Seems I have a rare situation that no one can find the cause. Low brake pedal in a 98 M3. Has 4 new rotors, rebuilt front calipers, all new pads, replaced the master, replaced the ABS hydro unit with a different used one. The only help has been the ABS replacement now offers a more progressive pedal feel, but still ends up below the accelerator pedal height. The brakes work well enough, but you'll never roll your foot for a rev matched down shift. Surely this can't be "normal" pedal in an M3 as some have suggested to me. I guess we'll go after the vacuum boost next, if no one has any other ideas.
Yep Makes sense. You might not have enough brake fluid or it might be diluted. Brake fluid does not compress, but air and other liquids are more compressible (and will result in lower brake pedal when depressed). So if your brake fluid is not pure you might have a low pedal. Good advice to flush it out as part of the process of elimination anyway.