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Technical PSA: Hyrdo-Boost Brakes.

Discussion in 'The Hokey Ass Message Board' started by porknbeaner, Sep 13, 2018.

  1. porknbeaner
    Joined: Sep 12, 2003
    Posts: 40,988

    porknbeaner
    Member

    OK we have not visited this brake setup for a year or so that I am aware of and I know that some of you guys swear by this setup. Power bakes driven off of your power steering pump.

    So the back story, just so that you will know that I am not touting something I read on line.

    Today I was driving a late model that has factory hydro-boost brakes across town. All was hunky dory. Well all was hunky dory until I discovered that the car had lost a power steering hose. I thought it felt a little sluggish but I was running at my normal 70 MPH down the freeway and it was still driving. Everything was fine until I had to do a panic stop. Guess what the peddle went straight to the floor. I grabbed the E brake and got it stopped and used the E brake to limp home.

    I have said this before and I'll say it again this is a dangerous brake system. I guess no more dangerous that any other brake system but how it works is if your pump is good you're golden, if you loose power steering or your engine dies or to throw a belt you got zero brakes. The people who are selling them to you will tell you that they will work one time but do not count on it.

    I don't care what anyone runs in their old hooptie just don't run whatever it is in ignorance. At the very least if you are running this system make sure that you have a functional E brake.

    OK my rant for the week. Play nice and don't fight.
     
  2. Stogy
    Joined: Feb 10, 2007
    Posts: 12,500

    Stogy
    ALLIANCE MEMBER

    Glad your still with us @porknbeaner...that's enough to make a mans gut sink.

    That also highlights a mechanically inclined response to a very critical situation and your heads up will provoke an inspection of what failed in your instance to those that have the system.

    Many if in the same situation would not have had been as fortunate.
     
    Last edited: Sep 13, 2018
    chryslerfan55 likes this.
  3. BJR
    Joined: Mar 11, 2005
    Posts: 5,600

    BJR
    Member

    Why do you loose all braking if the pump quits? I thought it was just a booster, like the name says, Hydro boost. I would think you would just loose boost, not all braking as a brake line has not broken. Please someone explain this as I don't get it.
     
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  4. belair
    Joined: Jul 10, 2006
    Posts: 8,017

    belair
    Member

    Thanks Beanner. Glad you had an E-brake and the presence of mind to use it.
     
    Stogy likes this.
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  5. anthony myrick
    Joined: Sep 4, 2009
    Posts: 4,271

    anthony myrick
    Member
    from al

    love mine but I did toss a belt last week
    and had that same OHHHHH S__T feeling trying to stop
    bought the more expensive made in USA belt this time
    I wish I could run a double belt set up on it
     
    Stogy likes this.
  6. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,433

    V8 Bob
    ALLIANCE MEMBER

    I don't know the system brand or vehicle you have, but the (original) Bendix Hydro-boost I've known and tested for many years on Fords and some GM has an accumulator that stores the p.s. fluid under about 1500 psi, and allows several normal brake applications during a p.s. pump failure before all power assist is gone, but has nothing to do with the brakes or master cylinder; you don't loose any braking, just power assist, similar to a vacuum booster when the engine quits.
    I'm betting you may have serious brake issues unrelated to the hydro-boost.
     
  7. anthony myrick
    Joined: Sep 4, 2009
    Posts: 4,271

    anthony myrick
    Member
    from al

    can that accumulator go bad?
    mine is hard to stop but will when ya push the pedal much harder when the belt came off
     
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  8. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,433

    V8 Bob
    ALLIANCE MEMBER

    You would simply have no power assist with a failed accumulator and pump.
     
    Last edited: Sep 13, 2018
  9. anthony myrick
    Joined: Sep 4, 2009
    Posts: 4,271

    anthony myrick
    Member
    from al

    this is my first build with those brakes
    the only used component was the booster
    everything else is 100% new even all the lines
    its hard to stop without the engine running, I tested it a couple time to see what it would be like to stop without the PS pump working
    so the brakes should work like normal for a couple braking attempts if the accumulator is working?
     
    Stogy likes this.
  10. saltflats
    Joined: Aug 14, 2007
    Posts: 9,346

    saltflats
    Member
    from Missouri

    Yes if the accumulator is working correctly you should have one or two assisted braking efforts.
     
  11. Truckdoctor Andy
    Joined: Jan 13, 2017
    Posts: 734

    Truckdoctor Andy
    Member

    If the medium duty trucks I work on everyday have hydraulic brakes, then they all have hydro boost systems. But, if they experience a loss of pressure from the power steering pump, a light and alarm come on and a backup electric pump comes on to provide brake assist. I’m six foot two, weigh slightly over 300 pounds and am very strong, but without the electric backup, I can’t push hard enough to stop these trucks.
    I’m very happy you are ok, Beaner!


    Sent from my iPhone using The H.A.M.B. mobile app
     
  12. anthony myrick
    Joined: Sep 4, 2009
    Posts: 4,271

    anthony myrick
    Member
    from al

    thanks for the clarifications
     
  13. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,433

    V8 Bob
    ALLIANCE MEMBER

    I'm pretty sure your medium trucks use a Bendix Hydro-Max booster, similar to Hydro-boost but with electric motor backup vs an accumulator.
     
  14. there is more going on then a failed power steering hose, as said above if the hydraulics fail you should have manual brakes, there is a mechanical connection there. ad you should have two assisted stops even after the failure. there are millions of these in service and, in my humble opinion, nothing unsafe about them.
     
