Technical PSA: Hyrdo-Boost Brakes.

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.

 

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.

 

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.

 

Thanks Beanner. Glad you had an E-brake and the presence of mind to use it.

 

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

 

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.

 

can that accumulator go bad?
mine is hard to stop but will when ya push the pedal much harder when the belt came off

 

You would simply have no power assist with a failed accumulator and pump.

 

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?

 

Yes if the accumulator is working correctly you should have one or two assisted braking efforts.

 

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!


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thanks for the clarifications

 

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.

 

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.

 

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

 

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.

 

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.

 

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 ...

 

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??

 

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.

 

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...).

 

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

 

always nice to be called a liar first thing in the morning thanks.

 

not a liar just an over active imagination

 

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

 

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..

 

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

 

If the shoe fits ??

 

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.

 

I doubt as I think.if hydro you would need more fingers and toes after all these years.to count recall numbers