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  • Hydroboost FAQ 1974-1991

    What is Hydraulic brake booster?
    A hydraulic brake booster (also called a Hydroboost) is a braking system that replaces your vacuum booster. It gives approximately 2-3x the braking pressure for the same amount of pedal pressure as vacuum operated brakes. It runs off of your power steering pump.

    If it runs off my power steering pump and my pump dies, the powers steering belt brakes, or the engine quits how do I stop?
    On a vacuum based system, if your engine quits or the booster goes bad, the system reverts to manual brakes. On a hydroboost system, there is a nitrogen-charged canister that is an accumulator for residual pressure in the event of losing the pump. The accumulator is the gold cylinder usually seen on the right side of the unit, and it's filled with 1,500 psi of nitrogen and when your pump is running it fills the chamber with power steering fluid and compresses a piston. Provided you have a full charge of nitrogen in your accumulator (yes they can go bad) you will have 2-3 full power brake applications in the event you lose the pump. After that, the system reverts to manual brakes.

    Can I use my existing master cylinder or do I need to buy one with the Hydraulic brake booster?
    1974-1980 (with power brakes) iron master cylinders will work with our hydroboost kit. It is still recommended to replace your master cylinder with one of our units.
    1981-1991 aluminum master cylinders will not work with our hydroboost kit and you must purchase a master cylinder with your hydroboost kit.

    Does it matter how I hook up the T-fitting for the return line?
    It is critical that the T-fitting is installed in only one way or you will have trouble with your system. This is the correct way:

    Are the hoses you sell a direct bolt up?
    1980-1991 only: They will bolt up directly to the Hydraulic brake booster. At the pump and power steering box it requires that you bend the hoses a bit to match.

    Can I fit a flared hose fitting (1974-1979) to metric o-ring ports?
    Yes, Hydratech Braking sells flare adapters that fit in the metric ports. Also, check out their low profile banjo fittings for increased clearance if required. If you have a 1974-1979 rig you can put a 1980-1991 FSJ power steering box and a 1980-1991 FSJ power steering pump to use our lines.

    What if my truck has drum brakes all the way around, will this still work?
    Possibly, but the set up is more involved. You will need to source a few more parts and drill two additional 3/8" holes in your firewall.

    Will I need to add a residual pressure valve to my brake system to use this with all discs or all drums, and which one would I use?
    Yes, if you have all drum brakes you may wish to add a 10lb residual pressure valve to the line that serves your front brakes although some who've done this will tell you it's not necessary. If you plan to run all discs you are best off to add a 2lb residual pressure valve to the line that serves your rear brakes, but again some will tell you they felt it wasn't required.

    The rest of my braking system is not in great condition. Will I still see improved braking?
    It is imperative that you bring your system up to safe operating standards prior to considering installing a hydraulic brake booster system. The increased pressure that the system will see can cause a deteriorated or worn system to fail.

    What do you recommend for power steering fluid?
    We recommend GM Goodwrench part number: 89020661
    Last edited by Ryan; 01-31-2013, 03:39 PM.

  • #2
    what are the cost for this upgrade

    Do you have a full kit that will make this possible?

    I have spent a lot money on this problem - brake master cylinder, brake lines and me it sounds like too many things to fix..vacuum leaks etc...

    Also what other expenses are going to be part of this kit
    Last edited by BossVP; 02-03-2013, 08:05 AM.


    • #3
      Yes, the kit for 74-91 is here:

      It includes everything you need.


      • #4
        Here is the correct hose routing layout:
        1. the passenger side single port on the accumulator side (shown where the white cap is in the photo below) connects to the pressure port on the back of the power steering pump
        2. the driver side rear port (shown where the green cap is in the photo below) connects to the pressure port on the power steering gearbox
        3. the driver side front nipple (shown with a black cap in the photo below) is the return to the pump. This connects via a Tee or Wye fitting with the return line from the power steering gearbox, and connects back to the low pressure return line at the pump.