Is the chattering produced on my wife's car's brakes when it rains something to worry about?

Dear Car Talk

Dear Car Talk | Nov 01, 2002

Dear Tom and Ray:

I'm having no luck convincing my wife that the chattering produced by her '99 Chevy Cavalier (30,000 miles, lots of brake pad left) when it rains is absolutely normal and not life-threatening. Despite my accurate call that the intermittent braking noise (only when wet) stops after lightly riding the brakes, and thus drying them, she feels that catastrophe can ONLY be averted by taking the car to an "expert" and writing a check for his sage advice. Help me out, guys, and give a totally discounted husband's diagnosis some credibility. -- Dave

RAY: Dave, your wife might have very good reasons for discounting your diagnosis. So we can't bail you out without knowing your track record.

TOM: For instance, what if your last diagnosis was "just the tire rubbing against the wheel well, hon." And it turned out to be a bad ball joint, the wheel fell off and your wife drove into a vegetable cart? Then we might sympathize with her desire for an expert opinion.

RAY: But you might be right, Dave. Drum brakes are notorious for "grabbing" when they're wet. So if this car has drums in the rear, they could be grabbing the first time you stop. And the chattering you hear is the anti-lock brake system kicking in to keep the rear wheels from locking up.

TOM: So if you have drum brakes in the rear and this only happens the first time you drive the car after a rain, then chances are you're right, Dave.

RAY: But if it happens more often than that, or if you have disc brakes in the back (which was an option on this car), then I think it's worth taking the car to the dealer and having the brakes checked and the ABS sensors scanned.

TOM: Given that you appear to be a cheapskate, like me, Dave, I'm guessing you didn't pay for upgraded brakes when you bought the car. So you probably are right.

RAY: But when you break the news to your wife, tell her I feel her pain, Dave. And so does my sister-in-law.

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