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  1. #1
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    Leaky brake connections

    I rebuilt my ’76 Beta Coupe master cylinder and calipers and installed new brake hoses and copper crush washers. I tightened everything down, pressurized the system, and found brake fluid weeping from the connections to the master cylinder and calipers. I replaced the copper crush washers with aluminum as they’re softer but still have leakage. Apparently the mating surfaces on the master cylinder and calipers must be irregular so the crush washers won’t seal. The 3-way manifold/connector to the mixed circuit on the master cylinder must be irregular as well. I’m wondering if anyone has experienced a similar issue. Other than replacing the master cylinder and calipers, are there other alternatives? In place of the crush washers, I’ve seen a washer called Stat-o-Seal. Any experience with those? Also, are new 3-way manifold/connectors available anywhere?

  2. #2
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    Re: Leaky brake connections

    Yes. Some of the new MC's available lately are not properly machined around the female side fitting so the male end of the hose can completely seat and seal. I think I posted about this. Its hard to see what's happening in that location, and I went round with this until I figured it out. It was leaking quite a bit around the MC. I had to machine down the knob that sticks out on the bottom. I just did it with a grinder. I had to pull the MC back out to do it. I also replaced the plugs it came with, or put something in there to keep metal shavings out of the orifices . Be careful you remove enough that it will fit without interference but don't get too aggressive and get into the passages. I think there's enough room but just a word of caution since you likely can't return it after modifying.

    Once you pull it back out and look at fitting size, you should be able to see what the issue is.

    I couldn't find a replacement for that 3 way connector or especially that banjo/connector bolt at the MC.

    You can also get new copper washers for calipers, etc at hardware store. I recommend replacing and tightening down well. They should be able to seal if threads are clean and fitted carefully and tightened adequately. Provided both the calipers, metal and rubber hose ends all have proper end type fitting as original.

    I have never used stat-o-seal and so could not recommend.

    Dave

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    Re: Leaky brake connections

    The master cylinder is the original so it's the correct design. It worked leak-free for its entire life until I decided it was time for a rebuild (stupid me). And the copper crush washers were new as were the aluminum ones. I’m kind of at a standstill. I’ll keep the forum updated if I come up with a solution.
    Thank you.

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    Angry Re: Leaky brake connections

    You're NOT supposed to do this but. There's been times in my past that the ONLY way
    I could stop the weepage on top of the calipers was to use TWO copper crush washers.
    And tighten the bajo thru bolts like Hercules. As for your MC leaks ... dunno. Good luck.
    Last edited by davidb; 1st November 2019 at 05:45 AM. Reason: add

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    Re: Leaky brake connections

    If the banjo bolt is too long and bottoms out in the thread before fully compressing the crush washer, then adding another washer is a reasonable solution. But I’m using the original banjo bolt which is the correct length. I’ll check the height of the new hose fitting - maybe it’s undersized and causing the banjo bolt to bottom out.

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    Re: Leaky brake connections

    Are the hose fittings often a cause for bolts bottoming out?

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    Re: Leaky brake connections

    No, I haven't heard of Beta hose fittings being undersized, it's just another hypothetical that could contribute to the leakage.

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    Re: Leaky brake connections

    Perhaps the new crush washers you're using aren't as thick as the OEM ones they replaced, allowing the fitting to bottom out before achieving a full seal. Also, are you using a crush washer on top AND below the banjo fitting -- i.e., bolt head - washer - banjo - washer - caliper?
    Best regards,
    -Tye (1979 Lancia Beta Zagato spider)

    "In theory there's no difference between theory and practice, but in practice there is."
    -Jan L.A. van de Snepscheut

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    Re: Leaky brake connections

    I've measured all the crush washers:

    Original copper: 0.028"-0.030 (these were used and already crushed)
    New copper: 0.040"
    New aluminum: 0.033"

    Yes, I'm using 2 washers per bolt as you say.

    I guess after 40+ years the aluminum surface of the caliper has pitted to the extent that it can no longer hold a seal. I'll keep you posted when I find a solution. Thanks to all for your interest and help.

  10. #10
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    Re: Leaky brake connections

    See that’s what happened when I put on new hoses: it felt as tho the bolt was bottoming
    out. So I guessed what I call the hose “shoe” the bolt goes thru was thinner. All I know
    for sure is two copper bottom washers worked wherever I had weepage. Go figure?

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