brake problems

[David Pertuz]

Symptom: groaning, and a shuddering (feel and sound) whenever I apply the
brakes, even at quite low speeds and at light braking force. Rather
alarming-sounding and -feeling. Note: by shuddering, I do not mean
something like a warped-rotor pulsating vibration. The car stops OK, but
it's not confidence-inspiring.

Observations: I just took the LF wheel off to check out that wheel (don't
have time to do the other one today coz I have to...ugh!, drive
somewhere!). Rotor surface looks normal - there is what appears to be a
very slight radial waviness to it, but not enough that you can feel with
your finger - just visual. Pad thickness is fine, and the same inside vs.
outside. The caliper seems to be sliding on its pins just fine (manual
test), and the pin that I removed is normal-looking. Rotor is about due for
replacement (slots are worn through), but that has been the case for a
while now.

This appeared fairly suddenly several days ago, though I think there were
perhaps signs of it a few days beforehand, which I didn't recognize at the
time.

Could a bad wheel bearing(s) be causing symptoms like this? Car has 177k on
the originals. The front end doesn't seem to be any noiser than usual,
there is no discernible extra noise in turns, and the wheels passes the
shake-it test, although I dont' think that's a very definitive test.

I will check the RF wheel tomorrow morning. If I can get a helper, I'll
also put the front up on stands and put it in gear and have someone apply
the brakes while I look and listen.

Suggestions? Ideas?

thanks,
david