First, here is what I have:
1986 Z28 with stock disc brakes up front. 12" Baer 1 piston brakes in the back. I didn't put the proportioning valve in, because I think if I can't lock up the back brakes, I shouldn't need to reduce the pressure to the rear. I replaced the front rotors recently. Pads are in good shape, semi metallic up front, and whatever came from Baer in the rear. I have some extra weight up front(BBC) And 255/50 R16 Kumho tires all around.

After the rear brake install, braking was very good in my opinion. I did a good solid stop from 60mph brakes only in 105 ft. (I paced it off, so it could be off a little)

Here is the problem. The braking sucks now. Is it possible that when I replaced the front rotors, I screwed them up or didn't break them in correctly? I can't say for sure whether the braking quality degraded after the replacement. When I push the brake pedal, it goes about 30% down, and then gets solid as a rock, almost like when I forgot the vacume hose... Sometimes, after I drive over a harsh bump, the pedal will go all the way to the floor when I brake. I know that all my lines are good and not getting pinched smashed.

Sorry its so long, wanted to give the best info possible, thanks.

 

Dunno man... sweet rims, they look like mine, well sorta.

 

Yea, I had to take the picture of the side where my label ripped off the center cap...

Yea, I'm proud of those wheels, paid $235 for all four, very nice condition, road tripped to N. Virginia one night with some buds to pick them up. 11:00pm I called the guy with a cell from his driveway. He was asleep, and we watched the lights come on before he answered... He was really nice about it, considering...

 

Start By replacing the master cylinder. If you still have the original brake booster then I suggest replacing that also. I think Wagner makes a combination unit that comes with the Brake booster and M/C.