ok so ive done some searching but nothin i've come across seems to help or im just not lookin in the right place.

lately ive been noticing that as im braking, my pedal seems to sink in the longer i have it pressed down, whether it be im slowing down or if im at a complete stop and waiting for a green.sometimes it gets to the point where it goes all the way down and i resort to using the e-brake.however there is a way i get around this and its by pumping the brake pedal every so often to keep it stiff.now my question is this, is this happenin because somewhere within my brake system im lossin pressure?i also understand that air can get in and can cause somewhat of the same response, and if thats the case would bleeding it out solve it?i've had the same thing happen to my clutch only to find out that the master cylinder needed replacing.would that mean that its time that i replace the brake master as well? or is it the booster? someone help me out on this as im very concerned seeing how i lend my mom my car every now and then, i dont want the brakes to go out and have somethin terrible happen.

 

have u bleed ur brakes lately? if so there still might be some air in the system...if u havent bleed the system anytime recent then most likely ur brake master cylinder is leaking internally..replace that

 

well the thing is the brakes haven't been bled since i first got the car, but it was fine then but now its not stiff like i want it to be, but ill try bleeding them and see what happens.if not then i guess imma have to shell out for another master, this time for the brake.

 

your brake master cylinder is out.
you need to replace it. i know because i have had that exact problem.
research here on h-t and found out it was my brake master cylinder

 

Its not your brake booster. If it was, the pedal would be hard to push down. If it was the master you would feel the pedal suddenly drop to to the floor when at a red light. Sounds like you just mite need to bleed your system. System may have air or fluid maybe old and have alot of moisture.

 

aww damn, well idk if thats it for sure imma try bleedin em first but if this keeps going after that then yeah, i guess imma have to get another one.ill see what happens when i do this tommorow

 

are you freaking dumb or what?
it will not "suddenly drop to the floor"
it will slowly drop until it can not drop anymore.
and you have to pump it until its back ontop.
but even then it will still drop slowly

 

its any easy fix.
and you can find a good master cylinder at a junk yard

 

aight well cool.thanks guys imma take care of this this week

 

have fun!

 

Hostile are ya

 

Start small,

Bleed your system first, then look into BMC's.

 

Wow if you never worked on brakes try not to sound like a smartass. "O i research here on h-t O its my master cylinder O im a bitch". When a bad master cylinder and a combination old fluids or even bad wheel cylinders, a person that never encounter the problem would descibe it as a "SUDDEN DROP". If you work in a shop long enough you would hear this from customers all the time. Dont go assuming its the MC every time this symptom shows up. Now like i said bleed your system first and see what you come up with before buying a new MC. Just like K said start small and work your way up.

 

you said " suddenly drop to the floor"
your saying it as if there is no brake fuild in the lines and the pedal just drop with NO RESISTANCE!