  15. Truckdoctor Andy
    Joined: Jan 13, 2017
    Posts: 734

    Truckdoctor Andy
    Member

    Bob, you are 100% correct, thanks for the clarification. The light duty stuff with Diesel engines have the accumulator set up.


    Sent from my iPhone using The H.A.M.B. mobile app
     
    Hnstray likes this.
  16. Stogy
    Joined: Feb 10, 2007
    Posts: 12,500

    Stogy
    ALLIANCE MEMBER

    I look forward to the final synopsis of Beaner's situation. Kinda like panic stopping in a 57 Chevy with full on brake fade your pushing the pedal right through the floor and still going strong...terrible feeling.
     
  17. 49ratfink
    Joined: Feb 8, 2004
    Posts: 17,256

    49ratfink
    Member
    from California

    I have a 78 Chevrolet motorhome on a van chassis. not sure if has the same set up but I have no working power steering and no power brakes and the brakes still stop the truck.... just really shitty, then they will grab and send all the crap flying from the cupboards in the back... got to fix that before I drive it again... not sure if these are "hydro boost" or something else.
     
  18. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,442

    2OLD2FAST
    Member
    from illinois

    Seeing you do a " panic stop " in a late model would have to include at least 1 donut , unless you blew a brake line or a brake cylinder or in the remote possibility the hydra- boost totally failed , your telling tales ...
     
    54vicky likes this.
  19. Have the Ford hydroboost system in my avatar. I love it. I have always assumed it would be like manual brakes, only harder, if the booster failed for whatever reason. I totally don't understand why having the hydroboost fail would cause the brake pedal to go to the floor. I don't think mine is Bendix, but my memory is failing me again.Saginaw??
     
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  20. KustomKreeps
    Joined: Jan 7, 2016
    Posts: 318

    KustomKreeps
    Member

    I would recommend you look at your pedal ratio. as well 6:1?
    When the unit fails for what ever reason you should be back to manual brakes - similar situation as if a vacuum booster would fail.

    im installing hydro boost setup.
    Has the accumulator that stores three or so full brake power presses.
    Will be also doing 6:1 pedal ratio just encase the unit dies, then accumulator dies and i end up with manual brakes as I hurtle down some hill.

    fact the pedal went to the floor makes me think you have something else wrong with your system such as air in it or something.
     
    54vicky likes this.
  21. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 7,715

    theHIGHLANDER
    Member

    I lost a belt on my 4 ton 4X4 Dmax dually. Yeah, no boost, yeah, stopping that big bitch sucked, yeah it stopped. Steering was even worse, go figure.

    Beaner, love ya bro, but what's the odds fluid got on the rotors and made a bad scenario a panty stainer? You've probably had time to dig in by now, spill it (no pun intended, maybe...).
     
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  22. 54vicky
    Joined: Dec 13, 2011
    Posts: 1,064

    54vicky
    Member

    I drove an off topic truck for many (20) and on occasion it lost a belt only had to press on pedal harder if steering to avoid something at same time was not easy but always stopped.so beaner what else was it as asked or were you just adding drama.= false reporting
     
  23. porknbeaner
    Joined: Sep 12, 2003
    Posts: 40,988

    porknbeaner
    Member

    always nice to be called a liar first thing in the morning thanks.
     
  24. 54vicky
    Joined: Dec 13, 2011
    Posts: 1,064

    54vicky
    Member

    not a liar just an over active imagination:rolleyes:
     
  25. anthony myrick
    Joined: Sep 4, 2009
    Posts: 4,271

    anthony myrick
    Member
    from al

    mine didnt go straight to the floor but you are the one that lived the experience
    but it does feel a lot different and gets your attention when it doesn't stop the way you expect it to
    what I learned was not to use the chepo chain store belts
    Im going to check out the accumulator situation out this weekend

    and adjust the e-brake and try to fix the pucker mark in the seat
     
    Last edited: Sep 14, 2018
    Chavezk21 likes this.
  26. jimmy six
    Joined: Mar 21, 2006
    Posts: 4,441

    jimmy six
    ALLIANCE MEMBER

    As we retrofit these modern systems on older cars with out the manufacturers hours of testing and electronics to protect them things like this are going to pop up time to time. I have been reluctant to even add disc brakes to the front of my 56 Ford but am getting closer.
    Off topic my new 2018 Ford F-150 has an electric E-brake which probably won't react the same as pulling a handle or stepping on a peddle. In an emergency reaching for the switch will be the last thing on my mind for sure. Thanks for the info..
     
  27. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 22,749

    Jalopy Joker
    Member

    do not know if this was part of original failure - in newspaper today article says that GM is doing a recall for 1.2 million 2015 pick-ups/SUVs - because of power assisted steering problems
     
  28. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,442

    2OLD2FAST
    Member
    from illinois

    If the shoe fits ??
     
    firstinsteele and 54vicky like this.
  29. Most of the new electric park brakes will not engage if the vehicle is moving, it is no longer an emergency brake, that's the purpose of a tandem master cylinder. Also just to be clear to Beaner, I was not implying in my post that he was crazy, or a liar or anything else, just stating how the system should work. We all have seen things fail in a way that defies logic, curious to see the outcome here.
     
  30. 54vicky
    Joined: Dec 13, 2011
    Posts: 1,064

    54vicky
    Member

    I doubt as I think.if hydro you would need more fingers and toes after all these years.to count recall numbers
     
    Last edited: Sep 14, 2018

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