Hard Brake Pedal

Discussion in '1965 - 1973 Classic Mustangs -General/Talk-' started by craig gaines, Jun 23, 2014.


  1. craig gaines

    craig gaines Founding Member

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    I recently installed the CSRP power brake kit and everything seemed fine except when I hit the brakes it goes down a couple inches and stops dead. The car stops but won't lock up. It just stops like the mc bottoms out, but when I unscrew a bleeder screw it goes all the way down. The vacuum line is hooked to the back of the carb and I'm running an Edelbrock RPM cam so not sure if that's hurting the booster performance. I have about 10 inches of vacuum at idle. Any ideas?
  2. 84Ttop

    84Ttop They make new pistons every day, so why worry? SN Certified Technician Mod Dude

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    10" of vacuum should do the trick. When you were bleeding the system were you sure to remove all of the air from the master cylinder by bench bleeding first? I have seen more goofy brake pedals as a result of air in the master cylinder than anything else. Also, did you clean the rotors before installation with brake parts cleaner? Was there a break in procedure for the pads that you used?
    I'm just thinking out loud here...
  3. horse sence

    horse sence Please don't call me Mom SN Certified Technician

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    A friend of mine just went through the same thing on his 66 convert .
    Bled the brakes several times and nothing ,took the calipers off and put a block of wood in them and bled them again and still nothing .The pedal was hard but the brakes would not stop the car . i drove it and standing as hard as you could on the brakes the best it would do was slow down. He changed the booster to a different company and they now work perfectly .
  4. craig gaines

    craig gaines Founding Member

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    That's the exact same problem I have. The brakes go down and then just stop about two inches down and the car slowly stops. The brakes feel the same whether the car is running or not. And I bench bled the mc and bled brakes until I'm blue in the face. No change at all.
  5. horse sence

    horse sence Please don't call me Mom SN Certified Technician

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    Those new boosters are not good ,he went through two of them with the same problem .
  6. craig gaines

    craig gaines Founding Member

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    Got an email today from CSRP. Turns out I have to have 15 inches of vacuum. All I have to do is buy a 150 to 200 dollar vacuum pump! Or switch my cam. Or go manual. Wish the paperwork would have mentioned that before I blew a couple hundred extra bucks. Live and learn I guess.

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