Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

´73 K5 Brake Problem Help ASAP

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by TallCowGirl, Oct 31, 2000.

  1. TallCowGirl

    TallCowGirl Registered Member

    Joined:
    May 20, 2000
    Posts:
    35
    Likes Received:
    0
    Location:
    New Mexico
    Hi There...I´m having a tough time trying to find out what´s wrong with the brakes on my ´73 K5 Blazer. The pedal is soft as a pillow and I can´t seem to fix the problem after replacing the front brake calipers, pads, master cylinder, rear wheel cylinders, shoes, and drums. I replaced the master cylinder twice, and I can´t find any fluid leaking. I´ve bled the brakes several times. The original problem was that the front calipers were stuck and hadn´t been touched in years. After I replaced the calipers, brake pads, and bled the brakes, the pedal went from sort of soft to like totally spongy. If you pump it enough times it´ll get hard and the brake light will finally go out, but it will get soft again and you can´t stop at anything more than like 10 MPH. The only thing that I haven´t replaced yet is the proportioning valve, but I don´t think that would make the the whole system fail. I need to use my Blazer to move stuff this weekend and I sure could use some help.

    Thanks,
    Diana
     
  2. FWP

    FWP CRS

    Joined:
    Oct 11, 2000
    Posts:
    3,845
    Likes Received:
    3
    Location:
    Prescott Valley, AZ
    Rubber brake lines rotten? Maybe expanding, but not yet blown out? Just a thought.

    <font color=blue>Maverick</font color=blue> <font color=red>CH 4 or 35</font color=red>
     
  3. Toad

    Toad 1/2 ton status

    Joined:
    Mar 15, 2000
    Posts:
    157
    Likes Received:
    0
    Location:
    Utah
    Are you pressing in the proportioning valve when bleeding the brakes? It is located underneath the radiator. You will see all of your brake lines running into it. One side has a rubber cap. Press that in and hold it while bleeding the brakes. It helps to have a friend hold it in.
     
  4. K5Junkie

    K5Junkie 1/2 ton status

    Joined:
    Mar 29, 2000
    Posts:
    499
    Likes Received:
    0
    Location:
    Gulfport, MS
    This my be a dumb question, but did you bench bleed the master cylinder? I believe you have to bench bleed it before installing it.

    http://k5junkie.coloradok5.com/
     
  5. DMK

    DMK 1/2 ton status

    Joined:
    Feb 20, 2000
    Posts:
    757
    Likes Received:
    0
    Location:
    CINCINNATI, OH
    Yes make sure master cyl is bled before bleeding brake lines. This will cause a spongy feel. Also make sure rear shoes are adjusted correctly and self adjusters work right.You can bleed the master cyl on the truck. But you will need 2 people, run two hoses off the fittings on the master cyl back in to the master cyl. Have someone push pedal and hold. Keep doing this until all air bubbles are gone. Rehook lines and bleed brakes. These hoses should have come with the new master cyl. If not should be able to get them were you bought it.
     
  6. Dieselmh

    Dieselmh 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    910
    Likes Received:
    0
    Location:
    Texas
    My 91 pickup did the same thing and it was the rubber hoses up front. They would expand when I pressed the pedal and cause the brakes to work poorly. They're pretty cheap and really easy to replace. It sounds like you've pretty much checked everything else other than making sure the m/c was bled before you put it in.

    Diesel

    If it ain't broke, fix it 'til it is.[​IMG]
     
  7. backlash

    backlash 1/2 ton status

    Joined:
    Oct 21, 2000
    Posts:
    519
    Likes Received:
    0
    Location:
    Northern, VA.
    Over the years I've done a lot of work to the brakes on my truck ... mostly aftermarket stuff. They always were spongy or jumped to the right when hitting hard.

    I have recently given up and replaced the entire system with GM components. Spent too much for the spongy braking capability. The biggest improvement came from rebuilding the calipers and replacing the proportioning valve and hoses up front. The brakes were still spongy and even though I had new 'stuff' on the rear I decided to turn the drums and put on GM shoes. That's what did it this time.

    What am I saying. As you did, I relaced a lot of 'stuff' kind of hit or miss, whether it's you, me ,a brake specialty shop, or a dealer it's sometimes difficult to narrow it down. I would try the advice on bleeding the proporting valve and the hoses ... least money.

    Reguardless ... these sytems were designed to stop with asbestose linning and you cannot get them any more. Look at any of the reviews for the newer Saburbans or Tahoes ... SPONGY BRAKES!

    BRAKE PADS WEAR OUT TOO SOON!

    Good luck! There is much more to this ....................
     

Share This Page