[FWDLK] brake problem?

["Edward X. Petrus" <desoto@xxxxxxxxxxx>]

Help needed from all you brake experts!  I've never had this problem
before, or even heard of it.

I asked several weeks ago about DOT 5 brake fluid, and the proper bleeding
sequence, for my 1957 DeSoto Firedome.  I elected to USE the DOT 5, and
installed new shoes, springs, rear wheel cylinders, and a rebuilt master
cylinder.  The front wheel cylinders where replaced about 5 years ago and
seemed alright.

Lots of bleeding got me a good pedal (Whew!  That DOT 5 is expensive!)  I
had all the shoe adjusters set properly, and everything seemed OK.  Drove
the car for perhaps 5 miles, stop and go, local traffic.  The pedal got
higher and higher on its own.  When I parked the car, you couldn't even
press down on the pedal, and the car wouldn't drift downhill in neutral,
and barely moved in drive.

I jacked each wheel up and sure enough, couldn't turn them.  No
self-adjusters, so the only thing I could think of was to open the brake
line fitting coming out of the master cylinder to release the
pressure.  Worked like a charm.  Drove the car several more miles, stopping
and starting as much as I could, and it seems perfect.

Was this a fluke?  Is there a defect in the master cylinder?  Air?  Do I
have to worry about it happening again?

Any ideas?  Thanks!

Ed Petrus