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hydroboost M/C onto a vacuum booster?

Discussion in 'Brakes' started by fast68chevy, Nov 30, 2020.

  1. fast68chevy

    fast68chevy I am the original fast68chevy

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    Joined:
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    Location:
    LINCOLN IL
    First Name:
    RANDY
    Truck Year:
    1975
    Truck Model:
    C20
    Engine Size:
    350
    i have a m/c from a 1977 1 ton with hydroboost system, how can i know ifd iit will or can fit on a 1975 C20 vacuum power brake booster annd is correct booster output push rod length etc..? here are two pics of the hydroboost m/c i have..
    and then i have a pic of the factory delco moraine power vacuum booster 1975 C20 with the larger heavy duty JB7 13" type of rear brakes system. the m/c is from a 14K GVWR truck, which is really basically more of a 1-1/2 ton truck, in all reality, based on it being that a typical normal basic 1 ton is around 10k GVWR. the diameter of the casting where the m/c sticks into the booster bore is about 1 and 6/10 of an inch(1.6") in which is just over 1 and 1/2 inches.
    and the piston end is not set into the casting very far at all, at rest, piston all way out against the retainer/snap ring.
    the power vacuum m/c dimensions i have no idea. cant measure with it on the truck - but i do have a couple pics of the delco moraine vacuum booster m/c while i had it off the truck earlier this year posted in this thread/posting also..
    and the piston/mounting end of it sure does look pretty much identical same to me as this 1977 hydrobooster m/c hmm.......

    althoguh it looks like the hydrobooster style m/c push rod hole in the end of the m/c piston is really deep-set into the end of the piston, whereas the delco-moraine vacuum booster pushrod hole is really not set-in deep like this.. hmm... so i dont now??

    maybe i should, and then i could have my answer myself i suppose. i know that manual brakes m/c are definitely not same as power ones.. but what about vacuum booster ones vs. hydrboost ones?? ive just never really known exactly, for sure.. all these past decades now, hmm..

    who knows what, here, about this, and for sure?

    ifg the push rod in the boosters are different, in which it appears tjey are,,, then i probly will just rmeove vacuum booster and just manual brake this truck, which i would prefer to have anyways... i haqve a couple or few differenut stock manual brake pedal push rods around here, one of them should be right length or i can make modify one to work, if i have to.. not a big deal really.. in which case i will have good stock C20 delco moraine vacuum power booster for trade or sale. i am looking for a stock 56" rear main leaf sapriiig and also top two or so springs also, so i can replace the cracked in half ones on my LH side leaf pack finally... oor trade for manual trans clutch link parts pieces mechanical style before 1985... including frame pivot bracket on frame rail and front half oof rear driveline for 2wd 4 speed trucks, and a clutch pedal and link part pieces, so i can swap from this TH350 to a 465 trans.. in the '75 C20 daily driver, because i really just hate auto trannies and I really badly miss having/driving a 4 speed truck, and need one anyways.. because i work the truck, not just drive it... finallly after over 2 years of searching trying to find manual trans clutch link parts pieces to do this swap conversion, finaly.. hmm.. impossible... this is the one only thing i really dont like about this truck, is that its a damn crappy auto trans truck.... hmm...



    thx 1977-mc-hydroboost2.jpg Pic-03142020-003.jpg Pic-03142020-004.jpg IMG_20180516_104749766.jpg 1977-mc-hydroboost3.jpg 1977-mc-hydroboost2.jpg Pic-03142020-003.jpg Pic-03142020-004.jpg IMG_20180516_104749766.jpg
     
    Last edited: Nov 30, 2020
  2. Tank6x2

    Tank6x2 Supporting Member Supporting Member

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    Location:
    Edmonton Alberta Canada
    First Name:
    Kurt
    Truck Year:
    79/86
    Truck Model:
    C30
    Engine Size:
    350, TH400.4:10 gears 2WD
    I am looking at doing this with mine as well, did you figure out sir?
     
  3. bucket

    bucket Super Moderator Staff Member

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    Truck Year:
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    Truck Model:
    K5 thru K30
    Engine Size:
    350-454
    Aa far as I know, it's not easily adaptable. It makes a lot more sense to just use a master cylinder with the correct bore step and pushrod style.
     
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