1964 Bird Dual Master cylinder conversion on a drum/drum setup

[64BBBird]

Hello All,

Me and My father recently purchased a Brittany Blue 1964 Thunderbird with a single pot drum/drum master cylinder setup which we are looking to upgrade to a dual master cylinder setup. We purchased a dual master cylinder from Pat Wilson's Tbird but are having some confusion on how the lines originally on the car will work with the dual pot master and if a proportioning valve is needed. If anyone has done this before and could offer any helpful insight it would be greatly appreciated!

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[68ChevyTruck]

With drums front and rear no proportioning valve required.
Traditionaly the larger bowl is plumbed to the front brake system and the smaller bowl to the rear.
My 57 is plumbed that way and works very well.
Good piece of mind having the dual circuit master cylinder there.

 

[74 Harley]

With a dual chamber master cylinder a proportioning valve is a requirement. And no, there's no added safety in having a dual chamber cylinder.

 

[aa010175]

Theirs lot of cars with dual M/C that don’t have a proportional valve in them. Like a 1962 Cadillac for example. The safety in a dual system is if one say rubber hose brakes or a leak in the wheel cylinder you won’t loose all the brakes in the car.

 

[74 Harley]

There's no way to bleed or balance a dual system without a proportioning valve. By not having a proportioning valve you cannot have equal action to the front and rear brakes.

 

[aa010175]

My understanding is if you have drums all the way around. You don’t need a proportion valve. If your running disc brakes on all four you don’t need a proportion valve. If your running disc in the front and drums in the rear you NEED a proportion valve. Is this a true statement? Thanks Dave

 

[74 Harley]

No, this is not true. The proportioning valve has nothing to do with the style of brakes. It has to do with the fact you can't have a completely separated brake system on one master cylinder. Case in point. If the front brakes were bled and the pedal solid, you wouldn't be able to bleed the rear because of hydraulic lock up. The same issue applies to brake wear. The front will wear first, creating the inability for the system to compensate. You wouldn't have front brakes until the rear wore to match.

 

[Kultulz]

I thing BRAKE VALVING is being confused here.

The 1964 BIRD, still DRUM/DRUM and is going to be left as? The DUAL RESERVOIR/OUTLET MC you purchased, is it a DRUM/DRUM or DISC/DRUM (there is a huge difference)?

If the car is left DRUM/DRUM, no valving is required other than RESIDUAL PRESSURE VALVES and those were mounted within the MC outlet bores (OEM). You have to know if the replacement MC you bough has the valves or you will either have to add the valves externally or use special wheel cylinder repair kits.

A PPV (PRO-PORTIONING VALVE) is used on a DISC/DRUM or DISC/DISC setup. Occasionally an application will surface whereas the manufacturer did not design proper brake bias (front and rear wheel ends) or the car has been modified whereas the original brake sizes (and/or or tire sizes) have been altered.

The PPV only provides anti rear end slide on a panic stop, especially wet road surface.

Post what MC you purchased and we will go from there.

 

[doug7740]

My understanding is if you have drums all the way around. You don’t need a proportion valve. If your running disc brakes on all four you don’t need a proportion valve. If your running disc in the front and drums in the rear you NEED a proportion valve. Is this a true statement? Thanks Dave

A proportioning valve is used to equalize braking action with front disc rear drum brakes. It's commonly located in the brake line to the rear drum brakes. The function of the proportioning valve is to limit the pressure to the rear drum brakes when high pressure is needed to apply the front disc brakes. Thus, the proportioning valve prevents rear wheel lockup and skid during heavy brake applications.

A metering valve is used on cars with front disc brakes and rear drum brakes. It's commonly located in the brake line to the front disc brakes. A metering valve is designed to equalize braking action at each wheel during light brake applications. A metering valve functions by preventing the front disc brakes from applying until approximately 75 to 135 psi has built up in the system. This overcomes the rear drum brake return springs.

doug7740
1955 Thunderbird Blue

 

[Kultulz]

From Post #8

The PPV only provides anti rear end slide on a panic stop, especially wet road surface.

I don't see an EDIT feature here -

That should read - The PPV only purpose is to prevents rear vehicle slide around in a panic stop (hopefully).

 

[BigClay]

Hello All,

Me and My father recently purchased a Brittany Blue 1964 Thunderbird with a single pot drum/drum master cylinder setup which we are looking to upgrade to a dual master cylinder setup. We purchased a dual master cylinder from Pat Wilson's Tbird but are having some confusion on how the lines originally on the car will work with the dual pot master and if a proportioning valve is needed. If anyone has done this before and could offer any helpful insight it would be greatly appreciated!

