Thread: Installing a brake system

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Hey, I've got some questions about making my own brake system. I've never done it, but I'm gonna learn, so here goes.
I'm planning on running all new brake line. Actually, a whole new system from MC to axle. But my main question is this:

I need to install an adjustable proportioning valve in my system. All the valves I can find have 1/8 NPT fittings. I have a 3/16 system. How does that work, or where can I get a valve with 3/16?

The fitting into the valve is 1/8" thread, is all. Most all brake lines are 3/16" diameter. No problems

So a fitting on the end of a 3/16 line should fit?

I'm the FNG, I know.

Originally Posted by JTyler

So a fitting on the end of a 3/16 line should fit?

I'm the FNG, I know.

NO!!!

You need the correct brass adapter. It has 1/8" male tapered pipe threads on one end to fit the proportioning valve and the correct 3/8"-24 female threads on the other end to fit the 3/8"-24 male fitting that is on the 3/16" brake line. Speedway motors has them. You will need the same fittings in your brake line system such as at a 'T' fitting.

Here is the link.

Click here



Here is a photo of the adapter.

yup, 1/8" just refers to the thread size in the valve. Don't apologize for being new at this stuff, everybody was once!!!! (Even though some of us are too old to remember that far back!!!! )

The proportioning valve comes with those brass fittings. Or at least all of them I've ever bought do. I usually use a Wilwood proportioning valve, I know both those and the Speedway brand proportioning valve come with the fittings.

Not all come with the fittings. I recently looked up the valves from different suppliers and not all came with the fittings.

Originally Posted by Dave Severson

The proportioning valve comes with those brass fittings. Or at least all of them I've ever bought do. I usually use a Wilwood proportioning valve, I know both those and the Speedway brand proportioning valve come with the fittings.

Originally Posted by paul274854

Not all come with the fittings. I recently looked up the valves from different suppliers and not all came with the fittings.

I'm sure some do come without fittings, as I said, the Speedway and Wilwood do come with fittings. These are about the only two I use on street cars, can't say much about the others.... I'm sure some of the fly-by-night companies leave the fittings out to help with the profit....

You may not need a proportioning valve.

Especially if you're running big and little's.

My 32 has the propo valve cranked almost all the way out so no proportioning is done and more than likely if I removed the valve the brakes would be the same.

If'n I was you, I'd plumb in a place where the propo valve could be easily added and try the car without one initially.

I plan to do that with my 31 on 32 rails roadster which has less disparity between front and rear tires than does the 32 roadster.

Fwiw - tire diameters on both cars:

32 = 30" rear, 24" front.

31 = 28" rear, 25" front.

Same engine/trans/rear axle combo in both cars.
And very close to the same brakes for both.

(462" Buick, T-400 and Ford 9".)

(68-70 Mustang 11" discs front, 68 Merc wagon drum brakes rear on the 32. Camaro 10 1/2" discs front, same drum brakes rear on the 31.)

I use the Speedway ones. Can't remember if fittings came with them or not . I have a huge box of fittings so I just find what I need.

Frisco is right. That's what you need. Also you may need residual valves if the MC is mounted down low. I use them anyway. These work pretty well.

If that's the case then I really don't need a proportioning valve as long as I don't jam on the brakes and try to stop on a dime.

Not necessarily. Without a PV, you can have one set of tires lock up before the other. That can cause a serious handling problem. Even if it only happens during a panic stop, it's still critical. Rmember, you MAY have to stop on a dime . . .

On a custom build, the only way you can tell whether or not you need a PV is to try it with (or without) one and see what happens.

A combination valve and a proportioning valve are not the same.. A proportioning valve goes in the rear brake lines to limit the amount of pressure to the rear wheels...

As pictured, the combination valve has a proportioning valve installed in the rear wheel brake line...

The two bowl valve will not close off a system when a line breaks, the bowl with the broken line simply runs out of brake fluid and all the braking is done with the functioning end. A combination valve will close off the line to the end with the broken line, allowing both bowls to supply brake fluid to the end still functioning.

Residual valves are designed to maintain a small amount of pressure on a brake caliper or wheel cylinder so that it takes less pedal travel and less time to apply the brakes. A residual valve is also necessary in a system whenver the master cylinder is floor mounted and below the level of the wheel cylinders or calipers. It then also acts as a check valve to prevent fluid drain back to the master cylinder...

To say they are not necessary because you don't plan on trying to stop on a dime is much the same as saying you don't need them because you don't plan on being in an accident!!!!! All of the components in a brake system are necessary pieces and need to be installed in the system. The braking system is not a good place to take shortcuts or try to save a buck or two.....

To say they are not necessary because you don't plan on trying to stop on a dime is much the same as saying you don't need them because you don't plan on being in an accident!!!!! All of the components in a brake system are necessary pieces and need to be installed in the system. The braking system is not a good place to take shortcuts or try to save a buck or two.....

You're absolutely correct. But I think you missed the point I was trying to make.

I did a little light reading, (a couple of Motor Manuals), and I learned...

To an amature builder, the way the Motors Manuals are worded, one can be misled to the wrong conclusion. The guys in Detroit are not idiots. They knew what they were doing when they designed the valves. My problem was that I couldn't tell one from the other. I know what a combination valve is, but I wasn't aware that they made the valves separate. My brake system has two separate valves. One valve is plumbed from both sides of the M/C with one line going directly to the front disc brakes, the line to the rear brakes goes to a second valve and out to the rear brakes. From Denny's diagrams I can see that the first valve is the Combo residual/fail switch valve and the second is the proportioning valve.

I really don't need a proportioning valve as long as I don't jam on the brakes

Right...Is there a day when we don't jam on the brakes???

Sorry guys if my post misled you.