RE: [alfa] Brake Bleeding Procedure

[White Anthony <anthony.white@xxxxxxxxxxxxxx>]

Jay et al.  

Bleeding brakes is done in order to expel all air from the system.  

Depressing the pedal expels fluid and air by decreasing the volume of the
system.  Releasing the pedal increases the volume of the system again, so
additional matter needs to enter the system to fill this volume.  If the
valve/nipple is open, then the easiest source of additional volume is the
atmosphere.  Closing the nipple/valve means that the only source of
additional volume is the fluid in the fluid reservoir.   

If you simply have a piece of tube running into a container of fluid, then
while some of the air might be expelled, you can't guarantee all of it will.
Rather, the air bubble with move back and forwards in same general area while
the pedal is pumped.  

If you're lucky, the only air in the system may well be near enough to the
bleed nipple that the fluid-in-a-jar method does work.  Equally, you may be
lucky enough that the fluid reservoir is the only high point in your brake
lines, in which case any residual air will gravity bleed itself out of the
system.  

You can't use the  fluid-in-a-jar method for changing your brake fluid, which
is recommended every two years, but which I think should probably be done
yearly on an enthusiastically driven street car, and more regularly still on
a car that sees any track time.  

Regards,
Anthony White
Wellington, NZ
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