New Brake pads, now it squeals.

External Since: Sep 02, 2006 Posts: 13

Had new rear pads put on my YZF600r. Now it makes a squeal when you are
almost to
a stop. If you push the brake hard it doesn't do it, but with light braking
it does.
Any ideas why this does this and how to remedy it? Thanks.

External Since: Jun 07, 2007 Posts: 521

Pete wrote:
>Had new rear pads put on my YZF600r. Now it makes a squeal when you are
>almost to
>a stop. If you push the brake hard it doesn't do it, but with light braking
>it does.
>Any ideas why this does this and how to remedy it? Thanks.

Your new pads have probably glazed from lightly contacting the disks as they
turn.

There is a little known ratio of sliding friction to breakaway friction that
riders encounter as they come to a full stop. Sliding friction is 1/3rd of
breakaway friction and, when a rider comes to a complete stop with a handful
of front brake, the retarding force on the front disks suddenly triples as
the disk stops turning. That's when the motorcycle transfers a lot of weight
to the front wheel and does a stoppie.

By the same token, when the rear wheel comes to a full stop with the rider's
hind leg pushing down hard on the brake pedal, there's a lot of retarding
force on the rear disk and the rear brake may lock up slightly.

Sometimes you hear a groaning sound when you use the rear brake to stop.
The groaning comes from the disk overcoming breakaway friction, the pads
slide, then grab, then slide, etc.

If you pop you pads out out and examine them, the surface of an aftermarket
semi-metallic brake pad will look shiny.

To stop semi-metallic pads from squealing just lay a piece of sandpaper on a
sheet of glass and work the pad in a figure 8 motion until the glaze is gone.

You can also clean the dark slick surface off the disk using some brake
cleaner and maybe a Scotch Brite pad. If you jack the rear wheel off the
ground and hold the pad against the disk while you rotate the wheel, you
won't get any strange swirly patterns on the disk.

Organic original equipment pads may look shiny all the time, you can knock
any glazing off the surface by hard application of the rear brake.

Don't go out and jam on the rear brakes an lock them up and fall down just
because I said that.

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