need help diagnosing brake issue

[Eman]

Originally Posted by GallopinGhost

Eman, yes you are correct on what I have done. Checking with the lines plugged sounds like a good step. If it's determined I need more volume in the MC, how is that spec listed ? I have an adjustable push rod on the MC, maybe if I can get a longer throw that might help. Check valves also seem like it's worth a try.



The thing that bugs me is after a few pumps of the pedal, all is good.





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I'd say the reason the pedal gets better when you pump it is the pads move out towards the rotor with the first pump so they have less to travel on the next pump. People tried springs to push the pads back and eliminate any drag from the pads rubbing the calipers. What happened was the first pump went almost to the floor. Just like when you do a disc brake job and push the piston back. You have to pump the pedal to move the pistons back out.
Someone mentioned pedal ratio which is important, usually 6:1 or better. You also have to be sure that the pedal can push the MC all of the way to bottom. You them have to be careful when you adjust the pushrod as sometimes you can cause brake drag especially when the brakes get hot.