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Which power brake booster do you have? *pic*

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Ryan B., Oct 12, 2003.

  1. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Which power brake booster do you have on your first gen and how would you rate your braking performance?
    [​IMG]
    The one i have been running for years on the left, and the "3/4 ton" booster on the right, i replaced it with.
    [​IMG]

    Here's something amazing I found out this weekend... My brakes have always sucked, I seemed to have to stand on the brake pedal to get the truck to stop or not roll. Steep offroad situations could be scary. My truck was this way when i bought it, I replaced everything. calipers, master cylinder, power booster.. was the same so i learned to live with it.
    This last week my vaccum brake booster went out on me... all of a sudden the brake pedal was really hard to stop the truck, had to stand on it. My engine idle was higher and rougher than normal and when i'd step on the brake pedal the idle would raise and then come back down. that would be the vaccum leak. /forums/images/graemlins/crazy.gif
    So i went to buy a new power brake booster, instead of buying one for my "1972 K5 Blazer" I ordered one for my "1972 3/4 Ton 4x4 pickup".
    The brake booster that came in my blazer when i bought it was the same style as the one on the left in my picture... It went bad and i replaced it with the same thing a few years ago... This weekend i put on the 3/4 ton vaccuum booster and it is like Night and Day difference with the braking in my truck. /forums/images/graemlins/eek.gif Seems to stop on a dime now. I don't have to stand on the pedal to stop now, just step on the pedal- The way it should be!
    I used to get in my dads '77 4x4 chevy and wish my '72 k5's brakes were like his... well now they are.. he has a big vaccum booster on his stock. /forums/images/graemlins/grin.gif
    This is the biggest performance difference i have seen from any single part i have put on my truck in the last 5 years... I wish i did this sooner.
    I can't describe how happy i am with the brakes now on my daily driver. /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif

    I've heard of some other guys on this board with crappy brakes just like i have described... I always wished someone would post something that fixed their s#!++y brakes problem.. so here is what fixed mine. /forums/images/graemlins/thumb.gif

    Power Brake Booster # 54-71007


    /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif /forums/images/graemlins/pimp1.gif /forums/images/graemlins/ears.gif
     
  2. NITRO

    NITRO 1/2 ton status

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    you are awesome....my brakes have always sucked...and i suspected the booster...but never took the time to change....looks like i know what im doin this weekend...thanx man

    NITRO
     
  3. clubba68

    clubba68 1/2 ton status

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    Thank you, I am getting ready to do something about the deathbrakes on my K5, and this is very useful information.
    -Andrew /forums/images/graemlins/usaflag.gif
    I also have 4 wheel drum non-power. I am in the process of swapping axles and swapping to 4 wheel power disc. Should make a noticable difference I hope. /forums/images/graemlins/grin.gif
     
  4. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Right on! /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif Post up and lets hear if this fixes the problem with first gen "deathbrakes" /forums/images/graemlins/rotfl.gif /forums/images/graemlins/pimp1.gif

    I am in love with my Blazer all over again now... A major difference, it'll be enjoyable driving my k5 everyday now- the brakes have never been this good. /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif
     
  5. 72 SAC

    72 SAC Registered Member

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    You are a god! It's the little things like this that I love about CK5. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  6. BobK

    BobK 1/2 ton status

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    Ryan
    My quest for some half decent brakes has led me to change everything you have.I even went to rear disk brakes with little improvement.

    I have a Hydro-boost sittin in my basement waiting to be installed.
    I might try the 3/4 ton booster 1st.
    Thanks /forums/images/graemlins/thumb.gif
     
  7. Greg72

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

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    Ryan, you're pretty smart for a 21 year old!! /forums/images/graemlins/thumb.gif

    (HAPPY BIRTHDAY DUDE)



    Remember my collapsed vaccum booster line from last year? I got a chance to run the same trails in Moab that I ran last year and can safely say that having a correct vaccuum hose (not gas line pretending to be vacuum hose) DOES make a difference.....BUT, there is still room for improvement. On the really steep hills, I still didn't have the braking power to hold the truck from creeping downhill..... not as fast and scary as last year, but when you step on the brakes I'd expect the truck to NOT move anymore!!

    Anyway, maybe it's time to swap in the larger booster.



