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Technical Mustang Master Cylinder Squirting

Discussion in 'The Hokey Ass Message Board' started by 53CHKustom, May 17, 2015.

  1. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Thanks! If I had lines above the m/c in height anywhere would I still have issues without the pressure bleeding approach?
     
  2. It sounds to me like your just over thinking this, girlfriend, wife, neighbor, anyone to just pump the pedal and it should get it handled in no time.
     
  3. jetnow1
    Joined: Jan 30, 2008
    Posts: 2,197

    jetnow1
    ALLIANCE MEMBER
    from CT
    1. A-D Truckers

    But keep the wife away from the girlfriend or it won't be the brakes bleeding!
     
  4. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Thanks I'll find someone to help. I just checked again on how it currently feels, the pedal doesn't go to the floor but it feels a little softer (not a huge amount though) after changing the rear shoes and wheel cylinders. When I pump vs non pumping it feels about the same in firmness.
     
    Last edited: May 18, 2015
  5. To be very honest, when I worked in shops, we used the Ammco pressure bleeders and did some manual bleeding if we had problems. On my Ford, I borrowed a vacuum bleeder and did it myself in the cold of winter. I did follow it up with manual bleeding a couple of rounds.
    The trick with finding a good helper is to train them on what to do, easy on the pedal, not to bottom out the piston in the master either. The person opening and closing the bleeders can also control what's going on by opening the bleeder only a slight amount towards the end. You also have to tell the pedal-pusher to go easier and ask how the pedal feels. The 3 best helpers I ever had for bleeding brakes were my mom, sister and my wife.
     
  6. sunbeam
    Joined: Oct 22, 2010
    Posts: 6,385

    sunbeam
    Member

    When you custom arc shoes they are arced to a smaller circle than the drum. Shoes that fit perfect do stop well in hard braking. Shoes will flex so under a lot of pressure the middle of the shoe will raise off the drum if they are arced a perfect fit. Take a shoe that is worn in it will not fit the drum. I had a car brought in that a customer had just bought you know the little old ladies car. The car had only been driven at slow speed and the car did not want to stop from highway speed. Took the shoes that had good lining and arced them and the car stopped fine.
     
  7. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Thanks. My last girlfriend hated helping me bleed the brakes so much.. I'm not asking any future girlfriends again :)
     
  8. This is how you weed them out... the good ones stick around. I dragged my wife around through 3 seasons of owning and driving stock cars, she married me anyway.
     
    clem likes this.
  9. unkledaddy
    Joined: Jul 21, 2006
    Posts: 2,865

    unkledaddy
    Member

    A couple of quarts of brake fluid, a couple of quarts of beer and your neighbor's daughter ought to get the job done!
    Just make sure she pumps slowly and doesn't bottom anything out.

    Bleed Baby, Bleed!!
     
  10. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    The pedal feels pretty good right now (compared to before) and I checked the system for leaks and see none except for the lid.

    I can hear a swish noise as I'm pressing down on the pedal so it must be squirting inside still. I have a leak from the rear of the lid still and I checked the seal and the surface the seal sits on and it seems ok. I put extra pieces of tubing on the lid clip just on the rear to try and get it to clamp there. It still leaks a little from there.

    I don't want to get another M/C replacement as this one was hard to put in and I have a heat shield, special types of fittings, etc that make it hard to get a wrench. I also had to grind the bottom of the flange to make it fit.

    Any advice? Would RTV be a feasible option? I head read another forum from a while ago where someone had a similar issue and tried that.
     
  11. I have never heard of a master cover leaking before. Make sure the gasket is clean and in place. The gaskets usually have a couple of little tabs to lock it to the cover. Make sure nothing is between the gasket and cover.
     
  12. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Thanks I'll check again but it all seems just fine, there is nothing between the gasket and lid. The lid and gasket are clean.

    The casting on the seal surface is a little rough on the back but not super rough. It is a Dorman M/C so not sure how great of quality part I have.
     
  13. Dorman's stuff use to be good. Check to see if the cover is bent. From there I'd say either replace it (a lot of work) or build up the flange with JB Weld and sand it flush. Does that react with brake fluid.. no idea.
     
  14. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Thanks, I had looked at the cover and it didn't look bent.
     
  15. Dooley
    Joined: May 29, 2002
    Posts: 3,089

    Dooley
    Member
    from Buffalo NY

    I had a mustang drum drum master that leaked out of the cover. it was pretty bad I had to get a new one, tried different covers and gaskets and even a double gasket.
     
  16. It's normal for the fluid to return to the M/C in a squirt. The rear shoe springs will pull the wheel cylinder pushrods back after brake application and push the brake fluid back to the M/C. It's imperative to get the lid to seal on the master cylinder because of that squirt.
    Regarding bleeding the system: If the master cylinder is physically higher than the wheel cylinders, I've found gravity bleeding is the very best way. Yeah, it's slow but no air bubbles are introduced into the system this way.
    If you're getting help bleeding the brakes I've found the best way is to have your helper simply push the pedal down with a single pump after you've opened the bleed screw....close the bleeder and repeat until no air comes out. The "pumper" should never "pump up" the brakes with repeated pumps as that aerates the fluid with tiny bubbles that won't come out. After a few minutes, the tiny bubbles coalesce into a single bubble again and your pedal remains soft.. one pump at a time works best for me and only if gravity bleeding is not an option.
    It sounds like you've almost got your brakes in operating condition right now....just a little final bleeding seems to be left to get a good pedal. BTW, if the shoes are not arced to your drums, the shoes will flex to the drum shape, causing the pedal to be soft as has already been discussed previously in this thread...either have them bent professionally or put up with a soft pedal until the shoes wear-in to the drum's shape.
     
