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Technical PSA: Hyrdo-Boost Brakes.

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

  1. Truck64
    Joined: Oct 18, 2015
    Posts: 4,056

    from Ioway

    Oh, NICE. Does it need a wifi connection too?
    seb fontana, egads and theHIGHLANDER like this.
  2. Both my '04 I was driving yesterday and the '05 that the wife drive says right in the owners manual that if your engine shuts off to apply the E brake and stop the vehicle.

    The service manager at the chebby garage warned the wife after we bought her Silverado that if she looses engine power or looses the belt that she has one stop left in it and that's all.

    When I read the literature on the system I installed on the '48 Lincoln a few years back it sounded as though there would be no brakes if the engine was not running. I explained what I suspected to the man who owned the car, it was his kit and I had already contracted to install it. He said he wanted it that I was mistaken. When his car was done he had no brakes when the car was not running. I ate my time and installed an E brake for him.

    Now just for chits n giggles I do not have a problem with someone disagreeing with me and I certainly welcome someone's educated insight on anything I post.

    I do not have the time nor the patience for fools. If all you are about is posting crap and thinking that it makes you tall because I am the beaner just save us both the time and the grief and go to my profile and hit the ignore button. Then you no longer have to see me and I do not have to see you. Done deal.

    @57 Fargo you shared information, you did not say that I came on here to start drama and was sharing "false news".
    Last edited: Sep 14, 2018
    Gasser 57 and saltflats like this.
  3. I can’t speak for any sort of aftermarket kits, just the factory setups, and am always willing to learn! I know there are some electric emergency brakes that work as stated, every manufacturer does things slightly different these days but alas, this is all off topic anyways... (electric e brakes that is).

    After reading what you said about your Chevy I’m going to do some research on Monday on the electric ones when I get to the college I work at.

    Sent from my iPhone using H.A.M.B.
  4. saltflats
    Joined: Aug 14, 2007
    Posts: 10,094

    from Missouri

    Sounds like more of a reason to just have manual brakes. :cool:
    If you can't stop the car with them, the system is not working correctly or you don't have the strength to be driving. ;)
    Joined: Jun 3, 2005
    Posts: 8,043


    'Beaner, I consider you a brother from a different mother so I hope you don't think my question was dissin ya. I just thought hose blown...oil (steering fluid)...front of the vehicle near the left front wheel...oil on the rotor?

    Now I only offered that thought because I'd been there too. I was 1 mile from home, live in the country, limped it there at 5 MPH. I had no oil problem, but I had really suck brakes because there was no boost. It was 4 years ago so I don't remember if I had 1 stop in it, shit was happening 1-2-3. I'd hate to have it happen at 70 MPH with a trailer full of Packard but blood pressure aside I feel confident I could survive it.

    Another aside, last year I put all new stainless lines on the truck (GM ought to shot n pissed on for the garbage they used OEM). When it came time to bleed I simply had the pedal being pushed, engine not running, and cracked bleeders like we'd do a vintage Ford or any other juice brakes system. Anti-lock trick aside (no $$$$ reader) it worked like it was supposed to.

    So to you, and anyone else that wants to know, PM me for any off topic talk about it, but I'd like to know if I was just lucky or did I have the potential for something really scary. Glad you're here to open the discussion on it.
  6. KustomKreeps
    Joined: Jan 7, 2016
    Posts: 325


    this is taken from the place I got my setup from:
    Q: What is the nitrogen reserve / accumulator cylinder and what are its benefits?

    A: The bottle on the side of most hydraulic brake assist units is referred to as an accumulator or nitrogen reserve. This stores up hydraulic power steering pressure in the event of an engine stall condition, to provide reserve brake assist power for up to 3 applications of the brake, similar to how a vacuum booster would function in an engine stall condition. Upon the first application of the brakes after an engine stall, you would find approximately 60 - 75% of the normal assist available, then if you were to release and apply the brakes again, you would find approximately 30 - 40% assist, then again approximately 10 - 20%, until you have depleted all stored reserve assist. Once you have depleted all of the stored pressure, the brakes will no longer have power assist and will be manual in their operations. The minute you start the vehicle back up again, the accumulator gets filled back up with pressurized ps fluid again and is ready to go!

