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Anyone here ever have problems with 4 wheel disk conversion?

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by florida4x4, Sep 23, 2002.

  1. florida4x4

    florida4x4 1/2 ton status

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    ... like spongy pedal, slow acting, mushy brakes? Well down here at the Looze Wheel Fabrication Shop(TM) I had that problem too. I made up a set of brackets for the 14FF, installed some eldorado calipers and the fun began! Immediately noticed the brakes were hard and un responsive. I tried swapping in 3/4 ton MC and PB, edlorado MC, bleeding what was probably a total of 3 gallons of brake fulid, cussin, kickin, screamin, replacing prop-valve (what the heck right?) and finally after many months of saying WTF over and over again, I noticed the back brakes dragging (they weren't to start with). So I thought - damn rebuilds, a few deep water crossings and they start seizing. They were leaking fluid too...

    Thanks to a lifetime warranty I replaced the calipers and started the beeding process again. This time I got smart and bought 1 gallon of fluid instead of several pints/quarts... /forums/images/icons/laugh.gif Damn things still seize - /forums/images/icons/confused.gif again. So I start checking pressures on the line - I am thinking the MC piston is not returing far enough and the line pressure isn't being bled off. It looked like the brake pedal linkage had enough free space to moove so I loosened the brake line at the MC. NOPE! there is no pressure on the lines there. So dang what next? Crushed line somewhere? Nope not anywhere I can see.. After a few nights of pondering I open a bleader valve on the caliper and fluid is coming out so fast I almost get a nasty pressure injection of brake fluid. ok, not nearly that fast - but faster than it should be having sat for a couple hours.

    Dang! All it can be is the rubber line going to the axle. I remove it and sure enough it had become a one way valve. So I break out the superlyyft braided brake line I had sitting around waiting for this, the right moment. I had already done the fronts several months ago when I noticed the originals were doubling as limiting straps. Well after some minor problems like the part I got obviously aint for a 72 jimmy and it's too late to return it.. /forums/images/icons/mad.gif I did some creative brazing to the original distribution block. Drilling, tapping, you get the pic. Finally get it installed...

    I grab my son and we goa bout bleeding again. He's 16 and a pro brake bleeder assistant after all this... Wife is too for that matter.. After a quick initial bleeding I'm sooo excited I get in the truck, crank it up, throw it in reverse and hit the brakes. Yes! the pedal has some travel, progressive action, and brakes feel like normal cept I think I have a little air or need to swap out the caddy MC for the 3/4ton MC... I'll get to that later. I am just glad I have nearly normal feeling brake pedal at this time. whew!

    In all this I never considered the condition of the rear brake line. At one point I got so desperate for a cure I even took it to a shop to get them to pressure bleed it but as usual (for me) they do no good/no fix it.

    Note that the truck would stop well it just took some extra effort. I can only guess I was fighting the restriction in the back. It is amazing what the brakes feel like now... more like a passenger car than some tuff old truck. whatever it feels like I call it good.

    Hopefully this will help you guys with the 30+ year old trucks and are having similar brake problems. /forums/images/icons/grin.gif
     
  2. TONYP

    TONYP 1/2 ton status

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    Ok, I have disks in front and drums in back, MS was droping alittle fluid so I thought, what the hell....Lets put a new one on. Get it on and do the deed but like you no stoppie..So, take a look at the PV and say what the hell... lets put a new one of those on too...Do the deed again, but now the peddel goes down about 1/3 of the way and feels like its hitting something, Check it out everythings fine.But it feels like i'm only getting 80% of the breaks. It stops but you have to be the Hulk to lock it up..I'm going to check that one way line...see if I got one of them.....
     
  3. Dieselmh

    Dieselmh 1/2 ton status

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    Those rubber brake lines are a killer. Whenever we work on a GM truck that's older than a few years, it seems like those brake lines have something to do with it. I've seen people spend hundreds of dollars, totally give up, and decide to sell the truck. One guy just wanted up to try and temporarily fix the problem so he could sell the truck. I told him, "No, but I'll permanently fix it for ya." Not only did replacing the rubber lines solve his pulling while braking problem, but he gave me another $100 as a tip. That's one of the first things I recommend to people now.
     

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