Gentlemen. Gentlemen.
When “dual system” brakes were first introduced, they were just that. One system (one pot of the dual master cylinder) fed the front right brake and the left rear brake. The other pot fed the left front brake and the right rear brake. This was so if one system failed, the other could stop the car in a straight line. Somewhere down the road, somebody switched that dual system to front brakes/rear brakes. It all depends how you run the brake lines. (Either will work, and provide some braking if one system fails). Your 64 single pot system feeds all four wheels. There are no “proportioning valves” in the system. When you introduce a dual pot master to the car, and simply hook both pots to the existing lines, you gain nothing. You HAVE to run new separate lines to “split” the system. I installed a front disc brake conversion (that I purchased from a reputable TBird supplier), and they told me I could just use the single pot M/C. It worked with NO proportioning valve. I recently added rear disc brakes and a dual master cylinder (out of a Corvette, as they come with 4 wheel discs). But corvettes HAVE front to rear proportioning valves. I did NOT install a proportioning valve, AND my car stops perfectly straight. The only thing I had to change was adding an electric “vacuum pump” because the disc brakes require a stronger (more vacuum) vacuum signal to work properly. (My 428 SCJ cam doesn’t provide enough vacuum).

 

[Tom Alpers]

No, this is not true. The proportioning valve has nothing to do with the style of brakes. It has to do with the fact you can't have a completely separated brake system on one master cylinder. Case in point. If the front brakes were bled and the pedal solid, you wouldn't be able to bleed the rear because of hydraulic lock up. The same issue applies to brake wear. The front will wear first, creating the inability for the system to compensate. You wouldn't have front brakes until the rear wore to match.

I see what you are saying but it's based on the idea that both pistons are directly pushed by the pushrod. Only the primary piston is. The secondary piston is pushed by fluid pressure. That could make bleeding somewhat odd feeling. Once the system is bleed and working properly, any unbalance created by wear is removed by the compensating port action that occurs each time the brakes are applied and released.

 

[Kultulz]

Gentlemen. Gentlemen.

When “dual system” brakes were first introduced, they were just that. One system (one pot of the dual master cylinder) fed the front right brake and the left rear brake. The other pot fed the left front brake and the right rear brake. This was so if one system failed, the other could stop the car in a straight line. Somewhere down the road, somebody switched that dual system to front brakes/rear brakes. It all depends how you run the brake lines. (Either will work, and provide some braking if one system fails).

Your first description calls out a DIAGONAL BRAKING SYSTEM and was not introduced (US) until the eighties/nineties w/ FWD vehicles. Intro DISC ( FORD 1965/66 ) was front disc/rear drum and used a SGL RSVR with DUAL OUTLETS w/ a factory calibrated PPV in the system. The DUAL RSVR MC was mandated by the FEDS in 1967 along with a PDV (PRESSURE DIFFERENTIAL VALVE).

Your 64 single pot system feeds all four wheels (ON A FOUR WHEEL DRUM BRAKE VEHICLE). There are no “proportioning valves” in the system. When you introduce a dual pot master to the car, and simply hook both pots to the existing lines, you gain nothing. You HAVE to run new separate lines to “split” the system.[/u]

The FRONT/REAR BRAKE BIAS (w/ SGL RSVR MC - FOUR WHEEL DRUM) is/was designed by engineers for balanced braking for each vehicle type. No valving needed other that RESIDUAL PRESSURE VALVE(S) as long as wheel end braking sizes are not modified..

I installed a front disc brake conversion (that I purchased from a reputable TBird supplier), and they told me I could just use the single pot M/C

Could you post the name of the vendor?

It worked with NO proportioning valve. I recently added rear disc brakes and a dual master cylinder (out of a Corvette, as they come with 4 wheel discs). But corvettes HAVE front to rear proportioning valves. I did NOT install a proportioning valve, AND my car stops perfectly straight. The only thing I had to change was adding an electric “vacuum pump” because the disc brakes require a stronger (more vacuum) vacuum signal to work properly. (My 428 SCJ cam doesn’t provide enough vacuum).

Th PPV has nothing to do with normal braking operation. It's main purpose is for an emergency full panic stop. You need to test the car on a skid pad (wet) to determine what the vehicle will and will not do.

It (PPV) can also be used to provide a somewhat brake bias correction(s) in some conversion systems.

