Upgrading from a Single Master Cylinder to a Dual

Brakes

I have had to make a few panic stops with the 64 and it stops great , I converted this years ago with no proportioning valve . I converted it exactly as the same way you did.

 

Way back in the late 80's on my 55 Chevy wagon I started out with only the"C" bracket to mount all junk yard parts. I used similar size junk yard car parts like Monte Carlo and smaller Buick.
While it worked fine eventually I slowly replaced everything with rebuilt parts exchanging the junk yard parts. This included a disc brake set up. I'd been better off just buying rebuilt or new parts and paying the extra for not having a core for parts.
But my 1955 Chevy has made many panic and regular stops since the 80's and works well. Had one fairly new front rubber line collapse causing the brakes to lock up 100 miles from home. Waited till caliper released and brake cooled then drove 100 miles home not using brakes as much as possible.
Also one used proportioning valve went bad. All that in over 25 years.

To me brakes and steering are the two most important things. At least if the steering goes out you can still stop!

 

The other thing to remember is that the drum brake master cylinder is different from the disc brake one. They are not interchangeable. The really odd thing is that 4 wheel drum, without power assist, were available on some cars into the late 70s. I know our 72 Dart had 4 wheel drums, with the dual master cylinder, and no power assist. I know a fellow who is redoing the brakes on a 71 Ford camper van right now, and it is manual, 4 wheel drum brakes with a dual system. He is replacing the master this weekend, as a matter of fact. Strange things were available back then!

 

A dual master used with four-wheel drum brakes do NOT use a proportioning valve. Disc brake-equipped cars do. I did the same conversion on my '66 Coronet in 2003. I used front brake rotors, calipers and master cylinder from a '73 Dart Sport, as well as the junction block and the proportioning valve.

Disc brakes were NEVER Federally-mandated, BTW. The dual master cylinder was one of the very first FVMSS standards ever put out, and applied starting in the 1967 model year. This was also the first year for mandatory front and rear seat belts for all new cars sold in the US.

 

From reading all you guys good advice and searching out more info, it appears drum/drum brakes only had single master cylinders.

As patrick80 stated; "The dual master cylinder was one of the very first FVMSS standards ever put out, and applied starting in the 1967 model year". As for the Chrysler TC, '67 was also the year front disc's became standard. That said, since a disc/drum dual master is not interchageable for a drum/drum setup, this Cardone 10-1327 dual master my dad got can't be used. Perhaps that's the reason why it was still in the box. He must have realized it after he got it and couldn't return it.

So, are there any Mopar heads out there that know of a dual master that will work on my drum/drum TC?

Below is some good info I found browsing around.

Here's a link to the full article of what I'm posting below http://www.motor.com/article.asp?article_ID=1969


Drum Brake Master Cylinder

A master cylinder designed for use with drum brakes will move less fluid volume than one designed for use with disc brakes.

A drum/drum master cylinder delivers equal volume and pressure to the front and rear brakes. It typically will be smaller than a disc master, and fluid reservoirs will be the same size. Drum brake master cylinders require residual valves. Original drum master cylinders may feature built-in residual valves. Aftermarket master cylinders may require residual valves to be added to the plumbing circuits.


Disc/Drum Master Cylinder

A dual master cylinder designed to work with a disc/drum setup will feature two different reservoir sizes. As disc pads wear, the caliper pistons will move further outward toward the rotor, causing the reservoir fluid level to drop more than it would for a drum brake reservoir. As a result, a disc/drum master cylinder needs a larger reservoir for the disc brake circuit to keep more fluid in reserve. If switching from a disc/drum setup to a four-wheel-disc setup, the original disc/drum master cylinder won’t be suitable, since a four-wheel-disc master requires a longer piston stroke
A disc/disc master cylinder (four-wheel-disc) features sufficient volume and stroke to provide required fluid volume to all four calipers. If a disc/drum master cylinder is used on a disc/disc system, the master cylinder will run out of stroke while trying to push fluid to the rear brakes, resulting in a long pedal travel and a spongy pedal feel.


