Brakes - Wives Tales & Misconceptions

[KULTULZ]

- IF IT DON'T GO - CHROME IT -

Add safety to your brake system with this 4 wheel disc brake (or DISC/DRUM) ... woo chromedidium ... woo (adds a minimum of fifty HP) proportion(ing) valve. When upgrading to a dual bowl master cylinder is it always wise to add a proportioning valve equipped with a safety switch (PRESSURE DIFFERENTIAL VALVE or PDV).

The safety switch built into this 4 wheel disc brake ...woo chromedideum ...woo proportioning valve senses when your brake system is producing unequal or lower pressure to one or more of the wheels, usually caused by a component failure. When the 4 wheel disc brake chrome proportioning valve senses this drop or change in pressure it will cut off the pressure to the port supplying fluid to the defective brakes, thus stopping the leak.

At this point you have noticed a change in your pedal feel, your brakes stopping ability and possibly the warning light on your dashboard (along with a windshield in your face, a stretched seat cover and possible soiled undies). You will now be able to safely pull the vehicle off the road without causing harm to you or your vehicle (maybe and hopefully).

Without this valve installed if a component fails on your vehicle your brake pedal will drop to the floor as you pump the pedal with little to no braking. Brakes are the most important component on your vehicle, do it right the first time, be safe.

SOURCE - 'Another Disc Brake Conversion Vendor'

(ADULTERATED BY KULTULZ)

******

Depending on where in the system the failure occurs will dictate how the PDV reacts. It is meant as an early warning and if a catastrophic failure occurs somewhere in the braking system, the valve will not cut off complete supply to the affected circuit but may delay complete fluid loss to hopefully have one emergency stop, not to drive it home. It moves a pintel in the PDV to illuminate a warning light.

It is a safety device to warn the driver that there may be a defect in the system.

[KULTULZ]

- TYPICAL COMPONENT WARNING -

******



NOTE - Looks as if we are back to the MAGISTERIALLY DISAPPEARING ILLUSTRATIONS MALADY AGAIN

******

It is how they remove themselves from liability.

[Jeff Norwell]

Hahahaha
this is funny,....
I still stick with a single master and my trusty factory brakes.

[KULTULZ]

Modernizing brakes is a serious safety issue but what some of these vendors advise is dangerous (IMO). They are more concerned about moving product than going about it safely.

Did you know the 57 FORD spindle was the same ...

(well, let me qualify that - the 57 spindle was upgraded until being replaced by the 1960 spindle. That's why small differences will be found 1957-1962)

... through 1960 and the 1960 was replaced by the 1962 model, leading one to having large self-adjusting drums brakes all around?

[JimNNN]

Without this valve installed if a component fails on your vehicle your brake pedal will drop to the floor as you pump the pedal with little to no braking. Brakes are the most important component on your vehicle, do it right the first time, be safe.

Interesting. Can KULTULZ or someone else explain something to me, an admitted novice in the brakes department? (Sorry if this is a dumb question):

Is the quoted article referring to a special type of proportioning valve when it mentions the PDV, or is a PDV found in all proportioning valves? I ask this because I recently converted my '65 T-Bird to a dual reservoir using a specific '65-6 T-Bird kit/package from a company called ABS, and I've still got to do some adjustments on the proportioning valve (which came in the kit) and maybe the push rod to the master cylinder, too. Other than needing adjustments, the brakes, booster and proportioning valve seem to be working ok. Car is stopping fine (though the car isn't officially "back on the road" yet.)

Also, I thought the whole point of a dual reservoir system was to be able to stop the car (though with diminished braking power) when there is a leak. So is the proportioning valve with the PDV (that cuts off or reduces fluid to a leak) providing - in essence - a redundant function to the dual reservoir master cylinder?

Sorry if I'm missing something. I just want to make sure I cover all my bases as I finish up the brakes on my car. Thanks.

[KULTULZ]

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Originally Posted by JimNNN

(Sorry if this is a dumb question):

Sorry if I'm missing something. I just want to make sure I cover all my bases as I finish up the brakes on my car. Thanks.

First off, there is no dumb question, other than my asking the wife to marry me ...

This is a question that will take a complicated answer.

Can you give me the KIT NO on what you bought?

BTW - You do need a DUAL RESERVOIR MC (well, not necessarily) for a DISC/DRUM CONVERSION. It is the valving that is complicated.

[miker98038]

Brakes are complicated systems. Residual valves, proportioning valves, combination valves, front delay application (disc drum combos to my limited knowledge) all have specific applications, but all look the same from outside. All I know for sure, is every time one of my buddy’s bought a “kit” with a chrome valve I could never get it to not leak at the line fittings. Which was too bad, ‘cause they were sure the car was a 1/10th quicker in the 1/4 mile.

FWIW, one of those buddy’s put an ABS system on a 56 Nomad. Disc for 14” rims on the front, dual master, combo valve, and booster. Works fine, once we traded the chrome combo valve for the plain brass one.

From my own experience, even when all the pressure readings are good at each wheel the front and rear linings (and their effectiveness) have to be matched to get balanced braking. The guy that does my brake work on modified cars has a ton of vintage racing experience, and that is what saved me.

[JimNNN]

It's kit # 9759 on page 100 the ABS catalogue I've linked to. Tried posting a pic of my kit installed but it wouldn't work for some reason. My car has disc fronts, drums in back per factory setup. The proportioning valve is a long cylindrical unit that I've mounted on a steel plate just below the MC. The valve is not chrome. Not much info in the catalogue, I'm afraid.



http://abspowerbrake.com/maincatalog_frameset014.html

[KULTULZ]

Originally Posted by JimNNN

Is the quoted article referring to a special type of proportioning valve when it mentions the PDV, or is a PDV found in all proportioning valves? I ask this because I recently converted my '65 T-Bird to a dual reservoir using a specific '65-6 T-Bird kit/package from a company called ABS, and I've still got to do some adjustments on the proportioning valve (which came in the kit) and maybe the push rod to the master cylinder, too. Other than needing adjustments, the brakes, booster and proportioning valve seem to be working ok. Car is stopping fine (though the car isn't officially "back on the road" yet.)

Also, I thought the whole point of a dual reservoir system was to be able to stop the car (though with diminished braking power) when there is a leak. So is the proportioning valve with the PDV (that cuts off or reduces fluid to a leak) providing - in essence - a redundant function to the dual reservoir master cylinder?

Sorry if I'm missing something. I just want to make sure I cover all my bases as I finish up the brakes on my car. Thanks.

I can't find the PN on their site and they won't allow me to download their catalog.

Can you describe (or show a photo) of exactly what you bought?

A COMBINATION VALVE is a combination of two or more valves in one body. FORD did no go to COMBINATION VALVES until about 1972. Before that, all valve(s) were separate in-line (PDV (1967- ) - PPV - METERING and the PRESSURE RESIDUAL VALVE for the rear drum brakes (itself) was within the MC). This is what is causing the confusion. Your 65 BIRD has (had) a PPV - PROPORTIONING VALVE already on it. That's why I need to see exactly what they sold you.

