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Master Cylinder Bore size

4 calipers is a lot of volume. John, heck, I have never been wrong....just ask my wife. Nah, better not.:D. Certainly worth checking into. Maybe see what is required for the brand of calipers that you have.
Metering valves are used in rear drive disc/drum vehicles to hold pressure off of the front discs until the hydraulic system overcomes the return springs on the rear drum brakes. The metering valve is usually a 15 psi valve. The purpose of the valve is to prevent front disc lockup on ice and snow in light braking situations.

Proportioning valves are most prevalent in a vehicle with disc/drum combos, but are used in disc/disc vehicles in certain applications. Proportioning valves hold pressure off of the rear drums in a panic situation to prevent rear wheel lockup. Adjustable prop valves are available from most of the aftermarket hot rod brake suppliers. An OE prop valve will not work well in our hot rods because they are engineered for a specifi c vehicle. ABS has all but eliminated prop valves in current OE applications.

Residual pressure valves were used at the OE level until 1972. They were nothing more than a “duck billed” rubber valve in the outlet ports of the master cylinder. Their purpose was to slow down the violent surge backwards through the hydraulic system caused by the drum brake return springs. This surge would cause the cup lips inside of the wheel cylinders to distort and when the cup lips distorted, they would “take air”.

OE solved this problem by using “expander plates” attached to the ends of the spring inside of the wheel cylinder. These plates held the cup lips tightly against the inside of the cylinder bore and would not let the cup lips distort. Around mid ’73, Raybestos Manhattan in cooperation with Gibson Corp. invented a cone shaped spring with each end of the spring spirals cone shaped to fi t the inside of the cup lips. This eliminated the snap on plates that could come loose and score the inside of the wheel cylinder. The expander plates and the cone shaped spring ELIMINATED the use of RPVs at the OE level.

Some aftermarket brake suppliers would have you believe that the RPVs they sell will stop siphoning of the brake fl uid when the master cylinder is lower than the calipers and/or wheel cylinders. In order for a liquid to “siphon” one end of the tube or hose MUST be open to the atmosphere. In the case of a closed brake system, this is not possible.

One other thing needs to be said about RPVs!! If you buy a rebuilt master cylinder for your project, there is a possibility that it could be equipped with the duck billed valves (rpv) from the rebuilder. This is because many master cylinder applications use the same casting. If you install a rebuilt cylinder (which I strongly discourage) be sure to check the outlet port of the master cylinder on the disc side of the system. If you leave the rpv inside the port on a disc equipped car, it will overheat the caliper, pads, and rotors and could cause a premature lockup problem.

I hope this clears up any misconceptions about hydraulic brake valves. As always, you can find me on the BBS most any evening if you have any questions.

By "FAT PAT" Anderson

Here is the dimensional data for making the adapter parts for the
GM intermediate calipers and rotors to the early Ford spindles.
The material for the bracket is 3/8" steel plate

Here is the detail for the Seal Surface and Bearing Adapter Sleeve.

And here is how it all goes together.

By George Barnes
Basic Brakes by Pat Anderson

There are 3 types of brake fluid available in the USA and choosing the right one for your particular situation is an important part of building your project. We will discuss the advantages and disadvantages of all 3. Then you will be able to make the decision on which one is right for you.

Dot 3
By far the most widely used by both import and domestic vehicles at the OE level. Dot 3 is highly hygroscopic meaning that it attracts moisture. If you read on the label of the Dot 3 or Dot 4 container it will say "keep container tightly closed to prevent absorption of moisture". The minimum "wet boiling point" (meaning with a 5% water content) is 284 degrees F.

The advantages of Dot 3 are as follows;
1. readily available at any parts outlet
2. easy to work with
3. reasonably priced

Disadvantages are;
1. attracts moisture
2. removes or damages paint

If you have ever bled a vehicle that is 5-6 years old and it was originally equipped with Dot 3 or Dot 4, you will notice that the fluid that comes out of the system during the bleeding process looks like muddy/rusty water. That is because that is precisely what it is. The highly hygroscopic nature of Dot 3 and Dot 4 will pull moisture from the air in the form of humidity right through your porous rubber brake hoses and contaminate and corrode the inside of the brake system and lower the boiling point of the brake fluid in the process. If you own an American made vehicle built since 1972, your owner's manual will recommend a brake system flush every 1-3 years. I don't know anyone who does this, but if they did the hydraulic parts would outlast the vehicle

Dot 4
Wet boiling point is 311 degrees

Dot 5 (silicone brake fluid)
1. non hygroscopic
2. will not harm paint

1. very expensive
2. somewhat susceptible to aeration if not handled carefully
Note: Dot 5 is not recommended for systems with ABS

Dot 4 is the same thing as Dot 3 with a slightly higher wet boiling point
I hope this short article gives you some insight on the brake fluid best suitd for your particular application.

