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Discussion Starter · #1 ·
This may be an easy one for the the right person.

I put drop discs on the front of my '55 and am running the stock drum rears.
I used a proportioning valve and bracket out of a '71 Chevy 2wd PU with manual disc drums. I used a new master cylinder (bench bled) and bled the rest of the system. They would lock up with two pumps on the brake but just seemed to soft and questionable. A knowlegable person said that the prop. valve may not be working right so I bought a GM brass block style from Speedway motors. It boted right in.

Still running it as manual, no booster.

The Question: Do I just bleed the brakes the regular way or do I need to do something special to get the air out of the proportioning valve first?
 

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I have always bled them the normal ay....A power bleeder would work great if you can get access to one!
 

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I own a power bleeder, and almost never use it. Start with leaving open all your bleeders, top off your cylinder, then give a few pumps, to get some fluid into the system. Then close off the bleeders, and start at the furthest wheel, then the next until all four wheels show no signs of air. I myself take it easy on pumping the brake pedal, as you don't want that proportioning valve to shift one side, from pushing on the brake pedal to hard. BTW: Make sure your rear brakes are adjusted right first. That could give you a low pedal right off.

:anim_25:
 

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Bleed normally, don't step hard on the pedal until the bleeding is complete.

Reason is, there's a shuttle in the valve that will close off the side that's not bled, if you apply the pedal firmly before you're done.
 

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Bleed normally, don't step hard on the pedal until the bleeding is complete.....Reason is, there's a shuttle in the valve that will close off the side that's not bled, if you apply the pedal firmly before you're done.
Didn't realize that Rick.....But makes total sense, now that you mention it....Thanks for the tip :):tu
 

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A few months ago, I replaced both front calipers on my F350...
I had a heck of a time bleeding them completely....

Until I used a trick I normally use on motorcycle brakes....

Fill a 90cc syringe with brake fluid then pop a small rubber hose on the end...
put the other end of the hose on the bleeder screw...
now reverse fill the system....

the air bubbles will be naturally pushed to the MC as you (SLOWLY) fill.

works every time. :cool:


You can get a syringe at your local Vet. for close to nothing $$
 

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Discussion Starter · #8 ·
I'll try that Auggie. Thay makes sense to me. Could get messy out there.

An article on line says to use a clamp and a block of wood to push the valve in (open) while you bleed them the first time.

Only one article referes to doing it this way. It claims that it lets fluid move evenly, the valve is supposed to keep fluid up front in its normal position.

Anyone hear of this?
 

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I'll try that Auggie. Thay makes sense to me. Could get messy out there.

An article on line says to use a clamp and a block of wood to push the valve in (open) while you bleed them the first time.

Only one article referes to doing it this way. It claims that it lets fluid move evenly, the valve is supposed to keep fluid up front in its normal position.

Anyone hear of this?
I was in the trade when the dual system came out, and we had a spring clip of sorts, that held that valve like you say. The clip was lost before anyone could use it, so we never used one. To clarify, don't fill and bleed just one end of the system at a time. Doing so will cause that valve to stay at one side, and it's a bugger to center. This is why we suggest to go slow and easy on the brake pedal, until you get most of the air out of both ends. Once the pedal firms up, you don't have to be as careful.
 

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Most of the time you can fill and gravity bleed the front calipers without ever moving the pedal, and they will be ready to go. Then you can fill and bleed the rear without worrying about the shuttle valve.

Many of these shuttles can't be pinched off or pushed off externally. You have to "create a leak" in the "good" side of the system to center it.
 

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Discussion Starter · #11 ·
Thanks everyone.

The brakes seem to be much better than before. I think the old proportioning valve was ok, the main problem I think is what Auggie said about the rear brakes not being adjusted right the first time. I turned the spurs about 5 rotations to get the drag on the shoes.

Meanwhile I opened both front and back bleeders, slowly pumpped about 6 times and let it sit for about 6 hours and let it drip. When my Son helped me bleed them there was virtually no air in the system.

Great sight support guys!
 
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