The Stovebolt Site Forums The Shop Area Driveline Brake Problems on my 56

Hi all,

I have been having brake problems recently with my 56 3100. The brakes are all stock except for a dual master cylinder & adapter from American Classic. All 4 drums were turned and new shoes installed about 500 miles ago and I put new lines on when I restored it 4 years ago. No power boost.

The brakes seem weak when I start pushing them and then when the pickup has almost come to a stop the pedal drops a little and the brakes grab hard. It feels like maybe I am getting only the front or rear brakes most of the time. Could it be air in the lines? Overfilled master cylinder? Something else? Any troubleshooting advice would be welcome!

Hey Gradpa! Just a few questions... did you install a proportioning valve with the dual master? How about residual valves on the lines? Both of these items are needed to make a dual master work properly. Lots of info out there in cyberland on plumbing up a modern mastercylinder.

Hi Smitty,

No external proportioning valve or residual valves. I didn't think they were needed with drums all around? The master cylinder is also designed for 4 wheel drums.

Thanks.

Normally you don't need a proportioning valve on drum/drum brakes and depending on what master cylinder your supplier sent you it may or may not have an internal residual valve. I would go back and revisit how the lines are installed and recheck the installation of all components. Also bleed the system again.
This is usually a fairly straight foreward installation and you should not have these problems. You may still have to install an adjustable proportioning valve for the rears to make the system function correctly.
Fred