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Very hard brake pedal on '55 NYer problem

From: Adam
Remote Name:
Date: October 21, 2003


The problem I'm having is that I only get a boosted brake pedal for about 1/5th of the total brake pedal travel, then it sort of hits a "wall" and becomes VERY hard to push. I can usually stop just fine with only one leg working the pedal, but even with both legs I can't lock up the brakes even at 30mph. The previous owner had the master cylinder/booster assembly rebuilt a couple years ago, and rebuilt all the wheel cylinders also. I took off the master cylinder/booster and it looks perfectly good to me. Rubber diaphragm is in good shape, and the new paint on the interior of the housing still looks perfect. Nothing rusty or bent that I can see. I also checked the vacuum line going to the intake manifold and it's fine (but like I said, I DO get boost for part of the travel, I know for sure it's working for that short part). I assume the check valve is in the big metal part that the vacuum line connects to, but I don't know how to check to see if it's good or not. I'd take apart the master cylinder to see if it's good or not but honestly I can't figure out how to. It's not the "independant" type like most cars as you guys probably know, it's somehow integrated with the booster. I'm not sure what I'd look for inside it anyways... Does anyone have any idea what might be wrong? The car doesn't pull to one side or the other at all and I know the rear brakes are working since they squeak a bit when braking. Up til now I'd just been dealing with the hard pedal and driving it anyway, but someone ran a red light in front of me the other day and it was a very close call, so I need to get this fixed. Thanks for any help!


Last changed: July 19, 2018