Archived Sinking pedal feeling

[scotty-u]

I just replaced the master cylinder. (Had the classic falling pedal syndrome) Bench bled the m/c, installed per service manual, bled as instructed(all but left rear wheel cylinder, it twisted off) and I still get the pedal to slowly fall towards the floor. Re-bled everything, still have the pedal falling. What next? No leaks in the system before or after the job. Rear brakes adjusted by backing up and coming to a complete stop. M/C is a rebuilt unit from local reputable auto parts store.

 

[Hoefler]

Look in the reservoir while some one is pushing on the pedal. Most Likely it is bypassing in the master cylinder, you will see a spout or movement in one side or the other. I always by new, not enough difference in cost to buy a rebuild. You might want to adjust your rear brakes manually, if they are very far out, you will not get them adjusted up doing the back up thing. It will work on a regular basis, if you back up kind of quick and brake very hard every time you back up, which no one does. Personally, I manually adjust the rear brakes, if they are drums, every time I change the oil.