keithb7 Posted June 30, 2018 Report Share Posted June 30, 2018 I was under my '53 Chyrsler today with a light doing a regular general inspection. Looking for signs of something needing maintenance. I noticed a drip of fluid handing right off the bottom of master cylinder boot. I touched it to see that it was brake fluid. This is a little concerning. I just rebuilt the master cylinder this winter. Shouldn't it be dry inside the boot where the push rood meets the piston? I assume brake fluid is somehow getting past the secondary cup. The brakes seem to work pretty well. I noticed that my pedal travel was increasing a bit lately. Just yesterday I adjusted my front shoes closer to the drums. I definitely noticed and improvement with less pedal travel when I took it out for a cruise last night. I was planning to do the major adjust on the rears today. However I found this brake fluid in the boot and stopped there. Piston stop is in place. Maybe my cylinder bore is worn just enough to let some fluid get by the secondary cup? Comments and advice appreciated. Thanks, Keith Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted June 30, 2018 Report Share Posted June 30, 2018 rear seal is by passing...this can usually be detected if you place you foot on the brake pedal with light pressure and the pedal will continue to the floor...but..if you press hard, the applied initial pressure is such that it will place the seal lip to the wall of the cylinder and stay sealed...only with light pressure is the by passing occurring.. Quote Link to comment Share on other sites More sharing options...
keithb7 Posted June 30, 2018 Author Report Share Posted June 30, 2018 Thanks. Usually a sign of a crappy seal or excessive bore wear I assume? Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted June 30, 2018 Report Share Posted June 30, 2018 usually a sign of seal deterioration due mainly to the environment in which the rear seal operates. That and the every present moisture in the area as the piston is moved forward and back exposing the end of the cylinder, this along with the boot itself with a slight gap on the plunger will itself act as a vacuum and suck in dust and such....a disassembly and clean up and installing of a new kit...you ought to be back in business.... 1 Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted July 1, 2018 Report Share Posted July 1, 2018 Had similar experience over the winter time with the master cylinder on my 39 desoto. Found out that after 30 years since I rebuilt the MC the check valve had a very small hole in the rubber gasket and this was my issue. rebuilt the unit and now had great brakes again. The slightest thing can cause an issue in the MC. Rich Hartung desoto1939@aol.com Quote Link to comment Share on other sites More sharing options...
keithb7 Posted July 1, 2018 Author Report Share Posted July 1, 2018 Thinking of going with this for a couple of reasons. Safety is a big one. Anyone installed one of these? Comments? http://www.ecihotrodbrakes.com/chrysler_master_assemblies.html Quote Link to comment Share on other sites More sharing options...
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