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Hello All! I'm a newbie to this forum and this is my first of probably many posts so thank you for such an amazing forum.

Here's my question...I have a 67 fastback with power drum brakes and I just received my Baer front disc brake conversion kit and I think I have everything figured out except for the plumbing of the lines. It sounds like running an adjustable proportioning valve is needed. Can I keep the stock distribution block and just place the proportioning valve in the line from the master cylinder to the distribution block port going to the rear? Or do I have to remove my current distribution block, place a new T distribution block for the front and have a line going from the master cylinder to the proportioning valve then out to the rear? I really don't want to spend the weekend learning how to bend and flare brake lines.

Thanks!
Magnum
 

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The distribution valve goes between the junction block and the rear brakes, I like to install it somewhere in the engine compartment around the steeering column.
 

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If you have rear drums, you don't need the adj valve as the brakes themselves are adjustable.
 

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If you have rear drums, you don't need the adj valve as the brakes themselves are adjustable.
That has nothing to do with it.

The stock drum/drum distribution block has no proportioning function in it and can be used again as a distribution block. Place the adjustable proportioning valve somewhere in the rear brake line. Make sure to use a disc drum MC. A stock 1967 1" MC should be a good match for the Baer calipers, but you may want to ask them.
 

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It has everything to do with it.

A prop valve is used on rear disc cars that want to run bias to put more power to the front.

If you can adjust the rear with the adjusters, you don't need the hydraulic version unless you want to use it as a line lock or something for convenience.

You run the rear line right to the master and cap the open spot on the dist block.
 

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Yes, you'll need to add a proportioning valve to the rear line if you go to disc in the front. Either way you mention will work but keeping the distribution block is easier and also retains the warning light function...

68Restoman
 

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mdjay, the adjustment on the drums adjusts the distance between the shoe and the drum. It has absolutely nothing to do with the line pressure which the valve adjusts.

If I understand you correctly, you're saying that you'd only want to slow down or quicken the rear brake effect instead of adjusting the shoe pressure against the drum? I'll take the proportioning valve, thanks.
 

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Well there's been several articles stating that don't need them. I ran this set-up for 10 years autocrossing and all and it worked great.

The cause and effect gives the same result.

Let's play devils advocate here:

How do you think the bias is adjusted on 4 wheel drums?

I'm not saying you can't use it. It's just more time and money. Anyone that says you outright need it just wants to sell you a proportioning valve.

If you're that set on it, come to my store, I'll sell you one...
 

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MDjay,

The factory put a fixed proportioning valve in line on these cars. When you change the power of the brakes at either end, you need a new set pressure for the rear to prevent premature lock up. The easiest way to get that is an adjustable valve.

Also, if you are a racer, you should be using an adjustable valve to get the optimum braking. The weight transfer to the front is greater on a sticky track, which unloads the rear wheels. You need to lower the rear brake pressure to prevent lock up. Likewise, on a slick track, you would adjust the valve to give more brake power to the rear.

My $.02

Brian
 

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I think we'll have to agree to disagree that "The cause and effect gives the same result" I don't buy it.

What I don't understand is how you expect to get past the fact that the drums automatically adjust themselves when you back up?
 

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I think we'll have to agree to disagree that "The cause and effect gives the same result" I don't buy it.

What I don't understand is how you expect to get past the fact that the drums automatically adjust themselves when you back up?
You're confusing drum adjustment with braking distribution force between front and rear. The Proportioning Valve allows a differential force between front and rear brakes to adjust whether the fronts or rears lock up first. The drum adjustment done by backing up simply adjusts how close the drum brake pads sit relative to the brake drum when no force is applied to the brakes.
 

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I'm not a competitive race driver but I have spent plenty of time at the track.

If I was competitive at the time, I would have been using 4 wheel discs with the proportioning valve accessible to me in the driver's seat.

When you change to front discs, the stopping force is much greater in the front already. I have never been able to adjust drum brakes effectively by simply backing up the car. I always backed off the rears. If you were to do nothing to the rear drums when you changed the front to disc, you are pretty close to home if not fine the way it is.

The factory put a fixed proportioning valve in line on these cars. When you change the power of the brakes at either end, you need a new set pressure for the rear to prevent premature lock up. The easiest way to get that is an adjustable valve.
That depends on the year of the car.

If you put the rear line straight to master as stated, there's no proportioning going on.
 

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I think you guys might have misunderstood my 'backing up' comment.

What I meant was, that if you are planning on adjusting the rear brakes with the adjusters and spend a bunch of time to get it perfect, all of your work goes out the window the minute you back up and apply the brakes. How do you get around that?

If I read what you're saying,
The cause and effect gives the same result.
by adjusting the rear brakes via the adjuster wheel on the wheel cylinder with a screw driver or similar, then you're adjusting line pressure like you do with a prop valve. That's just not correct.

The prop valve changes rear line pressure and the wheel cylinder adjsuter changes the distance between the shoe and the drum.

If I understood you wrong, please let me know.
 

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Jason
You're talking a very light adjustment. The rear brakes will not lock up ahead of the discs on the front. They just don't have the stopping power to do it. It's not a matter of fine tuning. You have a 65 so there isn't even a stock prop valve on your car.

On the end result issue, I'm saying applying less presure to the rear shoes to the drum. You can do this hydraulic or by adjusting the drum brakes.

Some people say you absolutely need it, some don't. My experience has been that you don't and it was applied experience, with the logic I've explained.

Happy Holidays...
Jay
 

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If the drum brakes don't have more than about 30% the stopping capacity of the front brakes (the front rear weight distribution is around 70-30 under heavy braking), then you don't need a proportioning valve. If you're only designing the system for heavy braking, you can just use the piston diameter of either the caliper or the drum cylinders to divide the front/rear brake capacity. A balance bar on a race type dual master cylinder accomplishes the same thing. I guess that's how they did it on four wheel drum brake systems: the front cylinders are 1 1/8" and the rear ones are 29/32".

With a proportioning valve, the system is a bit more advanced, with (relatively) more braking power to the rear wheels at lighter braking. I guess this gives a nicer brake feel, with less dive. Also, disc brakes have no self energizing effect, and require more pedal force. With a proportioning valve, you utilize the rear brakes better under light braking, when there's no risk for locking up anyway. The result is that less pedal force is required for the same amount of (light) braking.

While I agree that you don't need a proportioning valve by definition, I disagree with the statement that the adjuster mechanism in a drum does the same thing as a proportioning valve. They're just two different things.

Maybe you were thinking of a residual pressure valve? I guess they are not needed with the proper shoe adjustment.
 

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Discussion Starter #17
Almost all the research that I've done suggests installing an adjustable proportioning valve. The question isn't if I should install one but where. It would be easy for me to keep the stock distribution block and just add the prop. valve in the line coming from the MC going to the distribution block rather than adding it after the distribution block which is buried under my power booster. and hard to get to. The other option is to either use the stock distribution valve and plug the rear brake port or remove the current distribution block entirely and run a 1 in 2 out distribution block to the front and re-plumb the rear line from the MC to the prop. valve then to the rear line going back.
 
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