Dear Tom and Ray:

I am driving a 1985 Chevy Celebrity with approximately 39,000 miles. There is a loud clicking sound emanating from the left front wheel. The click is apparent at any speed, but it sounds faster at higher speeds. Three different mechanics have checked this wheel for causes and came up with nothing. Can you explain this? -- Tom

Ray: Sure, I can. What I can't explain is why these guys didn't at least try to sell you something anyway. Not even a new pair of fuzzy dice! We're going to have to drum these guys out of the Fraternal Order of Boat-Owning Mechanics.

Tom: My guess is that you have a warped disc rotor, Tom. The disc rotor -- which looks like an oversized audio CD -- spins along with the wheel. And the brake pads sit on either side of the disc rotor, just a nose hair away from it. That way, when you step on the brakes, the pads squeeze the rotor immediately, and there's no delay in slowing the car.

Ray: And if that rotor is warped, even a little bit, every time the high point in the rotor comes around, it pushes the brake pads back against the caliper. And that's what makes the clicking sound.

Tom: Have your mechanic check the discs for "run out" with his dial indicator, Tom. If they show signs of warping, I'd fix or replace them. Aside from that annoying click, warped discs make the car brake less effectively. And as they get worse, you may also notice that your brake pedal pulses when you slow down from highway speeds -- although with only 39,000 miles in 11 years, I suspect highway driving isn't one of your big pastimes. Good luck, Tom.

It's amazing how many bad driving habits and wacko theories have been passed down from generation to generation! Tom and Ray set the record straight in their booklet "Ten Ways You May Be Ruining Your Car Without Even Knowing It!" To order, send (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475. You can also order online.

© 1996 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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