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Hydro Vac Brake Boosters

Discussion in 'Early CJ5 and CJ6 Tech' started by mickeykelley, Nov 2, 2021.

  1. Nov 2, 2021
    mickeykelley

    mickeykelley Well-Known Member

    Republic of Texas
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    Has anyone installed one of these VH44 systems on their CJ?

    https://www.amazon.com/BRAKE-SERVO-VH44-BOOSTER/dp/B07HN8QN6J/ref=sr_1_2?crid=234AJ6YHV46YQ&dchild=1&keywords=Vh44&qid=1635883934&qsid=135-2068649-0063068&s=automotive&sprefix=vh44,automotive,227&sr=1-2&sres=B07XP3D2KX,B07HN8QN6J,B085HNKJ82,B07GZNYQLJ,B082ZP9M34,B086YJ9KDP

    I have already upgraded the master to the dual, the rears to 11” bendix and did the front Geo disc conversion. It made a lot of difference to me but the wife wants more of a power feel so I’m looking at this.
     
    Desertdog48 likes this.
  2. Nov 2, 2021
    colojeepguy

    colojeepguy Colorado Springs

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    You'll need 2....
     
  3. Nov 2, 2021
    Fireball

    Fireball Well-Known Member 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    My dad has had one on his GPW since the '70s and it's worked well. They are OE on 50's vintage T-birds. As noted by colojeepguy, you'll need one for each brake circuit. My dad still has a single circuit brake system on the GPW so he only needed one.
     
  4. Nov 3, 2021
    mickeykelley

    mickeykelley Well-Known Member

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    I’ve read where some have just used one for the front disc since they require more pressure and leave the rear alone. One of the manufacturers also says this.
     
  5. Nov 3, 2021
    colojeepguy

    colojeepguy Colorado Springs

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    Power front brakes & manual rear? This seems like a terrible idea to me...
     
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  6. Nov 3, 2021
    duffer

    duffer Rodent Power

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    2X That would be a great recipe to swap ends every time you hit the brakes reasonably hard. Or even not hard on anything slick.
     
    colojeepguy likes this.
  7. Nov 3, 2021
    garage gnome

    garage gnome ECJ5 welder 2021 Sponsor 2020 Sponsor

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    My Jeep has 4 wheel disc and Wilwood dual mc and I have to barely hit the brakes and it locks up all 4.

    If you ask me, that vac booster seems like another failure point and more headaches than it would be worth. If you want power brakes, put the mc on the firewall with a conventional brake booster. There’s a reason manufacturers don’t use remote boosters anymore.
     
    Rich M. likes this.
  8. Nov 3, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    I agree with Nate; the hydrovac seems like a technology whose time has passed. I presume you already have soft organic pads for the disk brakes. Raybestos also offeres organic shoes for your Bendix brakes - may or may not be different from what you have. The "right" way to upgrade would be to convert to hanging pedals with a vacuum booster. Your options are quite limited with the through-the-floor pedals. Chevy trucks are another source of conversion parts, and you might gain some ease by converting to the GM brakes instead of the (presumably smaller) Geo brakes. The larger you make the caliper pistons, the less force will be needed for a given stopping force. There are also caliper upgrades for the Delco brakes that have larger pistons - look on the Wagoneer sites for some discussion.
     
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  9. Nov 3, 2021
    mickeykelley

    mickeykelley Well-Known Member

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    The issue is not being able to lock up the wheels. I can get on the brakes and stop, lock ‘me up, etc. The issue is with the amount of leg required to accomplish this. At 65, 6’1” and 230 pounds, I can accomplish it and not a big deal. But the 5’4”, 120 pound wife is not comfortable with it. Part of it is we just get use to the ease of power assisted brakes and then going back to old school is uncomfortable. Having disc all around or any certain pads, will not change the part of how much leg you have to give it.
     
  10. Nov 3, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    I did not suggest disks all around. I'm not sure that disks can be easier than drums, which have more surface area and are self-energizing. I thought about suggesting front drums, and did not because I'm not sure it would be better. And I know the 4-wheel Bendix brakes do not resemble power assist.

    Softer pads - Well, yes it will. A softer pad has a higher coefficient of friction and will make more friction for a given pressure. It will also wear out faster. Larger cylinders in the calipers will add mechanical advantage, making it easier to stop with less force. Neither are power assist, but might be helpful.
     
  11. Nov 3, 2021
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    At the cost of increased pedal travel, am I right? No free lunches.
     
  12. Nov 3, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    Sure. I expect the problem for the OP is not how far the pedal moves, but how much force is needed. It becomes a longer lever.

    You could make the pedal really soft, and you might run out of travel. Like most things, there are limits.
     
  13. Nov 3, 2021
    garage gnome

    garage gnome ECJ5 welder 2021 Sponsor 2020 Sponsor

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    I have GM brakes in the front and the eee disc in the rear. I think the differences in piston size help with stopping ability. No need for a proportioning valve.
     
  14. Nov 3, 2021
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    Is the seat adjustable enough for your wife to be able to get good leverage when she pushes on the pedal?
     
  15. Nov 3, 2021
    colojeepguy

    colojeepguy Colorado Springs

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    I have the same problem (sort of) I'm 6ft tall but I'm getting arthritis in my right knee and the CJ is getting harder for me to drive. I don't want to convert to hanging pedals (& I'm not sure I have the fabrication skills to do it) but pretty soon I'm going to need power brakes.
     
    Glenn likes this.
  16. Nov 3, 2021
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member

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    Putting a one circuit booster on a two circuit system? You're seriously putting yourself into Test Pilot Territory.o_O

    Not that I don't think what you're proposing won't work, you just need to make sure the fronts lock up before the rears do.

    I have a couple of Bendix hydrovac's that I was intending to install on Tonk but after converting to 11" drums I found I don't really need the power boost. There are dual circuit boosters out there, essentially they're two boosters mounted back to back.


    [​IMG]
    2509140, Hydrovac



    [​IMG]

    I actually had a design to convert a hydrovac to dual circuit operation but it required machining a new cylinder & piston.
     
  17. Nov 4, 2021
    Steamboat Willys

    Steamboat Willys Member 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    I did a 4 wheel disk conversion on my CJ5. Standard through the floor pedals.
    The first go around I used semi-metallic pads and the braking felt horrible. It required an excessive amount of pedal force.
    A change to organic pads made all the difference in the world.
     
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  18. Nov 4, 2021
    mickeykelley

    mickeykelley Well-Known Member

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    I’ve looked at my stuff and the paper work does not say what type of pads they were. It was a complete caliper with pads. So at this point I don’t know if they were semi-Metalic or organic. If I recall, on the semi you will see some shinny parts in the pad, ie the metallic vs organic you don’t see any shinny areas. At some point I guess I need to pull a side and look. Maybe I’ll be able to see the edge of a pad to tell.
     
  19. Nov 8, 2021
    Keys5a

    Keys5a Sponsor

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    We're assuming you still have the brake master under the floor, just converted to dual circuit. You could install two of those hydrovac units remotely, but it would be lots of hassel. Late '50s/ and 60's British cars used remote hydrovacs, including big Jaguar sedans using two units for dual circuit brakes. Very complicated!
    In my opinion, it would be easier to convert to swinging pedals and use a conventional vacuum booster if you feel you need power brakes.
    -Donny
     
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  20. Nov 8, 2021
    mickeykelley

    mickeykelley Well-Known Member

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    I seriously may go back to the single MC.
     
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