    So basicly you get a few full power brake stops then its manual brakes. So keeping that in mind check the pedal ratio is 6:1 that is kinda standard.
    Would like to think most after market systems are much the same as this.
    Hnstray likes this.
  7. clem
    Joined: Dec 20, 2006
    Posts: 2,874


    .........for those that missed it in the first post...........:)

    porknbeaner likes this.
  8. Tim
    Joined: Mar 2, 2001
    Posts: 11,084

    from Raytown Mo

    Jesus, the guys done more shit than you’ve lied about and your first instinct is to say he’s full of shit because it’s never happened to you or the internet says it doesn’t happen?

    And you wonder why the hamb often gets a rap of being full of shit heads.

    Good grief.
  9. 41rodderz
    Joined: Sep 27, 2010
    Posts: 4,722

    from Oregon

    Lol . Gets your brain warmed up real quick , doesn't it . :D
    seb fontana likes this.
  10. 41rodderz
    Joined: Sep 27, 2010
    Posts: 4,722

    from Oregon

    Dang I am getting Dody. Sucked in to another old post. :D:oops:
  11. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,092

    Atwater Mike

    Beaner has more motorcycle time than most that I know...He wouldn't get in a jam he couldn't probably drive out of. (when you ride, you watch for 'escape routes', just in case)
    If he stated the pedal was gone, trust him. It was 'gone'.
    He wouldn't post some 'rumor' or other 'fearsome story', he hasn't got time.
    Oh, and another thing: He just lent creedence to the 'parking brake' actually being the EMERGENCY BRAKE! Yes, they do exist.
  12. Highlander
    The transfer pipe on the rack blew. It was an interesting situation. I guess in '04 they used several steering rack setups, I actually had to have the vehicle vin to get the correct transfer pipes No oil on the rotors.
    I talked with the brake man at the GM dealership. He said, "Well Ben its a hydraulic cylinder. You are not stupid it is simple, no hydraulic pressure no brakes. There is no mechanical link it is a hydraulic cylinder. The accumulator should have stopped the car but I would not trust it in a panic stop and if you had been driving in traffic you probably used it up or close to it before your emergency. Now on that particular car the system is a little tricky. The brakes should work once you get the air out of the system but better bring it in for me to give it a quick once over before you drive it much. No charge my friend."

    We also discussed some other brake stuff but it is not relevant to the conversation. You all can take it or leave it.
  13. First off, since my prior post I have found out my '01 Mustang hydroboost unit is a Bendix unit, not Saginaw as I previously thought. While recently looking for a leak repair kit, I read that most units regardless of Ford, GM, or Mopar are all made by Bendix and are similar. I was trying to find a sectional view of a unit after reading what Beaner's mechanic told him about not having a mechanical link. All I could find was this exploded diagram.
    Kinda hard for me to see how they all fit, without an assembled view, but my guess is the output shaft fits down into the piston giving the mechanical link others mentioned.
  14. deathrowdave
    Joined: May 27, 2014
    Posts: 2,152

    from NKy

    It is supposed to work as explained , you should get a couple assisted stops , then no power . The accumulator is your reserve , I don’t how to determine or know if it could leak off with out pressure from the pump applied to fill it . I do know there are different sized accumulators to be seen on various sized cars and trucks . My old Power Wagon has Hydra Boost brakes from a GM bolted straight up to the Dodge pedal no fab what so ever . It stops 100x better than a Vacuum booster . I replaced with the Hydra Boost at the Diesel swap time . The Diesel has no vacuum to power the OEM booster . My pump is gear driven no belt to brake , but the hoses are another story . That old tank weights in at 7000 lbs , it would be a real chore to steer and stop with no power . I have owned a 2 1/2 ton military truck with air over hydraulic assist , now this is scary with a single master cylinder . We are talking 15000 lbs of mass to think about stopping . But Uncle Sugar has unlimited funds and people , if the worst would happen . Hopefully I never need to test my , back up storage stopping on the Power Wagon a bumper made from a section of School Bus frame would really wrinkle up a newer designed auto , that would be a little tough to buff out in a weekend . Hydra Booster is by far the best braking assist on anything I have ever driven with a hydraulic brake system . I want to hope OEM engineers have a factor of safety , built into this stuff .
  15. I have had one apart there is no mechanical link. Granted the one I had apart was from a Ford Product not a GM. Needless to say the man I spoke with I have known for a longtime and that is what he does is brakes, he doesn't change oil or spark plugs or transmissions he is a brake tech.

