86 f250 4x4 soft brakes

Discussion in 'General Discussions' started by jake wells, Aug 15, 2013.

  1. jake wells

    jake wells Full Access Member

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    anyone know what would cause the brake peddle to go to floor before it can stop the truck. it stops but it seems weak and the brakes are not spongy the master cylinder is full and there is no leaks.
     
  2. iowaredneck

    iowaredneck Administrator

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    You must have air in the brake lines somewhere

    sent from area 51
     
  3. jake wells

    jake wells Full Access Member

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    either air in the lines of a messed up master cylinder wouldn't suprise me the least. it still stops decently i might have the local ford dealership look at it because i really dont feel like messing with it.
     
  4. Lunchbox213

    Lunchbox213 Junior Member

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    Check the mounting plate that the master cylinder bolts to, they have a seam that will split from the firewall and make you loose brake and clutch pressure.
     
  5. Schooney

    Schooney Junior Member

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    I am having the same problem on my 88 F350. The whole system has been changed an I meen the whole thing. Master cyl. vac. boost, calipers, the lot.
    A mech told me it could be the pads are not sittng in the calipers properly and not pushing them in flush. This is a total rebuild truck and it is the only thing not working.
    Any help would be appreciated
     
  6. Roush PSD Interceptor

    Roush PSD Interceptor 7.3L Straight Piped Diesel

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    The pads being suspect, from maybe from Princess Auto
    have given you the correct part?

    Maybe the surface area where the pads slide
    on the rebuilt calipers have slag from casting
    and a die grinding applied to lightly touch up the surface
    to smooth it out?

    Hi temp caliper grease on the areas where the pads touch
    the caliper to permit free movement,
    doesn't take much.

    If the rubber caliper hoses are still the original ones,
    expansion can occur in the old rubber causing a spongy
    pedal.
     
  7. Schooney

    Schooney Junior Member

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    I just got my problem fixed. I had the master cyl. replaced in Nov. but that did not solve the problem. After changing the vac booster twice due to a faulty new part it just made things worse.
     
  8. Schooney

    Schooney Junior Member

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    As a long shot I took the truck into Fountian Tire and they discovered the new master cyl was faulty. There were no leaks but the fluid was bypassing the seal internally. Frustrating to say the least but finally fixed
     
    Roush PSD Interceptor likes this.
  9. Roush PSD Interceptor

    Roush PSD Interceptor 7.3L Straight Piped Diesel

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    Glad you finally figured it out.
    Never think new part was the problem but it was.

    Sent from my SM-G930P using Tapatalk
     

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