Dear Tom & Ray:

I own a 1990 Honda Civic DX with about 80,000 miles on it. In March 1994,
the front brake pads were replaced and the rear brakes were adjusted. Since
then, the brakes make a grinding, metallic crunching noise whenever I apply
them. At first the noise was not that noticeable, but now it's louder and
very annoying.

I did take the car back to complain, but the service station couldn't find
anything wrong. So I took it to another station, and they also said the
brakes were fine, and that the noise was probably "dust impregnation," and
nothing to worry about. What is this "dust impregnation" problem? -- Kathy

TOM: Dust impregnation is an epidemic among teen-age dust particles, Kathy.
And we join with the surgeon general in recommending education and
abstinence to combat it.

RAY: What I think your mechanic is referring to is the metallic dust that
has worn off the brake pads. Brake pads and discs are both made of metal,
so when they rub together and create friction to stop the car, some of that
metal inevitably gets worn off. And some of that dust may stay on the discs
and make a little noise. But that's only a small part of the problem,
Kathy.

TOM: Most of your noise is being created because those new pads you got are
vibrating. When brake pads don't fit absolutely perfectly, they move
around. And even a very small amount of movement by the pads, when it's
happening very rapidly, can make a surprising amount of noise when you
apply the brakes.

RAY: And in our experience, most aftermarket brake pads don't fit as well
as original-equipment brake pads, and for that reason, they make more
noise.

TOM: Here's what I would do. I'd go back to the service station and ask
them to put a set of genuine Honda pads in there. In our experience, these
original-equipment pads seem to work best.

RAY: And make sure your mechanic installs all of the auxiliary hardware
that comes with the original pads, and that special grease they give you,
too. Those clips and shims, safety pins and Post-it-notes all play a role
in keeping the pads in their proper place, and keeping them nice and quiet.
Good luck, Kathy.