TECH -

Single vs. Dual Reservoir Master Cylinders | Master Power Brakes

When it comes to brakes, you need think of a complete system consisting of components working together to stop your vehicle...

mpbrakes.com

Frequently Asked Questions | Master Power Brakes

Find answers to your most common questions. Our FAQs cover everything about our Disc Brakes, Master Cylinders, Power boosters, and valves.

mpbrakes.com

https://www.brakes-shop.com/brakepedia/general/brake-proportioning-valves

https://www.motor.com/magazinepdfs/102012_07.pdf

 

[Tom Alpers]

Your first description calls out a DIAGONAL BRAKING SYSTEM and was not introduced (US) until the eighties/nineties w/ FWD vehicles. Intro DISC ( FORD 1965/66 ) was front disc/rear drum and used a SGL RSVR with DUAL OUTLETS w/ a factory calibrated PPV in the system. The DUAL RSVR MC was mandated by the FEDS in 1967 along with a PDV (PRESSURE DIFFERENTIAL VALVE).



The FRONT/REAR BRAKE BIAS (w/ SGL RSVR MC - FOUR WHEEL DRUM) is/was designed by engineers for balanced braking for each vehicle type. No valving needed other that RESIDUAL PRESSURE VALVE(S) as long as wheel end braking sizes are not modified..



Could you post the name of the vendor?



Th PPV has nothing to do with normal braking operation. It's main purpose is for an emergency full panic stop. You need to test the car on a skid pad (wet) to determine what the vehicle will and will not do.

It (PPV) can also be used to provide a somewhat brake bias correction(s) in some conversion systems.

TECH -

Single vs. Dual Reservoir Master Cylinders | Master Power Brakes

When it comes to brakes, you need think of a complete system consisting of components working together to stop your vehicle...

mpbrakes.com

Frequently Asked Questions | Master Power Brakes

Find answers to your most common questions. Our FAQs cover everything about our Disc Brakes, Master Cylinders, Power boosters, and valves.

mpbrakes.com

https://www.brakes-shop.com/brakepedia/general/brake-proportioning-valves

https://www.motor.com/magazinepdfs/102012_07.pdf

The proportioning valve has everything to do with normal braking. It is always in action. It is used to drop line pressure from the IN port on it to the OUT port on it. I have used adjustable proportioning valves on a couple vehicles to achieve the desired relationship between the "power" of the front vs rear brakes so as to avoid premature rear wheel lockup as well as proper balance in normal braking.

 

[Kultulz]

The proportioning valve has everything to do with normal braking. It is always in action. It is used to drop line pressure from the IN port on it to the OUT port on it. I have used adjustable proportioning valves on a couple vehicles to achieve the desired relationship between the "power" of the front vs rear brakes so as to avoid premature rear wheel lockup as well as proper balance in normal braking.

Here is what I posted -

Th PPV has nothing to do with normal braking operation. It's main purpose is for an emergency full panic stop. You need to test the car on a skid pad (wet) to determine what the vehicle will and will not do.

The OEM PPV reacts to applied pedal pressure(s), and an ADJ PPV not so much. If one installs a DISC/DRUM CONV w/o a PPV, the brakes will operate satisfactorily up to certain points. It (ADJ PPV) cannot give continuous and correct balanced braking at all applied pressures. It can only give a compromise.

This is what I was attempting to relay/inform.

It (PPV) can also be used to provide a somewhat brake bias correction(s) in some conversion systems.

Study knee-point and slope.

 

[64ZCODE]

Gentlemen. Gentlemen.
When “dual system” brakes were first introduced, they were just that. One system (one pot of the dual master cylinder) fed the front right brake and the left rear brake. The other pot fed the left front brake and the right rear brake. This was so if one system failed, the other could stop the car in a straight line. Somewhere down the road, somebody switched that dual system to front brakes/rear brakes. It all depends how you run the brake lines. (Either will work, and provide some braking if one system fails). Your 64 single pot system feeds all four wheels. There are no “proportioning valves” in the system. When you introduce a dual pot master to the car, and simply hook both pots to the existing lines, you gain nothing. You HAVE to run new separate lines to “split” the system. I installed a front disc brake conversion (that I purchased from a reputable TBird supplier), and they told me I could just use the single pot M/C. It worked with NO proportioning valve. I recently added rear disc brakes and a dual master cylinder (out of a Corvette, as they come with 4 wheel discs). But corvettes HAVE front to rear proportioning valves. I did NOT install a proportioning valve, AND my car stops perfectly straight. The only thing I had to change was adding an electric “vacuum pump” because the disc brakes require a stronger (more vacuum) vacuum signal to work properly. (My 428 SCJ cam doesn’t provide enough vacuum).

I'm not understanding this. My '64 (all stock as far as I know) has a single master with a brass fitting that connects to two brake lines. One line goes to the front wheels and the other line goes to the rear wheels. Aren't the system lines already "split"? I've been assuming that if and when I install a dual master with internal residual pressure valves on this drum/drum setup, I'll just need to connect those existing brake lines to the two ports on the dual master. Is that correct?

