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Do disc brake kits need power assist?

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  • Brakes: Do disc brake kits need power assist?

    It would be interesting to hear from members who have personal experience with any of the disc brake conversion kits that are available for Studebakers like Turner and Hotrodandbrakes. Most modern cars with disc brakes have power assists. The few times I've heard talk about cars with factory disc brakes and no power assist it has sounded like the pedal pressure required was very high. What is the feeling from people who have used the kits? I know the stopping power is much improved, but is the pedal pressure something that might be a deterrent perhaps to your wife or teenage daughter? And what have users done to convert the disc systems to power assist? Thanks.

  • #2
    I have had both. The short answer is no, not at all. Going from non-power drums to non-power discs is still a good step in the right direction. It takes a bit more input from the right foot, but it is not at all a problem if the master cylinder is big enough. I also have a 70's Porsche which has 4 wheel disc brakes without power assist from the factory and it stops better than anything else I own.

    The lark has been converted to 4 wheel power disc brakes, which works very well, but I think it's actually overkill. I have to be rather mindful of how quickly I apply pedal because it will lock up all four on gravel without effort.

    Hope that helps.

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    • #3
      Originally posted by hitbyastick View Post
      I have had both. The short answer is no, not at all. Going from non-power drums to non-power discs is still a good step in the right direction. It takes a bit more input from the right foot, but it is not at all a problem if the master cylinder is big enough. I also have a 70's Porsche which has 4 wheel disc brakes without power assist from the factory and it stops better than anything else I own.

      The lark has been converted to 4 wheel power disc brakes, which works very well, but I think it's actually overkill. I have to be rather mindful of how quickly I apply pedal because it will lock up all four on gravel without effort.

      Hope that helps.
      I have to disagree. Not a Studebaker, but I converted my '59 Sprite from drum brakes to front discs, no power boost. The pedal effort went way up, perhaps double. I was able to reduce the pedal effort by going to a smaller (3/4" bore) master cylinder from the original 7/8" bore. A larger bore master cylinder increases the pedal effort.

      Disconnect the vacuum boost on any modern disc brake car, and you'll need both feet on the brake pedal.

      Factory original is a different animal. Those cars will have the correctly proportioned cylinders.

      Locking up on gravel is meaningless. If you can't lock up on clean, dry pavement, your brakes are not good enough.

      Comment


      • #4
        Yes, No, Maybe. It all depends upon:

        1. The pedal used; the power brake pedal is different than the manual brake pedal.
        2. The friction material used. Since essentially all OEM disc brakes today are vacuum or hydroboost assisted, a harder friction material is chosen for longer wear and reduced fade. It's difficult to find the old-school softer pads and shoes.
        3. The diameter and weight of the tires and wheels. Larger diameter wider tires have more rotating inertia. Takes more effort to whoa them down.
        4. Disc/drum or four-wheel-discs?
        5. The size/weight/strength of the driver. We have a member here who's a fine figure of a man and has driven without power assist for years. Take a more lightly built female or a member who's getting way up in years, he/she won't be safe without power assist.

        jack vines
        PackardV8

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        • #5
          I’ve wondered about this modern disc brake stuff. I found a Turner brake setup at a swap meet about fifteen years ago. I bought it to install on my son’s 63 disc brake GT Hawk. I was told you didn’t need the booster which intrigued me as his booster was acting up. Have never installed the setup but eventually will. I think it used Mustang or Chrysler pads? I know the surface area of the pads was at least larger by a factor of two or more.

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          • #6
            I'm going to use the Turner 4 wheel disc system on my '64 GT Hawk. I am also adapting a suspended pedal (Lark) and adding a power booster. At this point I don't know what master cylinder I'll use, I need to talk to Jim Turner about it. I want it to be easy for my wife to drive and the power assist will make us feel more confident about it's safe operation. Bill

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            • #7
              It depends on what you are replacing and the master-cylinder it used if you are going to continue with that m/c. If you have a m/c that required a booster to work originally, it will continue to do so with almost any conversion. All the best.

