I have a 1996 Honda Prelude and recently changed the rear calipers, rear rotors, and took apart and lubes the front calipers. I bled the entire system and drove it 500 miles and they worked great. Then today while driving and coming to a stoplight i all of a sudden felt the pedal go to the floor. It turns out that low RPM's the brake pedal is mushy and goes to the floor. AT higher RPM it feels normal. I couldn't visibly see any vacuum leaks or hose cracks on the brake booster. I am wondering if their is still air in the system somewhere, or possibly my master cylinder seals went bad. Help or suggestions would be appreciated.

 

I would check for leaks. Those bolts and bleeder bolts really need to be tight.

 

i would double check for air in the system. Is the cylinder getting low once the pedal sinks? if so i'd change the master cylinder. Mine would do this for awhile if it was warm out. Coming to a stop or sitting at a stop light the pedal would slowly sink to the floor. Changed the master cylinder fine every since.

 

sounds like a master cylinder problem to me as well

 

Problem solved the drivers side rear banjo bolt for the Brake like on the caliper was about a turn and a half loose. My dad must not have tightened it all the way. I tightened it and bled the system as there was much air in that line and Pedal feels amazing now. Thanks, glad it was not my MC.