A DUAL RESERVOIR MC may/will allow complete system failure w/o the PRESSURE DIFFERENTIAL VALVE used, although you are better with one that without (IMO).

The actual safety feature is within the MC itself (seperate pistons and seals)

Did you notice the MC you removed had one reservoir but two line outlets?

[rich b]

I never thought a PDV blocked fluid flow to the failed side; at least they never seemed to in the occasions when I have had one side brake failure (rusted lines). The failed side has always drained it's half of the master quickly. Maybe Ford's valves are different than GM?

If that is the case; maybe it would be a smart thing to add a stand alone PDV when converting a drum/drum car to a dual master since a combo valve in usually used.

[KULTULZ]

Originally Posted by rich b

I never thought a PDV blocked fluid flow to the failed side; at least they never seemed to in the occasions when I have had one side brake failure (rusted lines). The failed side has always drained it's half of the master quickly. Maybe Ford's valves are different than GM?

If that is the case; maybe it would be a smart thing to add a stand alone PDV when converting a drum/drum car to a dual master since a combo valve in usually used.

Let me try to make this clear as I know it is confusing.

A PRESSURE DIFFERENTIAL VALVE will not nor was designed to block flow from a sound failed circuit (a circuit being either front or rear brake system deriving from the use of a dual circuit/reservoir MC).

It merely trips a pintle within the PDV if system pressure is determined to be different from front/rear circuits. When that pintle moves, it allows the switch to display a warning lamp on the dash.

Depending on where in the complete system the failure occurs and the severity of the failure will determine if there is enough fluid/pressure to stop the vehicle.

Obviously if a hard line or hose fails, it is going to be catastrophic. If there is a wheel cylinder slightly leaking fluid or ingesting air, that should be picked up by the PDV.

There is no doubt in my military mind that the split system is better for system operation and/or safety. The trick is understanding how the system operates and studying OEM will give you that answer. There is a big difference in street and race/road race systems.

[KULTULZ]

Here is an animated description of a tandem MC operation -

https://www.youtube.com/watch?v=Xk2zGvKfrhc

Other videos within that page.

[JimNNN]

Originally Posted by KULTULZ

Can you describe (or show a photo) of exactly what you bought?


Did you notice the MC you removed had one reservoir but two line outlets?

I still have my original MC. It has two outlets as you describe. Interestingly, the two outlets are different in the apertures for some reason.



I'm going to try to post a different pic of the kit I bought...it's before installation on my family room floor. For a long time I couldn't post pics on Fordbarn...then I could...now I can't again.



If this pic works I'll try posting pics of the different apertures.


EDIT: Okay the photo worked. The proportioning valve is on the underside...hopefully you can get a larger view of it. ABS sent the entire unit assembled, with the proportioning valve just kind of hanging in space, held in place by brake lines going into it. I didn't like that setup at all, so I made a steel bracket for it to sit on and the bracket attaches to the MC at the stud from the booster. I'll try posting the other pic again.

[JimNNN]

Originally Posted by miker98038

FWIW, one of those buddy’s put an ABS system on a 56 Nomad. Disc for 14” rims on the front, dual master, combo valve, and booster. Works fine, once we traded the chrome combo valve for the plain brass one.

From my own experience, even when all the pressure readings are good at each wheel the front and rear linings (and their effectiveness) have to be matched to get balanced braking. The guy that does my brake work on modified cars has a ton of vintage racing experience, and that is what saved me.

I think the ABS will work good on my application, too. Some guys at the T-Bird forum expressed concern that the booster in the kit might be on the small side, but I haven't noticed any reduction in stopping power or other problems. As I say, however, I still need to do some adjustments and check things out. If I could find old car experts I trust around here for brake work, I'd probably go that route rather than trying to figure it out myself. In fact the reason I went with a vehicle specific conversion kit from a brake company is because I don't want to do my own amateur engineering on such an important conversion.



BTW, if anyone else has a fourth gen T-Bird and they're thinking about doing this conversion, DO NOT - I repeat - DO NOT throw away your original proportioning valve. They are very hard to get and valuable among the T-Bird community. I even see units in need of a rebuild for sale for hundreds of dollars. I don't know exactly what they end bringing, but they have value. I still have mine and will probably end up selling it.

[KULTULZ]

Originally Posted by JimNNN

EDIT: Okay the photo worked. The proportioning valve is on the underside...hopefully you can get a larger view of it. ABS sent the entire unit assembled, with the proportioning valve just kind of hanging in space, held in place by brake lines going into it. I didn't like that setup at all, so I made a steel bracket for it to sit on and the bracket attaches to the MC at the stud from the booster. I'll try posting the other pic again.

All I see is an ADJ PPV, no PDV or METERING VALVE. Did they say whether their MC had a RESIDUAL PRESSURE VALVE in it for the rear drum brakes? The outlet lines are also on the wrong side of the MC and can possibly be effected by exhaust manifold heat. Did you buY a new booster also?

There is (or was) an OEM PPV (2B091) below the MC INSTALL. Is it still there (mounted on rail or apron) or did the KIT INSTRUCTIONS say to remove it?

Below is an ILL of the 1967 LINC DUAL MC INSTALL as I don't have the FORD ILL CATALOG of the period. Same system.

2B257 - PDV (Not used on 1965 BIRD install)
2B091 - PPV
2B161 - METERING VALVE (The BIRD may not have had this)

You cannot use two PPV on the same circuit.

I hope the ILL is readable -

[JimNNN]

Originally Posted by miker98038

FWIW, one of those buddy’s put an ABS system on a 56 Nomad. Disc for 14” rims on the front, dual master, combo valve, and booster. Works fine, once we traded the chrome combo valve for the plain brass one.

From my own experience, even when all the pressure readings are good at each wheel the front and rear linings (and their effectiveness) have to be matched to get balanced braking. The guy that does my brake work on modified cars has a ton of vintage racing experience, and that is what saved me.

I think the ABS will work good on my application, too. Some guys at the T-Bird forum expressed concern that the booster in the kit might be on the small side, but I haven't noticed any reduction in stopping power or other problems. As I say, however, I still need to do some adjustments and check things out. If I could find old car experts I trust around here for brake work, I'd probably go that route rather than trying to figure it out myself. In fact the reason I went with a vehicle specific conversion kit from a brake company is because I don't want to do my own amateur engineering on such an important conversion.



BTW, if anyone else has a fourth gen T-Bird and they're thinking about doing this conversion, DO NOT - I repeat - DO NOT throw away your original proportioning valve. They are very hard to get and valuable among the T-Bird community. I even see units in need of a rebuild for sale for hundreds of dollars. I don't know exactly what they end bringing, but they have value. I still have mine and will probably end up selling it.

[KULTULZ]

I still have mine and will probably end up selling it.

I should stay out of this but the one you removed is a much better quality and operational piece than what they sold you. The DIALING-FOR-BRAKES ADJ is not going to give the same service even if it can be setup somewhat correctly (which it can't because it is not a true PPV).

