Apr 18, 1998
RAY: We're back. You're listening to Car talk with us, Click and Clack the Tappet Brothers and we're here to discuss cars, car repair and the new puzzler.
TOM: OK, I can hardly wait.
RAY: All right. Well, I realize that I haven't really done any automotive puzzles for a long time, because a really, a good automotive puzzle, so --
TOM: Yeah. Well you haven't been to work for two months. That'll do it, I mean you'll forget.
RAY: Yeah. A customer who shall remain nameless called up the other day and said that a brake job we had done had gone awry. We had done a brake job on his old Volvo and we had put on new pads and new disk rotors and it was all right for several months. And, and then Dick says, oh, did I say nameless, he says, gee now when I step on the brakes, he said, I get a rumbling. And he said, the harder I step on the brakes the worse it is. In fact, I don't really feel it at low speeds or if I step on the brake gently even at high speeds, but if I really lay onto the brakes, I feel that shuddering in the car. He says one of those new disks must be warped. And we say I doubt it. Anyway, he brings the car in and we drive it around and sure enough, he's right. It is doing, it is doing the - classic symptom, a warped disk. We put the car up --
TOM: Those are pretty hefty disks.
RAY: Those are hefty, meaty, beefy disks.
TOM: Those are hefty, meaty, beefy, they're not cheap little Yugo disks.
RAY: No, no, no.
TOM: Those are serious.
RAY: Yeah, Yugo, they get the rejects from I-HOP and they just, they slap a brake caliper...
TOM: You can still read Coca-Cola on some of them.
RAY: Anyway, we put the dial indicator on it and determined that there's nothing wrong with the disk, of course.
TOM: If you had, there would be no puzzler.
RAY: That's correct. That's correct.
RAY: But, we check all the bushings -- cause a bad tie-rod end or a ball joint or a control arm bushing, or a bad strut mount, anything can cause this vibration. We check everything. We check everything. And we can find nothing wrong, but to humor him we put four new disks on.
TOM: You do?
RAY: Not really. We just told him we put, no, we put four new disks on, figuring that maybe one of our instruments is off a little bit. We drive the car, of course, what --
TOM: Same thing.
RAY: Exactly the same thing. Back up on the lift it goes. And hours go by. And we have Ralph chained to his toolbox until he figures this out. And he's standing there and he's right in the middle of the car.
TOM: Was he lying down?
RAY: No, no. He's, no, he's standing and the car's on the lift. He's standing there right smack in the middle of the car with wrenches in hand and he's ready to remove something. And I say to him, what are you doing? He says, I know what's wrong with it. What's he gonna remove, and why does that fix it?
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: 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 the 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.
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, eh?
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.