Brake Pedal Goes Slowly to Floor

Discussion in 'Ranchero Tech Help' started by colnago, Nov 29, 2018.

  1. colnago

    colnago In Fourth Gear

    Messages:
    309
    Location:
    Ridgecrest, CA
    Okay, I have drum brakes all around on my '64. I've had the car a little over a month. When I first got her, the brakes were very firm, and very responsive. The other day, I was sitting at a stop light, and the pedal slowly moved to the floor. I had to use my foot to pull it back in place. Since then, it seems like it doesn't take as long for the pedal to move down (sometimes it moved down in the middle of braking), but it always springs back if I lift my foot off the brake (it was only that one time where I had to actually lift the pedal back up).

    I checked the reservoir this morning, and it was full, but it was very dark. So, I probably don't have a leak in the system. If I do, it's letting air in, but it's not letting fluid out. The Master Cylinder is pretty crusty, though. It has a single reservoir, and a single line going out from the pressurized side. Right now, I'm thinking that I need to replace the MC, and run some new fluid through the system. But I've never had a combined front/rear brake system before.

    Would a faulty wheel cylinder affect the whole system? It seems to be getting worse over the last few days. Are there other things to look at? At the very least, I need to run new brake fluid, just to clear out an unknown age of crud.

    Joseph
     
  2. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Very poorly adjusted rear brakes can cause that, but most likely you need a new MC or to rebuild the one you have.
    The crud does need to be flushed out also.
     
  3. Mark Wiggins

    Mark Wiggins In Second Gear

    Messages:
    47
    If the pedal goes slowly to the floor without losing fluid you have a bad master cylinder. You can rebuild or replace it. Yes the fluid should be flushed, if it was mine I would do the wheel cylinders also.
    Mark
     
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  4. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Is your MC a single-pot one? This might be a good time to upgrade to a dual chamber unit, if it isn't.
     
  5. colnago

    colnago In Fourth Gear

    Messages:
    309
    Location:
    Ridgecrest, CA
    It is a single-pot MC. Right now, the priority is just to get brakes working again. I think you're right about splitting it up, long-term. Maybe I can start planning to do that after the holidays. Probably be a @#$%^& to get the lid on a dual-pot MC, though, because it sits right under that welded-in diagonal brace.

    Joseph
     
  6. Jeff B

    Jeff B In Maximum Overdrive BRONZE MEMBER

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    If you have no booster (manual brakes) have a look at where the master bolts to the firewall and under the dash where the rod comes thru and see if you can detect any fluid leaking out of the back of the master. It does sound like a master
    and there are a number of Mustang single to dual MC conversions to look at to see if it something you want to tackle.
     
  7. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

    Messages:
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    Location:
    Portland OR
    colnago, a new single pot M/C would be the easiest & least costly. I installed a dual M/C for my front disc brakes, and although it's not quite as accessible as the single, it's not really a problem; you can pop off the cap & pour fluid in just fine. This photo looks worse than it actually is:

    MC plumbing.jpg
     
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  8. colnago

    colnago In Fourth Gear

    Messages:
    309
    Location:
    Ridgecrest, CA
    BB,

    What did you use for the front disc brakes? Did you get a kit, or did you scrounge it from some other vehicle? Maybe a later-model Ranchero or Mustang?

    Joseph
     
  9. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Yeah, that pesky brace. But as Beerbelly said, there is just enough room to pop the lid and be able to pour (I'd wrap scrap plastic around the brace and tape it before pouring, as I had a customer with a '68 Cougar that was in fairly solid condition).
     
  10. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    Location:
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    colnago, I can't say enough good things about this place I got my kit:
    http://www.chockostangclassicmustang.com/discbrakepowersteering/discbrakeconversions.html
    Good price on quality parts, and he (Dan) personally answers the phone every time you have a question. You can go down to your local NAPA, O'Reilly's, Autozone etc. and get replacement parts for any '65-'67 Mustang.

    The issue you will have for your '64 is you will need to change some of your steering components (spindles, center link) to '65 V8 manual steering parts. My car came that way, but the components and geometry changed (for the better) in '65. Contact Dan at Chockostang and he'll let you know what you need.
     
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  11. colnago

    colnago In Fourth Gear

    Messages:
    309
    Location:
    Ridgecrest, CA
    Wow, that's cheaper than I expected!

    Joseph
     
  12. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    Location:
    Portland OR
    Yeah, and it's one of the few kits that includes the dual M/C and a proportioning valve. I did have to do a little brake line fitting, but otherwise, no issues. You won't find better customer service- tell him Jay sent you.
     
  13. TestDummy

    TestDummy In Maximum Overdrive SILVER MEMBER

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    Do what he said ^^^^^
     
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  14. MaxInValrico

    MaxInValrico In Maximum Overdrive GOLD MEMBER

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    1,967
    Get yerself a dual chamber MC.
     
  15. colnago

    colnago In Fourth Gear

    Messages:
    309
    Location:
    Ridgecrest, CA
    For now, I replaced the singlepot MC with an identical unit. I tried to flush out the old system, thinking that something could have jammed under the lip of the piston, but it didn't help. So, I swapped in a new MC. It's very good to stop again! Maybe after the holidays, I can look into a dual-pot unit.

    I don't think the old unit was the original, since it had a plastic lid. But the old fluid sure was blecch. The exterior of the old MC was pretty crusty, too.

    Joseph
     
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