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Car guys, brake ??

Big Al1Big Al1 Senior MemberPosts: 8,063 Senior Member
Grand youngin' was given a '93 Bronco (POC) but the brakes are in question. The pedal goes to the floor before they engage, and you can hear air leaking from the pedal area. I'm thinking brake booster/master cyl. Tried bleeding the brakes but no go.

Replies

  • zorbazorba Senior Member Posts: 24,190 Senior Member
    Flintstone it!

    Sounds like you're on the right track to me.
    -Zorba, "The Veiled Male"

    "If you get it and didn't work for it, someone else worked for it and didn't get it..."
  • HAWKENHAWKEN Senior Member Posts: 1,720 Senior Member
    Sound like it could be a vacuum leak at the booster........robin
    I don't often talk to people that voted for Obama, but when I do I order large fries!
    Life member of the American Legion, the VFW, the NRA and the Masonic Lodge, retired LEO
  • Big Al1Big Al1 Senior Member Posts: 8,063 Senior Member
    HAWKEN wrote: »
    Sound like it could be a vacuum leak at the booster........robin

    That would work, he wears 13's!!
  • Big Al1Big Al1 Senior Member Posts: 8,063 Senior Member
    zorba wrote: »
    Flintstone it!

    That should work, he wears 13's!!
  • roadkingroadking Senior Member Posts: 3,056 Senior Member
    My 99 F-150 is the opposite...hard pedal. but brakes don't engage for about 1 or 2 seconds...first time was an eye opener!

    Vac line, most likely on the Bronc.

    Matt
    Support your local Scouts!
  • TeachTeach Senior Member Posts: 18,428 Senior Member
    Boosters are NOT supposed to have an audible airflow. The booster diaphragm has a leak. Pedal going to the floor means he's only stopping on two wheels. Find a safe area like a big parking lot with few or no cars, accelerate, and then nail the brakes HARD. I'll bet only two wheels slide.

    He probably needs a complete brake overhaul. Replace the booster and master cylinder (rebuilt ones come together) and inspect all the brake lines for leaks, and the wheel cylinders and calipers for free movement, leaks, etc. Don't forget to check out the flex lines front and rear.

    People who bet their lives on cheap brake work would probably draw to an inside straight! The very best brake repair is just barely good enough!
    Jerry
  • Big Al1Big Al1 Senior Member Posts: 8,063 Senior Member
    Thanks all!! Now I know where to start.
  • DoctorWhoDoctorWho Senior Member Posts: 9,496 Senior Member
    I have seen mechanics using a brake lathe that have no idea what run out is or how to check it, and those folks do not check for minimum rotor thickness or drums, a poor mechanic does a poor marginal cheap brake job.
    "There is some evil in all of us, Doctor, even you, the Valeyard is an amalgamation of the darker sides of your nature, somewhere between your twelfth and final incarnation, and I may say, you do not improve with age. Founding member of the G&A forum since 1996
  • earlyearly Senior Member Posts: 4,950 Senior Member
    I had the rotors turned on My pick up. Should have replaced them. Thing vibrates well braking under heavy load. Very irritating. Live and learn.
    My thoughts are generally clear. My typing, not so much.
  • TeachTeach Senior Member Posts: 18,428 Senior Member
    The rotor turning isn't the problem- - - -I'll bet the shop reinstalled the wheels with an impact wrench and warped the rotors after they were machined. A panic stop and a deep puddle can warp a rotor from thermal shock, also.
    Jerry
  • earlyearly Senior Member Posts: 4,950 Senior Member
    Either one is possible I'm sure.
    My thoughts are generally clear. My typing, not so much.
  • DoctorWhoDoctorWho Senior Member Posts: 9,496 Senior Member
    Add to that the inferior quality of many relatively inexpensive aftermarket rotors, OE while more expensive, works much better.
    "There is some evil in all of us, Doctor, even you, the Valeyard is an amalgamation of the darker sides of your nature, somewhere between your twelfth and final incarnation, and I may say, you do not improve with age. Founding member of the G&A forum since 1996
  • coolgunguycoolgunguy Senior Member Posts: 6,624 Senior Member
    DoctorWho wrote: »
    Add to that the inferior quality of many relatively inexpensive aftermarket rotors, OE while more expensive, works much better.

    I can't comment regarding the metallurgy of cheaper rotors, but I can confirm they are usually MUCH thinner than OE replacements, one brand I can't recall being only about. 012" over the 'minimum' spec for a vehicle being worked on.
    "Bipartisan" usually means that a bigger than normal deception is happening.
    George Carlin
  • breamfisherbreamfisher Senior Member Posts: 13,561 Senior Member
    coolgunguy wrote: »
    I can't comment regarding the metallurgy of cheaper rotors, but I can confirm they are usually MUCH thinner than OE replacements, one brand I can't recall being only about. 012" over the 'minimum' spec for a vehicle being worked on.
    I think that's termed "designed obsolescence." Make it fail/wear out early so you have to buy more.
    Overkill is underrated.
  • coolgunguycoolgunguy Senior Member Posts: 6,624 Senior Member
    I think that's termed "designed obsolescence." Make it fail/wear out early so you have to buy more.

    I call it "getting exactly what you paid for". Frankly, I use the cheaper rotors on my stuff, but then I also don't consider machining the rotors when they warp...I just put new ones on. Things are simpler that way. YMMV.
    "Bipartisan" usually means that a bigger than normal deception is happening.
    George Carlin
  • DoctorWhoDoctorWho Senior Member Posts: 9,496 Senior Member
    When they warp badly, no amount of machining can correct it because you go too thin, run out may exceed any possibility of rectification.
    "There is some evil in all of us, Doctor, even you, the Valeyard is an amalgamation of the darker sides of your nature, somewhere between your twelfth and final incarnation, and I may say, you do not improve with age. Founding member of the G&A forum since 1996
  • coolgunguycoolgunguy Senior Member Posts: 6,624 Senior Member
    DoctorWho wrote: »
    When they warp badly, no amount of machining can correct it because you go too thin, run out may exceed any possibility of rectification.

    No kidding? :wink:

    Seriously though, if a rotor has warped once, making it thinner is only going to make it more susceptible to warping in the future. Less metal = less ability to handle heat. Even a 'slightly' warped rotor is too far gone in my opinion. Again, YMMV.
    "Bipartisan" usually means that a bigger than normal deception is happening.
    George Carlin
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