  17. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Thanks for your advice. I don't think gravity bleeding would work because my M/C is underfloor and I believe the wheel cylinders are higher in height than the M/C.

    The pedal feels pretty decent right now and I imagine will change a bit once I drive it and the shoes break in to the drum shape.

    My biggest problem is the leaking from the squirt. It is annoying to have to change out the M/C. I'm not sure what else might get me by. Also the squirt is when I press on the pedal not when I release. Hmmm.
     
  18. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Thanks so I'm probably going to need another one? My only guess would be the casting surface not being super smooth. I could perhaps smooth it lightly with sand paper but not sure I should be doing that.
     
  19. Also........there's been no discussion regarding new brake "seating" in this thread. Its' important and there may be threads explaining this procedure. Real basically, it entails driving the car at about 30 mph and slowing as fast as you can without sliding the tires...do this 7 or 8 times and let the car sit a bit, cooling the linings and letting any errant air bubbles go to the master cylinder and going to the top of the fluid.
    Do this procedure 3 or 4 times and you should be good...don't slide the tires as doing that does nothing for your brakes and flat-spots your tires...pisses off the neighbors too.
     
  20. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Thanks for that advice.

    Regarding the leaking.. someone suggested to try using 1/16th" thick cork gasket material to make a gasket and double up on the rubber gasket.
     
  21. rfraze
    Joined: May 23, 2012
    Posts: 2,009

    rfraze
    Member

    Didn't you previously post that you were running the M/C with a low fluid level to help eliminate the leak? If so, the returning fluid may be squirting up on the lid, instead of just returning to bowl. Fill closer to top and see if that doesn't solve problem. Check with top off to make sure it is not squirting above top of fluid level.
     
  22. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Interesting, thanks. I was running a little under the halfway point and sometimes a little below that but it was still squirting higher than where the lid would seal.

    I will try your suggestion of filling closer to the top to see if the squirt goes away. I also think I should make it seal regardless of whether the fluid is squirting or not. If fluid can get out moisture can get in right?
     
  23. V8 Bob
    Joined: Feb 6, 2007
    Posts: 3,132

    V8 Bob
    ALLIANCE MEMBER

    Correct. The lid should be air-tight to prevent moisture from getting into the fluid.
     
  24. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    One interesting thing, I hear the swish (with the lid on) and see the squirt with the lid off as I press on the pedal not as I release. Could this perhaps be an issue with the space between the front seal and rear seal inside the M/C assembly and maybe fluid being pushed up the equalization port (I can't remember which hole the fluid squirts out of)?
     
  25. rfraze
    Joined: May 23, 2012
    Posts: 2,009

    rfraze
    Member

    I'd say, you are right. The seal should seal, but ... let's see if we can reduce the amount of fluid that hits lid. Think of a toilet tank lid. Water does not come out, unless there is a problem inside tank, which shoots water up on the lid.
     
    Last edited: May 22, 2015
  26. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Thanks. Part 1 will be for me to make it seal. I'm not sure on eliminating the squirting. It happens as I press down on the pedal so I'm confused on how the level of the fluid might affect the squirt since the fluid level has never gotten low enough for air to enter from the reservoir. The only slight effect from the fluid level I see is hydrostatic pressure to mitigate the squirt but it seems it would be a very small effect.

    What if there is a stubborn air bubble between the front and rear seal inside the M/C assembly. Maybe as the pedal pushes it compresses any air in that space once the second seal pushes forward.
     
  27. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    I forgot to mention I have a 10 psi residual going to the rear. There is probably a 10 psi residual in the M/C port going to the rear but I didn't check. I had read on ECI's website that having more than one can't hurt if you are unsure whether there is one already.

    When I press down on the pedal really slow it doesn't squirt up in the rear reservoir as I'm doing it.
     
    Last edited: May 22, 2015
  28. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    I imagine the fluid that squirts must be coming out like I've drawn in the red arrow below as the pedal is pressed. Maybe the geometry causing it to squirt that high.
    poopsa.jpg

    On mine, the front reservoir is larger than the rear however I had to remove a 10psi residual in the front. It must have been set up for front drum rear drum.
     
    Last edited: May 22, 2015
  29. rfraze
    Joined: May 23, 2012
    Posts: 2,009

    rfraze
    Member

    What happened when you raised fluid to near top? Squirt went away, right?
     
  30. 53CHKustom
    Joined: Jun 24, 2014
    Posts: 1,433

    53CHKustom
    Member

    Hi I put fluid about 3/4 up to a little more and the squirt didn't go away. I did get the the lid to seal with cork but not sure I should keep chasing the squirt issue?
     

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