Master cylinder rebuild

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crooked1/2dozen

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My 1964 Valiant needs a master cylinder rebuild. When I took it out for the summer and checked all levels, I noticed my reservoir was basically empty. Hadn't touched the pedal so refilled. No leakage evidenced at the four corners. The firewall paint has been compromised, though no fluid observed. And the carpet is dry where the pushrod enters. Meant to check since then, but you know..are brakes important?!! So yesterday had a low pedal and turns out my reservoir is dry again. So, I obviously refilled. Long story short (too late!) I'm going to do an old school poor boy rebuild. NAPA has a kit to do so. Anyone done it? I have a hone, I'll let you know how it turns out. I'm a bit concerned with removing the master. Can I leave it in place for the rebuild? Or must it be removed. It's always good to get input from the knowledgeable, versus just winging it and doing a bunch of unnecessary work!

TIA
 
You should find the leak first.Is more likely to be a wheel cylinder. Remove all four wheels and inspect. Pull away rubber dust boots to find leaks. Inspect all rubber hoses. You may need more than a M/C rebuild.
 
Perfect time to upgrade to a dual master cylinder. (67 a body) Any leak in your system while driving will resuit in NO brakes. Zero.
Sounds like your car needs a thorough inspection. Wheel cylinders, hoses, lines, etc. Parts are cheap. Did it to my 64 Val. Also switched to DOT5 fluid so paint not affected by leaks or spills.
 
I would SERIOUSLY consider NOT rebuildiing a master, and when I was young, I've done a few

1.....Agree with above....Consider upgrading to dual master

2....If you insist on using a single, check first, the availability of new or rebuilt masters. and WHY? Because master rebuild kits are not all that cheap. For many years, you could buy a rebuilt master for just a few dollars more than a rebuild kit, AND THE REBUILT is guaranteed. And above the cost of the kit, a kit does not come with a lid gasket, and if you don't have a hone, you'll have to buy one of those
 
My 1964 Valiant needs a master cylinder rebuild. When I took it out for the summer and checked all levels, I noticed my reservoir was basically empty. Hadn't touched the pedal so refilled. No leakage evidenced at the four corners. The firewall paint has been compromised, though no fluid observed. And the carpet is dry where the pushrod enters. Meant to check since then, but you know..are brakes important?!! So yesterday had a low pedal and turns out my reservoir is dry again. So, I obviously refilled. Long story short (too late!) I'm going to do an old school poor boy rebuild. NAPA has a kit to do so. Anyone done it? I have a hone, I'll let you know how it turns out. I'm a bit concerned with removing the master. Can I leave it in place for the rebuild? Or must it be removed. It's always good to get input from the knowledgeable, versus just winging it and doing a bunch of unnecessary work!

TIA

I have done a bunch over the years and I can tell you the first thing to check is pitting in the bore.
If it’s pitted don’t waste your time.
Most are pitted by the time a rebuild is needed.
 
Check along the frames for wet spots.
A rusted out steel brake line is easily overlooked, till everything else has been replaced .
 
The dual master cylinder swap is an extremely good idea if you want to live.

Get a new master cylinder (this one), don't futz around with "remanufactured" garbage. It'll bolt right in place of your existing single-pot master, and your existing pushrod will work; see here for how to rmeove the pushrod from the old master.

You'll need a distribution (splitter) block; this can be had used from any A-body with 4-wheel drums, '67-up, but those aren't exactly common in the yards any more, so probably easiest to get it new from Inline Tube. You'll need to run dual hardlines from the new master to the splitter block. Be sure to bend at least one fully-circular loop in each of them to let them flex. Steel line is standard and is a pain to work with; Cunifer is a lot easier (and better).

All that said, you do need to pay attention to the rest of the brake system to find and fix the leak(s) and whatever other problems might exist.

DOT5 (silicone) brake fluid doesn't attack paint like regular brake fluid does if you spill it, but the silicone fluid brings other problems and issues. I find it best to use the regular fluid and avoid spilling it.
 
A font of knowledge this site is! I will probably go ahead with the dual MC as recommended by slantsixdan. I'll get a friend who has an Amazon account to purchase it for me, I'm a bit of a Luddite as far as online purchases go. The specs say it is Made in China, Mr. SSD, I wasn't expecting an offshore recommendation, however on your say so I'll go ahead! My brother has an automobile recycling business, or as the local government officials who are trying to shut him down call it, a "junkyard". He should be able to find the distribution block. As I recall from reading about MC upgrades before, isn't there a compensating valve or something similar also required? I'll search the archives and find out, and post regarding my results.
And I have crawled around underneath and found no evidence of leakage. The rebuild kit here in Calgary is only $21CN, but upgtades are always a good way to go.

Thx again for all the advice. We have a short season in Calgary to drive a convertible, so I'd better get on it!
 
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