Cause these are the brakes!
#1
Hey guys. Last weekend I replaced the front suspension on my Mach. While I had it all out I cleaned up the front calipers, replaced the flexible lines and copper washers. I flushed the brake fluid and then bled the system. I go out for a drive and its just awesome now except that the front brakes are not releasing. Turning the bleeder valve released the calipers so I am pretty sure its not them. I didn't have this issue prior to the removal.

Any ideas? I have never had this issue on any previous car and am kinda stuck (pun intended).

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#2
I don't know what could of happened during the flush and bleeding to cause this condition. It is usually the master cylinder or the push rod between the master cylinder and vacuum booster is too long that causes issues like that. Does the brake pedal feel the same as it did before the bleeding and flushing? Are the calipers are lubed well with brake caliper synthetic grease at all the sliding points and not sticking?

Regards,
Mike
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#3
Very possible the flushing loosened some sediment crud etc. that plugged the master cylinder and its not releasing. Try this pull the cap off the master cylinder and slowly push the pedal down as far as you can. Now take your foot off the pedal quickly, while watching the fluid in the master cylinder you should see a small geyser in the front /larger chamber, indicating backflow of fluid when released. You may even see some backflow in the rear chamber. But the front chamber is the one we're worried about since it controls the front brakes. Give that a shot and let us know what happens. Hope it helps JTS 71 Mach1
"We built these cars to drive the "HELL" out of them, not to be museum pieces!"  Carroll Shelby

2008 Mustang V6 5 speed "Diablo Sport Predator" tuner, 87 octane tune. WOW!
1994 Ford F150 Shortbed
1986 Honda 450 Rebel
1995 Honda Pacific Coast
1989 Jacobra / Jag xjs
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#4
If my memory is correct on disk/drum dual reservoir master cylinders, there is usually a large and small reservoir in the master cylinder. The large reservoir is tied into the front disk brakes. On front disk/rear drum systems the front disk brake calipers require more fluid and fluid movement than the rear drum brake wheel cylinders. Thus, the disk brake calipers are tied into the larger pistons and larger reservoir of the master cylinder, usually the rear reservoir.

Regards,
Mike
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#5
The large rear section is for the front brakes.
Back to the problem - I would guess that when the bleeding was being done the full stroke of the cylinder was used.
If there is many years collection of crud in there then damage to seals by pumping over it happens. The seals can also be damaged by moving over pitting on the cylinder bore. The movement of the floating piston can be restricted and (as brake fluid is hyrdoscopic) the springs can be rusted out and ready to snap when moved to their full extent.
Rebuild the master cylinder.
                                   
___________________________________________________________
                                    Good; Fast; Cheap.  Pick any two.
                                    The best mechanic you know holds the steering wheel when you drive  Thumbsup
                                     Current Rides:
                                     The Daughter's '70 Mach 1.  Nana
                                     My: 3 x E32; 2 x E38; X5 BMWs; 2 x BMW MINIs (R50 & R55);
                                     Daimler Sovereign(s)  S1 and X40     Cool
                                     Parts car:  E38 Confused    
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#6
Turned out to be the new copper gaskets. They were thicker than the factory ones and I just happened to notice them. Put the originals back on and no more problems. I assume it was causing the bolt to be too far off the correct placement of the hole in the line. Crazy shit. Of course I probably would have noticed it if I wasn't 5 beers in a 12 pack when I put them on. :)

As always thanx for the replies. The new suspension made huge improvement on the cars ride.

[Image: sig.png]
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#7
Noted for future reference!
                                   
___________________________________________________________
                                    Good; Fast; Cheap.  Pick any two.
                                    The best mechanic you know holds the steering wheel when you drive  Thumbsup
                                     Current Rides:
                                     The Daughter's '70 Mach 1.  Nana
                                     My: 3 x E32; 2 x E38; X5 BMWs; 2 x BMW MINIs (R50 & R55);
                                     Daimler Sovereign(s)  S1 and X40     Cool
                                     Parts car:  E38 Confused    
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