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  1. #1
    Join Date
    Aug 2010
    Posts
    432

    Default Pedal not returning all the way up?

    I am in the process of finishing up the install of a DSE booster and master cylinder on my 69 Firebird track car. I feel confident that the brakes are bled well all the way around. I am using a Wilwood proportioning valve in the system and as far as I can tell I have no leaks. The motor also makes plenty of vacuum for the booster. The problem I am having is that the pedal doesn't want to return all the way up after it is pressed down. Everything seemed to line up well when I bolted up the booster to the firewall. The clevis pin was a little hard to line up, but I got it through. Thoughts?
    Joe
    1969 Firebird Project
    1967 Frirebird 400 convertible
    2013 Boss 302

  2. #2
    Join Date
    Sep 2004
    Location
    Arizona
    Posts
    192

    Default

    The vacuum booster has an internal spring that returns the pedal to it's up position.. I just returned a booster that had a problem with the internal spring.... push the brake pedal and it would not come all the way back up..... new booster, no more problem... That was my issue.

  3. #3
    Join Date
    Sep 2010
    Location
    Beach Park IL
    Posts
    2,352
    Country Flag: United States

    Default

    Did you open up the hole in the firewall? Sometimes it drags on there.

    Likely a bad booster. Yes there is a spring but there is also a valve that applies vacuum to balance the negative pressure on both sides of the diaphragm. If the valve closes to early, the pedal won't return all the way
    Donny

    Support your local hot rod shop!

  4. #4
    Join Date
    Aug 2010
    Posts
    432

    Default

    I looked under the dash at the firewall hole. There doesn't appear to be anything close to binding (the rod is nearly centered in the firewall hole) and the rod looks straight. When the motor is off, the pedal springs up as normal. I talked to DSE this morning. They think that my motor isn't making enough vacuum (I think it is and will verify again with Texas Speed and will put my vacuum gauge on it) or the brand new booster is bad! Not sure how low booster vacuum would still give me a softer pedal with the motor running.
    Joe
    1969 Firebird Project
    1967 Frirebird 400 convertible
    2013 Boss 302

  5. #5
    Join Date
    Aug 2010
    Posts
    432

    Default

    17" of vacuum at idle.....looks like I have to replace the booster. ...Joy.

    Joe
    1969 Firebird Project
    1967 Frirebird 400 convertible
    2013 Boss 302

  6. #6
    Join Date
    Aug 2010
    Posts
    432

    Default

    There has been a development. I ordered a new booster-master from Summit last night. It always bothered me that the clevis pin that goes through the booster rod-brake pedal took so much convincing to get through the holes. I figured I was gonna have to pull the Sparco front seat anyway when I chenged boosters over...its only 4 nuts anyway...so I took the seat out and laid on the floor to get another look at the pin.....super tight. I had to use a punch and hammer to get it pushed out. I installed a Wilwood pin that I had that is much smaller...went in by hand. I started the car up and booom...pedal springs back up! The Wilwood pin was a little too small and produced a fair amount of slop in the pedal, so I turned down the center of the DSE pin to remove the bind at the pedal hole. I will be taking the car out for a spin to confirm, but I think I may have solved the problem!
    Joe
    1969 Firebird Project
    1967 Frirebird 400 convertible
    2013 Boss 302



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