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Thread: SoCal brake pedal - how much travel needed to floor?

  1. #1
    NSRA member Tudor Simon's Avatar
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    SoCal brake pedal - how much travel needed to floor?

    Evening all - please can anyone using SoCal brake pedal set up measure the travel they have between the back of the pedal and the floor/toeboards?

    I'm building the floor, toeboards & tunnel for my 32 at the mo and trying to set up brake pushrod length relative to getting decent travel and position of toeboards etc - using standard SoCal chassis & brake pedal, non-power MC.

    Question is how much of the (very long) pedal stroke is actually needed once its all bled and working? - I don't want the pedal standing miles off the floor as it makes it tricky to switch from gas to brake, so how much travel is needed in the real world?

    I ask because I would need to space the toeboards closer to the driver to allow the 'under floor' half of the pedal to sit fully parallel with the underneath of the board like an original car, as the firewall angles don't match the pedal position properly. The neatest build would lose me maybe 1" off the end of the possible travel (empty MC). As this would end up with the brake pedal sitting really high up anyway and a shorter pushrod fits below my planned floor, question is does the MC need its full travel? I doubt it

    Thoughts appreciated
    Simon

  2. #2
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    Isn't this a mathematical quiz? I think it must be! Master needs the ability to be fully stroked even if it won't necessarily see that in normal service. That's probably 1" or 1.25" - measure it. Pedal ratio? Measure and work out. Lets say it's 5:1. So in this example the pedal stroke needs to be itro 5 to 6 and a bit". Shorten the pedal under the pad to suit. This will affect the pedal ratio ever so slightly. Best make up a card or ply version first?

    The master needs the full throw
    1. for bleeding (and down the line would you fancy having to remove the floor to re-bleed the brakes? Admittedly vac bleeding etc could sidestep this)
    2. to maybe give a bit more fluid that might just help stop you, or lose some speed, in a major fluid loss situation.



    Chris
    Bumper sticker - This is an historic vehicle and only has three speeds....... if you don't like this one you sure as hell won't like the others.

  3. #3
    NSRA member Tudor Simon's Avatar
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    Thanks Chris
    Geometry is pre-set by the SoCal pedal & brackets and works out about 5:1 which is obviously well proven.
    The pedal has the usual 90 degree shape and the lower half normally sits below the floor with the upper half sticking into the car. On mine, to get full travel to bottom out the MC piston would need the pedal to start its travel with the bottom part of the pedal sitting a little ABOVE the natural toeboard position, which would need a recess in the floor to allow the pedal to ocme up further - seems excessive and I don't think anyone actually sets the pedal this high- there must be a happy medium in practice with pushrod length to allow it to sit below the floor and still have enough travel left?
    cheers
    Simon

  4. #4
    NSRA member kapri's Avatar
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    A properly sized m/c should give 10-12 mm travel AT m/c . Multiply that by pedal ratio and that SHOULD be the amount the pedal moves to full application. As Chris said needs full stroke to bleed unless you vacuum bleed so a removable section of toe board would be best practice.
    Galations 6:7

  5. #5
    NSRA member Tudor Simon's Avatar
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    Food for thought thanks guys, have only mocked up so will change tack a little.

    Still interested in pedal to floor distance if anyone can measure theirs using a SoCal chassis/pedal please
    Simon

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    Sounds like your pedal pivot point is too far forward relative to the toe board position. Having said that I've don't recall anything aftermarket fitting like you'd expect it to, even for specific applications as opposed to generic, one size fits none types. Reshape or remake the pedal?

    You could just rotate the pedal down so it sits where you want. If you do this watch out for the 'clocking' of the pedal where it connects to the rod. This want to start at say 4 o'clock and end at say 8 o'clock (or 5 and 7 or similar, but not start at say 6 or 7 o'clock as by the time it's rotated to 8 or 9 o'clock the movement on the rod is more or less vertical and not linear. If you have this issue you might get away with just redrilling the pedal, else it's a cut off, reshape and glue back on.

    Any such misalignment can also bind the rod into the master, but possibly not on the SoCal as that has an extended rod iirc.

    Fun, innit

    Chris
    Last edited by Happydaze; 07-11-18 at 02:12 PM.
    Bumper sticker - This is an historic vehicle and only has three speeds....... if you don't like this one you sure as hell won't like the others.

  7. #7
    NSRA member kapri's Avatar
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    This confirms that I should throw together a booklet listing all the tricks and wheezes of how brakes work, how to size etc etc that I'v learned over 45 years rodding and selling brake componentswith many technical courses attended . So many peopel build a car and then say " what m/c should I fit? " or " I can't get a m/c to fit ?" when it should all be planned as a package from the outset , a brake m/c shouldn't just something you find room for

    Mind you, it's alright writing one , would anyone ever buy it would mean admiting not being born knowing everything ?
    Galations 6:7

  8. #8
    Guest yjohnb's Avatar
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    Quote Originally Posted by kapri View Post
    This confirms that I should throw together a booklet listing all the tricks and wheezes of how brakes work, how to size etc etc that I'v learned over 45 years rodding and selling brake componentswith many technical courses attended . So many peopel build a car and then say " what m/c should I fit? " or " I can't get a m/c to fit ?" when it should all be planned as a package from the outset , a brake m/c shouldn't just something you find room for

    Mind you, it's alright writing one , would anyone ever buy it would mean admiting not being born knowing everything ?
    I for one would definitely by one , we sat last night trying to remember how bore size of MC effects braking , eventually following some digging of literature, we remembered.

    Our situation on the altered was we needed more pressure as we don’t have vacuum assist for the rear disc brakes, answer in part smaller bore MC.

    So if you write an guide I will happily donate, put me down for one .

    Cheers

    John


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  9. #9
    NSRA member nitro1471's Avatar
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    Quote Originally Posted by yjohnb View Post
    I for one would definitely by one , we sat last night trying to remember how bore size of MC effects braking , eventually following some digging of literature, we remembered.

    Our situation on the altered was we needed more pressure as we don’t have vacuum assist for the rear disc brakes, answer in part smaller bore MC.

    So if you write an guide I will happily donate, put me down for one .

    Cheers

    John


    Sent from my iPhone using NSRA mobile app

    I would buy one as well, so if there is a list please add me
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