Master cyl woes
 

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?

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.

:banghead 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. :driving

master cly woes
 

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

I read this thread and I was wondering where you guys got a dual reservoir master cylinder that fits in place of the old singe reservoir? Thanks

Interesting that after TWO YEARS, no one can answer the previous posters question with respect to a correct replacement dual master cylinder; maybe everyone is in retirement homes now, or afflicted with alzheimer's disease.

Actually, this is a common question and there are many options to choose from. Chances are the op found the answer on another site, like this one:

Dual Bowl Master Cylinder... - Vintage Thunderbird Club International

~Steve

Thanks for the link... following up on the last post in that thread showing a Mustang MC.

I'm in the process of doing a dual master on my 64 right now. I don't know what year your car is, but a 73 Mustang master probably will fit. It has almost the same stroke as the Tbirds, so there should be no modifications needed. The master is an A1 Cardone from Rock Auto, and I got all the fittings I needed from Summit. I can post the part numbers if you want. Remember that they may not be the same for other years.
Terry
64HT

I have two '64' hardtops and two '63 converts. Looking to do one of the '64's first then hoping what I learn can be used on the rest of them. Actually I'd like to find the parts necessary to convert them to front disk eventually, looks like the '65 parts are hard to find.

Don't forget that the master cylinders are different for all drum and disc/drum brakes. Unless you convert to disc/drum (or all disc) at the same time, you'll be replacing the master twice.
Terry
64HT

Was just forced to replace the Master cylinder on my 63 Monaco; car was sitting our in the desert for 21 years.

The replacement looked very close to the stock one it replaced, however, I discovered that I had to adjust the booster rod quite a bit.

I've read that on dual MC replacements, the booster rod adjustment is even more critical than it is correct than it is on a single.

I understand that a master cylinder from a 1973 Mustang with power drum/drum will fit using the original rod on a 64. I suspect a 63 would be similar.
Planning to get at mine in a couple of weeks. I'll take photos.
Terry
64HT