Power vs. Manual Brakes

If the brake system is manual (no power booster), the master cylinder bore diameter should be less than 1 in., otherwise a very hard pedal will result. A power brake master cylinder will typically feature a larger bore diameter than a manual master cylinder. A manual master cylinder can be mounted to a power booster, but a power master cylinder likely cannot be used without a power booster, because its larger bore size will result in a hard pedal, and the piston hole will be too shallow, which may allow the pushrod to fall out of the piston’s pushrod hole. A master cylinder’s rear pushrod hole must be deep in order to keep the pushrod in place.


NOTE: Brake fluid is hygroscopic. which means it sucks up water like a magnet, grabs grinding dust from your workbench. As little as 3% moisture content can cut your brake fluids boiling point in half! Even the best and most expensive brake fluid will not last forever.

 

Huh???

Let's back up. Through the 1966 model year, the feds did not require dual circuit brakes, so all brake systems (at least with drums) used a single circuit master cylinder. Starting with the 1967 model year, the feds required dual circuit brakes for an added level of safety. Thus both drum/drum cars and disk/drum cars got dual circuit brakes (and corresponding M/Cs). Disk and drum-only cars use different M/Cs.

The proportioning valve is a completely different issue. This is required for front disk cars to prevent premature lockup of the self-energizing rear drums. It is NOT used or desirable for a drum/drum configuration. Do not confuse the distribution blocks used on 1967-up drum/drum cars with proportioning valves (though many people do make this mistake). The 1967-up cars with dual circuit brakes were also required to incorporate a differential pressure valve that illuminates the BRAKE light on the dash if you lose pressure in one half of the brake system. Personally, this has to be the most worthless piece of instrumentation on the car, as the light will come on only after you press on the brakes and the pedal goes nearly to the floor. :banghead3:

To convert a single circuit drum/drum car to a dual circuit system, get the correct dual circuit drum/drum M/C for the 1967 model of your car. Whether or not you need to retain the distribution block depends on the configuration of your car. If the dist. block is one in/two out, then remove it and simply connect the front brake line to the port for the front brakes and the rear brake line to the port for the rear brakes (note that nearly all drum/drum M/Cs use the same size pistons front and back, so it really doesn't matter which line goes to which port on the M/C). If the dist. block is one in and three out (one to the rear and one to each front brake) then plug the outlet port to the rear, hook the rear line to the rear port on the M/C, and hook the dist. block inlet to the front outlet port on the M/C. Bleed and you're done.

As for fittings, if you are plugging an inverted flare port, you MUST use an inverted flare plug, not a pipe thread plug. Dorman products sells these. Also, most manufacturers used non-standard flare nuts at different ports on the brake system to avoid mis-connections on the assembly line. All the aftermarket brake line specialty houses sell these flare nuts, as do NAPA and other auto parts stores. Don't expect the teenager behind the counter to know what you are talking about, however.

 

Great post Joe. I got most of my short lines and fittings off junk yard cars.

 

That's certainly an option if you can find ones that are not rusted. Here in the mid-Atlantic, 1960s cars are virtually nonexistent in junkyards and the ones that you do find are pretty rusted up.

 

Great posting reply Joe! You just summarized all the posts in this thread in one easy to read and understand packet.

As you stated, "Starting with the 1967 model year, the feds required dual circuit brakes for an added level of safety. Thus both drum/drum cars and disk/drum cars got dual circuit brakes (and corresponding M/Cs).

I totally understand what you're saying, but I believe all '67 Chrysler TC's, Newports, 300's, New Yorkers & Imperials came standard with front discs and rear drums with a dual master using proportioning valves.

What I don't know is if ANY post '66 Chryslers came equipped with drum/drum brakes using a Dual MC. That's the million dollar question...

