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1970 blazer D60 & 14 bolt swap but how about brake system?

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by jello, Feb 10, 2003.

  1. jello

    jello Registered Member

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    Howdy, I'm needing information on a braking setup. I plan to change out my 1/2 ton gear for 1 ton stuff. Thanks for any help in advance, its appreciated. Here's the question(s):

    What are others doing to support the larger braking systems when they convert?

    This is my situation. I got a good deal on a complete running 1984 1 ton chevy truck (D60 disc, 14bolt drum). I'm planning the axle converstion. I'm unsure about how to proceed with the brake system. The donor truck has hydralic assist or 'hydro boost' brake setup. It looks stout and has been factory 'engineered' to work with the 1 ton brake parts in the wheels. I think I'd like to use this hydro gear but not sure exactly what I'd be getting into - Not sure how difficult or complicated the conversiton would be. The blazer (70) has a power boost drum system so it seems unlikely mounting holes for it and the pedal assemblies would mate up with minor reworking, etc.

    On top of this, I'm also looking at swapping out the auto for the 4 speed tranny. This work would require (I think) that the pedal assembly out of the 84 truck (hydralic clutch (?) be reworked somehow into the 70 balzer. Is this a seperate stand alone project or does it relate or facilitate the possiblity of re-using the hydro brakes in the older blazer?

    The blazer's motor is a 350 the tranny a TH350/NP205. The donor's a 6.2 liter, it has 4 speed SM465/NP205.

    Again, thanks for any info you can supply, I'm all ears - /forums/images/graemlins/ears.gif

    Jeff
     
  2. ntaj*ep

    ntaj*ep 1/2 ton status

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    I have yet to do this swap however I have most of the parts as you do. My plan is to use a brake booster out of a c/k 30 about '70. They use a dual dia. booster. My master I think I will use an aftermarket unit fo the application.
     
  3. LKJR

    LKJR 1/2 ton status

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    if you don't do that swap let me know I might be interested in buying that hydro setup off of you.
     
  4. IGOR

    IGOR 1/2 ton status Premium Member

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    What is the advantage of going to a "dual dia booster?"

    Would it be better to go to a setup like from 73 and up?
     
  5. jello

    jello Registered Member

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    Whats the 'dia' stand for?

    Are the power bosters from 73 on larger (in diameter) than the earlier ones i.e. 1970 or does it have another diaphram and more effective?
     
  6. ntaj*ep

    ntaj*ep 1/2 ton status

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    Diaphram. /forums/images/graemlins/thumb.gif
     
  7. jello

    jello Registered Member

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    Roger that.
     
  8. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Jeff,

    I swapped 1-Ton gear under my '72.... I didn't mess with anything related to the brake booster and everything works great!

    TWO CAVEATS:

    1. I'm using a disk brake conversion in the rear. Not sure if that would make a difference, but it makes my swap slightly different.

    2. Vacuum Hose from booster to manifold - At some point in my trucks life, this hose was replaced with fuel line (NOT correct!) and it collapsed under vacuum pressure. The effect was that my brakes had no "boost" and worked like crap until I discovered this problem.

    I did Moab with the "bad" hose, and it really bummed me out on steep hills...the truck simply would NOT hold itself on the steeps.....Since replacing the hose, I've done some local wheeling and can now hold steady on whatever hills I want!



    My $.02
     
  9. cleszkie

    cleszkie 1/2 ton status

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    Greg72 -

    What is the correct type of hose/tube to run between the manifold and booster? Is there a rubber line specified for vacuum purposes, or should it be a section of metal tubing?
     
  10. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

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    Were did you get the correct hose for the booster? I have looked and everyone keep telling me to use fuel line.
     
  11. ntaj*ep

    ntaj*ep 1/2 ton status

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    It is actually called vacuume booster hose. If you use fuel hose it will as Greg said collapse after a while and presto no boostie /forums/images/graemlins/eek.gif
    I found my hose at the local parts store on one of those big rolls of hose they usually have behind the counter. It says on it for vac. applications only. /forums/images/graemlins/thumb.gif
     
  12. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    What Aaron said!!!

    It's a 15 second experiment.....take off the existing hose and try to blow air through it.....if you CAN'T, you have no vacuum-assist on your brakes!!!!!

    That hose can really make things a LOT better.....trust me! /forums/images/graemlins/thumb.gif
     

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