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Discussion Starter #1 (Edited)
When I bought my nova I noticed that my brake pedal got harder towards the end of the travel and at the very end was like pushing on a brick wall, and I could not lock up the brakes. The prior owner had a power disk brake conversion installed with a 7" single diaphram booster, dual MC, and prop. valve. I posted a thread last winter about my displeasure and got some good tips. I changed to a 9" single diaphram booster and a noticed a difference but I still had the hard brakes at the end of the travel and couldn't lock 'em up. I then noticed that the original installer didn't use both ports on the prop. valve for the front calipers, so I fixed that; still to no avail..this is driving me nuts!!!! I checked the front pads for glazing, bled the brakes a million times, used the right piston rod, and adjusted the clevis per the booster instructions; I've also adjusted the rod to the point where the brakes were applying with no help from me. Oh, I have 18 inches of vacuum all day too. Still have the hard brakes at the end of the travel and can't lock 'em up. Maybe the MC is no good, should I start replacing parts there???? Help:mad: :mad: :mad:
 

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If you master cylinder isn't sealing properly it is possible that you aren't building enough pressure in your lines? I just installed the kit in my car and if you would like a photo of my master cylinder/proportioning valve setup I can get it for you. Are you positive all your lines are hooked up right?
 

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Discussion Starter #3
I am not because I was not the original installer but I will check all the lines tonight. I'm guessing that everything is good because I get lots of fluid squirting out from the bleeder screws when I have a helper bleed the brakes. A pic would be great!!!
 

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Discussion Starter #4
Nate, lines are definitely hooked up right. I'm thinking maybe I have a bad caliper?? How do your brakes feel towards the end of the travel, and can you lock them up??
 

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Brakes Again?

JB; You might want to insatll a vaccum canister (reserve) it sounds to me like you're actually "running out" of vaccum to help you push. Do you have a lumpy cam with a rough idle? Lots of valve overlap? Take a look at a vaccum gauge while you're applying (driving) and see if it drops below 10". If everything looks okay (12"-14" or higher) look for leaks.
 

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Discussion Starter #6
I've got a stock '88 350 with a solid 18 inches of vacuum all the time.
 

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jerkyboy said:
Bore size is one inch.
Power brake setups usually have 1.125" bore and manual setups use the 1" bore.
Smaller bore requires less leg effort but more pedal travel while the larger bore will require more effort (provided by the booster).
Good chance this is your problem.
 

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Discussion Starter #11
I installed the cheapest NAPA brakes last night. They are made from asbestos; I didn't think they used that material any more?? Anyhow, I'll let you know how they feel after the test drive.
 

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Man you just got rid of chevy's ultra rare prototype anti-lock brakes :eek:
 
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