spoungy brakes

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by newschool72, Feb 2, 2012.

  1. newschool72

    newschool72 Veteran Member

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    Guys, i have an issue with my brakes that i thought maybe someone on here could help me figure out. I bought a full system from ABS in california that consists of 13" drilled and slotted rotors on all four corners, aluminum 4 piston calipers on all four corners, braided steel flex hoses from the original hard lines to the calipers. In the back i mounted a tee to the body (above the driveshaft tunnel, in front of the gas tank) then ran 1/8" hardline to the braided flex hose at the back calipers. Its a power brake set up with an 8" booster.
    My problem is a very soft peddle. The kind that takes your breath away when you first start to hit the brakes, thinking you have none. it stops really good after you get down to the bottom of the travel, but i probably only have 2" of peddle left before it bottoms out. Ive run at least a gallon of brake fluid through it, so i am confident there is no air in the lines.
    I had my son push the brakes hard and then i pulled the lid off the master cylinder, then had him let off the brakes. there was NO rush of fluid back into the master, so i think its big enough bore size for my set-up.
    WHAT GIVES????? PLEASE HELP!!!!
     
  2. purpleflame

    purpleflame Veteran Member

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    bad or no vacuum to the booster or master may be on its way out,what master do you run and is all of this new or just rotors and calipers and lines? Im actually in the process of rebuilding mine so would like to follow this and see to make sure i don't end up with a soft pedal as well.
     
  3. newschool72

    newschool72 Veteran Member

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    Brand new stuff all the way through. the only thing left originally on the car are the hardlines.
    Wouldnt the peddle be hard if the vacuum was low?
     
  4. kboxx

    kboxx Veteran Member

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    I don't know if this applies to your brake kit, but I had a similar situation with a rear brake kit. There were two bleed screws on the SSBC kit I purchased. One on the caliper and one higher up on the banjo fitting that went into the caliper. I kept bleeding the lower one on the caliper not the higher fitting. There was lots of air hiding at the higher fitting. Hope this helps.
     
    Last edited: Feb 2, 2012
  5. newschool72

    newschool72 Veteran Member

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    Thats a great point. i had a similiar situation on these brake in that i had the front calipers on the wrong side, with the bleeders facing down. I fixed that problem and it helped some ie. i dont have to pump the brakes anymore, but still have the soft pedal problem.
     
  6. FlaJunkie

    FlaJunkie Veteran Member Lifetime Gold Member

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    The operation sounds normal to me...did I miss something?
     
  7. newschool72

    newschool72 Veteran Member

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    Its not normal on any other car ive owned or built. I have 3" of dead peddle at the top and the brakes dont even start to work till the peddle is 1 1/2" off the floor. Not alot of room for fade!
     
  8. FlaJunkie

    FlaJunkie Veteran Member Lifetime Gold Member

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    OK, this seems like the push rod is too short or in the wrong hole. Some pedals have multiple holes.

    Possibly the master cylinder is wrong for the car.
     
  9. newschool72

    newschool72 Veteran Member

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    I have the pushrod in the lower hole, which is the right one for power brakes. I also had my son help me with the old master cylinder trick. I had him mash the brakes hard and hold them till i took the lid off the master. when he released the brakes, there was no big rush of fluid back into the master, so the master should be big enough for the brake system.
    I wonder if the 1/8" lines in the back are too small to move the volume of fluid it takes to clamp those big calipers in the back?
     
  10. purpleflame

    purpleflame Veteran Member

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    I could be off but it sounds like your master is not right, you should have some travel but not that much almost sounds like the rod in the booster doesn't apply till to the master till your close to full travel. Gotta be the master going out or wrong rod length causing the issue, you have too much travel before engagement.
    try this pump the pedal up several times and hold it and see if it starts to fade to the floor if so master is bad or leaking past the seal inside.
     

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