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Old 11-11-2010, 11:19 PM
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Power brake/pedal problem

Hi guys
I am building a '65 Chevy truck which I just started for the first time after a complete engine build last Sunday. I am now trying to tie up some loose ends so that I can take it around the block. I am currently working on the brake system and have run into a strange problem. Here is a quick summary of my system, disc front/drum rear, booster and master cylinder off of '97 s10, disc/drum proportioning valve. I modified the pushrod to ensure proper travel, I have bench bled the master cylinder, bled the entire system, and have a fairly stiff pedal when the truck is not running. As soon as I start the truck and the booster kicks in I can push the pedal to the floor without any resistance. I have vacuum tested the booster and it is good. I have also tried a new master cylinder with no luck. Any thoughts as to what could be causing this issue?

Thanks

Derek

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Old 11-11-2010, 11:58 PM
richard stewart 3rd's Avatar
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Hi Derek,
From what you have written, I can only look at the booster as the cause of the problem. I fail to see how it could be anything else.
Rich
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Old 11-12-2010, 09:05 AM
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Quote:
Originally Posted by richard stewart 3rd
Hi Derek,
From what you have written, I can only look at the booster as the cause of the problem. I fail to see how it could be anything else.
Rich
Thats what I thought too, but everything I read says that a bad booster will make the brakes rock hard not soft. Also the booster hold vacuum when I tested it.
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Old 11-12-2010, 09:23 AM
richard stewart 3rd's Avatar
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Hi,
The break pedal goes to floor.
Causes,
low break fluid
Contaminated Brake Fluid
Worn Brake Pads or
Bad Brake Power Booster
Rich
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Old 11-15-2010, 03:18 PM
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I ended up replacing the s10 master cylinder that I was using with a larger mc off of a C10 and it solved the problem. The s10 mc just couldn't push enough fluid even though it had an 1.125" bore.
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Old 11-15-2010, 03:48 PM
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Quote:
Originally Posted by dlisabeth
I ended up replacing the s10 master cylinder that I was using with a larger mc off of a C10 and it solved the problem. The s10 mc just couldn't push enough fluid even though it had an 1.125" bore.
Hummmm!!!!!!!!!!!! strange enough i guess. Would have thought the S-10 would have worked i know others that have used them and they were fine.
Well at-least you got it fixed.



Cole
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