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Discussion Starter #1
have been messing with what i thought was a simple project all afternoon. have a 68 camaro that originally had standard drum brakes. it was upgraded to power assisted drum brakes. I did not drive it for about 4 months and went to use it and discovered I had very little brake pedal. No fluid leaks and the master cylinder was full. I figured it must be an internal master cylinder problem----cheap, easy fix. Took the old one off, not knowing for sure what would replace it, and carried it with me. A 1969 master cylinder seemed to match perfect, so i bench bleed it and bolted it on. lines were perfect and started bleeding the lines. Well two hours later, still bleeding and the pedal level is still at about the same postion it was with the old master cylinder. no leaks, no fluid loss, just can not get but about an inch of pedal at most. I now think think the old cylinder was probably ok as this one is giving same problems. The brakes will lock on dirt....and all 4 wheels are braking------just no pedal as it is on the floor when this happens. Thanks for any help offered!!
 

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I would think you instaled new lines up ft anyway. If so it suprised me how hard it was to get air to move down hill to the bleeder. I ended up useing a power bleeder. It could also be the need for changing the location the push rod where it conects to the pedal. there may be two holes check that to. What type of valve do you have on it now? 70s style is popular with many kits.
 

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i don't think new lines were installed, but not sure. someone else did that work. everything was fine until car sat for about 4 months. the replacement cylinder appeared identical except it did not have bleeder screws on the cyclinder itsself at the lines. the lines lined up perfect and were the correct size.
 

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Discussion Starter #4
new piece of the puzzle

i went back to the original i removed and discovered a stamped number on it. it cross references to a 1967 -1969 impala as well as some c-10 trucks. I am now thinking the person who converted this used an impala booster and mastercylinder set----and perhaps that is my problem why i can not get the master cylinder that i bought today----a 1969 camaro drum w/booster model----to bleed. anyone know if either the push length of the cylinder or perhaps the volume it pumps could cause my problem? i am curious if these are standard with all master cylinders or if they vary. thanks
 

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When I upgraded my drum to power, I used the MC for a drum/disc application. Put the pedal rod in the lower hole and it was perfect. I bench bled the MC and power bled the lines. It is rock solid. Did you put the booster rod in the lower hole of the brake pedal?
 

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If you just have a low brake pedal and the pedal doesn't feel spongy, you've successfully bled them!.....All you'll need to do to raise the brake pedal is simply adjust the brakes self adjusters out and hope the adjusters are not frozen while attempting this!
 

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Discussion Starter #7
all this was already done.....and worked fine. just sat for three months and when i went to use it, had not pedal----thus figured master cylinder had internal leak. did not remove booster.
 

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I have had sucess with just cracking the bleeders and letting it sit overnight.....just a crack and make sure mc is full.
 

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Start from the beginning.
Is the master good, is it bled well? Remove the lines, and block off the ports to the master, with it installed on the car. bleed the master, the pedal should be rock hard and very little play in the pedal, maybe an inch.
If the pedal is hard, and pedal does not move much, the problem is not the master.

Try this and let us know.
Dale
 

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Discussion Starter #10
swapping masters again first today. got a master that the stamped part number on it was cross referenced rather than going by what parts books said. will see if i notice any change.
 

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did you bench bleed the master?
 

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You can measure the bore of the master, it should be 1 1/8"
Dale
 
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