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Question about brake bleeding with hydrovac

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  • Question about brake bleeding with hydrovac

    I just had the front flex brake hoses replaced on my 1962 Hawk (non-disc). There may still be a little air in the system. My question is, should the hydra-vac unit on the firewall always be bled whenever any kind of bleeding is done somewhere else in the system? I know the shop did not bleed the unit in this case. In fact, when I picked up the car, the mechanic was surprised when I told him it had power brakes!
    "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

  • #2
    If the brakes are bled properly at each wheel cylinder starting with the one furthest away from the master cylinder I blieve all the air in the lines should have been expelled.My presemt car does not have power brakes but I don't recall a bleeder screw on the power unit.

    Comment


    • #3
      You need to bleed the hydovac inlet first, then the outlet. (two bleed screws.)


      Studebaker On The Net
      http://stude.com
      Studebaker News Group
      http://groups.google.com/group/alt.autos.studebaker
      Arnold Md.
      64 Daytona HT
      63 R2 4 speed GT Hawk
      63 GT Hawk
      63 Avanti R1/AC
      63 Avanti R2/4 speed
      62 Lark 2 door
      62 GT(parts car)
      60 Lark convert
      60 Hawk
      56 Power Hawk/4 speed/289
      51 Commander
      JDP Maryland

      Comment


      • #4
        I only remember seeing one bleeder screw in the diagrams in the manual, but there are so many parts, I'm not surprised if I did not notice another one.

        So, are you saying, JDP, that the hydravac (hydro-vac?) booster should be bled in this case?

        Update: I talked to Carl Thoms and he says it shouldn't be necessary to bleed the unit if they were only dealing with the other side of the system.
        "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

        Comment


        • #5
          I always do a full bleed whenever the system is opened.



          Studebaker On The Net
          http://stude.com
          Studebaker News Group
          http://groups.google.com/group/alt.autos.studebaker
          Arnold Md.
          64 Daytona HT
          63 R2 4 speed GT Hawk
          63 GT Hawk
          63 Avanti R1/AC
          63 Avanti R2/4 speed
          62 Lark 2 door
          62 GT(parts car)
          60 Lark convert
          60 Hawk
          56 Power Hawk/4 speed/289
          51 Commander
          JDP Maryland

          Comment


          • #6
            If there is some air in the booster unit, will it make the brakes seem more like manual brakes (in other words, will it reduce the level of brake boosting the booster gives)? My brakes seem fairly hard to apply for being power brakes. I don't trust these *&%*& hydravac boosters. This one was replaced twice already, the first rebuilt unit being defective!

            I certainly wouldn't want to make a panic stop.
            "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

            Comment


            • #7
              If they are as hard as you are saying it is not working properly. Mine will put you through the windshield with little effort. I would check the vacuum line and the inline check valve to make sure it is in the right way, and make sure you do the bleeding per the shop manual. I happen to like Hydrovacs, pretty neat device and it can be put anywhere!

              Dan White
              64 R1 GT
              64 R2 GT
              Dan White
              64 R1 GT
              64 R2 GT
              58 C Cab
              57 Broadmoor (Marvin)

              Comment


              • #8
                OK, but does anyone know if any air in the booster will also result in hard braking?

                I'll have to check those things, Dan.
                "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

                Comment


                • #9
                  Is there a good replacement for one of these? I have a 62 Lark that did not have power brakes, but I would like to add one to the system. Any advise on a cross over..Thanks!!

                  Comment


                  • #10
                    quote:Originally posted by Scott

                    OK, but does anyone know if any air in the booster will also result in hard braking?
                    Air in the system results in a soft, squishy pedal. If it takes a lot of pedal pressure to stop the car, it sounds like the booster isn't working properly.


                    Dick Steinkamp
                    Bellingham, WA

                    Comment


                    • #11
                      quote:Originally posted by prager

                      Is there a good replacement for one of these? I have a 62 Lark that did not have power brakes, but I would like to add one to the system. Any advise on a cross over..Thanks!!
                      The hydrovac is a remote booster (not attached to the master cylinder). A lot of hot rods use a remote booster made by Midland and other vendors. I'm sure one could be adapted to your Lark. The new ones are much smaller than the original hydrovacs and can be mounted almost anywhere.

                      OTOH, a '62 Lark has a suspended brake pedal and a firewall mounted master cylinder. I would think a '63 and up Lark or Avanti firewall mounted combination booster/master cylinder might be made to work.



                      Dick Steinkamp
                      Bellingham, WA

                      Comment


                      • #12
                        I HATE Hydrovacs!!! What a waste of my money to take it out, put it in, take it out, put it in, get a rebuild, watch it fail, pay for freight, put new one in. Watch it fail, take it out....
                        "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

                        Comment


                        • #13
                          quote:Originally posted by Scott

                          I HATE Hydrovacs!!!
                          You can remove it and/or plumb around it. If you do that, I believe you also need to put in the non power brake pedal assembly. Different geometery.



                          Dick Steinkamp
                          Bellingham, WA

                          Comment


                          • #14
                            Ok going by the photo, which one is the inlet and outlet screw?[?] I have one of these units bleed all 4 wheels had great brakes. Let the car sit and the pedal will go through the floor [:0]. It is a new unit, new M/C and W/C's. Any thoughts?

                            Rodney
                            60 Black Hawk
                            "sometimes down"

                            Comment


                            • #15
                              Scott if you are having that much trouble with your hydrovac unit you may have someone that doesn't know what they are doing doing the rebuilds. I bought mine at a swap meet, had it rebuilt and installed and 8 years later it is still working great.

                              If the brake pedal is going to the floor you may have a bad piston seal in the MC. It may be NOS or "new" but it may still have bad seals! I would not necessarily blame the hydrovac yet.

                              Dan White
                              64 R1 GT
                              64 R2 GT
                              Dan White
                              64 R1 GT
                              64 R2 GT
                              58 C Cab
                              57 Broadmoor (Marvin)

                              Comment

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