 

[Kultulz]

I'm not understanding this. My '64 (all stock as far as I know) has a single master with a brass fitting that connects to two brake lines. One line goes to the front wheels and the other line goes to the rear wheels. Aren't the system lines already "split"? I've been assuming that if and when I install a dual master with internal residual pressure valves on this drum/drum setup, I'll just need to connect those existing brake lines to the two ports on the dual master. Is that correct?

Hold on, we will get it figured out for you..

As to the best of your knowledge, the car has not had any attempt to install a FRONT DISC BRAKE CONVERSION?

Below is an ILL showing the1964 MC INSTALL (DRUM/DRUM) (highlighted in RED) and the 1965/ MC INSTALL (DISC/DRUM) highlighted in YELLOW). Does you install appear as either?

What is being 'discussed' as 'split' is referring to a DUAL RESERVOIR MC. You have a SGL RSVR MC with DUAL OUTLETS (1961-64).

The 1965/66 BIRD also had a SGL RSVR MC with DUAL OUTLETS but it was for DISC/DRUM before the DUAL RESERVOIR MC became mandatory in 1967.

It can be confusing, and I am in no ways a good teacher.

Is a photo possible?

​

 

[Tom Alpers]

I'm not understanding this. My '64 (all stock as far as I know) has a single master with a brass fitting that connects to two brake lines. One line goes to the front wheels and the other line goes to the rear wheels. Aren't the system lines already "split"? I've been assuming that if and when I install a dual master with internal residual pressure valves on this drum/drum setup, I'll just need to connect those existing brake lines to the two ports on the dual master. Is that correct?

This guys video (link below) tells you what you need to know. As he says, you can use a proportioning valve in the rear line if you decide you need it's up to you. He also mentions a "combination valve" which a lot of factory systems used because that was how they turned on the dash warning light that the feds required. Some combination valves also had a built in proportioning valve for the rear circuit. If you are keeping the all drum system then get an all drum dual master. As he mentions, if you think you might put front disks on at some future date you can use a disk/drum master. It will have a higher pressure "hold off/residual" valve in the front circuit and larger bowl. From what people say about how these conversions perform it doesn't seem to make much difference when you use the disk/drum with an all drum system. This guy used a disk/drum master and says it's worked fine for him with all drums.

 

[Kultulz]

This guys video (link below) tells you what you need to know...

Now that was scary ...

 

[Kultulz]

DUAL RESERVOIR MASTER CYLINDER CONVERSION (DRUM/DRUM) - 1964 THUNDERBIRD

John Knight

Fellow Birders,

I finally stopped planning the duel master cylinder project and just
when out and did it. My Brittany Blue 64 HT had a bad day about a month
ago. I was away on the mainland and my daughter was driving the 64. The
stock single master cylinder developed a fluid leak into the booster and
left her with NO brakes. She went down a steep hill and straight through
two busy intersection before she could get to a small hill where she was
able to stop the car! No one was hurt and the car was fine but my daughter
refused to ride in the car anymore.

That was the last straw. I went out and got a 73 Mustang Drum/Drum master
cylinder and proceeded to start the project.

The MC cleared the shock tower but I had to go to the auto parts
store and get some brass fittings to hook up the brake lines and the brake
sending unit. It took a total of nine brass fittings to make the
conversion. I was able to use four of the fittings off of the original MC.
One of the issues on a 64 is that the brake sending unit is mounted on the
stock MC. The 73 Mustang MC has no provisions to mount the sending unit. I
solved this problem by adding a "T" brass fitting to the rear brake line.
All the brake lines were able to fit with a little adjustment. One thing I
noted was to forget the white teflon (sp?) tape. Use permatex thread lock on
all the brass fittings except where the break line attaches to the fittings
on the MC. The thread lock will prevent air from being sucked into the
system. (I learned the hard way. I blead more then 64 oz of fluid through
the system before I finally pulled the unit back out and took off the teflon
tape and added the thread lock.)

The last thing I need to do is go the the junk yard and find the driver's side
shock tower cowl support strut from a
65 or 66 bird.

This is necessary because the new MC won't clear the strut.
In 65 Ford redesigned the strut and shock tower mounting plate on the
driver's side to allow for a little more room to clear the MC. I have photos
of the MC with all the fittings attached before installation and photos of
the new MC installed in my car. Feel free to e-mail me for the photos.

Thanks

John Knight

​

- BELOW PHOTO NOT FROM ARTICLE - SHOWS LINE ROUTING ON A PERIOD FORD DRUM/DRUM CONVERSION -

​