The 1965-1967 FORD KH DISC BRAKE SYSTEM (also used on GM and MOPAR) was a well thought out design. It was replaced due to component cost.

[JimNNN]

The booster came in the kit. I talked to the guy at ABS last year when I bought the kit and he said the kit included everything I need. I didn't like that the outlets being on the inboard side either, but that's how it came. I'd estimate the outlets on the new MC are about 4" away from the manifold but that's a guess..might be 5". To be honest, the outlets of the original aren't on the outboard side either (they're in the center) and the downward angle of one of the original outlets may have run the line even closer to the exh. manifold. I didn't measure the original when it was installed, though.

[KULTULZ]

I hate to say this but all you actually needed to upgrade to a DUAL RESERVOIR MC was a 1967 BIRD MC and possibly a PDV - DISTRIBUTION BLOCK (free standing).

The factory included all you needed from there.

You kept the front calipers correct? Did they say there was a PRESSURE RESIDUAL VALVE in the drum brake circuit of the MC?

I hate these so-called KIT VENDORS.

[JimNNN]

As far as the '67 MC, I don't think it would have worked, KULTULZ. I have a set of valve covers on the engine that I really like (Ansen) - first of all they seal nice (which I could never get my originals to do) and I also really like the way they look. The problem with them is they won't fit with the original size booster. Only a smaller booster will have the clearance. Believe me, I tried. They aren't the high ceiling valve covers, either, but the lowest that Ansen has for my application.



The other common clearance problem with 4th gen T-Bird dual reservoir conversions is the under hood brace. The brace on the MC side is slightly different to clear the relatively short factory MC, but longer dual reservoir MC's typically still don't fit and it's common for T-Bird owners to go on a quest for something will fit...or it's common to cut a notch out of the driver side brace, which I definitely won't do. The other thing people do is buy modified braces. I don't know who makes them or if they're a cottage industry, but I know they have them for '66's, and maybe '64-5 too.


I'm going only off of memory, but I'm pretty sure the '67 MC won't fit without modding the brace. It's been covered at length on the VTCI forum, but please, anyone correct me if I'm wrong. Don't want to spread rumors or myths.



I had to look a fair bit to find something that would fit the setup I have. I read decent reviews on the ABS products, but I'm not trying to make the case that this kit is the premium or optimum set up out there. Like I said, I didn't feel at all comfortable trying to engineer something myself. However, I definitely will call ABS and ask them about the PDV and pressure residual valve function that may or may not be in my kit.

[58Yeoman]

Originally Posted by Jeff Norwell

Hahahaha
this is funny,....
I still stick with a single master and my trusty factory brakes.

I've always thought this, also. My '58 Chevy has a single MC and drums all around. So did my '63 Galaxie. I always figured the OEM engineers knew what they were doing.

UNTIL my 1988 Chevy K1500 PU. I bought it used in '89 with 15k miles on it, and the brakes just never felt right. I checked or changed everything I could to get them to work right. I finally went to the Chevy dealer where I had once worked and got to talking with one of the top mechanics. He told me that Chevy had a recall on the MC booster...they were too small. It was Chevy's fault, and it still cost me a hundred bucks.

[rich b]

Originally Posted by KULTULZ

Let me try to make this clear as I know it is confusing.

A PRESSURE DIFFERENTIAL VALVE will not nor was designed to block flow from a sound failed circuit (a circuit being either front or rear brake system deriving from the use of a dual circuit/reservoir MC).

That's what I felt I knew; guess I misunderstood part of your first post discussing the brake company's wording.

Now if people can be made to understand how a dual master functions and the need to design for full pedal travel if they are to gain any "safety" by the installation of one.

[KULTULZ]

Originally Posted by JimNNN

As far as the '67 MC, I don't think it would have worked, KULTULZ. I have a set of valve covers on the engine that I really like (Ansen) - first of all they seal nice (which I could never get my originals to do) and I also really like the way they look. The problem with them is they won't fit with the original size booster. Only a smaller booster will have the clearance. Believe me, I tried. They aren't the high ceiling valve covers, either, but the lowest that Ansen has for my application.

I didn't realize the engine had aftermarket rocker covers.

The other common clearance problem with 4th gen T-Bird dual reservoir conversions is the under hood brace. The brace on the MC side is slightly different to clear the relatively short factory MC, but longer dual reservoir MC's typically still don't fit and it's common for T-Bird owners to go on a quest for something will fit...or it's common to cut a notch out of the driver side brace, which I definitely won't do. The other thing people do is buy modified braces. I don't know who makes them or if they're a cottage industry, but I know they have them for '66's, and maybe '64-5 too.

I'm going only off of memory, but I'm pretty sure the '67 MC won't fit without modding the brace. It's been covered at length on the VTCI forum, but please, anyone correct me if I'm wrong. Don't want to spread rumors or myths.

And I forgot about this (apron brace) on the BIRD. That is my fault.

I had to look a fair bit to find something that would fit the setup I have. I read decent reviews on the ABS products, but I'm not trying to make the case that this kit is the premium or optimum set up out there. Like I said, I didn't feel at all comfortable trying to engineer something myself.

However, I definitely will call ABS and ask them about the PDV and pressure residual valve function that may or may not be in my kit.

OK, I understand now as to cause a DUAL RESERVOIR to fit without modifying the brace, a smaller booster was also used. Now it makes perfect sense to me.

What I do not agree with is their use of a SPIN FOR DOLLARS ANTI-BIAS VALVE. The things are dangerous for a street car .

[KULTULZ]

Originally Posted by rich b

That's what I felt I knew; guess I misunderstood part of your first post discussing the brake company's wording.

Again, that is my fault. I should have quoted their description fully and then made my snide remarks. I am getting old and go into b!tch mode WAY TOO EASILY (and I have been retaining water lately).

Now if people can be made to understand how a dual master functions and the need to design for full pedal travel if they are to gain any "safety" by the installation of one.

You are correct again. The true safety factor is within the MC design, not the PDV.

[KULTULZ]

Here (IMO) is a good tutorial on MC operation. Mind you that a much later style is being discussed but the dynamics are the same.

So grab a cold adult malt beverage and some snicky-snacks and peruse -

https://www.youtube.com/watch?v=Be4wNFSvxLc

[KULTULZ]

Sponsored Links (Register now to hide all advertisements)

Proportioning Valve Selection

Selecting the correct adjustable proportioning valve for your vehicle entails not only selecting the proper point at which slope limiting begins (the kneepoint), but also selecting the proper rate at which rear brake line pressure builds after that point (the slope).

Nearly every adjustable proportioning valve on the market today has an adjustable knee point (the point at which the rear brake line pressure begins to be controlled), but a fixed slope (the rate at which it builds beyond the knee point). While one parameter is adjustable, both are critical to system performance.

SOURCE - CENTRIC - https://centricparts.com/getmedia/d9...ing-valves.pdf

[JimNNN]

BTW, what's the opinion (if any) on bleeding the proportioning valve during installation? I bench bled the master cylinder for my car and when it was installed I hooked up the lines to the proportioning valve and bled those components (with clear hoses back to the MC.) I don't think I read to do that in the manual or anywhere else, but it seemed like a good idea. Maybe it wasn't. Of course once I got all the other lines hooked up, I bled the whole system. Is bleeding the proportioning valve by itself an unnecessary step? Or even a bad idea?

58Yeoman said:

My '58 Chevy has a single MC and drums all around. So did my '63 Galaxie. I always figured the OEM engineers knew what they were doing.

I don't want people to think I don't trust single reservoir master cylinders...I do. I put a new single master cylinder and had the original booster rebuilt in my '61 Mercury, and I'll drive it anywhere. I did that because it's a very original car and I wanted to maintain originality. If all the components of a single MC system are checked regularly, and are in good condition, I feel the systems are safe.

I put the dual reservoirs in my T-Bird and wagon because it was my understanding that there's even better safety with those types of systems. Thanks to this thread, I'm learning that the truth is more complicated than that, and will proceed from this point with that new understanding. I had never even heard of a PDV or a pressure residual valve before this thread. Many thanks to KULTULZ and others for the education on these type brake systems. I WILL follow up on this stuff for my car.

[KULTULZ]

Originally Posted by JimNNN

BTW, what's the opinion (if any) on bleeding the proportioning valve during installation? I bench bled the master cylinder for my car and when it was installed I hooked up the lines to the proportioning valve and bled those components (with clear hoses back to the MC.) I don't think I read to do that in the manual or anywhere else, but it seemed like a good idea. Maybe it wasn't. Of course once I got all the other lines hooked up, I bled the whole system. Is bleeding the proportioning valve by itself an unnecessary step? Or even a bad idea?

Actually, unnecessary. The valve(s) would be bled during the complete system bleed procedure (after bench bleeding the MC).

The only time you should need to bleed a PDV is after a system failure and repair and the pintel fails to center after the system bleed. Then you would bleed line(s) @ the PDV until it centered.

I put the dual reservoirs in my T-Bird and wagon because it was my understanding that there's even better safety with those types of systems.

Thanks to this thread, I'm learning that the truth is more complicated than that, and will proceed from this point with that new understanding. I had never even heard of a PDV or a pressure residual valve before this thread.

And you are wise in your thinking. The only way I would use a single is if the car is a dedicated restoration. Even then, the fluid needs to be changed (flushed) at the least every two years.

In the photo you showed of the MC INSTALL -



I do not see a switch to activate a WARNING LAMP on the dash so it must just be an ADJ PPV?

Was the OEM PPV you removed a cylindrical cast iron or a brass valve?

Is there any way you can show or give the lengths of the two boosters? The aftermarket booster along with their MC gave you the clearance needed for the MC to clear the apron reinforcement?

[56sedandelivery]

My head hurts. I am sure I will be going through this when I get to that point.

[5851a]

Brakes are very complicated. The original engineers took into account weight or load of vehicle at the time of manufacture. They would vary brake shoe width, drum size, wheel and master cylinder size. They would alter suspension mounting points to reduce nose dive on panic stops. I can't out think an entire branch of Dearborn so I just stick with what Ford said was good for me at the time. I once owned a 64 Thunderbird with all drum brakes only modification was radial tires. It stopped good, not on a dime but enough to leave a goose egg on your forehead. I also still own a 78 5.0 Fairmont. I swapped in a rear end from a new 82 Mustang, the rear brakes would lock at slightest touch. All the brake parts were the same, except the wheel cylinders were 1/32? smaller on the Mustang rear. Installed new Fairmont cylinders and back to normal. That 1 tiny change made a world of difference. I understand dual circuit brakes but don't think they are going to save you. Maintenance and driver awareness will. Just my take on it. My wife of 30+ years knows couple of jobs I will not do for friends or family, 1 is brakes and other is automatic transmissions. FI cars is a close 3rd.

[KULTULZ]

Originally Posted by miker98038

All I know for sure, is every time one of my buddy’s bought a “kit” with a chrome valve I could never get it to not leak at the line fittings. Which was too bad, ‘cause they were sure the car was a 1/10th quicker in the 1/4 mile.

FWIW, one of those buddy’s put an ABS system on a 56 Nomad.

Disc for 14” rims on the front, dual master, combo valve, and booster. Works fine, once we traded the chrome combo valve for the plain brass one.

It might have gone quicker if there was no leakage ...

You know, that CHINESEUM FLASH CHROME cuts the wind resistance through the traps. All that flash under the hood helps confuse the TECH INSPECTOR and you can get away with more ...

The problem is that they allowed the plating to reach the threads. Hope they also use this on their tanks ...

[KULTULZ]

1955-1957 BIRD FRONT DISC CONVERSION

New rear wheel cylinders are provided with the kit. The different diameter in them eliminates the need for a proportioning valve.

SOURCE - https://www.ctci.org/disc-brake-conversion/

The basic conversion kits for the Thunderbirds do not contain a combination valve.

Disc brakes without a proportioning/metering system will work.

SOURCE - https://www.ctci.org/disc-brake-performance/

In addition a 10 lb residual pressure valve can be installed in the fluid line to rear brakes. A residual pressure valve is a one way check valve that maintains enough pressure on the rear brakes to keep the shoes close to the drums without drag resulting in a firmer pedal.

SOURCE - https://www.ctci.org/disc-brake-performance/

Gil Baumgartner
CTCI Authenticity Chairman

... say what ... ?

[KULTULZ]

- ADDENDUM CONTINUATION -

1955-1957 BIRD FRONT DISC CONVERSION

In addition a 10 lb residual pressure valve can be installed in the fluid line to rear brakes. A residual pressure valve is a one way check valve that maintains enough pressure on the rear brakes to keep the shoes close to the drums without drag resulting in a firmer pedal.

SOURCE - https://www.ctci.org/disc-brake-performance/

A 10# RESIDUAL VALVE does not hold the shoes closer to the drum at rest. Only proper adjustment and/or self adjusters will do that.

The purpose of the valve is to not allow the wheel cylinder(s) pistons to slam shut after application release (return spring pressure) so as to prevent wheel cylinder cup shuddering allowing either fluid leakage and/or air ingestion.

And yes, it (RPV) does affect pedal height on a DISC/DRUM APPLICATION.

The industry went to WHEEL CYLINDERS with CUP EXPANDERS later to eliminate the valve but this was generally on a different style drum brake (not self-energizing).

Two types of COMBINATION VALVES shown below -

COMBINATION VALVE - A COMBINATION VALVE assembly consists of two or more individual brake valve(s) functions - PDV - PPV - METERING - RESIDUAL PRESSURE (Drum Brake Circuit)

TOP SHOWN - PDV and PPV

BOTTOM SHOWN - PDV - PPV - FRONT METERING

FORD usually had the RPV in the MC DRUM CIRCUIT FLUID OUTLET.

Gil Baumgartner
CTCI Authenticity Chairman

... say what ... ?

... yes, I am retaining water but I hope this shows how important it is when buying a kit and/or making brake modification(s) a correct source of information is supplied.

And this is across the board.

[Gene F]

I changed over my 67 ElCamino to front disc, and DOT-4. I got the system from Performance Suspension Technologies. They were the vendor that for years advertised on the back cover of Hemmings. It worked perfectly. My advice, but an engineered system that way it will all work together.

[miker98038]

In line with what Gene said above, an acquaintance with a 56 Ford put a front disc system on from Prestige Thunderbird. He’s local and was able to go over and go thru it in detail. He was impressive with their knowledge and research, and has been pretty happy with it. There are some vendors who do have good systems and there are some who just throw parts in a box and ship it. The hard part is telling the difference.

I have an OT ‘67 with a well engineered and completely modified suspension, done by a major vendor. They told me the whole brake system was a Wilwood design, from the pedal ratio to the pads. All their parts and design. If I were ever to do a conversion again I’d look into it with them. Probably have a heart at when I got the price, but I’d bet it was right.

[KULTULZ]

Disc brakes became an option on some Ford vehicles from the factory in the early sixties. FoMoCo provided a proportioning system on all their vehicles as part of the overall package. The proportioning valve soon evolved into a combination valve which provided proportioned pressure to the rear brakes and metered pressure to the front disc brakes. The basic conversion kits for the Thunderbirds do not contain a combination valve.

Disc brakes without a proportioning/metering system will work.

CTGI -

Let's repeat that statement -

The basic conversion kits for the Thunderbirds do not contain a combination valve.

Disc brakes without a proportioning/metering system will work.

Sure they will ...

-'TYPICAL' BIRD FRONT DISC KIT-

Upgrade your TBird with front disc brakes.

For added safety see combination valve sold seprately. Part# 2B257K

Actual shipping charges will be applied to this item.

This brake kit seems to be assembled by one company and sold through these BIRD VENDORS. DROP SHIP FREIGHT CHARGES indicates that.

On their 2018 catalog (PRESTIGE), there is no mention of a separate COMBINATION VALVE being available, although it seems someone at other vendors woke up at some point and offered them separately.

CTGI says their MC does not contain an RPV for the drum circuit and had to have an external installed. Most likely a CHI-COM MC.

This is what I am trying to get across. But I seem to be wasting my time.

[bobss396]

I keep it real simple. I still trust a single master system on drum brakes. Providing all components are in good shape. My Ford has a dual master and front discs. No fancy plumbing, just a distribution block that takes the old Ford pressure switch.

[KULTULZ]

Originally Posted by Gene F

I changed over my 67 ElCamino to front disc, and DOT-4. I got the system from Performance Suspension Technologies. They were the vendor that for years advertised on the back cover of Hemmings. It worked perfectly. My advice, but an engineered system that way it will all work together.

Just wondering, do you have the KIT PART NUMBER they sold you? Did it come with a GM STYLE COMBINATION VALVE or 'SPINNING FOR DOLLARS' bias valve? GM low drag calipers (METRIC) with quick take-up MC?

Originally Posted by bobss396

My Ford has a dual master and front discs. No fancy plumbing, just a distribution block that takes the old Ford pressure switch.

And this car is street driven?

[KULTULZ]

Originally Posted by bobss396

I keep it real simple. I still trust a single master system on drum brakes. Providing all components are in good shape. My Ford has a dual master and front discs. No fancy plumbing, just a distribution block that takes the old Ford pressure switch.

I did too until I learned the value of one when I went over an embankment in a 62 CHEV, convertible at that.

[KULTULZ]

Tagging these threads -

AXLE HOUSING SEALS -

https://www.fordbarn.com/forum/showthread.php?t=313498

BRAKE DRUM DIA - LINING WIDTH - LINING LENGTH

https://www.fordbarn.com/forum/showthread.php?t=314448

- within the discussion as it describes rear drum brake woes.

AND THIS - REAR BRAKE SELF-ADJUSTERS ADDITION -

https://www.fordbarn.com/forum/showthread.php?t=314775

[KULTULZ]

- 1300HP MERC COMET BRAKE FAILURE -

https://www.reddit.com/r/cars/commen...brake_failure/

[KULTULZ]

- WHILE CAROUSING WITH MY BROWSER -

To Wit - Question Asking If An External PRV Is Needed ...

You have a choice. The idea is to keep your rear shoes adjusted close to the drums. Two methods prevail, self-adjusters or residual valves.

Now we get to 'personal preference'...
When self adjusters work as they should, nothing is better because they actually turn the star wheel which expands the shoes.

Residual valves simply prevent the shoes from retracting by keeping ten psi on the hydraulic line. That means the pistons keep extending, and extending as the shoes wear. Eventually, a piston may pop right out of the bore. Yes, I've seen it happen. That leaves the rear brake circuit inoperable (with a soaking mess of brake fluid inside one drum).

11" self adjuster kits are very inexpensive and available at just about all auto parts stores. That is what I use.

Now this is on a respected FORD RELATED FORUM.

People, I am getting scared.

[rich b]

^^^
Worst part, people believe these "experts" and turn this misinformation into facts as it is repeated.

[KULTULZ]

- WHAT'S WRONG WITH THIS PICTURE -

[KULTULZ]

The below from a website discussing the GRANADA SWAP (FRT) -

When you're getting the spindle assemblies at the Salvage Yard, don't forget the distribution block. Most any post-1970 Ford distribution block for dual circuit braking systems will work.

The unit has a pressure sensing diaphragm which, when detecting a pressure drop, will close off fluid flow to the dropped circuit. This will allow you to still have either front or back brakes. Take the connector and a partial strand of the wiring, as you may wish to hook up a "Brake Warning" light later.

A diaphragm? It is a pintle (and it will not block cross-flow).

I think the writer is describing the PDV (PRESSURE DIFFERENTIAL VALVE) as FORD did not actually release a COMBINATION VALVE (an assembly consisting of two or more individual braking valves) until 1972. PDV, PPV and METERING were separate.

As for the PDV, if one does not want or need the WARNING LAMP FEATURE, actual DISTRIBUTION BLOCKS are available for a neater appearance.

While this particular tech write-up has a 2001 date, it is still online and should have been corrected (IMO of course).

[ms fowler]

Sponsored Links (Register now to hide all advertisements)

I have a friend who lives in AMC world. He constantly complains about these ne "experts" and the false information they confidently spew. I thought that maybe those people were somehow all attracted to AMC vehicles. Alas--I see they have infected FoMoCo world too.

[KULTULZ]

Originally Posted by ms fowler

I have a friend who lives in AMC world. He constantly complains about these ne "experts" and the false information they confidently spew. I thought that maybe those people were somehow all attracted to AMC vehicles. Alas--I see they have infected FoMoCo world too.

No ma'am, it is hobby wide and industry wide. I have seen some things you wouldn't believe.

[KULTULZ]

Originally Posted by KULTULZ

- 1300HP MERC COMET BRAKE FAILURE -

https://www.reddit.com/r/cars/commen...brake_failure/

Follow-up video to MERC incident -

https://www.youtube.com/watch?v=Z-FqKRHnEBE

[KULTULZ]

- BRAKE PROPORTIONING VALVES -

1. If you have the deeply-rooted need to install your own adjustable proportioning valve, be advised that they should NEVER be installed if the factory unit is still in place.

Proportioning valves in series with one another can do nasty, unpredictable things!

2. If you have the deeply-rooted need to install your own adjustable proportioning valve, be advised that they should NEVER be installed in-line to the front brakes. The effect would be to make your vehicle rear-biased before you could say “terminal over-steer.” Front brake line pressure should always be left alone – only the rear pressures should be considered for proportioning.

3. In all cases, the basic brake system balance needs to be close to optimized to start with. This is the only way that a proportioning valve can be effectively utilized. You should never assume that simply adding a proportioning valve will address all rear-bias conditions, as even the best proportioning valves must be well-matched to the target vehicle.

SOURCE - BRAKING VALVE THEORY - CENTRIC BRAKES

- https://centricparts.com/getmedia/d9...ing-valves.pdf

[Patrick brophy]

Originally Posted by KULTULZ

- WHAT'S WRONG WITH THIS PICTURE -

They have good taste in hand tools. Knipex tools are top shelve.

[KULTULZ]

You're correct there.

BUT, after scarring the hell out of the piston, won't he be surprised when the other one pops out ...

[miker98038]

I worked with a really good construction superintendent for years. The tool/caliper reminds me of his old line.

“When all you’ve got is a hammer, everything looks like a nail”

When all you’ve got is water pumps……..

[KULTULZ]

And what are the odds he didn't open the caliper bleed screws and allowed the old fluid to go back into the ABS PUMP?

[KULTULZ]

If you think that was salty, watch this procedure. He begins @ 5 seconds on the video -

https://www.youtube.com/watch?v=wSqDP-pwj2s

Now I don't know but this seems a little gnarly for me. On my personal ESCAPE, the pistons had to be rotated LH so a SPECIAL SERVICE TOOL was needed. I finally found the required adapter @ FORD of EUROPE and yes, it came from JOLLY 'OL ...

That piston is on a ratchet. You mess that ratchet up (don't even mind gnarling the piston or cutting the dust boot) and there is no self-adj feature. You then have to buy a new caliper or have in your tool box specialty tools to rebuild the caliper and also purchase service parts ($$$).

I used to see things like this on a daily basis. This is why I am so CDO (OCD in correct alphabetical order).

[KULTULZ]

Originally Posted by miker98038

I worked with a really good construction superintendent for years. The tool/caliper reminds me of his old line.

“When all you’ve got is a hammer, everything looks like a nail”

When all you’ve got is water pumps……..

It seems the BFH and HOT WRENCH are the go to instead of a specialty tool.

And if a BFH (big f*cking hammer) doesn't work, go out to the shed and find the sledge ...

(Yes, I am retaining water this evening)

[KULTULZ]

If you have the time (and have the interest), watch this video describing a COMBINATION VALVE and see if anything described is wrong (if anything is wrong) -

https://www.youtube.com/watch?v=g63mP4HwVEQ

[KULTULZ]

OK, there seems to be little interest but over 3500 hits.

Here is another discussion that should make you sit up straight -

https://57fordsforever.com/smf/index.php?topic=9149.0

[KULTULZ]

Another discussion concerning the need for a correctly adjusted MC push-rod -

https://www.jalopyjournal.com/forum/...issue.1272098/

[5851a]

I don't have more than a basic caveman education on brakes. I will only work on my own. I will not work on anyone else's brakes period. From an 81-shop manual they have a slope chart covering all the fox platform cars for the combination valve. Since all of the cars use the same brakes with exception of the wagons. Seems though they concentrated on the amount of weight of the rear of the car. Some of the cars used different size rear wheel cylinders. 1/16th diameter difference does matter. Some of the cars used a different combination valve. My 95 truck and 91 Escort wagon had a brake valve hooked to rear suspension. I assumed it was a load sensing valve to hold off brakes empty and apply more pressure when loaded. When you start messing with brakes it takes a lot of experimentation. Dual master cylinders and hydro boost are not the end all cure all. Brakes are a science; I didn't do great in science. Figured Ford's glass house had lot more smarts and time than me. Yes, there is no emergency brake, always referred it to a parking brake in manuals.

[KULTULZ]

Originally Posted by 5851a

... there is no emergency brake, always referred it to a parking brake in manuals.

BOOTLEGGER'S TURN - https://www.wikimotors.org/what-is-a...ggers-turn.htm

[KULTULZ]

Originally Posted by 5851a

From an 81-shop manual they have a slope chart covering all the fox platform cars for the combination valve. Since all of the cars use the same brakes with exception of the wagons. Seems though they concentrated on the amount of weight of the rear of the car. Some of the cars used different size rear wheel cylinders. 1/16th diameter difference does matter. Some of the cars used a different combination valve.

My 95 truck and 91 Escort wagon had a brake valve hooked to rear suspension. I assumed it was a load sensing valve to hold off brakes empty and apply more pressure when loaded. When you start messing with brakes it takes a lot of experimentation.

Dual master cylinders and hydro boost are not the end all cure all. Brakes are a science; I didn't do great in science. Figured Ford's glass house had lot more smarts and time than me.

The sizing of the actual service brakes depends on the car weight on either axle. That is where friction material, size and MC/caliper/wheel cylinder bore sizes also come into play. That basic design will bring the vehicle down other than a full panic stop.

That is where the PPV comes in. As the vehicle slows, weight is transferred to the front axle and the rear axle becomes light, allowing the rear brakes to lock. When they lock, especially on a wet road surface, the rear of the vehicle may come around.

Where the real problem comes is when an enthusiast will swap brake designs from different vehicle(s) onto his project. Everything is thrown off. This is where an ADJ PPV (or anti-bias valve) comes into play as the OEM PPV is not calibrated for the mix-max. It is really a guessing game unless thought out and a skid-pad is used.

Even a tire size change or vehicle lowering/raising can/will change the factory PPV settings for the car.

On an OEM PPV, KNEE POINT is when the applied pressure to the rear brakes begins to be restricted and the slope is the degree of further pressure restriction according to the level of the hard/panic stop. On an ADJ PPV, only KNEE-POINT is adjustable, slope is not.

A HYDRO-BOOST install will generate greater brake line pressure(s) than say a vacuum booster.

I am a firm believer in a dual reservoir MC as when I was young I went over an embankment in a 62 IMPALA (conv yet with the top down) after the MC decided to quit. It took months of recovery and physical therapy to rid my self of the induced trauma of sucking up two feet of seat cover. Luckily the cover material was cheap vinyl rather than cloth ...

