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Would like to identify '36 brake master cylinder from my S 2 and get exploded diagram to see where the circular brass baffle/disc is located. It's been left out after a refurb & piston not pumping fluid. Any ideas? TIA. David.
@johnboyd submitted the following:
Note that S1 and S2 use the same master. Assuming you are still using the original master cylinder, I believe replacements are available from http://oldmoparts.com&source=gmail&ust=1769025949488000&usg=AOvVaw0mwW-HUPx2ZPjNdv1RLsl Q">oldmoparts.com and probably from http://mmpar.com&source=gmail&ust=1769025949488000&usg=AOvVaw2AUIB7qqZ1zlPU4E3W1Ej v">mmpar.com. This is from the 1936 DeSoto Parts List:
The NDC library may also have references available. Library requests are free to club members.
Hello David, I have an idea why your master cylinder might not be pumping fluid. A couple of things. First, the thin brass washer that is missing is typically not provided in the modern master cylinder rebuild kits available today. Instead, there is either a very thin piece of brass or other material permanently attached to the bottom of the metal piston that serves the same function as the brass washer. Or, the brass washer is pre-stamped into the solid rubber cup. Here are two examples of what I am describing.
Modern replacement metal piston with thin "washer" permanently attached to it. (The "washer" is the thin black material with six holes punched in it):
Modern replacement solid rubber cup with brass washer pre-stamped into the rubber cup:
Not to dismiss your concern about the brass washer, as I am too someone who wants everything to be correct, but I don't believe it is the main reason why your brakes are not pumping up. I would bet there is a problem with the valve & seat assembly in the master cylinder. The original type of valve assembly is all one piece with a tiny spring inside of it and is different than what is provided in modern master cylinder rebuild kits. If you follow the assembly order outlined in the original parts or shop manual, it will not work correctly. The rebuild kits available now require a rubber washer, which is usually provided, to be inserted before the metal valve can be installed. Without that rubber washer, the master cylinder will never pressurize. Often times the rubber washer that is supposed to pair with the metal valve gets placed in between the solid rubber cup and the metal piston. This is a common mistake since, as you have found, a stand-alone brass washer not provided in modern rebuild kits, so people think that the rubber washer is used in its place and goes between the solid rubber cup and metal piston. Which is incorrect.
1936-40 Brake Master Cylinder exploded diagram and NOS master cylinder rebuild kit:
1936-54 Brake Master Cylinder internal pieces diagram using metal valve & seat that requires an additional rubber washer:
(Note the design of the valve & seat in the NOS rebuild kit vs. the metal valve & seat and additional rubber washer found in modern rebuild kits. It's quite a bit different!)
I hope this helps and let us know if this information resolves your issue!
Thanks for that info David - I shall let the rebuild company know of the apparent problem and hope it can be resolved without mail order from the U,S, I think it's the only S 2 in the U.K. Its stable mate, the Chrysler Airflow was assembled & marketed over here but I purchased mine in Sweden. Regards,David.
