re: Brake Squeal, an enlightened approach.

[Kent Christensen <lkchris@xxxxxxxxxxxxx>]

So many people fail to realize that there is a periodic maintenance
requirement for disk brakes.

Squealing has very little to do with age of pads or age of rotors or
kinds of pads/rotors or the legendary "glazing," but rather is simply
the result of natural phenomena.

If there were no clearance between the brake pads and the caliper,
there would probably be no squealing, but the brakes would be locked
up and wouldn't work.  Since there is the required clearance, there is
room for the pads to vibrate under application, and the sound of that
vibration is what we perceive as squealing.

To combat the sound, the goal is to "dampen" the vibration, and that
is achieved by application of some sort of padding or otherwise
resiliant material.  This varies by application, and some pads are
coated on the backs and edges with what appears to be thick, soft
paint, and other systems introduce some spring steel shimming to help.

For the most part what you have to do--and you have to do it regularly
as preventive maintenance--is to apply some goo to the backs of the
pads where they contact the piston and to the edges of the pads where
they move through the caliper.  Then, at some point, this stuff needs
to be cleaned out since it will become mixed with brake pad dust, and
reapplied.

One of the provided links shows the BMW goo that comes in small
packages.  Here is another product, which will likely prove to be a
lifetime supply for a do-it-yourselfer.
http://www21.3m.com/dr/v2/ec_MAIN.Entry10?xid=28181&SP=10023&PN=1&V1=267717&DSP=&CUR=840&PGRP=0&CACHE_ID=0

Obviously, don't get any of these products on the friction material of
the pads or on the rotors.  Of course eliminating all friction will go
a long ways toward stopping vibration, but this still isn't the way to
go.  It will be just going and no stopping.

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