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1964 GT Hawk R2 Brake Issue

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  • Brakes: 1964 GT Hawk R2 Brake Issue

    Hi Members, Looking for some help.
    I am the proud new owner of a 1964 R2 Hawk. My first Studie. For those that followed, it's the one that just sold at Mecum Glendale in AZ. 64 V1085.

    OK, here is what I found.

    I drove the car home. Brakes seemed as if the power booster was not operating. Car would stop, but a lot of pedal pressure was required and there were no brake lights.

    Investigation found the following (note I have ordered a shop manual, but don't have it yet, so learning on the fly).

    Pedal is connected to a dual master cylinder that looks very clean and is mounted under (with virtually no room to remove the cover and fill or check it) the floor boards on the frame. I traced one brake line to the rear and it has a proportioning valve about under the driver's seat area.

    The other line goes to the front disc brakes.

    My car has the Bendix Hydrovac booster on the driver's site fender. There is where the brake light pressure switch is mounted and the wires are present.
    I followed the brake lines from the booster and they are not connected to anything. Explains why the pressure switch is not being activated and no brake lights.

    So, here are my questions:

    Is what I described on the split system booster a factory installation?
    If so, were the brake lines just mounted around (i.e. bypassed) the booster and I have manual brake now?
    Was the system originally split, front/ rear? Pretty progressive for the day, if it was!

    I am assuming my booster needs to be rebuilt and/or replaced. I saw another thread on the forum on a couple of places that may be able to help. Any recommendations are appreciated.

    From what I described, can anyone tell me what I should have found on the car if the brake system was stock? If not, what should be there.
    Then, any recommendations on how to correct?

    Thx. Art

  • #2
    Does the car still have its original type Bendix/Dunlop front disk brakes or a later conversion i.e. Turner? The original master cylinder under the floorboard was not a dual master cylinder. There should be a reservoir mounted on the firewall with a line down to the cap on the master cylinder to keep it full of fluid. The line from the master cylinder is routed to the Hydrovac. The wheel cylinders are connected to the Hydrovac, not the master cylinder. Apparently the system has been modified? If the lines from the Hydrovac are not connected to anything I would assume the brake switch is not being activated. If the system is filled with silicone brake fluid the brake switch has probably failed anyway.


    • #3
      "Is what I described on the split system booster a factory installation? NO
      If so, were the brake lines just mounted around (i.e. bypassed) the booster and I have manual brake now? YES
      Was the system originally split, front/ rear?" NO

      On manual brake cars the pressure brake lamp switch is in the fitting where the line from the master cylinder meets the front brake lines. It sounds like your switch is not in the system, being connected to a bypassed booster.

      I've never had any problem with silicone DOT5 brake fluid and pressure switches. I have one that's been working fine since '86 and another since '95.


      • #4
        Sounds like your car has been modified, at least to some extent, in effort to make the brakes more safe and/or efficient. Along the way, brake light wiring may have been screwed up, and brake fluid changed to something else. (Since DOT 3 and 5 are incompatible, must figure out what it has now.) First, need to know if your car came stock with PDBs. If so, in addition to the MC, and maybe the fluid, need to know what else has been swapped out/modified. Since the MC has been swapped, at the very least, the plumbing has been altered, which is a no-no with factory PDBs. With factory PDBs, if the rears are plumbed to bypass the hydrovac, they are rendered nearly inoperable.

        Key questions:
        Does your car have a wide brake pedal pad? How tall is the brake pedal, measured from top of pad the floor? Does the hydrovac have one, or two bleeder valves? Is there a brake fluid reservoir mounted on the passenger side of the firewall? Looking under the front end, at inboard side of the front wheels, does your car have front discs? If possible, it may be good to take pix of the components and post them here; also order a copy of the factory production order for your car, to see what it came with. Also, you can go to Bob Johnstone's web site here to look at pix to compare with yours.

        Advice from here depends on what your car came with, and what it has now. If it came with PDBs, and not heavily modified, it may be easiest to restore them to original, with any needed fresh components. Then, they will work as good as anything else out there, and far better than most cobo-jobs. To restore them to OEM, the dual MC must be removed, and an OEM one reinstalled, with original plumbing restored to go through the HV. Again, first need to know what came in the car, and what is in it now.

        Hope this helps.


        • #5
          First, welcome to the forum! There is a ton of good advice on this site and if you join a local chapter of the SDC (and of course the national club) you will likely find many folks willing to lend a hand or opinion. Owning a Hawk, you will get excellent advice from non other than Joe Hall (above) who has 3 of them and drives them regularly. He is a Hawk brake mastermind, so his word is pretty darned good (and he's a really nice guy too). Good luck with your car, hope you visit here often. Bill


          • #6
            Good Morning! Wow, thanks for the early morning responses. I do plan to join the local chapter here in AZ.

            Looks like I have work to do.

            I will do some searching on the car. Really didn't know where to look for original brake stuff, as the Hawk is configured very different from any 64 I own : )

            I will get the dimensions of the brake pedal. I will go out on a limb and say it was an original power brake system. No car I own had the booster on the fender, so at first wasn't even sure what it was. I will get the details.

