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Technical Wish me luck...

Discussion in 'The Hokey Ass Message Board' started by David Gersic, Jun 20, 2020.

  1. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,181

    David Gersic
    Member
    from DeKalb, IL

    Going to do battle with some of that super smart brake fluid today.

    Driver side caliper started sticking, so its coming off.

    While I’m at it, the master cylinder needs to come off so I can get the pushrod set correctly. Right now, a couple of washers between the master and its mounting surface are providing clearance.

    Hoping the brake fluid doesn’t outsmart me.



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  2. blowby
    Joined: Dec 27, 2012
    Posts: 6,707

    blowby
    Member
    from Nicasio Ca

    If brake fluid is so smart why can't it bleed itself? o_O
     
    partsdawg and loudbang like this.
  3. Doublepumper
    Joined: Jun 26, 2016
    Posts: 617

    Doublepumper
    Member

    Brake fluid is smart...but it's really lazy. Have to give it a push to get it motivated;)
     
  4. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,181

    David Gersic
    Member
    from DeKalb, IL

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  5. My better half is a world class expert at “pump and hold”. I’m a lucky man.


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  6. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,181

    David Gersic
    Member
    from DeKalb, IL

    I haven’t t yet been outsmarted by the brake fluid. It’s still safely stored in its bottle, where it’s going to stay for a while yet.

    Swapped the caliper, no problem there. Couple slider bolts, one banjo bolt, and it’s off. Reverse and the new one is on.

    Then I tackled the master cylinder. I replaced the master a couple years ago, and it didn’t go well. Couldn’t get the system to bleed. Finally got them bled and working, but had them locking up. Was pretty sure it was pin to plunger clearance, so I added a couple washers between the booster and master, which worked, but bugged me as being wrong.

    So, I pulled the master and started measuring. First thing I found was this:

    [​IMG]

    adjustable pushrod, with the end cut off:

    [​IMG]

    That was the first clue that this wasn’t going to go well. The shortened pushrod doesn’t actually bottom in the booster. The flats of the nut end are just slightly too big to fit in the hole. So, yeah, it’s just riding on 1/64” of steel. That turns out to be ok.

    I made a depth gauge and started measuring. I could not come up with a pushrod length that made any sense. The master is from a local muscle car parts shop, and works with either manual (long pin) or power (short pin plus a plug to fill the hole in the plunger). But either setup was too long.

    I took the butchered adjustable rod and ground the flats off so it would fit in the hole. But even with the pushrod removed, I couldn’t mount the master to the booster without forcing it down on the studs.

    Pushing the brake pedal showed something interesting:

    [​IMG]

    [​IMG]

    The booster doesn’t push out the pushrod. It has a plunger that extends. And that plunger is what’s actually pushing on the master. The pushrod isn’t doing anything other than maybe keeping the plunger from the master centered on the master.

    That’s not going to work. After looking at a bunch of pictures, I think I’ve identified the booster as 1987 Chevy, but it takes some weird looking master. I pulled the booster, and will have to go get one that will actually work. That’ll probably mean running new lines too.

    Eventually I’ll get to the point of refilling and bleeding the system. But not tonight.

    Today’s lesson is that mismatched parts don’t work well.



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  7. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,181

    David Gersic
    Member
    from DeKalb, IL

    I work alone. Wife not the least bit interested in pump-and-hold. A check valve bleeding kit is my method of choice. I go high tech, though, using my phone to provide a remote view of the caliper to my tablet on the dash, so I can see what it’s doing.



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    loudbang likes this.
  8. LOL

    Ben
     
  9. Lol,,,,I didn’t think he was talking about bleeding the brakes,,,,LoL .
     
  10. blowby
    Joined: Dec 27, 2012
    Posts: 6,707

    blowby
    Member
    from Nicasio Ca

    Brake bleeding with my wife:

    OK honey, pump... hold...nothing, are you pushing?
    No, you said hold it so I quit.
    Argh, OK push down all the way.
    I can't, the seat's too far back.
    Shist, hang on.. OK, try it now.
    Your steering wheel is all greasy.
    Get out!
     
  11. You might need to check the rubber brake line, as they age they can and will collapse when hard braking, I chased my tail for a couple of months, I replaced the caliper and the brakes were still pulling. HRP
     
  12. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,181

    David Gersic
    Member
    from DeKalb, IL

    The hoses are new (2017). Caliper was hard to retract, even with the bleeder open so no pressure on it.



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  13. 34Larry
    Joined: Apr 25, 2011
    Posts: 1,256

    34Larry
    Member

    While cussing and cursing MSD as I have the past week, I also completely rebuilt my front brakes. Two new caliper pistons, (two of the four were okay, four new pads, bought and installed new inner and outer wheel bearings, & seals. Bought and installed new transfer pipes also and had new lines made up that were just barely long enough, adding more length of course. Have that all back together, looking good and so I am also going to get with Mr. DOT 3, right after my two daughters come for "our" (fathers) day. Mr. Mighty Vac, made his appearance last night and is awaiting his opportunity to once again do his magnificent job.
    And if you have followed my MSD rant of last week, (if you did, my sincerest of apologies), the new wires are complete on the car and next in that saga is wiring the new 1 million dollar distributor which is no big deal. All this is as the result of searching out and fixing the higher RPM miss that I pledged to do earlier this year before Satan decided to bless humanity with his favorite devilish pleasures.:mad::mad::mad::mad::mad:
     
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  14. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,181

    David Gersic
    Member
    from DeKalb, IL

    I’ve tried the vacuum bleed several times. A friend of mine swears by it. I’ve never gotten it to work satisfactorily.


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  15. The trick is to wrap all your bleeder threads with teflon tape. Without the tape, many will just suck air around the threads. Makes all the difference in the world....
     
  16. ramblin dan
    Joined: Apr 16, 2018
    Posts: 2,074

    ramblin dan

    I vacuum bleed my brakes all the time and yet to have any issues.
     

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