[miker98038]

Somewhere in my past I saw one of those “height sensing valves”. I think it was a Saab. No surprise with the front engine/drive combo with a lot of nose weight. Not to mention the aircraft engineering base of the company. This was after the 2 stroke engines IIRC.

[KULTULZ]

- BENDIX TREADLE-VAC AS USED ON EARLY MERC-EDSEL-LINC -

If one has an early car with TREADLE-VAC and wishes to convert it to a DIAPH VACUUM BOOSTER, you may want to read these referring URL's -

https://57fordsforever.com/smf/index.php?topic=1377.0

https://www.jalopyjournal.com/forum/...stion.1271208/

[KULTULZ]

- DISCUSSION of 1957/1959 MASTER CYLINDERS -

- MANUAL & POWER - BORE SIZE -

https://www.fordbarn.com/forum/showthread.php?t=315599

[joshharper873]

[emoji3059][emoji3059]


Sent from my iPhone using Tapatalk

[KULTULZ]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by joshharper873

[emoji3059][emoji3059]

Sent from my iPhone using Tapatalk

...hmmpf ...

Wonder which imoji I got imoji'd with ...

Natives are starting to get restless again ...

[KULTULZ]

- AND IT JUST KEEPS GOING ON -

The answers are all over the board I will add one more as was told to me by a rebuilder that did power brake units for our auto parts store. A residual check valve is used in disk brakes to keep slight pressure on pads since they always have contact on the rotors and have no springs to pull the pads back. He also said drum brake MC's do not have a residual check valve. This is what I have been told and used this practice in all of my builds over the last 50 plus years. Just something to think about

SOURCE - https://www.jalopyjournal.com/forum/...rakes.1220793/

(POSTERS NAME WITHHELD TO PROTECT THE INNOCENT)

[KULTULZ]

- AND IT JUST KEEPS ON ROLLING -

https://www.jalopyjournal.com/forum/...acuum.1273530/

[KULTULZ]

Here is a really interesting perception on braking dynamics -

https://www.jalopyjournal.com/forum/...#post-14651920

[KULTULZ]

Another In The Continuing Saga of

- 'THEMS' THE BRAKES' -

- https://www.jalopyjournal.com/forum/...estio.1277085/

[KULTULZ]

- LATEST CONTRIBUTION AND DISCUSSION -

To wit - https://www.fordbarn.com/forum/showt...25#post2180525

[KULTULZ]

While I am in B!TCH MODE ...

Read this thread discussing CHI-COM MC's, the origional application and the last post in the thread specifically -

To Wit - https://www.vintage-mustang.com/thre...alves.1185634/

[KULTULZ]

The other common clearance problem with 4th gen T-Bird dual reservoir conversions is the under hood brace. The brace on the MC side is slightly different to clear the relatively short factory MC, but longer dual reservoir MC's typically still don't fit and it's common for T-Bird owners to go on a quest for something will fit...or it's common to cut a notch out of the driver side brace, which I definitely won't do. The other thing people do is buy modified braces. I don't know who makes them or if they're a cottage industry, but I know they have them for '66's, and maybe '64-5 too.

Here is a possible alternative for the MC -

-ABS BRAKES -

[Old Redneck]

I was having trouble with my brakes on my 56 T-Bird. I got a Disc. Brake kit from Hill's in southern Ohio. Very nice kit all the brake lines come with it. The only thing I had to buy was brake fluid and a brake safety switch. When I remove the old master cylinder it ws suppose to have 4 bolts holding it on. Two bolts just stuck in nothing holding them and the other two finger loose. When I push the brake the master cylinder would push out about a inch. The brake fluid was black in color, not good. No wonder I had a poor brake. I installed the Hill's brake kit and wash out the brake lines with brake clean and air pressure. Then what type brake fluid ti install. Dot 3,Dot 4 or Dot 5. Well I did install Dot 5. It's purple in color. Several talk against it for different reason and a couple that use it love it. We will see how it will work. My brake peddle seams firm but it snowed here and 23 degrees not good for a road test. Maybe next week and will let you know the results how the brakes work.Thanks for all your advice and help.

[KULTULZ]

When dual reservoir master cylinders originally made it onto the scene, one of the reservoirs was much larger than the other. This was generally considered the reservoir for the drum brakes due to the sheer volume of fluid needed to push the brake shoes out followed by the return of all that fluid back to the master cylinder. Disc brakes didn’t require the same volume in the reservoir. Today, most master cylinders have the same size reservoir as well as masters sharing the same reservoir. These are still considered dual reservoir systems because the internals are separated front to rear.

SOURCE - https://techtalk.mpbrakes.com/master...ster-cylinders

Does anyone else see the mistake made in the above description or is it me just being overly sensitive?

[Gene F]

Originally Posted by KULTULZ

The sizing of the actual service brakes depends on the car weight on either axle. That is where friction material, size and MC/caliper/wheel cylinder bore sizes also come into play. That basic design will bring the vehicle down other than a full panic stop.

That is where the PPV comes in. As the vehicle slows, weight is transferred to the front axle and the rear axle becomes light, allowing the rear brakes to lock. When they lock, especially on a wet road surface, the rear of the vehicle may come around.

Where the real problem comes is when an enthusiast will swap brake designs from different vehicle(s) onto his project. Everything is thrown off. This is where an ADJ PPV (or anti-bias valve) comes into play as the OEM PPV is not calibrated for the mix-max. It is really a guessing game unless thought out and a skid-pad is used.

Even a tire size change or vehicle lowering/raising can/will change the factory PPV settings for the car.

On an OEM PPV, KNEE POINT is when the applied pressure to the rear brakes begins to be restricted and the slope is the degree of further pressure restriction according to the level of the hard/panic stop. On an ADJ PPV, only KNEE-POINT is adjustable, slope is not.

A HYDRO-BOOST install will generate greater brake line pressure(s) than say a vacuum booster.

I am a firm believer in a dual reservoir MC as when I was young I went over an embankment in a 62 IMPALA (conv yet with the top down) after the MC decided to quit. It took months of recovery and physical therapy to rid my self of the induced trauma of sucking up two feet of seat cover. Luckily the cover material was cheap vinyl rather than cloth ...

Height sensing valve....I hear that some of the late 1970's early 1980s Rolls-Royce's had a brake setup that was tied to the suspension. I wonder if this is something like that.

[miker98038]

The reference I made in post 62 above was like that. It was many years ago, but the valve was on the frame, and the rod went to the rear axle. A simple beam as I remember, typical for an early FWD vehicle. How well it worked I don’t know, but obviously there would be a difference in rear pressure as the chassis shifted under braking. How well that compensated for dry vs wet I don’t know. Modern antilocks make all that moot.

[KULTULZ]

Originally Posted by Gene F

Height sensing valve....I hear that some of the late 1970's early 1980s Rolls-Royce's had a brake setup that was tied to the suspension. I wonder if this is something like that.