            The car does have front discs, but the type are unknown to me. I will try to take a picture if I can. I can confirm that the brakes feel as if the rears are doing nothing. Also, I was very suspicious of seeing a little brake proportioning valve on the system. Did not look stock or even appropriate. Might have been an attempt to comp for the new config (which I can attest, didn't help).

            Also, it did seem to me that the big Bendix Hydrovac unit only had 1 "in" line and 1 "out" line, so it made me think that it was more like a traditional 64-esque brake system where all brakes are on one system, not split.

            OK, Please give me a day or two and I will get some pics, dimensions, etc and get a post back up. Car is temporarily stored in a rented garage. Will need to get over there and get info.
            I really appreciate the help. More to come.




            • #7
              If it is an R2, then it would most likely also have been equipped with factory disc brakes (Dunlop/Bendix). It also would have the type "F" Bendix Hydro-Vac brake booster. There would have been a remote filler reservoir mounted on the passenger side of the firewall. Also the brake pedal leverage would be set up for the power brakes, and is far less mechanical advantage over non power brakes. That is probably the biggest issue with needing so much pedal pressure to stop it after the booster being disconnected. Yes, the original system was a single circuit, and there is only one line in, and one line out of the booster. The easiest way to get where it stops safely and well, would be to purchase a new disc brake type booster from Studebaker vendors like SI. and hook up the front circuit to it. It is ok to have the rear non power assist, since the rears only contribute 30% of the stopping power.
              The 2nd route to go would be to find a non power brake pedal with more leverage and see if that makes it good enough for your satisfaction. Also a higher coefficient of friction brake pad will also contribute to it stopping better than the stock friction materials.
              Bez Auto Alchemy

              "Don't believe every internet quote" Abe Lincoln


              • #8
                stopping power with Bendix booster and disc brakes on 63-64 Studebaker is underwhelming. Has anyone tried the simple fix of installing a non-power brake pedal on one of these cars? With dual system and poor braking it usaually means the mc is bad and only one side is working. Or maybe somebody screwed it up, which , in my experience, is just about all the darn time. Gonna have to check it all out, but no problem since the Chinese virus has us spending lots of time at home and SI and Rock Auto are still open.


                • #9
                  Not related to your problem, but something that you commented on a couple of times. All Studebakers, other than Hawks, power disc brake cars and Standard models, had a dual master cylinder split brake system from the factory starting with the 1963 model year.
                  Gary L.
                  Wappinger, NY

                  SDC member since 1968
                  Studebaker enthusiast much longer


                  • #10
                    Hi Forum,

                    Thanks for the additional information. While I have not been able to go over by the car (I'm one of the lucky ones still working : ), it appears to me, this is some type of modification from original. Im sure the intentions were noble, but the results are a bit unsettling after about 45 mph.

                    Picking up on one comment above:

                    Where do I get a copy of my factory production order for my car? Apparently it has a little history. NY auto show, first Hawk manufactured for 64, etc. Love to have the info.
                    Let me know.

                    More to come.

                    Thx All

                    SCW AZ


                    • #11
                      The production order can be ordered from the Studebaker National Museum. You can do it online.

                      EDIT: If your car spent most of its life in Colorado, I believe that I remember it from years ago.
                      Gary L.
                      Wappinger, NY

                      SDC member since 1968
                      Studebaker enthusiast much longer


                      • #12
                        We also have a 64 R2 GT with power disc brakes, we converted to a dual master cylinder Turner brake system. If you can figure out exactly what front disc you have I could take pictures of how we plumbed ours. you can pm me ore email me at for my phone number if you wish to talk. Also I agree Joe Hall is the guru for anything brale related, his advice is well above my expertise!
                        It is an addiction!


                        • #13
                          This looks like your car. Very nice


                          • #14
                            I was under the impression that the production order went with the sale of this Hawk.
                            Gary L.
                            Wappinger, NY

                            SDC member since 1968
                            Studebaker enthusiast much longer


                            • #15
                              Originally posted by az64stude View Post
                              This looks like your car. Very nice
                              If this is the OP's car, there is no mention of PDBs on any of the paperwork I could see, unless they are included in the, "37 HI PERF PKG R2". However, I can see that it has the reservoir on the firewall, but a HV for drum brakes. So, if it has DBs, no mater if OEM or Turners, they will never work well (hard pedal) with the lower PSI drum brake HV. Nor will the rears work well with the tandem MC, plumbed to bypass the HV, if they are 11" drum type, which came with factory PDB. On the other hand, if they are the 10", self energizing type that came with front drums, they will work quite well if plumbed separately, provided the shoe liner is good quality.

                              No need to buy a Production Order, as a perfectly readable one is shown in the ad.

                              Option 122, GAS TANK DRAIN PLUG is interesting, and no charge listed.
                              Last edited by JoeHall; 03-24-2020, 08:15 PM.