    The one in the Envoy isn't even attached to the brake peddle. The brake peddle goes into a normal looking brake booster and master which activates the spool valve in the hydro-boost cylinder. Like I said the brake man said it is not straight forward.

    You all can run what you want I did what I felt necessary.
    Texas57 and TrailerTrashToo like this.
  16. Thanks Beano, HRP
  17. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,627

    V8 Bob

    I'm trying to learn more about your brake system, and all I've found so far is it's either vacuum or hydro boost assist. The above description just does not make any sense, no disrespect intended to you or your brake man.
    There is an ABS system down stream that could be causing some confusion?
    The hydro boost looks (from a few internet pictures) very similar to the Bendix systems I am familiar with, and there is definitely a mechanical link through the booster. DOT 105/135 brake tests require any booster to be bypassed for the "inop power" stopping distance portion of the test. When the booster is bypassed, the pedal will normally be high and hard after the accumulator is depleted, just like a vacuum booster. But the pedal has to be able to apply force to the master cylinder when the assist is rendered in-operable.
    Maybe a picture or two of the problem system, and/or some shop manual info would shed some light?
    Last edited: Jun 14, 2019
  18. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,471

    from Quincy, IL

    @V8 Bob . @porknbeaner My simple minded interpretation of this "no mechanical link" issue is as follows.....I think that statement means there is no mechanical link between the accumulator and the master cylinder (only hydraulic). NOT that there is no mechanical link between the brake pedal and the master cylinder (because there is).

    The accuracy of saying there is "no mechanical link between the two" depends on which 'two" of the three are being referenced in the speaker's or listener's minds.....and THAT is what makes the statement true or false.

    Edit: the illustration shown in post #49 below shows there are mechanical links between all three sections with the hydraulic boost being applied both mechanically and hydraulically in concert with the pedal input. Thanks, Gimpy for the clarification.
    Last edited: Jun 15, 2019
  19. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,163


    There is some confusion here, and terminology matters.

    Hydro-Boost was a Bendix designed product. Hydro-Boost is now a registered trademark of the Robert Bosch Corporation.

    It describes one thing, no matter what else others might tell you.

    It has a direct mechanical connection between the pedal, and the master cylinder, through the booster, which is hydraulic, and mounted between the firewall, and the master cylinder.

    Common variants, with a Nitrogen cylinder, look like this:

    That which is not directly behind the master cylinder is not Hydro-Boost. It might be a hydraulic assist, but it is something else.

    A GMC Envoy does not have Hydro-Boost. If you look at what is behind the master cylinder, you will see a vacuum booster. The ones that we put in out cars, often due to poor vacuum signals, are the like the ones shown above. There are millions of those in service. From GM records, at-least, they have an exceptionally low warranty claim rate. It is actually lower than that of vacuum boosters. (For the uninitiated, I am an Automotive Engineer, at GM, and have the receipts).

    The failure mode is manual brakes, after the Nitrogen assist piston runs down. How much/long that is depends on how fast you are going, and how heavy the vehicle is. If the pedal goes to the floor, there is another problem.

    I have had one in every single diesel truck that I have owned. I had one in my Jeep. Now I have one in my Falcon.

    I blew one hose (ram assist) in the Jeep, and I was able to stop. I drove the Falcon, for two-weeks, without the booster even hooked up. It wasn't ideal, but I managed.

    I have no reason to question P-N-B's account of what happened. Just clearing the air about the parts involved.
  20. KenC
    Joined: Sep 14, 2006
    Posts: 409


    Great info, thanks!

    I wonder what the symptoms of a N2 cylinder leak would be?

    It seems that a depleted accumulator could result in no backup boost available. That could result in a feeling of 'no brakes', especially if using a low ratio pedal arrangement.

  21. khead47
    Joined: Mar 29, 2010
    Posts: 1,666


    I hate em ! Twice I have lost the belt on C30 Chevy motorhomes. Real pucker times trying to steer and stop. Accumulater did nothing.
  22. There is no mechanical link in the hydrobooster. It is a hydraulic cylinder. At least the couple that I have had experience with are.
    gimpyshotrods likes this.
  23. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,163


    You won't find out until you have a hose or pump failure.

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