[s-cars] Weird brake pedal behavior

[Lee Levitt]

Guys,

I need some help in diagnosing a weird brake pedal behavior. Car is my '95.5
S6 avant with BIRA System 3 (Carrera C2 calipers).

With the engine running, when I depress the brake pedal I get a sensation
about 2/3 of the way through the pedal travel...a bit of a click or a bump
(tough to describe). Almost like something's in the way of the pedal travel
or like a piston's binding as it moves through a cylinder.

With the engine off I do not get this sensation.

I've done a brief walkaround. Pads look good, calipers seem fine, reservoir
full of SuperBlue. No obvious problems from the outside.

Thoughts?

Thanks!

Lee
'95.5 S6 avant
'96 A6 quattro avant