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Need Some Brake Help

Discussion in 'The Garage' started by TeK, Sep 9, 2006.

  1. TeK

    TeK 1/2 ton status

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    Ok my truck is a '79 K10 w/ D60s front/rear w/ discs also front/rear. I just put all new stainless lines on them and bled them. My pedal is still spongy(was before I replaced lines) and I have to pump the pedal to get somewhat good brakes. Should I bleed them some more or do I need to change out MC or MC/Booster? Please help, I'm afraid to drive my truck on the street now and want to be able to drive.



    Mike
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    I can give you my experience with spongy brakes...bled for hours, still spongy pedal, but truck would stop. Figured since I had no baseline, that's just the way they would feel.

    Months later, sitting at a light, brake light comes on, pedal drops, truck starts rolling forward. Pumped the pedal a few times, got some pressure, kept driving. While later, does same thing again, drive home, park it, replace MC, problem gone.

    There are other possibilities, I'm sure others will post up with different solutions that worked for the same problem. Not sure how you are SUPPOSED to eliminate particular brake components with them still installed, to narrow down the real cause.
     
  3. TeK

    TeK 1/2 ton status

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    well I know(or at least think) there are different MCs for disc/disc and disc/drum setups. I'm just wondering since the '79 K10 originally came disc/drum if I should try and find a disc/disc MC that will work?
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    There was some luck finding a (P-series??) disk/disk master that fits our trucks, try a search. It will probably take some time to find, but I think that portion of the update was within the last 6-12 months.
     
  5. MattK

    MattK 1/2 ton status

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    there are lots of things it could be. i would make sure you've bled properly, maybe try imprperly, diff orders, elevations, reverse, etc. it's also necesary to keep all the components in good working order(new/reman lol)
     
  6. ntsqd

    ntsqd 1/2 ton status

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    If the m/c had junk down near the end of it's bore then bleeding may have put the piston seals into that junk.

    The only functional difference btwn a m/c intended for disc/disc and one intended for disc/drum is the Residual Pressure Valve behind the sealing cone in the rear brake port. The bore size might change, but within the same bore diameter this is the only functional difference.
     
  7. TeK

    TeK 1/2 ton status

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    well I bled the brakes really well again and then I checked all the fittings and I had one that was loose. I just cleaned up the rear discs and calipers and made sure everything worked cleanly and properly. When I get done eating I'll do the front.
     
  8. dremu

    dremu Officious Thread Derailer Premium Member

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    The P30 master is only for hydroboost booster; vacuum boosters will kill them. Ask me how I know ... and I only say that as I'm pretty sure Ward, the local counterman at my good parts house, doesn't read this (he warrantied two of them out for me :whistling: )

    -- A
     
  9. mudbog42

    mudbog42 1/2 ton status

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    If you figure it let me know.:wink1: I have an 86 K-5 with a new booster, master cylinder, wheel cylinders, pads, and that pedal is still spongy. I can't figure it out:thinking:
     
  10. TeK

    TeK 1/2 ton status

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    well mine works fine now. Its a little spongy and I'm gona add a vacuum resivoir. Should take care of the sponginess. I'll do that when I replace the rear lines.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    Not to convolute this thread, but I did a bit of my own "research" if you will, as I found the thread I was thinking of, where you mention the issues you have.

    Comparing this MC:

    http://coloradok5.com/forums/showpost.php?p=1572027&postcount=40

    to the one on my truck in the pic "airintakeDS.JPG" on this page:

    http://dyeager535.topcities.com/TPI/index.html (sorry no hotlinking nor better stock MC pic I'm aware of)

    It seems to me that piston travel is PROBABLY different, or that the fluid ports are in a different location. Could just be me, but there are certainly some obvious external differences that lead to my conclusion.
     
  12. dremu

    dremu Officious Thread Derailer Premium Member

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    Which issues? I've had lots =))

    The MC in the CK5 thread above is not the P30 master, it's the 'other' disc/disc MC ... forgot about that.

    I'm running hydroboost on the truck with the P30 master now, btw, and other than the occasional burp, which I attribute to the hydroboost, I've had good luck with it.

    -- A
     
  13. TeK

    TeK 1/2 ton status

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    dremu,

    I've been contemplating using hydroboost but I'm afraid when running a carb and then truck gets on an angle the carb doesn't like and dies that my brakes might fade away. I'm not extremely familiar with the hydroboost but I know it works off of power steering pump and thats about it.

    Let me know what all you used to convert to it. Also, let me know if you have any help on finding a MC that would work for me.
     
  14. dremu

    dremu Officious Thread Derailer Premium Member

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    Vacuum booster is your typical big donut thing behind the master, powers itself (duh :) ) from the vacuum source.

    Hydroboost instead uses the hydraulic power from the steering system, much smaller unit, more hoses. You can search, but basically you get the brake pedal, booster unit, power steering pump, and master from a one-ton or diesel truck as donor, and swap.

    If the engine dies, you're gonna lose vacuum just as you'd lose hydraulic, can't fix that.

    -- A
     

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