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1971 1/2 ton - Power Brake upgrade probs

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by 2Dogs, Mar 20, 2004.

  1. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Hey All,
    Trying to help my neighbor with what appears to be a problem.

    The truck came with front disks (all stock 2WD, original owner /forums/images/graemlins/thumb.gif). He recently added a power brake booster - a stock item/kit according to him purchased new/rebuilt from a local
    parts store.

    Problems/observation:
    He said he believes that the brakes had more power BEFORE the power upgrade. This morning I drove it and I also think that it does not feel like power brakes. Feels very smooth and firm but not quick and powerful like I would expect.

    Any advice or suggestions? Can anyone give me a part number break down on what SHOULD be there?

    Details:
    New/rebuilt prop valve and booster
    17lbs vacuum thru the check valve
    regular dot3 brake fluid (not synthetic)

    Thanks!
     
  2. clubba68

    clubba68 1/2 ton status

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    There is a post on here about using a 3/4 ton booster. It is supposed to help a lot according to those who have done it. I am going to be doing that swap on mine (which is non-power right now) this week sometime hopefully. I will look and see if I can find the post. If not, I'm sure someone else knows which one I am talking about.
     
  3. R72K5

    R72K5 Banned

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    does booster hold vacuum after engine is turned off ? you should get 2 or three pumps of pedal weith vacuum assist after engine is off

    also you should be getting 18-22 on vacuum, adjust timing a little to get 18-22
     
  4. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Yes it holds vacuum. Most noticeable when disconnecting hoses, less noticeable in affecting pedal actuation.

    Sorry for lack of verbosity - I am drunk'ed /forums/images/graemlins/eek.gif /forums/images/graemlins/peace.gif /forums/images/graemlins/rotfl.gif
     
  5. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Well it sounds like theres your problem, he's running the 1/2 ton power booster. /forums/images/graemlins/rotfl.gif /forums/images/graemlins/ignore.gif /forums/images/graemlins/deal.gif

    http://coloradok5.com/forums/showflat.php/Cat/0/Board/firstgen/Number/872712/page/13/view/collapsed/sb/5/o/o/fpart/all

    /forums/images/graemlins/peace.gif /forums/images/graemlins/waytogo.gif /forums/images/graemlins/woot.gif /forums/images/graemlins/bow.gif /forums/images/graemlins/pimp1.gif /forums/images/graemlins/k5.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/whistling.gif

    Power Brake Booster # 54-71007


    /forums/images/graemlins/grin.gif
     
  6. jasonkh2tg

    jasonkh2tg 1/2 ton status

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    hmmmm you said he added a power brake booster and prop valve, Did he swap out the MC also they are diffrent units....If the MC was swaped out are you sure you bled the brake correctly...
     
  7. clubba68

    clubba68 1/2 ton status

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    Thank you Ryan. That is the one that I was talking about. /forums/images/graemlins/thumb.gif
     
  8. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Thanks Guys! I'll pass the info over the fence /forums/images/graemlins/grin.gif
     

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