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)

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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 -

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

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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.