or off the car, you have to do at least two passes to do it right, and that takes a good half-hour of labor. You add the cost of using the machine, and you have to charge 60 bucks a rotor. And you can buy some brand-new rotors now for 30 bucks! So machining them rarely makes sense.

TOM:

There are exceptions. Some rotors won’t come off without breaking the wheel bearing, and we’ll machine those rotors right on the car if there’s enough metal left. But the vast majority of cars that come in for brake jobs these days get new pads and new rotors.

RAY:

And for those of you concerned about the environmental impact, don’t worry. Once a week, a guy named Stumpy comes in and collects all the used rotors for recycling - where they’re shipped over to China and come back as fireplace tools. Click & Clack (Tom and Ray Magliozzi) dispense advice about cars in Car Talk every Saturday. Email Click & Clack by visiting the Car Talk section of

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