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Turner conversion - pedal pressure? (Was: brakes)

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  • Brakes: Turner conversion - pedal pressure? (Was: brakes)

    I just had a Turner disc in stalled on my 63 hawk, I had done anearlier Turner dual master conversion.
    problem now is it takes way too much pedal pressure to stop it what did I do wrong?
    Mark Riesch
    New Bern, NC

  • #2
    Are you using the dual master cylinder that Jim Turner recommends for his disc brakes? Have you discussed this issue with Jim?

    Did your Hawk have factory disc brakes prior to installing the Turner setup? If it had drum brakes, did it have a Hydrovac or manual brakes?

    Are you using a Hydrovac with the Turner setup, or running them as manual brakes?
    Paul
    Winston-Salem, NC
    Visit The Studebaker Skytop Registry website at: www.studebakerskytop.com

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    • #3
      Originally posted by TXmark View Post
      I just had a Turner disc in stalled on my 63 hawk, I had done anearlier Turner dual master conversion.
      problem now is it takes way too much pedal pressure to stop it what did I do wrong?
      If you replaced drum brakes with a Turner setup, you're experiencing 'physics'. It takes more pedal pressure to actuate disk brakes than drum brakes.
      64 GT Hawk (K7)
      1970 Avanti (R3)

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      • #4
        Originally posted by 64V-K7 View Post

        If you replaced drum brakes with a Turner setup, you're experiencing 'physics'. It takes more pedal pressure to actuate disk brakes than drum brakes.
        If you did replace drums with discs, you can still turn it into a very sweet setup, by adding a hydrovac. Be sure to get the HV that is for discs instead of drums, as it provides the needed, higher PSI. Only plumb it through the front discs, and leave the rear drums without power assist.

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        • #5
          With most disc brake set ups you will need a booster. I've heard Wilwood has nice large brake pad and you can get by without a booster. But I've no experience with them. That was the Dunlop's problem--small brake pads so lots of pressure was required. (Just 'cause you have a hydrovac in the engine bay doesn't mean it works. Almost all have never seen maintainance.) Original drums are nice and big, are reliable, don't fade, and a simple upgrade in shoes can give you just as much stopping power as good disc brakes.

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          • #6
            Originally posted by Jeffry Cassel View Post
            With most disc brake set ups you will need a booster. I've heard Wilwood has nice large brake pad and you can get by without a booster. But I've no experience with them. That was the Dunlop's problem--small brake pads so lots of pressure was required. (Just 'cause you have a hydrovac in the engine bay doesn't mean it works. Almost all have never seen maintainance.) Original drums are nice and big, are reliable, don't fade, and a simple upgrade in shoes can give you just as much stopping power as good disc brakes.
            The size of the brake pad makes no difference other than you might be able to use a softer pad with a little higher coefficient of friction with a larger pad. The biggest reason that disc brakes require more force compared to most drum brakes is that the applied force on the braking surface is proportional to the brake pressure while the drum brakes are non linear due to the wedging action of the shoes. With a drum brake if you double the applied brake peddle force you might get 4x the braking force. This is also why drum brakes are harder to modulate than disk brakes. Now the size of the brake pads will make a difference in how long they will last.

            As far as drums not fading, made a couple of stops from 100 mph in a 1960 Hawk when I was 18. I learned very quickly what brake fade was! Took the car home and put it up on blocks and proceeded to change it to disc brakes. After that the only Studebaker without disc brakes was a 63 Hawk in which I installed metalic linings . Not as good as disc brakes but better than the standard drum brakes.

            You can use calipers with larger pistons or more pistons to get more piston area and higher forces. A smaller master cylinder piston will also increase the hydraulic pressure for a given peddle force. You can also change the peddle ratio to increase force at the brakes. Each of those changes will also increase required peddle travel.
            David L

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            • #7
              TXmark , please be sure to post an adequate title for your topics. One word titles are not very good for getting results, or for those searching for the same information. Thanks.

              Clark in San Diego | '63 Standard (F2) "Barney" | http://studeblogger.blogspot.com

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              • #8
                I have a '63 GT Hawk with Turner disc brakes, no hydrovac, and stainless braided hoses. The dual master cylinder is the Mitsubishi, with 1/2" cut off the previous Studebaker brake push rod that enters the mc. I have not had real issues with the amount of pedal pressures required, though its significantly more than power brakes. I did notice when I also added Turner rear discs and Fairborn flanged axles a few years later that the pedal pressure required now is even more satisfactory.

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                • #9
                  Wow...
                  IF...done with the proper parts, you DO NOT need a brake booster. Been there, more than once..!

                  To TXMark -

                  What size piston master cylinder did you use ? From your explanation, it sounds like either you installed the residual (anti-backflow) valves backward, or you used a too small a piston diameter master cylinder.

                  I've done this swap a few times, ALL without a booster, as in, no booster required for an easy two toe stop.
                  In all cases, I used a 1.00" piston master cylinder. I used caliper piston sizes from full sized GM and Ford cars, nuthin fancy.

                  One more possibility, how long is the brake pedal from the pivot to the pedal center ? It could be too short for the M.C. piston size that you used. If it's a top swing, you may have better luck with a smaller piston. If it's a floor swing, a 1.00" piston should be fine.

                  There is information all over the net, there are several good books you can read, to get the information that you need.

                  Mike

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                  • #10
                    Mike did you use a DUAL Master Cylinder as as Mark (TXmark) did?

                    THAT is where most get into trouble, using one, or the WRONG one.

                    Since we STILL do not know the answer to Paul's Post #2 Questions,
                    A lot of banter about how "Other Cars" worked, does not apply to THIS one, we don't know the whole story here. REAR Brakes do Matter!
                    StudeRich
                    Second Generation Stude Driver,
                    Proud '54 Starliner Owner

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                    • #11
                      I forgot to mention in post #8 that my brake pedal is from a manual car, giving more leverage. See pictures on Bob Johnstone's site showing both kinds with measurements.

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