Replacing single reservoir M/C with dual reservoir on four wheel drum system

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shortmort37

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I recently bought 13" tires for my '63 Valiant wagon; more recently, I've been thinking about disc brakes for the front. Argh! They are only available for 14" and 15" wheels and tires.

Plan B is to buy new drums and shoes, and a dual master cylinder (for manual braking). Has anyone done this - and can a recommendation be made?

Dan
 
It is hard, since you just bought 13 in tires. In todays world I would buy 15"x 6" Ralleye wheels, Wheel Vintiques 61-565404 Wheel Vintiques 61 Series Chrysler Rallye Silver Wheels | Summit Racing and get a set of original Kelsey Hayes disk brakes or 10 in drum brakes. The 9" brakes are weak and I would not put any money into them. You can easily convert to a dual master cylinder, all you need are new front brake lines and a 67 A-Body up splitter. What are your long term goals for your wagon?
 
66fs said:
It is hard, since you just bought 13 in tires. In todays world I would buy 15"x 6" Ralleye wheels, Wheel Vintiques 61-565404 Wheel Vintiques 61 Series Chrysler Rallye Silver Wheels | Summit Racing and get a set of original Kelsey Hayes disk brakes or 10 in drum brakes. The 9" brakes are weak and I would not put any money into them. You can easily convert to a dual master cylinder, all you need are new front brake lines and a 67 A-Body up splitter. What are your long term goals for your wagon?
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I plan to keep the wagon as my daily driver... Can you make a specific recommendation for a dual master cylinder?
 
Thank you. Do I understand correctly, that if I keep drums on all four corners - I don't need a proportioning valve? That one is required, when you have discs in the front (pads in contact with the rotors) and drums in the back (shoes not in contact with the drums)?
 
I used a manual disc brake master cylinder when I did the upgrade on my 64 Valiant, Vixen. I have rebuilt Kelsey Hayes discs for the front, but have not installed them yet. The car stops great and does not prematurely lock the brakes like everybody always says. I only wanted to do the master cylinder swap once, so I went ahead and installed the disc brake unit and it works fine. I still have yet to install the disc brakes ans it still works great.
 
slantsixdan said:
Read this, which contains specs and links to the parts you need.
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Apologies, Dan - but I'm trouble sorting through the posts that link to posts, that link to posts... And much of this seems to pertain to drum to disc swaps. Because I bought new 13" tires, and because I can't put discs on a 13" wheel, I'm going to stick with drums - but hope at least go to a dual master cylinder (no power brakes). Given my plan, is this MC that you link in one of the subposts appropriate for my application? And, no proportioning valve needed?

Thanks
Dan
 
The bore size of the dual m/c needs to be the same size as the single m/c. So that can be measured or obtained from a service manual. According to my Motors Manual 1960-64 Ply Val used a 1" bore m/c.
No proportioning valve needed. With drum brakes, 'proportioning' is done with the wheel cyl size & the width of the brake shoes.
 
Bewy said:
The bore size of the dual m/c needs to be the same size as the single m/c. So that can be measured or obtained from a service manual. According to my Motors Manual 1960-64 Ply Val used a 1" bore m/c.
No proportioning valve needed. With drum brakes, 'proportioning' is done with the wheel cyl size & the width of the brake shoes.
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Thanks for answering my question about the proportioning valve.

According to this, the bore size of MC36412 mentioned in one of @slantsixdan's posts is 1.031". Close enough, or not quite right?

I'm hoping for a specific recommendation that will bolt up, require no changes to the push rod, work without power braking, yada yada. A direct swap (after splitting, of course). Any help, anyone?
 
Frank Mopar said:
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This is a great article - thank you. It clearly shows the difference between drum and disc/drum MCs. But,
The purpose of this article is to help identify correct original equipment master cylinders from the '67-'74 Mopar muscle car era.
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I'm not looking to identify original equipment - I'm looking to replace OE with something else. And, my Valiant is a '63 - none of the parts identified in Table 1 for 4 wheel drum vehicles is for any vehicle before '67.

So I'll ask again, this time informed by @Frank Mopar's advice - can anyone provide a P/N for a 4-wheel drum dual MC that will bolt up in replacement of a single MC in a non-power brake '63 Valiant, and requiring no changes to the push rod?
 
none of the parts identified in the tables are for pre 67 because they weren't making dual masters until 67.

so, any 67~70 a-body drum master will work. which is what @66fs said in post #8

you'll more than likely need a different push rod, though. if you can't find an OG one, several vendors make adjustables that work great.
 
junkyardhero said:
none of the parts identified in the tables are for pre 67 because they weren't making dual masters until 67.
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Ah. 'Splains it!
junkyardhero said:
so, any 67~70 a-body drum master will work. which is what @66fs said in post #8
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Got it. Thanks @66fs!
junkyardhero said:
you'll more than likely need a different push rod, though. if you can't find an OG one, several vendors make adjustables that work great.
Click to expand...
OG?

Thanks for the help - Dan
 
The master cylinder I used was for a 1970 Duster with manual disc brakes. It bolted right on and used the same pushrod. Even though I still have drums all around, it stops fine. That's what I would do if you are even remotely thinking of upgrading to discs in the future.
 
OK, some more questions:

1) What's a good source for a 2808577 or 2808599 compatible unit? I see that the Raybestos MC36221 is compatible, but I also see that it's made in China...
2) Some of the pictures of the cover are stamped "use only DOT 3 from a sealed container", or some such thing. Do they mean to say - use only DOT 3 (and not DOT 5, my preference)? Or, *if* you're going to use DOT 3, be sure the container is sealed?
3) I'll be replacing the brake line tee - is there something for dual circuits that will bolt on in its place?

Thanks
Dan
 
shortmort37 said:
Apologies, Dan - but I'm trouble sorting through the posts that link to posts, that link to posts... And much of this seems to pertain to drum to disc swaps.
Click to expand...

My fault; I linked to the wrong past post; the one with the links to the correct parts you need is here.
 
they say dot3 from a sealed container because dot 3 (and 4) are hygroscopic, meaning they will absorb moisture when exposed to air.

you can switch to dot 5, but must flush the system throughly (i like to use denatured alcohol). there usually isn't a compatibility issue with seals, especially when using new components. however, i will note that dot 5 seems to find and exploit even the teeny-tiniest gaps in the system and results in leaks that sometimes isn't a problem with dot 3/4
 
DOT 5 is not overall better, it's just different. Regular brake fluid (DOT 3, DOT 4, and DOT 5.1, in order of increasing boil point) is hygroscopic for a good reason: that way, a fair amount of the water that inevitably enters the system can be chemically sequestered harmlessly, slowing down corrosion in the hydraulic system to a pace slow enough that a periodic brake fluid flush, every couple years or so, effectively eliminates the problem.

DOT 5 is not hygroscopic, so the water which (again, inevitably) enters the system will coalesce into slugs at the lowest points in the system, where it will more aggressively corrode whatever it's in contact with. And if enough water coalesces near enough to the brakes themselves, like in the wheel cylinders, then that water can boil with brake heat, turn into steam, and oops, now you've got compressible gas instead of uncompressable liquid in the hydraulic system, and you don't got a brake pedal no more.

Use the (general) kind of brake fluid the system was designed and specced for. There's enough variety in what's available that you can surely find one that'll give you a warm fuzzy to use.
 
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