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Calling all 1-TON First Gen's.....stock brake booster or upgrade?

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Greg72, Sep 11, 2002.

  1. Greg72

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

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    Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    This question is for the 1st Gen guys who have completed a 1-Ton axle swap.....

    I have recently completed this conversion, and didn't have any time before Moab to contemplate the swapping over of the 1-Ton Brake Booster. The brakes seem fine on the street, and if a slam on them I'm sure they will lock up.

    I do notice that the amount of pedal pressure needed to hold the truck at a stoplight is higher than other vehicles I've driven....it often "creeps" forward unless I make a conscious effort to hold the brake pedal down. In Moab, there were some STEEP downhills where I felt like I needed to stand on the brakes with both feet to keep my truck from moving..... /forums/images/icons/shocked.gif

    I'm wondering if this is a result of a 1/2-Ton booster trying to do the job of a 1-Ton...and there simply isn't enough hydraulic pressure to do the job? It's not a good feeling to "wonder" about your brakes....and I'd like know if any other 1st Gen guys have noticed this same thing, and/or have resolved it with the larger booster?

    It seems like a "no brainer" that if the factory designed the larger booster for the larger axles, it should also be used for 1-Ton "swaps" too.... /forums/images/icons/tongue.gif
     
  2. Burt4x4

    Burt4x4 3/4 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    Well Mr. 1Ton I have some input on this, if that's ok? Hey I have a 1Ton rated rear D60 and a beffy D44 so I have no Idea what tonage I am /forums/images/icons/crazy.gif /forums/images/icons/tongue.gif
    Anyway, the bosters come in two styles that I know of. Single diaphram and double. My father-in-law did the swap to the double on his 72stepside and that thing had some serious brakeing power, very cool!
    Someday I will goto the double.
    I would totaly do the swap if I were you. Heck even my whimpy lil 1/2-3/4ton K5 has troubles or could use more help breaking!
    Just DoIT!
    heheheh
    Later Bro
     
  3. BigMac

    BigMac 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    Have you presure bleed your brakes?

    my brakes are feeling spongy before the upgrade and I have new master and booster... my presure bleeder needs overhauled before I can try it.. just a thought...
     
  4. Greg72

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

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    Martin,

    The brakes feel strong (no sponginess) just like there's not ENOUGH of it!!

    That's what has been driving my thinking about a setup that can move MORE fluid into the larger calipers. Oh, and I have rear disks on the 14BFF which I know is yet another variable, but it should offer even better stopping power once I get it all figured out.

    If you can't tell, I'm looking for "cheap" stuff to play around with on my Blazer now that the paychecks have stopped again.... /forums/images/icons/frown.gif
     
  5. BigMac

    BigMac 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    maybe a junk yard 4 wheel disk master cylinder setup...
    I was eyeballing a newer chevy delivery truck that pulled up to work here. It had rear disks stock. It's had me thinking ever since about the bore diamiter of my current master cylinder. I know that in motorcycles we increase the bore diamiter of the master cylinder to give a more positive feel to the brakes.. it seems the same would apply here. I hope you get it worked out! Im going to have the same problems...

    what did you do for an e brake?
     
  6. Greg72

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

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    e-brake is on the rear driveshaft, but the caliper for it is sitting on my workbench.....

    One of the "TO-DO" list items that didn't get done in time for Moab.

    /forums/images/icons/grin.gif
     
  7. 70~K5

    70~K5 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    OK Greg you're back and you have plenty of time now, so I want to see the E brake mounted by the party next week. /forums/images/icons/grin.gif
     
  8. smp

    smp 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    I've been running 1 ton for awhile with the stock booster and stock prop. valve with disk brakes in the rear with no problems for almost a year now.
     
  9. 69K5

    69K5 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    greg

    i dont have the one ton yuou know but i am going to swap in a one ton on mine two. red aights are hard as hell to hold it still. someone i forgot who did it and saisd they had no probs. just my 2 cents

    nathan
     
  10. harry

    harry 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    I have not driven mine yet (still being put together), but I decided to go to the 3/4 ton booster. My 69 balazer (D60, 14 FF, doubler, bla bla bla) now weights more than my freinds 70 K20. I decided to use the 3/4 ton on that reason alone.
     
  11. roostr3269

    roostr3269 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    Hey Greg, I also have the 1 ton setup but stayed with the half ton brake system. I have to stand on the brakes like u in order for it to stay put. I havent had it where I have been on a steep incline yet, but I am sure i wouldnt like it too much. Let us know what u decide cuz.... I'm in the same boat.
     
  12. 72THING

    72THING 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    Greg, I did the rear disc conversion and one ton MC and booster a while back and it makes a tremendous difference. My stock booster was a single diaphragm type and I swapped in a dual diaphragm booster and the difference was night and day. Now I can actually press the pedal down. Before I couldn't hardly move the pedal down. Go to the parts store and get a booster for a '72 C20 or K20 or C30. I had them compare PN and they're all the same. Plus they'll bolt right in with no modifications. Hope this helps.

    Will
     
  13. BigMac

    BigMac 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    is there a differance between the master cylinders on 1/2 and 3/4 tons? would it be worth while to replace both the master and booster?

    I whish I had known the differance in the boosters when I replaced mine a year or so ago...
     
  14. harry

    harry 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    there is a difference on the master. I got a master and booster for a '71 K20 like 72THING did. The master cylinder part # is 1534 for A1-Cardone and 39075 for Reybestos. The Booster part # is 5471007 for A1-Cardone and I do not have the Reybestos #.

    If converting from 1/2 ton you will need to get new master to prop valve lines (inline tube). In 3/4 tons the front reservoir is for the rear brakes.
     
  15. 69K5

    69K5 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    greg

    one more tip i forgot. be careful on the doublefoot breaking. yesterday i was pumping up my breaks like i always do and my pushrod on the pedal snapped in 2. luckily i was in the parking lot at school and not trying to stop. i am assuming this is from how hard i have to press to stop and stay stopped. on an incline its nearly impossible.

    good luck

    nathan
     
  16. Triaged

    Triaged 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    If you want less peddle effort you want a smaller master cylinder bore. If you do want to swap that out measure the bore of the 3/4 ton MC to see if it is larger or smaller.

    The double diaphram sounds cool. Wish I knew about it when I swapped my booster. Your other option is Hydro-Boost off of a newer desiel.
     
  17. 69K5

    69K5 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    triaged

    how do I find out about a hydro boost system and how to install one? How new of a diesel would it have to be?

    thanks

    nathan
     
  18. 72THING

    72THING 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    I've heard about getting a smaller bore MC for less pedal effort. I'm not sure if the 3/4 ton MC has a smaller bore or not, but I figured if I got the 3/4 ton booster then I might as well get the 3/4 ton MC. I thought about a hydraboost setup, but I wasn't sure if it would be a bolt-on affair due to the brackets on the firewall being different from those on later models. Has anybody else installed hydraboost on a 1st gen?

    Will
     
  19. Triaged

    Triaged 1/2 ton status

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    Re: Calling all 1-TON First Gen\'s.....stock brake booster or upgrade?

    I think your best bet would be to search on the 73-91 forum for hydro boost info. I have seen a few systems but haven't seen what it would take to go into a 1st gen.
     

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