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Thread: Strange power booster

  1. #1

    Default Strange power booster

    Ok, our Fire Dept brush truck, wich I am in the process of putting back into a somewhat stock configuration since I own it, has a Vaccum brake booster mounted on the frame rail under the drivers side, at this time it has a guard on it. but the brake lines run into it, then out, but there is no mechanical linkage going into it, just vacumm, I am assuming it nust activate with vacumm and brake pressure, and have not cut the running boards and guard off of it. I knwo the brakes work very well in this truck as long as they are not leaking. I have spent hours and hours knocking down trees fighting brush fires in it. has anyone ever seen these before. my dept built this truck in the early 80's and the members dont remember adding this to it.


    Duane

  2. #2

    Default

    Yep but not on the frame rail!!

    Mine has this one mounted above the alternator boosting the single circuit master cylinder.



    5quarter posted this:



    Mike's (503m715) has the same one as 5quarter.

  3. #3
    Bushytails Guest

    Default

    I've heard of those, but have never seen one... If you do pull it, send it over this way! Some boost would be nice with the big tires, insulated shelter,...

    --Bushytails

  4. #4
    Join Date
    Jan 2007
    Location
    Georgetown, CA
    Posts
    418

    Default

    It is usually called a "Hydro-vac" which I think is a brand name actually. It essentially functions like a regular power brake unit, except that instead of linkage, it uses the brake pressure from the stock master cylinder to activate it.

    Bushytails, . .A power brake unit off of a 70's-80's FSJ, pickup or cherokee is an easy install, you get both power brakes and a dual master cylinder, have to do minor work on the brake lines, drill a couple holes in the firewall, and modify the pushrod for the booster, .. .I did the whole thing in about 3 hours. . .

  5. #5
    Join Date
    Oct 2008
    Location
    Central MA
    Posts
    356

    Default

    Any reason not to just keep this booster? Seems like a great way to free up some room in the engine compartment if you need space for other things...

  6. #6
    Join Date
    Dec 2006
    Location
    canby Oregon
    Posts
    359

    Default

    I took mine off. It is laying in the bed now. It would have been in the way of my heater and fording parts.

  7. #7

    Default

    Yes thats a hydro-boost unit they were common on med. duty trucks back in the 1960's an early 70's. They were popular because they could be remotely mounted anywhere, allowing the veh. manarfacturer to keep their exsisting m/c arrangements. They quickly vanished after compact integrated m/c boosters came along.
    68 M-715 MVPA #2710

  8. #8

    Default

    I am pretty sure I am going to keep the booster, mounted along the frame rail under the drivers door it is out of the way. and I know it works. I will post some pics of it when I get the guard off.

    Duane

  9. #9
    Join Date
    Jul 2007
    Location
    Rhoadesville, Virginia (five miles from no place)
    Posts
    5,125

    Default

    Quote Originally Posted by moosejr View Post

    Bushytails, . .A power brake unit off of a 70's-80's FSJ, pickup or cherokee is an easy install, you get both power brakes and a dual master cylinder, have to do minor work on the brake lines, drill a couple holes in the firewall, and modify the pushrod for the booster, .. .I did the whole thing in about 3 hours. . .
    With a stock 230 though, you have a clearance issue with the air cleaner if you add a booster on the firewall. Probably why the Hydro-Vacs were popular.
    "Free advice is worth what you pay for it."™

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