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73 Blazer Brake Prob..(Continued)

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by TallCowGirl, Nov 1, 2000.

  1. TallCowGirl

    TallCowGirl Registered Member

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    Hi Folks...Yes, I did bleed BOTH the master cylinder and the brake lines. I did the m/c before I installed it. I bled the right rear, left rear, right front, then left front in that order. I can't find any leaks or see any fluid loss in the master cylinder and the brakes are still spongy. One of you suggested that it might be the rubber brake lines on the front expanding (it has a 4" suspension lift and I don't know how old the hoses are), so I'll try replacing that next. Any other suggestions? The pedal is still soft after replacing the front calipers, pads, rotors, brake shoes, wheel cylinders, master cylinder, and bleeding the lines.

    Thanks,
    Diana
     
  2. Goose

    Goose 1/2 ton status

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    I had a '77 a while back that I never could get the brakes bled good. So when I replaced my m/c on my '73 a couple years back I got a new (not reman. w/lifetime warr.) from Midas and had them install it. It took at least two (maybe 3) of their shop guys 1.5 to 2 hrs to get the brakes bled out right. They couldn't believe what a pain it was. Anyway, have you tried depressing the release valve on the combination valve?? It will be on one end of it underneath a little black plunger. There is a special tool to hold it in when bleeding brakes, or you can get someone to hold it in while you pump the brakes and a third works the bleeder valves. I would also suspect the brake line to a degree. I just got ProComp's steel braided brake lines for my '73. From what I can tell, the originals have gone bad and caused the lf front caliper to hang up. The new lines are also made for a 4" lift. Cost $98 including shipping from Summit. Includes both front lines, rear line, and all washers, clamps. Re-use old clamp bolts, etc.

    Cruisin in my '73.
     
  3. Gold Rush

    Gold Rush 1/2 ton status

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  4. backlash

    backlash 1/2 ton status

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    As Gold Rush said,

    When I replaced the rear shoes it took care of the problem. Do you have a strong emergency brake application? If not make sure your rear self adjusters are working correctly and are adjusted right. Try doing the backup brake routine also.
     
  5. Toad

    Toad 1/2 ton status

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    I just lifted my beast and was trying to put on the new ProComp stainless steal brake lines when snap! I guess I wasn't holding the nut on the inside of the frame properly and ended up twisting the brakeline tubing that runs on the inside of the frame in two. Crap!!!

    This morning I'm just going to take it to a brake shop and have them replace that line and then intall the three stainless lines. It is easier for them to bleed the brakes anyway and I can work instead of wasting hours at home.

    By the way, if you have a local 4WheelParts Warehouse in your town, you can get the brake lines for $89.
     
  6. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Well if your doing the old pump and hold method give it up. Go hit the parts store and they should have a vacume kit that has a hand pump and a resivior. Thats how I have been bleeding mine and never had a problem. Even have gotten away with not pressing the button on the proportion valve. You will need to wrap some Teflon tape around the bleed screws. You will see some very fine bubbles even with that as it pulls air around the screw, Thats normal.
    Also you can damage a Master cylinder by bottoming it out. NEVER push hard when it hits bottom when bleeding. Really try to stop before it bottoms.

    Diging it in the dirt with my K5's
    Grim-Reaper
    http://grimsk5s.coloradok5.com/
     
  7. Wheels

    Wheels 1/2 ton status

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    I would look at the hoses seriously. And if you have to replace them go to the stainless braided type. Also, if you can, look at the condition of the metal brake lines. The chemicals that make up brake fluid is known to be hygroscopic. This means that it readily takes up and retains moisture. This moisture in the brake system causes many things and one of them is rust. The wear and tear of the rubber components, small metal particles, rust particles can cause the metal brake lines to act as restrictors. Air will trap in high spots in the brake system while fluid will go to the low spots. When pumping the brakes, the air will move back and forth and when you release, it will migrate quickly back to the high spot. With spongy brakes, air is most likely the culprit, fluid blowing by seals is the other. The difference between air and fluid is that you can compress air (which is why it seems spongy) but you cant compress liquid (fluid). I discovered this process many years ago with a 1st gen Bronco. I blew a steel line that rusted from the inside out in the middle of no where. While I was rebuilding my 79, I pulled all the steel brake lines and cut a few open and found some serious rust forming in them. One way I found to get all the air out of the system was to use a Mighty Vac vacuum pump. I had a friend keep the master cylinder full, pinned the pro valve and start pumping. This kept a steady stream of fluid coming down the line. I saw a lot of air come through even after I had the system bled (I was still having a spongy brake). Brakes are firm and solid now. Also, on the rear brakes, adjust the shoes all the way to the drum prior to starting. If you can't adjust them, take the drums off and with a small block of wood on each side to protect the pads, use a speed clamp to keep them from flexing during the bleeding. Readjust them after you are done. Start bleeding them from the fartherest cylinder (ie, left rear, right rear, right front, left front). Anyway, that's my .05, sorry this is long but good luck.
     
  8. mlaux

    mlaux 1/2 ton status Premium Member

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    I went through this one myself. Never did get the brakes back on the truck. It haunted me for years, until someone else had the same problem. When you replaced the calipers you might have put them on the wrong sides. Make sure that the bleed screw is on the top side of the caliper where the air is.
     
  9. TallCowGirl

    TallCowGirl Registered Member

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    Hi Folks...In case you ever read this old post, I did find out what was wrong with my front brakes. They were on upside down! Whoever had the truck before me decided on not buying extended length brake hoses. When they did the 4" lift they just swapped the brake calipers and put them on upside down. Air was strapped inside like air in a water trap. I took the truck to a shop and felt really silly when I found out what was wrong.

    Diana
     

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