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Technical Hydroboost warning for builders

Discussion in 'The Hokey Ass Message Board' started by anthony myrick, Jun 15, 2020.

  1. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    I added a hydroboost unit on my sons truck, I have used them before and love them, This time I didnt use power steering.
    If you uses a hydroboost without power steering DO NOT plug the pressure hose side for the steering box! The hudroboost booster does not bypass. you can burn up a pump. We didnt but found this answer quickly. Research on the subject said to use the steering box side as an extra return. We did this and its working (yard driving) so far.
    I was surprised that the fluid pressure from the booster to steering box is not very high.
    If anyone here has done this please chime in.
    if you plan to do an install like this you still need the PS pump with dual returns.
     
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  2. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    I found info on the web suggestion to just plug off the steering side, I had to dig deeper to find out this was incorrect.
    this is why I posted
     
  3. Thanks for the information. In my world of medium and heavy trucks, hydroboost is very common, but I’ve never seen a set up without power steering.


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  4. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    same here, I have the set up on the bus and it works great (bus has PS) The truck steers great without the PS. I also wanted to see if it was possible, not every one likes PS.
    I will install a PS box if I have to in order for the brakes to work properly if I have to. My questions would be does the PS box cause any back pressure needed for the booster? now Im curious at what pressure a GM PS system operates on, The pressure from the steering side of the booster seems low.
    an Alan Grove PDF stated the gm pump delivered 1000-1200 psi. There is no way this pump is doing that from the booster to steering gear port
     
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  5. I’m not sure what the GM operating pressure would be. I’ve seen medium duty Internationals run at 1200 psi, but obviously will go higher if dead headed.


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  6. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    hmmmm wonder why it seems low on the steering side?
    the brakes seem like they have plenty of boost.
     
  7. Pinball Wizard
    Joined: Jul 25, 2008
    Posts: 91

    Pinball Wizard
    Member

    The pressure is low because you're using it as a return. If you plumbed it to the steering box, there would be a restriction and more pressure.
     
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  8. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    so the pump can see a need for pressure or it can increase if needed?
    one online source suggested using a pressure regulator on the steering line but couldn't back that up with anything other than assumption
     
  9. The pump just creates flow, the restriction through the steering box is what creates the pressure.


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  10. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    found this on the web
    "There are two distinct functions that the power steering pump is designed to perform. The first function is to deliver a constant flow rate to the power steering rack or box control valve. The flow rate will determine the sensitivity of the control valve when input is applied through the steering wheel. In conjunction with the control valve design, a given flow rate will result in a given steering feel and performance. Adjusting the flow rate is a fine tuning adjustment of the steering system and is not considered an all-inclusive adjustment.

    The second function of the power steering pump is to provide enough pressure to assist the driver in overcoming steering load. The pump only builds pressure when it is required to by the steering rack or box control valve."

    and this
    http://prod.lv2014.gener8cms.net/in...st/1103-hydraulically-assisted-power-steering

    I like learnin
     
    Last edited: Jun 15, 2020
  11. Well being as how they are a positive displacement pump, as in they move, or flow, the same volume every revolution of the pump then it is the restriction to that flow that causes pressure. The directional control valve in the power steering gear is what determines the resistance to the flow.




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  12. Have Hydra boost on two GM's and would like to take it off of one....
     
  13. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    I like the set up we installed on my short bus. My only advise is buy a quality belt and change them regularly.
     
  14. CyaNide
    Joined: Mar 2, 2006
    Posts: 196

    CyaNide
    Member
    from Texas

    Funny you post this. I am building my shoebox with a 302, no power steering, with hydroboost and I had the same question. I was planning on running both return lines. One going through a cooler. I like the hydroboost set up since it does not take up a lot of space and I just happened to have one left over from a parts car. I just mounted it on the firewall a few days ago. Got a lot of work still ahead before I know how good it is. Let me know if you run into any other issues.

    CN
     
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  15. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    I read some guys plumb both return lines into a single line. Some of them said this affected pedal feel?
    Logic seems having 2 into one could increase line pressure on the returns
     
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  16. Mr48chev
    Joined: Dec 28, 2007
    Posts: 26,857

    Mr48chev
    ALLIANCE MEMBER

    I'd have to go out and open the hood on ,my dualie to figure out the hose routing.
    I can see not plugging the pressure hose to the steering box because you have then created a full time 100% pressure situation on that line. Worse case us that you have to put a restriction in the hose to put more pressure to the hydrovac If too much pressure is bypassing.

    I'm not sure on teeing both return lines into the single return on the can. It may provide the restriction you need for the line that went to the steering gear but may cause more restriction for the return line for the hydrovac than you want. Then again it may have very limited effect.

    SIDE NOTE!!! you don't have to change the whole pump, all you need is to change the can on he pump to a two return line can if you have a Saginaw pump.
     
  17. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    going to look into that. Im going to work out the wiring issues and drive it a little. It seems to stop well but the pedal seems a little softer than my other ride with it. Going to re-bleed the brakes again then check. Everything is new on the system. On a side note, I used a master cylinder for an auto (single cyl Vs the tandem the manuals had) for the clutch master cly. Works great.
     
  18. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 8,039

    mgtstumpy
    Member

  19. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,686

    anthony myrick
    Member

    I like the note for the T on the return. seems logical
    but that "high pressure" line to the steering gear was my only question on the set up originally. I have a barb adapter on that pressure line to test using it as a return. I expected to see a lot more pressure. It does flow a lot, but not much pressure. My concern was if the pressure from the steering gear port on the booster would be too much for a standard return line.
    Most answers to this question when I researched it was people asking why run a hydroboost and not use a PS gear box? I guess some of us are just weird like that
     

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