I'm looking for some input. I replaced my booster, and master with Aisin brand (Japan) just for looks I didn't have any brake issues. My pedal now is spongy/low on first depression. I bled this thing forever, perform function/ leak test as per repair manual. Depressed pedal several times, held for 30 seconds, no drop in height. Pedal drops when depressed while engine is started. Also I can't get the front brakes to lock up when slammed on. I tried swapping the master to my daily driver and it's fine, so I put it back in. Tonight I swapped out the boosters, the pedal issue traveled to my daily driver, and the brakes would lock up if I wanted it too. My blue truck still wouldn't lock up the brakes, it's would take like several feet to stop.
I think I have two problems here, bad booster and something else. I have the rear brakes adjusted a little tighter than it should be to rule out the low pedal on initial application. I can stand burn the tires so I know the front can hold, I was thinking to turn the rotors, what do u guys think?