Master cyl woes

[bondobird]

1965. Replaced jelly jar master cyl with modern double setup. fluid seems to be forced out of top of rez at gasket. only front rez seems to get low (that is for the back brakes). the gasket is good, surfaces are flat, bail is tight. did not replace the apportioning valve in rear brake line. what could be forcing the fluid out?

[redbird1]

My guess would be dirt in one or more brake lines.
Fluid isn't reaching the wheel cylinders because of a clog, and pressure builds up in the mc.
Bob.

[bondobird]

The REASON the fluid was comming out was that the REBUILT master cylinder was resurfaced and the cap was hitting on the ever-so-slightly WIDER M/C due to the taper of the sides (outward at the bottom)and removal of some height due to the resurface job in some unnamed feorign country. I hand-filed off material on the outside edge all around and now the lid and gasket fit DOWN better. I also sanded the top surface with 600 amd a wood block to glass smooth. This had better work, I think it will.

[Buster53]

Hi, I'm new to the Tbird forum but not to car repairs. I changed my brakes over because of safty reasons. with the daul cylinder you don't loose all of brakes if one side fails or gets a leak. My frist car is a tbucket built from scrach. learned about the brakes on this the frist time. When replacing master cylinder if front brakes are disc, a 2psi check valve is required down stream in brake line. The rear brakes requires the proportion valve and if using drums on rear a 10psi check valve, or 2 psi if using disc. Open proportion valve all the way open. Test drive somewhere safe! Close the proportion valve slowly forcing more fluid to front brakes until they feel correct. Front brakes take the blunt of stopping the car. Once proportion valve is ajusted brakes should be OK, may need to tweek them a little while fine tunning. But should be well worth it, only not original. Buster53