RAY: Hi! We're back. You're listening to Car Talk, with us Click and Clack, the Tappet Brothers, and here is the answer to last week's puzzler.

TOM: What was the puzzler?

RAY: Ah.

TOM: You're going to tell us.

RAY: I'm going to tell because this is not the kind of puzzler that you'd remember. Most aren't, actually.

TOM: No. Yeah, it doesn't matter.

RAY: A customer, who shall remain nameless, called up the other day and said that a brake job we did had gone awry. We had done a brake job on his old Volvo, we had put on new pads, new disc rotors on all four --

TOM: Oh yeah. The bad rotors.

RAY: And it was alright for several months and all of a sudden, Dick calls and says --

TOM: Oh Dick.

RAY: Gee, now when I step on the brakes I get a rumbling. In fact, when I step on the brakes really hard the worse it is. If I step on them gently, it's hardly noticeable, if at all, but when I really step on that peddle. Boy, those things rumble and shake like crazy. Geez, I don't know. One of those discs must be warped he says. He brings the car in. We drive it around and sure enough, he's right it is rumbling. Classic symptom of a warped disc.

TOM: Yeah.

RAY: Anyway, we put the dial indicator on this thing. It was determined that there's nothing wrong with any of the new discs so we check all the bushings, the tire rod ends, the ball joints. You name it. We check everything figuring that any one of these front end components could be wobbling and causing this problem because there are interesting dynamics set up when you slow the wheels down.

TOM: Sure. Sure.

RAY: But we find nothing.

TOM: Hmm.

RAY: So, since Dick is a pain in the neck --

TOM: What's his last name?

RAY: We put four new discs on figuring that maybe the dial indicator is off. Who knows?

TOM: Sure.

RAY: I mean why not? The guy's a good customer.

TOM: Even though all evidence is to the contrary, the customer is always right. He says he's got bad discs, he's got bad discs.

RAY: Right. And he spent thousands on this job anyway.

TOM: Thousands?

RAY: We drive the car. Guess what? The same thing happens. Back on the lift it goes and hours go by. We have Ralph chained to his toolbox until he figures the thing out and he's standing there underneath the car, right in the middle of the car with wrenches in hand and he's ready to remove something and I say, "What are you doing?" And he says, "I know what's wrong with the car." What's he going to remove that's right in the middle of the car that's going to solve the problem?

TOM: Oh yeah.

RAY: The brake parts in the middle of the car.

TOM: When you said this, I said, "The hanger bearing." You said, "No." I said, "The transmission mount." You said, "No."

RAY: You were close. You were close.

TOM: Ah.

RAY: Ah.

TOM: Drive shaft!

RAY: Yes, Dick had a seized universal joint.

TOM: No kidding?

RAY: So, when you step on the brake. What happens is this, when you step on the brake at low speed at all, when you step on the brake gently...

TOM: I've got it, of course.

RAY: The angle of the car doesn't change much with respect to the ground, but when you step on brakes hard, the car does something called nosing or diving, the front bumper dives to the ground.

TOM: Half gainer?

RAY: Half gainer and the drive shaft has universal joints on it which must flex, but if one of those universal joints is seized when you're asking it to flex to accommodate this new angle of operation, it begins to shake like crazy.

TOM: Yeah.

RAY: It was only doing it on hard braking. Ralph figured out that it was because the thing was nosing and causing that seized joint to have to try to bend and it couldn't that was causing the vibration. Pretty nifty ay?

TOM: So, he took out the drive shaft and sure enough, you found that to be true.

RAY: No, it was all right actually. We sold him new U joints and rear struts. No, that was it and it solved the problem. Who's our winner, Tommy, of our 10th Anniversary Car Talk T-shirt this week?

TOM: I'm looking. I'm looking. I'm looking for his name. I've got pieces of paper. Here it is. The winner is Dan Visentin.

RAY: OK.

[ Car Talk Puzzler ]