On Sat, Jan 05, 2002 at 12:37:46PM -0600, BOB NOGUEIRA wrote:
>
> I'm rebuilding the a brakes on my project car. The wheel cylinders look to
> be in good shape but have a lot of grease etc on the out side. I was going
> to glass bead blast them but got to wondering if I should protect the bore
> and inlet pipe hole first . Will bead blasting the bores screw up the
> cylinder ?
After thinking about it a bit, if I were doing it I'd be very
careful to block off the innards to prevent any beads from making
their way in.
The problem is that glass beads love to stick to the crevices inside
parts. If there's any left inside the cylinder, they could
work loose later and damage the seals, causing you to lose your brakes.
If they didn't do that, they would still cause excess wear on the
piston and cylinder.
The other issue is that you don't want to bead blast the inside
of the cylinder, since a rougher finish there won't seal
as well and will wear the piston more. (actualy this depends on
the type of brakes-- on drum brakes the seals move in the cylinder,
on discs they move infrequently, since it's the elastic of the seals
that pulls the brake pads back from the disc. The specs for smoothness
of the different type of cylinder might differ as a result).
Also, my understanding is that you don't use bead blasting to get
grease and dirt off, because it pollutes your blast media (and
if it's thick enough, it just absorbs the media). Just paint and rust.
Eric
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