Symptoms of a bad brake booster.

Discussion in 'Fox 5.0 Mustang' started by Mustang5L5, Nov 21, 2009.

  1. Mustang5L5 Founding Member

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    Would you guys replace the booster in this situation.


    Cobra brakes (99+ front calipers). Running an 95 V6 used Booster with a brand new 93 cobra MC.

    I don't drive often, so i can't remember if it's been slowly degrading over time. Basically, i hear a light hiss when i press the pedal and sometimes if i jump on the brakes fast while pushing in the clutch, it stalls the car out.

    Also, i notice at higher RPM's, the brakes are a little harder than at low RPM's. Car still stops nicely, but the pedal is a little inconsistent.

    With the engine off, the pedal pumps up hard as a rock. With my foot on the brake, i start the car and the pedal sinks a bit as it gets vacuum.

    I also notice playing with the 1-way valve on the booster does affect how it feels. It's almost like it leaks slightly. Can i pick this part up separate somewhere?

    So what would you guys do? Should I just order up a new 93 cobra booster over the winter? Brakes are important to me, and i should have just installed a brand new booster from the beginning.
  2. 94gtfreak Active Member

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    Personally I would just get the Cobra booster. Brakes are not an area to slack around in.

    I'm not 100% positive but I think you can get a new one way valve, but idk?:shrug:

    Maybe someone with a lil more intelligence will speak up and help out a lil more?
  3. 87GT Drop Top New Member

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    The hissing sound is the booster going bad. The diaphram has a hole in it. It's going to go out completely without warning. You are going to use the brakes and them BAM no power assist. Hopefully you don't hit anything. I would replace it ASAP.
  4. Mustang5L5 Founding Member

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    Guess i'll order one over the winter. Car's going to sleep til next spring

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