1956 special power brakes

Hello again. Today's question is with regards to the power brakes on my

56 special. Lots of pedal, but little stopping power. I checked the

linings which look to be new. I can't find any vaccum leaks, vaccum

can inside the drivers fender well looks to be in good condition, no

fluid leaks i can see... Car stops, but not like it has power brakes.

Pedal is hard too.

Would anyone have some suggestions on where to start?

Thanks!

Tom V

Sounds like your booster isn't working.

Usually the diaphram in the booster is leaking and not "assisting" in applying pressure to the hydraulic cylinder. You can detect a vacuum leak in a diaphram by hooking up a tach to the engine and with engine running shut off vacuum supply to booster. Any change in engine RPM means you have a vacuum leak in power brake unit or line, resevoir. Note: to shut off vacuum supply you need to "plumb in" a small "shut off" valve in the vacuum line.) Rebuild kits are available and not too difficult to install although I did have to make a "special Tool" to rebuild mine.

Thanks!

Thanks! I'll try that.

You say the linings appear new. If they are like new and not glazed and fully contacting the drum they will feel exactly as you described. I had the same problem with a 57. I even sent the brake booster back to the rebuilder as defective. It turned out the new linings were too hard and not seating. New softer linings cured the problem after a few miles of break in.

To test booster operation.....With engine off, pump brakes several times to deplete vacuum tank. Hold brake pedal down while you start engine. If booster is functioning properly you will feel the pedal move down slightly as engine vacuum builds........Bob.