My brake pedal is very mushy and doesn't start braking until it's almost at the bottom. If it works similar to how my clutch works, it's leading me to believe it'd be the master cylinder. I push the pedal down just so far, then the pressure that's there lets go and the pedal goes down some more.
Car just rolled over 200k miles on the original master cylinder, so I'm guessing that's what it is. :o
If so, is this an easy fix? I'm about to swap the LS1 out for a 6.2L, so would it be best to change the master cylinder when the engine is out of the way or would it make no difference?
Try holding the brake with light pressure and see if it slowly continues to fall towards the floor tell tale sign that its bypassing internally. But like some others have said bleed the brakes first to rule out any air in the lines
master cylinder would make a slight noise if bad, at least my old chevy did, I would bleed them starting with the back right, then back left, then front right, then front left, get some 3/8 or 5/16 hose and a bottle of brake fluid, put the 10mm wrench closed end on the bleeder first then hose that leads down to the bottle of brake fluid and remove the brake res. lid and start slowly pumping, stoping to make sure you got plendy of fluid in the bottle and the res, then with a 2/4 hold the brake down and run back and close the bleeder then repeat, if that dont fix it, go to napa and spend some money..