    Any other problems with compatibility? I'd read something about a change to the rod length, or some other little detail like that which can screw up the conversion. I'll have to check my CK5 printouts again..... /forums/images/graemlins/wink.gif
     
  8. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Thanks Greg. /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif /forums/images/graemlins/pimp1.gif
    Everything bolts up the same, that's why i ordered a '72 3/4 ton power booster- because i figured it would bolt exactly the same to my 72 K5.
    The rod length does not change, just the larger brake booster is bigger so the master cylinder sticks out further in the engine compartment now.
    Really, its less than a 10 minute job to swap these boosters. 6- 9/16" nuts and the clip for the rod.
    /forums/images/graemlins/k5.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/pimp1.gif

    I can't wait to go try out my brakes offroad again now and see the difference. /forums/images/graemlins/thumb.gif
     
  9. jasonkh2tg

    jasonkh2tg 1/2 ton status

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    Yea I did that mod to my truck a while ago...I know you guys will say YOU SUCK for not letting the secret out but ryan is right...also the master cylinder from a ck5 3/4 ton is the same tell 77, but the booster is the same only for 71-72.....Yea the 3/4 ton cylinder is 1 1/16 or it might be 1 1/4...the point is know that ryan is not the only one that can confirm this...in the pic you can see the 3/4 ton booster and cylinder....ALSO don't forget when intalling the larger cylinder the brake output on the front goes to the rear and the back goes to the disc's in the front....I installed TSM disc in the rear and it will stop on a dime...
    [​IMG] [​IMG]
     
  10. bouncytruck

    bouncytruck 1/2 ton status

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    Wow, good news. I wonder if it is the same for my rig. The PO did the front disk swap, so I'm not really sure what I have. I know the proportioning valve isn't in the stock position, instead it is sitting down below the radiator.
     
  11. BobK

    BobK 1/2 ton status

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    Jason, you swapped in a 3/4ton M/C as well?

    Ryan just swapped out the booster,not the M/C.
     
  12. jasonkh2tg

    jasonkh2tg 1/2 ton status

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    Yes I have a 3/4 ton m/c as well...the 3/4 ton is plumbed diffrent the front of the MC goes to the rear brakes and the rear of the MC goes to the front disc's...

    [​IMG]
     
  13. Triaged

    Triaged 1/2 ton status

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    But isn't the 3/4 ton MC the same size bore as the 1/2-ton?

    I was under the impression that they were all 1.125"

    If anything they sometimes bump UP the size of the MC on the larger trucks (hydroboost has a 1.250" bore which would make it real hard to push the peddle if it wasn't for all the assist) which would be the opposit of what you would want.

    I don't see it being worth the hassle changing the lines around for the same size bore...I wonder why they swapped the lines front to rear?
     
  14. blaz72

    blaz72 Registered Member

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    I have also tried it and it works great /forums/images/graemlins/cool.gif /forums/images/graemlins/usaflag.gif
     
  15. Don

    Don 1/2 ton status

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    I have the big one, the one on the right in pic.
    Work's very well! /forums/images/graemlins/grin.gif
     
  16. TONYP

    TONYP 1/2 ton status

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    I'm in the same club as you guys...whats the cost of that thing?
    I'm going wheeling this weekend or I would of changed it over tomorrow... /forums/images/graemlins/thumb.gif
     
  17. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    ~$120 and $25 core charge.
     
  18. TONYP

    TONYP 1/2 ton status

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    that's not to bad, it's less then the bumper of the guy who cuts me off and not being able to stop in time... /forums/images/graemlins/eek.gif
     
  19. jasonkh2tg

    jasonkh2tg 1/2 ton status

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    Well I looked over my old assembly notes and I noted that the
    MC had a bore of 1.25....I guess it's who you ask I like a firm pedal with little movement (sports car), but at the same time very affective....with a small bore you would have less pedal effort but more travel(luxury car)...Also I can honestly say the 3/4 ton booster has no problem driving the 1.25 MC.....but as far as the front of MC to rear of brakes don't know Ive looked at a lot of older chevy up to 77 that are routed that way....and the 71 GM service manual has it listed that way... /forums/images/graemlins/k5.gif
     
  20. Burt4x4

    Burt4x4 3/4 ton status

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    Sup my long lost Brother...
    Good topic
    Is that one you got considered the 'Dual Diaphram'. Or did it say? Also what brand is that part #?
    Rock on RB..

    Oh by the way F'n SWEET First gen you got there Bro! You ROCK!
     

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