Here is a brief explanation of a HEIGHT/WEIGHT SENSING PPV -

Height-Sensing Proportioning Valves

Some vehicle’s proportioning valves go one step farther, as the knee-point on the graph can vary with the amount of weight on the rear axle. Effectively, as the rear axle weight increases, a linkage between the axle and the body is compressed. This linkage acts on a cam inside the proportioning valve which increases the preload on the proportioning valve spring. The end result is that more rear braking (bias) is allowed as weight is added to the rear axle, helping to take advantage of the increased traction now available at the rear tires. Figure D illustrates this relationship quite clearly.

FULL EXPLANATION HERE - https://www.brakes-shop.com/brakeped...tioning-valves

A TRIM-HEIGHT SENSING VALVE is also used on air ride cars so they can be confusted easily.

[KULTULZ]

Allow Me To Add This Information Here For Future Reference -

- BRAKE VALVING MISC FACTOIDS - PDV

One myth that often pops up during conversations is the misconception that if the spool in the pressure differential valve gets (PDV) pushed off-center due to (for example) a brake line failure, it seals off the bad side, allowing you to still have brake pressure on the good side. This is incorrect! It is merely a warning system.

The ends of the spool are turned down to allow brake fluid to pass when it is pushed to one side. If the spool was designed to cut off the brake fluid to the side where the pressure has dropped it would seal the fluid between the master cylinder and the distribution block. This would cause the brake pedal to be rock hard and you would have no brakes at all because the trapped fluid would not give. The dual master cylinder is the safety feature that allows pressure at the good end.

There is nothing inside the pressure differential valve to replace when rebuilding except for two special o-rings and a crush washer.

[56sedandelivery]

Geeeze I have a lot to figure out.

[KULTULZ]

Originally Posted by 56sedandelivery

Geeeze I have a lot to figure out.

How are you planning to do your '56?

[56sedandelivery]

Originally Posted by KULTULZ

How are you planning to do your '56?

Well though disc/drum was way to now not so sure. Thinking about 4 wheel disc but that probably open up a whole nuther can of worms. Car will be mainly street crusier. Now if I can just find someone local that can do a door reskin, Do not think I am that good of welder to tackle it myself

[KULTULZ]

4W DISC is a little extreme (IMO) unless you have a show car and open wheels to see the install.

FRONT DISC/REAR DRUM will bring it down quicker,

[miker98038]

56sedandelivery, FWIW (and ignoring the above discussion). All the front disc conversions I’ve seen for the 55-57 thunderbirds just seem to work pretty well. Typically a Mustang or Fairlane disc/drum master and Fairlane caplipers. Granada rotors with the center turned down to fit the early wheels. I’ve owned them, they work. If you add power, it’s the factory style booster, and only used on the front disc. There’s a spacer for the bearings that move the front wheels out about 1/8”, but that’s no a problem with anywhere near stock tires.

An acquaintance on SoCal has a set on his 56 Vicky that he bought from Prestige Thunderbird for his 56. After visiting them and getting all the specifics. Long time knowledgeable racer, he’s happy, so they’re ok.

As Kultulz mentions above, 4 wheel disc get more complicated. You don’t want to hear the time and cost involved at that point. I know, because mine work.

[RKS.PA]

I know this series goes back to mid-2022 and is about disc conversions and it's really definitive...thank you.

When I first got my '56 T Bird about a year ago, the stock booster brakes worked okay, with a sudden lock up at low speeds. So, opened up the system and the fluid was the color of a stirred up mud puddle. Flushed the system completely, replaced the line from the MS to the booster, and replaced the booster vacuum hose.

Now, the brakes work great. Don't think converting to from discs would improve much for me, considering the effort and expense.

[KULTULZ]

Sponsored Links (Register now to hide all advertisements)

So, opened up the system and the fluid was the color of a stirred up mud puddle. Flushed the system completely,

THAT'S GREAT! The 1955/56 FORD and period BIRD brakes were more than adequate, other than road racing (or a THUMPER ENGINE is not installed).

Now don't take this wrong, but if there was that much trash in the system, you might want to consider rebuilding the MC and wheel cylinders as corrosion is sure to follow. Don't forget the valve on the booster.

Brake fluid needs to be changed at the minimum of every two years even if the car is not driven often.

[KULTULZ]

- EXCERPS FROM POST #45 (ABBREVIATED) -


- 12 JAN 2024 -

Originally Posted by KULTULZ

The below from a BRAKE TECH FAQ website discussing the GRANADA swap

To Wit -

When you're getting the spindle assemblies at the salvage yard, don't forget the distribution block. Most any post-1970 ford distribution block for dual circuit braking systems will work.

The unit has a pressure sensing diaphragm which, when detecting a pressure drop, will close off fluid flow to the dropped circuit. This will allow you to still have either front or back brakes. Take the connector and a partial strand of the wiring, as you may wish to hook up a "brake warning" light later.

Above Is Incorrect -

One myth that often pops up during conversations is the misconception that if the spool in the pressure differential valve gets pushed off-center due to (for example) a brake line failure, it seals off the bad side, allowing you to still have brake pressure on the good side. This is incorrect! It is merely a warning system. The ends of the spool are turned down to allow brake fluid to pass when it is pushed to one side.

If the spool was designed to cut off the brake fluid to the side where the pressure has dropped it would seal the fluid between the master cylinder and the distribution block. This would cause the brake pedal to be rock hard and you would have no brakes at all because the trapped fluid would not give.

The dual master cylinder is the safety feature that allows pressure at the good end. There is nothing inside the pressure differential valve to replace when rebuilding except for two special o-rings and a crush washer.

Source - PHOENIX BRAKE SYSTEMS

When you're getting the spindle assemblies at the salvage yard, don't forget the distribution block. most any post-1970 ford distribution block for dual circuit braking systems will work.

EDIT - Wrong again. Each PPV within a combination valve is calibrated for the vehicle it was released for.

The unit has a pressure sensing diaphragm which, when detecting a pressure drop, will close off fluid flow to the dropped circuit. This will allow you to still have either front or back brakes. Take the connector and a partial strand of the wiring, as you may wish to hook up a "brake warning" light later.

A diaphragm? It is a pintle (edit - actually shuttle) (and it will not block cross-flow). When the shuttle valve moves to one side or the other, it initiates an electrical switch (2B264) that will illuminate a warning lamp on the instrument panel (if so equipped - 1967/ ).

I think the writer is describing the PDV (pressure differential valve) as FORD did not actually release a combination valve (an assembly consisting of two or more individual braking valves) until 1972. PDV, PPV and metering were separate. Actually the PDV at that stage was included in a distribution block (or, it can be said the distribution block was actually part of the PDV), hence one thinking it was a combination valve)

As for the PDV, if one does not want or need the warning lamp feature, actual distribution blocks are available for a neater appearance.

While this particular tech write-up has a 2001 date, it is still online and should have been corrected (IMO of course).

[KULTULZ]

Originally Posted by miker98038

56sedandelivery, FWIW (and ignoring the above discussion).

I heard that Mikee ...

[KULTULZ]

- BRAKE QUESTION ON A 1954 MERC -

https://www.fordbarn.com/forum/showthread.php?t=335072