              Comment


              • #8
                Originally posted by PackardV8 View Post
                Yes, No, Maybe. It all depends upon:

                1. The pedal used; the power brake pedal is different than the manual brake pedal.
                2. The friction material used. Since essentially all OEM disc brakes today are vacuum or hydroboost assisted, a harder friction material is chosen for longer wear and reduced fade. It's difficult to find the old-school softer pads and shoes.
                3. The diameter and weight of the tires and wheels. Larger diameter wider tires have more rotating inertia. Takes more effort to whoa them down.
                4. Disc/drum or four-wheel-discs?
                5. The size/weight/strength of the driver. We have a member here who's a fine figure of a man and has driven without power assist for years. Take a more lightly built female or a member who's getting way up in years, he/she won't be safe without power assist.

                jack vines
                Jack is exactly correct here.

                There are a LOT of variables to be considered. I changed the drum brakes on my VW to four wheel disks with no power, using the same master cylinder, and it stops great! Easily 200% better with just a tiny bit more required pedal effort. It doesn't always work out that way though. About 30 years ago we put disk brakes (no power) on the front of my dads '53 Coupe using a kit from Dave Leveque. He is and has been very happy with them since. I had not driven his car until a couple years ago, and I don't know how he can get it to stop. He still says it stops great, and he's over 80, 24 years older than I. I can't drive his car, it takes way more pedal effort than I can muster for more than a couple stops. My stock '62GT no power drum brakes required FAR less pedal effort and will stop the car in FAR less distance than I can stop his car in. I still found the GT's stock brakes to be barely adequate for driving in today's California traffic. I swapped them for the entire 4 wheel power disk system from a 2004 Mustang. The two cars have the same weight bias and overall weight (actually the Hawk is a little bit lighter).
                sigpic

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                • #9
                  I installed the Turner front disks on my '64 Daytona HT without a booster. The resulting pedal effort was just about the same as the drum brakes had been. Unfortunately, i don't recall the M/C diameter that I used.
                  Jim Bradley
                  Lake Monticello, VA
                  '78 Avanti II
                  sigpic

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                  • #10
                    OK Hijack time.... Does anybody know what that pad material is called that some folks are using? it's supposed to be much better at stopping non-power discs.

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                    • #11
                      It is a question of hydraulics.
                      What pressure do you need at the caliper to obtain the braking effort you need.
                      How do you mechanically create that pressure based on pedal effort?
                      There is some mechanical multiplication done at the pedal pivot level.
                      But most of the pressure creation has to do with master cylinder piston size/stroke as it relates to caliper piston size/stroke.
                      Change one thing, it changes everything else.
                      Keep your quest simple and do
                      not try to skimp when it comes to brakes.
                      HTIH (Hope The Info Helps)

                      Jeff


                      Get your facts first, and then you can distort them as much as you please. Mark Twain



                      Note: SDC# 070190 (and earlier...)

                      Comment


                      • #12
                        Originally posted by Mrs K Corbin View Post
                        OK Hijack time.... Does anybody know what that pad material is called that some folks are using? it's supposed to be much better at stopping non-power discs.
                        A legitimate question.
                        The answer is as clear as marketing mud.
                        But... In basic terms...
                        The more aggressive the brake pad/shoe material, the more aggressive the braking will be.
                        The tradeoff is disc/drum life and brake noise. The softer the pad/shoe, the smoother the braking effort is, and the longer the disc/drum life will be.
                        Usually the softest pad/shoe lining is the OE initial install. The OE's major concern is customer satisfaction and getting through the warranty period.
                        HTIH (Hope The Info Helps)

                        Jeff


                        Get your facts first, and then you can distort them as much as you please. Mark Twain



                        Note: SDC# 070190 (and earlier...)

                        Comment


                        • #13
                          I only buy Callahan brake pads. The warranty on the box makes me feel good.
                          Attached Files

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                          • #14
                            To add some serious content, I do run non-power disc front and drum rear on my Studebaker. But there is nothing Studebaker in the entire system so not sure how relevant my experience would be. I read up on pressure and pedal ratio a lot first, so tried to engineer it properly. I don't mind the brakes, but it does require a pretty heavy foot. I used a pedal from a power brake truck, then relocated the hole to get a better ratio. It's still not ideal but better.
                            I never once considered brake pad material, but after reading this thread I might now.

                            Comment


                            • #15
                              To K. Corbin, the pads you are asking about are EBC "Green Stuff" per prior threads on these pads. Supposed to be very good, and I intend to find them for my Hawk when the time gets here. Hope this helps you, Bill.

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