Proportioning Valve mystery - Team Camaro Tech
Brakes, Suspension & Steering Conversion questions, Steering & Handling

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post #1 of 16 (permalink) Old May 16th, 07, 06:41 AM Thread Starter
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Proportioning Valve mystery

Here is my dilema. I have a 67 that came with drum/drum. The guy I bought the car from had disc put on the front. According to Rick's the calipers are from a 69, going by the way the hoses are. Anyway, I am working on the conversion for the rear and my system doesn't seem to have a porp valve. The only thing it has is a black block under the m/c which has the brake light switch in it. I have been all over the car, front to rear, top to bottom and there is no prop valve. Is it possible that the distribution block, as it has been called, is actually doing the work of every thing? How can I identify a combo valve? The car stops fine, but can always be better. I don't experience front/rear lock up unless I make a panic stop. Any help you can offer would be greatly appreciated.
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post #2 of 16 (permalink) Old May 16th, 07, 07:30 AM
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Re: Proportioning Valve mystery

In a drum/drum car there is no proportioning valve. The proportioning is done with the wheel cylinders and brake shoes.
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post #3 of 16 (permalink) Old May 16th, 07, 07:33 AM
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Re: Proportioning Valve mystery

youll definately need a combo valve for sure


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post #4 of 16 (permalink) Old May 16th, 07, 07:38 AM
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Re: Proportioning Valve mystery

A lot of disc cars didn't have a proportioning valve either. There was none on my '69 Bird with discs.

Good Luck!

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post #5 of 16 (permalink) Old May 16th, 07, 07:43 AM
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Re: Proportioning Valve mystery

Can you post a pic of the valve you have under the master. It probably is your combo valve.
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post #6 of 16 (permalink) Old May 16th, 07, 07:45 AM
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Re: Proportioning Valve mystery

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Originally Posted by 72Tugboat View Post
A lot of disc cars didn't have a proportioning valve either. There was none on my '69 Bird with discs.

Good Luck!
What was the setup there?
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post #7 of 16 (permalink) Old May 16th, 07, 09:26 AM Thread Starter
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Re: Proportioning Valve mystery

I am having trouble getting the pic on, but if you go to D&R Classic Automotive and click on Brakes. Then click on 67-69 Distribution block. It looks exactly like that.
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post #8 of 16 (permalink) Old May 16th, 07, 09:36 AM
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Re: Proportioning Valve mystery

That would be a drum / drum (or possibly applies to disk /disk) distribution block. It had no valving in it at all, just the sensor for the brake light and the fluid ports.

If that's all there is, then you do not have a proportioning valve in the system.

Did you look along the frame rail on the drivers side, it could very likely be there.





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post #9 of 16 (permalink) Old May 16th, 07, 01:22 PM Thread Starter
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Re: Proportioning Valve mystery

JimM I have been all over the car. Top to bottom, front to back. I have followed each brake line and that block is the only thing.
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post #10 of 16 (permalink) Old May 16th, 07, 01:35 PM
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Re: Proportioning Valve mystery

Then you don't have a proportioning valve.

Big question is, how are the brakes under a full effort stop?

A "good" brake system is balanced. The fronts will lock slightly before the rears. Rears locking first is dangerous, the car wants to swaps ends on you, not a good thing in a panic situation.

Many brake systems are "balanced by design." The brakes in a C3 vette are a good example, they never had any proportioning, the balance was achieved by juggling the piston sizes front to rear. All Drum systems are the same way, no proportioning needed. There are, of course, disk disk systems that are not properly balanced and need a valve to reduce the rear line pressure so the front's lock first.

All disk / drum systems are inherently "unbalanced." The rear drum brakes simply require much less pressure to lock then the front disks do.

Still, if you floor the pedal and the backs don't lock first, you don't have a problem. It's not what's there, it's how it performs that counts.





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post #11 of 16 (permalink) Old May 16th, 07, 01:54 PM
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Re: Proportioning Valve mystery

Mine was a drum/drum set-up too and I went to a disc/drum and didn't use a proportioning valve just kept the drum one. I have big tires on back and littles on the front so maybe that helps ?
I have the one from the kit still is you need it, it's yours cheap (new in bag,unused).

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post #12 of 16 (permalink) Old May 16th, 07, 05:35 PM
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Re: Proportioning Valve mystery

I did the same conversion but found a factory valve (mounts beside the distribution block) and had it rebuilt. Car couldn't stop better!

Last I knew the factory valves weren't being reproduced - Does anyone know otherwise?
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post #13 of 16 (permalink) Old May 16th, 07, 08:01 PM
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Re: Proportioning Valve mystery

My SSBC kit came with an inline adjustable prop valve to put on the rear lines. You could add the same thing to yours pretty easily.


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post #14 of 16 (permalink) Old May 16th, 07, 10:32 PM
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Re: Proportioning Valve mystery

If the rear brakes don't lock before the rears, you don't need to add a proportioning valve.


The valve underneath the booster on a stock factory disc brake first gen Camaro is not a proportioning valve.
The proportioning valve is down on the frame rail, IF there is one.

Disc brake equipped cars have a round "Metering Valve" or "Hold Back Valve" just below the master cyl connected to the rear port.
Below that is a rectangular combination distribution block/brake light switch.
Drum brake cars got just the distribution block and some with lots of front end weight got the prop valve.

Check my web page for First Gen Camaro suspension info:
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post #15 of 16 (permalink) Old May 17th, 07, 06:17 AM Thread Starter
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Re: Proportioning Valve mystery

Thanks guys for all your help. I'll keep you in mind Doug G if I need the valve. I'm torn right now bwtween the rear disc conversion and saving for the T-56 swap.
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