Close



Results 1 to 6 of 6
  1. #1

    Default Multiple master cylinder failures?

    I bought my 86 Mustang five years ago, and have had to replace the master cylinder four times. It's showing the same symptoms again. I've flushed the system, used new master cylinders, rebuilt cylinders and even a nos Ford cylinder. Each one lasts a year or less. Even had one fail completely without warning leaving me with no brakes at all, which I didn't think could happen on a dual circuit system. Has anyone else experienced this or have a possible solution?

  2. #2

    Default

    It's hard to say without knowing more, and inspecting the MC in person.

    Some questions:
    1) Where did you buy the MCs?
    2) What brands did you buy?
    3) What are you using for brake fluid?
    4) How are you bleeding the system?


    You may have been getting counterfeits. Counterfeit auto parts is a SUPER MASSIVE MEGA market!!
    Unfortunately, you can not buy a new Ford part, made by Ford, from a Ford dealer, and bought in person.
    Imho, anything else, and you're playing Russian Roulette. That's real life. :-|


    Fwiw, Many/Most replacement Delco/GM parts are rebranded PURE CR*P! I have 3 GM older cars. I speak from a lot of experience.
    So, don't buy a Delco replacement part, and think that you're getting anything that makes any sense on installing on any vehicle (for other than looks, and being non-functional).


    Imho, a MC is dirt cheap!
    Don't screw around, buy a good Name Brand part, from a Top company:
    https://www.summitracing.com/parts/agb-mc39531

    Also, use at least Prestone Dot4 brake fluid. There are better brake fluids.
    However, Prestone isn't expense, and is easy to get.

    Bleed brakes the using the only proper method - pressure bleeding. Other methods "may work". Then again, driving while high on cocaine, and pig drunk "also works" sometimes for people. Many reasons why the other brake bleeding methods are a joke. Although, pressure bleeding one of those cast iron MCs can be a PITA, messy, requires some skill/experience, and it requires a GOOD heavy-duty pressure plate.

    I have not used the Motive early model pressure plate. It looks half-decent:
    https://www.motiveproducts.com/colle...nd-marine-kits


    Name:  0105_1024x1024.jpeg
Views: 91
Size:  63.2 KB



    Fwiw, I have a professional Diaphragm-type pressure bleeder (current model - https://www.amazon.com/GEARWRENCH-37...dp/B003U459B8/) and adapters. Imho, I've wasted far too much time in the past screwing around doing things the cheap/half-@ssed way.
    Fwiw, after doing my M2300K brake upgrade, I was having a hard time fully bleeding the rear brakes. My former neighbor (passed away ) was a professional mechanic and also my mentor. He brought over his professional Diaphragm-type pressure bleeder and professional adapter plate, we bleed the whole brake system in a near blink of an eye! :-O
    I then went out and bought my own $$$$ setup. Expensive, yes. But, over the past ~20 years, it has saved me a ton of time. Especially since I like to bleed my Stang's brakes every year (after it's been sitting over the winter).


    Good Luck!
    Last edited by stangPlus2Birds; 03-20-2021 at 07:25 PM.

  3. #3
    FEP Power Member Broncojunkie's Avatar
    Join Date
    Jan 2015
    Location
    Barboursville, WV
    Posts
    1,773

    Default

    Have you tried pulling one apart to see what happened? You can even buy rebuild kits, if you want try that. If you dismantle it and find the specific problem, it should help you prevent it happening again.
    79 Pace Car - 331, t5
    79 Pace Car- 302, 4 spd
    79 Cobra - working on 351w, t5
    82 Capri- working on 302, t5
    82gt - working on 408w, c4

  4. #4
    Moderator wraithracing's Avatar
    Join Date
    Jun 2010
    Location
    Grand Junction, CO/RR TX
    Posts
    14,206

    Default

    I would recommend verifying your pushrod length in the Booster before doing anything else. Sounds to me like maybe your pushrod is adjusted too long and is over stroking the M/C and damaging them internally.
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  5. #5
    FEP Senior Member Patrick Olsen's Avatar
    Join Date
    Mar 2013
    Location
    Where the Navy sends me...
    Posts
    680

    Default

    Quote Originally Posted by wraithracing View Post
    I would recommend verifying your pushrod length in the Booster before doing anything else. Sounds to me like maybe your pushrod is adjusted too long and is over stroking the M/C and damaging them internally.
    That's what I was thinking.

  6. #6
    FEP Power Member Broncojunkie's Avatar
    Join Date
    Jan 2015
    Location
    Barboursville, WV
    Posts
    1,773

    Default

    Fwiw, I can tell you what happened to mine when the pushrod was to long. The brakes would work fine, but then the rears (drums) would start dragging. I could pull over and let them cool down and they'd be fine again. It wasn't the brakes cooling down, but the master cylinder area. The heat from the engine would create enough expansion to where it was basically like I was touching the pedal. I'm not saying your results can't be different, but that's my one and only experience.
    79 Pace Car - 331, t5
    79 Pace Car- 302, 4 spd
    79 Cobra - working on 351w, t5
    82 Capri- working on 302, t5
    82gt - working on 408w, c4

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •