soft pedal
 

I have a brake problem that is wearing me out - my local mechanic too. It's a 1994 Corolla, has about 300,000 miles and was on original rear brakes. I replaced drums and brake shoes, adjusted out what I believe enough. Still has very low pedal and slides the fronts when floored. I thought problem was master cylinder, installed new one, same symptom. Tried bleeding more, seems no air in lines. Thought maybe I had rubber line swelling and "wasting" the line pressure - can't find such. Front rotors are almost new, same for pads. Car is not ABS equipped.
What is most likely cuase - how do I troubleshoot? I can either borrow a :!: brake pressure gauge from a buddy if needed, then plug things off and check pressures that way I suppose. What is normal pressure front/rear? Need help before I kill myself or someone else!