Hello! I am a new member. I have been helping a buddy of mine try to fix his brakes on a 97 GMC sierra 1500. He has them but he has to floor the pedal before it will stop. When it does stop it is hard. It builds enough pressure after a few pumps to brake where it should, but when we go to brake again it's too the floor. We have replaced the booster, master cylinder, both cylinders in the drums, and have bled the lines and it still won't brake properly. Have any of y'all had this issue?

 

Welcome from Florida. Did you bench bleed the new master cylinder?

 

No we did not. Is there something that bench bleeding does that regular bleeding does not?

 

It bleeds the air out of the master cylinder before you bleed the rest of the system. It needs to be done first, or you will not be able to bleed the rest of the system.