brakes acting strange

[The Mic]

well when i brake the car brakes fine but when i pump the brake peddle a little when im stopping it sinks all the way to teh bottom till i hit the floor. This also happnes when i press the brake pedal for too long ;anyway in both cases i have to let go of the pedal to regain brake pressure. Any1 have an idea to whats the prob?

[Touchdown038]

Make sure the brakes are bled properly. If they are bled, I wanna say the master cylinder but don't take my word for it.

[Cyberkreig]

If the petal slowly looses height as you hold the brakes down then it is an internal leak in the master cylinder. You will need a new one

[The Mic]

so if i have to get a new master cylinder, how much is it? ill prob go to the local autozone to see if they can special order it for me. Btw i have an sr, would that make any difference?

[Touchdown038]

Nope, the braking system on the 240 doesn't change after a swap, as long as you still have stock brakes. (IE not 300zx brakes)

They are pretty expensive if I remember correctly, around $100 for a rebuilt one, or $50 for a rebuild kit if you're up for it.

[180fan]

I see you're in CA. Go to kragens and get their rebuilt BMC if you're gonna get it. 60+ 40 core. Comes with limited lifetime warranty.

[240slider]

Also check your calipers for leaks if there leaking you'll notice glazed rotors .And if ti is the master cylinder don't forget to properly bench bleed it before installation