why do my brakes suck?

[davidpertuz@mindspring.com]

As described above, my brakes suck.
They are not very confidence-inspiring.
WHen I use them more than lightly, they
simply don't stop the car very well.

If I use them hard, I hear a slight
groaning from the front brakes. It can
be felt lightly in the pedal, but it is
not a bang-bang-bang type of shudder.
Nothing nearly as strong as a warped-
rotor shudder - it is more heard than
felt.

If I honk on the pedal they feel shitty
for most of the stop, until the pedal is
all the way down and the car is close to
stopping, when they will grab good.

AFter reading a message by Wayne recently
I made sure that the pads were free to
slide and not binding or dragging. No diff.

I am wondering whether this could be
symptomatic of a dying master cylinder.
The MC is slightly suspect as a (literal)
handful of times in the last coupel of
years the pedal would sink deeply before
braking power kicked in - classic sign of
a failing MC, but it hasn't happened in
at least a year and only a few times ever.

Hardware: OE-replacement SMC/Powerstop
slotted rotors, Porterfield R4S pads,
Motul fluid, stainless lines, original
(160k miles) master cylinder and calipers.

Any insight is appreciated!

thanks,
david