As always, you can find me on the BBS most every evening and I will be delighted to answer any questions you may have.p> "Fat Pat" Anderson

BRAKE BASICS BY Fat Pat Anderson

This article will stop you in your tracks!!

There are 2 different designs of drum brakes

Servo type or self energizing

Non servo or non self enewrgizing

They are very easy to identify. A servo type drum brake will have a common anchor for both brake shoes. The non servo type will have separate anchor for each shoe.

Also non servo type drum brakes will have shoes of the same length, while a servo type drum brake will have 2 different lengths of shoes. We will discuss servo type first, as they are far more prevalent.

For this article, I will be talking about the left rear of the vehicle facing the drum brake. The shortest shoe or primary shoe (the metal frame of the shoe is the same, but the friction material is shorter) ALWAYS goes toward the front of the vehicle.

When the brakes are applied, the short shoe grabs hold of the rotating surface of the drum and then mechanically multiplies the pressure, through the adjusting screw, to the rear shoe. (That is why the secondary shoe or the long shoe will always wear fastest) It takes about 1/2 as much pressure to operate a drum brake as it does a disc brake! (350 to 500 psi)!

On the non servo type of drum brake, we do not have the capability of multiplying the pressure to the secondary shoe because we have separate anchor pins. So the front shoe will ALWAYS wear the fastest. The only time the secondary shoe does anything on a non servo type is when you are backing up.

Brake Drums
Brake drums should ALWAYS be turned prior to overhauling the brakes! Most drums have a minimum thickness cast into the outer rim of the drum. The reason for the mini-mum thickness is for heat dissipa-tion and correct shoe to drum contact. HEAT is a huge factor when talking about any type of braking system. It is always a good idea to check shoe to drum con-tact by placing the shoe inside of the drum and checking the shoe to drum contact. We want about 80% shoe to drum contact. Re arced shoes used to be available for drums that have been turned out to maximum specs, but they are no longer available, so this is something to watch for.

Backing plates

Clean the backing plates thoroughly with brake cleaner and a wire brush or soap and water. Lubricate the brake shoe rests with white grease or any lubricant that is not susceptible to heat (the brake shoe "rests" are small raised places on the backing plate where the edge of the brake shoe rests) The brake shoe "rests" should be cleaned with a wire brush or some type of abrasive.

Brake hardware

ALWAYS use NEW brake hardware when overhauling a drum or any type of brake. Drum brake hardware is available in axle sets from your parts sup-plier. Return springs and hold downs lose their tensile strength because of the heat that they are subjected to. These axle hardware kits are called Maxi Packs at NAPA and Combi-Kits at any other sup- plier that is selling Wagner Parts.

Self adjusting hardware

Self adjusting hardware is available from your local parts supplier in wheel kits. If you can lubricate your old hardware and make it work freely, then I would most likely use it over again although cable type self adjusters are very susceptible to stretching. The cables are available by them-selves.

Wheel Cylinders
Overhauling wheel cyl-inders is almost a thing of the past, but if you insist on overhauling them instead of replacing them, try to get "H" kits from NAPA. They include new sintered iron pistons that sweat a silicone lubricant when subjected to heat.

Replacing the brakes
I ALWAYS replace one side at a time so I can use the other side for reference purposes. (This coming from a brake expert is probably good advice!)

Please use the correct tools when working on drum brakes. Using needle nose pliers to remove return springs is not only dangerous ... they don't work very well either. There are correct tools available at any parts house and some chain stores will loan them to you.

I hope this helps some of you who are using drum brakes. I should add that there is absolutely nothing wrong with drum brakes below 100 mph. The ONLY advantage of a disc brake below that speed is the fact that disc brakes have a foolproof self adjuster and drum brakes self adjusters are sometimes a little "balky"

If you have any questions or I have forgotten to cover some thing you can find me on the BBS almost every evening.

Fat Pat

Editors note: Fat Pat "Brakeman" Anderson is a brake expert who has produced brake videos and taught courses on brake repair and service. Pat has a long history with automobiles, parts and T-buckets (though with the sale of the flaming chicken Bucket, he is currently without the best ride in the world!) Thanks Pat for this article, keep 'em coming!

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