Again if any Chrysler/Mopar head knows what Dual MC can be used on a '66 TC with drum/drum brakes that would be great. I'm pretty sure no parts person at the local parts store would know unless they're in their 60's - but as you know most all parts people are kids working behind the counters where the car is two if not three times older than they are.

 

I think only Rambler and Cadillac had dual circuit brakes before the feds required them.

http://www.ebay.com/itm/1962-Ramble...241?pt=LH_DefaultDomain_0&hash=item53ec9e03f1

 

M/C

This is what I used on my 64 wagon conversion .

More Information for RAYBESTOS MC36221
Professional Grade; Bore Size=1"
Raybestos hydraulic brake master cylinders use aluminum and iron castings for an exact match to the design of your vehicle's original equipment. Technically advanced components ensure safe and reliable braking.

Feature: Castings match Original Equipment Design; Aluminum per O.E.
Benefit: Reduced weight does not stress the brake booster mounting

Feature: Like metals used
Benefit: Prevents chemical reaction that leads to corrosion and early failure

Feature: Ultra-smooth cylinder bore finish
Benefit: Longer service life
Material Type: Cast Iron
Number of Outlets: 2
Primary Outlet Size: 9/16"x20
Secondary Outlet Size: 1/2"x20
Alternate/OEM Part Number(s): 2536221

 

The answer is quite easy - disc brakes were an OPTION on ALL Chryslers through the 1970 model year. I've owned Newports, a '68 NY, a '68 Monaco, a '68 Polara wagon, and a '69 300 that were ALL drum brake cars. It's real easy to determine whether a Mopar (excluding Imperial) was a drum or disc brake car from the factory - the disc brake cars had 14" wheels during that time, where the disc brake cars had 15" wheels. Even the wheelcovers during those years (on certain models) will say "DISC BRAKES" on them!

Nope, there were thousands more '67 - '70 drum brakes "C"-bodies built than there were disc-brake cars.

 

I was going to say that even if the Town and Country had standard front disc brakes, the other full sized wagons did not, and neither did the sedans and coupes. Therefore, you have a raft of donor cars with the dual drum/drum master to choose from: Plymouth Fury (I, II, III and Sport) and VIP, Dodge Polara and Monaco, Chrysler Newport, Newport Custom, New Yorker, as well as Imperial. I would hazard a guess and say the mid-sized Plymouth and Dodge models also used that same master.

 

Well, I'm certainly not a Chrysler expert (and don't even play one on TV), but disk brakes were quite rare on American cars until the 1970s. I can pretty much guarantee that they were not standard on Chryslers in 1967.

As for which M/C to use, a simple glance at the RockAuto catalog yields the following:

A stock 1966 T&C M/C for power drum brakes:



A 1967 T&C M/C with power drum/drum brakes:



And finally, a 1967 T&C with the optional power disk/drum brakes:



Note that all three have the same mounting flange that bolts to the power booster. Also note that the disk/drum M/C has different-sized reservoirs, whereas the drum/drum M/C has the same size reservoirs. On the disc/drum the front brakes must be plumbed to the larger reservoir which is at the rear of the M/C. On drum/drum brakes it doesn't matter, as the pistons are the same diameter for both front and back, but if you want to duplicate what the factory did, plumb the front brakes to the rear port.

Also note that there is one possible concern with this swap. Again, I'm not familiar with Chrysler details, but on the same vintage GMs, the bore in the piston in the M/C that the pushrod from the booster fits into is deeper on single circuit M/Cs than on dual circuit M/Cs. This means that the pushrod is shorter on boosters from 1967-up. I don't know if Chrysler is the same, but be sure to check the depth of that hole in the piston in the back of the M/C before mounting. If the dual circuit M/C has a shallower hole than the single circuit M/C, you will either need to shorten the pushrod on the booster by the difference or swap to a 1967-up booster.

 

M/C

The one I used is in the second pic. After measuring the depth of the stock single master cylinder and the new dual master cylinder the depth was the same ,but I would check any new one that you are using to verify this.