1969 Skylark master cylinder problems

I have a 69 skylark with manual drum brakes. I replaced all the wheel cylinders and shoes all around. I then replaced the master cylinder and my brake pedal is hard as a rock. Brakes barely slow you down. I believe my problem is that my new master cylinder has a different bore depth. It is not a deep bore cylinder. If that makes any sense. I cannot find a master cylinder at any of my local parts stores that is a deep bore. Can anyone help me out with a part # or somebody has one. Thanks a million.

 

My friend had the same exact problem with his but he had a 72 with power brakes. It was a faulty booster though. Pedal was like concrete. Did you bench bleed your new M/C and make sure the cylinder moves?

 

Did the brakes work fine prior to replacing the master cylinder? Have you replaced the flexible rubber brake lines front and rear? They go bad and usually there are not any visible signs. They can be totally blocked or simply restrict the movement of fluid which can result in weak braking.

Robert

 

I think there are 2 holes in the brake pedal. One for power brakes the other for manual,make sure the master rod is connected in the right hole.Phil

 

Thanks for the replays... I did bench bleed the new master cylinder, everything was normal. I replaced all the hoses. The brake pedal was very soft before. Would go almost to the floor. If you bleed the brakes either by gravity or with someone pumping the pedal you get all fluid. No air and plenty of fluid. The pedal will only go about 3/4 to the floor when you open a bleeder. Like the master cylinder bottoms out. I am going to mess with it tomorrow evening. Will post anything I find out. Thanks again guys.

 

Did you master come with one of those rubber boots that fit over the piston hole? If so, maybe it is kinked and jamming the master? I would think if you have a deep bore master with a short brake rod, you aren't going to get much pedal at all. If you have a short bore master and deep rod, I would think your brakes would always be engaged. I suspect that you either have some sort of line blockage or that you have a new master cylinder with a different bore diameter. If the master you bought has a larger bore diameter, it will give you a harder pedal. You have to be careful, because some of the parts store masters will not specify a bore at all, or will specify the wrong bore for you application. Also, as suggested above, make sure your brake rod is connected to the right hole on the pedal. For manual brakes, if there are two holes, it should be the one closer to the pedal pad since you need more leverage to achieve optimum brake line pressure without a booster.

 

I will double check the rod tonight but I think there was only 1 hole in the pedal. I also had a parts store we deal with at my work trying to track down a deep bore master cylinder. It seems like something is binding or there is a blockage but I get good fluid to each wheel cylinder. It's a head scratcher for sure.

 

Figured out the problem, was a bad new master cylinder. Thanks for the help guys

 

Was the Master Cylinder brandy new or was it a rebuild? Glad you got it solved!