soft pedal, brake lights stay on

Discussion in 'The whoa and the sway.' started by brothermo, Feb 2, 2016.

  1. brothermo

    brothermo Well-Known Member

    I'll work on that. If you can recommend a good source I'd be glad for one. When I looked before, all I came up with were reman units. Part number is 18M1048.

    Thanks, Lou.

    -Matt
     
  2. GSX 554

    GSX 554 Gold Level Contributor

    Is this a Disc brake car ???


    http://www.rockauto.com/en/moreinfo.php?pk=496384&cc=1017504&jsn=497

    Rock Auto lists a lot of brands . Some say REMAN on the title . This is a Delco that should be NEW

    I'm sure even Napa can get one if you tell them you want NEW.
     
  3. brothermo

    brothermo Well-Known Member

    Yes, discs up front, drums in the back. When I went looking for MCs the first time, the biggest challenge I ran into was finding one with the ports on the engine side of the unit. I'm searching now...
     
  4. CJay

    CJay Supercar owner Staff Member

    A few years ago, the master went bad on my 71. I went through 4 reman masters. I thought I was losing my mind. I finally got ahold of a new one and problem solved
     
  5. GSX 554

    GSX 554 Gold Level Contributor

  6. brothermo

    brothermo Well-Known Member

  7. brothermo

    brothermo Well-Known Member

    NAPA has an MC that will fit, but I'll need to order it. I have confirmed that the one I got from RockAuto previously WAS new.

    I am trying to submit a warranty claim with RockAuto, which is currently being rejected (by the automated system, not a person) because "the part was not intended to fit this vehicle." I'll call customer service in the morning to try to work this out, but it brings up a question.

    Why are all the MCs (Moraine) listed for my vehicle (1970 Estate Wagon) ported on the left not on the right? I have seen no indication as I worked on the brake system of my wagon that anything fundamental (e.g., hard lines, valves) has been changed from stock. The MC I'm replacing is a reman unit, ported on both sides. The right side ports were hooked up to the hard lines, the left side ports are plugged. The apparent originality of the brake system combined with the choice to use the right side ports on the reman unit leads me to conclude that the original MC that left the factory was ported on the right, yet auto parts stores don't show any with that configuration for a 1970 Estate Wagon (that I have seen).

    I have my theories as to why this may be, but they're purely speculative. Anybody out there who can shed some light? If nothing else, it may help me in my conversation with RockAuto in the morning...:TU:
     
  8. CJay

    CJay Supercar owner Staff Member

    I think there were two different masters for a big car. Bendix or Moraine. The Bendix style has a stop screw on the bottom of the cylinder
     
  9. telriv

    telriv Founders Club Member

    On the '70 Estate wagon I had many years ago the lines went to the right. That system is now on my Riv. & they STILL point to the right.
     
  10. brothermo

    brothermo Well-Known Member

    The update: RockAuto won't do anything about the warranty because the MC I purchased is not listed in their system as a fit for my vehicle (AC Delco part #18M1048). Can't say I'm very happy about that resolution...

    Still in the hunt for an MC that is correct (and new). I've found Cardone 10-1420. A brake rebuilder in Dallas suggested that part number, and so far the part appears correct. Can anyone here confirm? Can't find it new (yet).

    Thought I'd found a possible MC at Napa, but the ports are on the wrong side for my application.
     
  11. CJay

    CJay Supercar owner Staff Member

    Do you have the original master that was on the car? If so, why don't you just send it out to Apple Hydraulics for a sleeve and rebuild?
     
  12. brothermo

    brothermo Well-Known Member

    Jason, I've had the same thought. I called the place I've done business with before, but they no longer do the sleeving/rebuilding. I'll give Apply Hydraulics a call. Have you had experience with them?

    Thanks for the suggestion.

    -Matt
     
  13. CJay

    CJay Supercar owner Staff Member

    They rebuilt the master on my Riviera this past spring. They did a great job. But be warned, they aren't cheap. The rebuild cost me $250.

    Quality is remembered long after price is forgotten!
     
  14. brothermo

    brothermo Well-Known Member

    No question. Sometimes you get what you pay for.
     
  15. brothermo

    brothermo Well-Known Member

    Update:

    Found the correct part number for the MC: Cardone 10-1420. Can't find it new, but O-Reilly has the reman available, so I got one.

    Bench bled the MC, installed. Pressure bled all 4 wheels (about 20 psi). Same result as before: still no firm pedal, rear brake lights on. I suspect my issue is with the front part of the system. Tomorrow I'm going to plug the front reservoir on the MC and see if I get a firm pedal for the rear drums. Make sense?

    Any chance a faulty hold-off valve would cause the problems I'm experiencing?

    The wife suggested that perhaps the devil is farting directly into the hydraulic system. That's at least as good a theory as any I've come up with thus far. :)
     
  16. CJay

    CJay Supercar owner Staff Member

    Lets backup for a moment. What was the reason for the overhaul? Was there an issue with the master and booster that it was replaced or was it replaced as preventative maintenance as part of the overhaul? If there is nothing wring with the original master and booster, and they are "known good" parts, as a last resort why don't you reinstall the originals back on and see if the problem goes away?
     
  17. brothermo

    brothermo Well-Known Member

    Yes and no. I had not touched the brakes since I bought the car (2013), and it was time for pads and shoes. I decided to replace calipers, wheel cylinders, and MC (and hoses) as a preventative, since I didn't know when they had last been attended to. That said, in the 3 weeks or so before doing the brakes, I was losing pedal pressure when stopped (pedal would very slowly sink toward the floor at stoplights, when parking, etc.).

    I sent the original vacuum booster for remanufacture. I have no reason to believe that it is not now working exactly as it should. The master cylinder I pulled (a reman, not the original), on the other hand, is fairly crusty. I'm hesitant to put it back on the car, for fear of sending trash through the brake lines and fouling the new parts downstream.
     
  18. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I can tell you this. If you look in the Buick Chassis Manual, they tell you to depress the pin on the hold off valve when bleeding a disc brake system. The pin is under the rubber boot on the hold off valve. Most people either don't know this, or disregard it, and manage with no problems, but the fact remains, it is in the Chassis Manual.

    The hold off valve is there because of the difference in disc and drum brakes. Drum brakes operate with some clearance and have to overcome spring pressure to apply. Disc brakes are almost instant acting in comparison. The hold off valve "holds off" the disc brakes until a certain pressure is attained in the drum brake half of the system.

    There is a special tool to depress the pin in the hold off valve, but a C clamp works just as well. I've posted this a number of times over the years. Might be worth a try?
     
  19. brothermo

    brothermo Well-Known Member

    Thanks for the insight, Larry. I will definitely give it a try. So I'm clear - the pin on the hold off valve should be depressed the entire time I'm bleeding the front brakes, then released?

    Thanks,
    Matt
     
  20. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    No, leave it depressed for the entire bleeding operation.

    [​IMG]
     

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