Recommend a brake booster

Discussion in 'The Bench' started by buicks, Nov 8, 2016.

  1. buicks

    buicks Well-Known Member

    Gonna need one anyway, looking for recommendations on an upgrade in booster performance from stock for a 72 Skylark.
    Could be an aftermarket piece or a stock one listed as for another car.
    Thanks
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

  3. buicks

    buicks Well-Known Member

    Cool, so improved over stock replacement then? Any idea if there is an issue if I have TA performance aluminum valvecovers?

    It says
    "Notes: Engines with tall valve covers may have clearance issues."
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    There is no improvement in braking with the booster, it functions as stock. Will it interfere? Not sure.
     
  5. buicks

    buicks Well-Known Member

    I'm looking for a better performing / performance one.
    Figured someone on here has upgraded at some point.
     
  6. CJay

    CJay Supercar owner Staff Member

    If you cant get a nice soft pedal with an 11" booster, then you have something else wrong. The booster works off vacuum. If you have poor vacuum, there isn't a vacuum assisted booster made that will give you a nice soft cushy pedal
     
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The booster just provides assist, and I am unaware of any booster that will give more assist. I might be wrong about that. Using a master cylinder with a smaller bore will produce more psi at the wheels.
     
  8. CJay

    CJay Supercar owner Staff Member

    Maybe we should put the brakes on and back up a bit :grin: and ask what specific symptom your having with your brakes that your trying to correct.
     
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Per the 1st post, seems like he needs a new one for whatever reason and feels if he can get one that generates more assist, that is what he wants. Pretty sure the stock 11" is the best. Not sure about tall valve cover clearance though.
     
  10. Mark Demko

    Mark Demko Well-Known Member

    I used the same booster from Summit.
    No issues with the TA cast valve covers.
    No such thing as a "Performance" booster, that I've ever heard.
    The only thing the "booster" does is provide assist for the drivers leg.
     
  11. buicks

    buicks Well-Known Member

    Well, I'm thinking of a result requiring less pedal effort than stock. (Its drums but I don't really want to change that) For example do full size Buicks or Caddys use a larger booster? (Usually larger deeper not wider.) Or even a Suburban, etc.
    In my other hobby car, Pontiac Fiero, folks put in a booster from an S10 pickup and they get a" more modern" pedal feel, less effort.

    What is making me finally change the booster anyway is a soft pedal that goes farther down than it should before any real braking occurs. It wasn't like this originally, but now has this problem. I think the booster may be "leaky". I changed the master a few years ago and it didn't fix the issue. There is no air in the lines, the hoses are new too.
     
  12. CJay

    CJay Supercar owner Staff Member

    There is a lot more to a low pedal than a booster. Providing what you say is correct and that there is in fact no air in the lines, there are a few other items that can contribute to a low pedal. Are the rear brakes adjusted up correctly? Is the rod in the booster that contacts the master adjusted correctly? Is "cup" in the back of the master correct or is it too deep? There could be too much travel of the pedal before the rod contacts the master. The rod that goes from the booster to the pedal is also adjustable. It could also be a combination of a few small issues that add up to a larger problem
     
  13. buicks

    buicks Well-Known Member

    All brakes are adjusted correctly. When I got the master cylinder it was from Napa and for this car.

    It could be too much travel of the pedal before the rod contacts the master, how does one verify and remedy that?
     
  14. CJay

    CJay Supercar owner Staff Member

    Unbolt the master from the booster and see if you can move it forward a little with the lines attached and take a peek. You should have like .020" clearance between the pin and the receiving cup in the back of the master. The pin somewhat resembles an adjustable pushrod in an engine.
     
  15. buicks

    buicks Well-Known Member

    Wouldn't the pedal be low even when not pushed if this were the case?
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    You are condemning the booster and it may be fine. If it were leaky, you would hear that as you shut the engine down, it would hiss. A spongy pedal is due to air in the system. Have you flushed the system completely with new fluid? Maybe try gravity bleeding all four bleeders until the fluid runs clean. A simple test for the booster is to pump the pedal 3-4 times with the engine off. Then hold down the brake pedal and start the engine. If the booster is functioning correctly, the pedal should drop away from your foot as the engine starts.
     
  17. CJay

    CJay Supercar owner Staff Member

    No, you would just have a lot of travel till the pin came out far enough to contact the master. Been there, done that.
     
  18. buicks

    buicks Well-Known Member

    Been flushed and gravity bled even after the fluid was clean, just to make sure.
    I can try that test sometimes but I would think even a poorly functioning weak booster would do that.
    It does boost, I had a 68 GMC 4x4 with no power brakes, its nothing like that caveman brake system :D
     
  19. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    What you are describing is pretty typical of an all drum system. Drum brakes operate with more clearance than disc brakes. That is why adjustment is more critical. If the booster was leaky, the pedal would be harder not softer. I don't think a new booster is going to make things better. Booster assist is a function of diaphragm surface area. The 11" is the best there is.
     
  20. buicks

    buicks Well-Known Member

    They are adjusted as tight as proper without too much drag, and the car wasn't like this for the first 6 years I had it.
     

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