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All 4 breaks seize up?!? |
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70javluvr
AMC Addicted Joined: Dec/22/2007 Location: Canada Status: Offline Points: 603 |
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after getting back home I jacked both ends up in the air and tried to turn all for wheels all were locked. Rubber hoses are new and don't see that being problem but could be a cheap check. MC has a small large configuration for disc breaks. Any dance it could be the booster or check valve itself I have never seen one of these fail but what would be the result and how would you check for it?
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70 Javelin Donohue Tribute car Sonic Silver/Shadow Mask/360/Custom Interior
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tyrodtom
AMC Addicted Joined: Sep/14/2007 Location: Virginia Status: Offline Points: 6199 |
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Just because the master cylinder has the small, and large reservoir, doesn't necessarily prove it's a disc. brake master cylinder.
Leaving the master cylinder uncovered for several days will result in moisture contamination. Brake fluid is hygroscopic, readily takes on moisture from the surrounding air. Normal brake fluid boils at about 450 degrees, I use some in my race car that boils at about 600. If you get moisture in you brakes fluid, it separates from the fluid and boils to steam at 212, you can easily reach that temperature in a normal stop. The steam expands and locks the brakes. This can cause a problem even with nothing else wrong with your brakes, one brake application will heat the fluid enough that from that point on the pads never fully retract, and the fluid keeps getting hotter till more of the moisture goes to steam and finally developes enough steam pressure to lock all the brakes. |
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66 American SW, 66 American 2dr, 82 J10, 70 Hornet, Pound, Va.
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pit crew
Supporter of TheAMCForum Joined: Jul/08/2007 Location: delete Status: Offline Points: 5341 |
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Could it be something as simple as the brake Z bar linkage being rusty enough that it is sticking? We had a 74 Javelin in the shop the other day where after the owner pulled a panic stop it locked up the brakes. Turns out the Z bar pivoted more than normal into a rusty area where it promptly froze in place.
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73 Hornet - 401EFI - THM400 - Twin Grip 20 |
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FuzzFace2
AMC Addicted Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10343 |
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OK happens to all 4 wheels and the car has 3 new hoses so I would say it is not the hoses. Could it be water in the fluid boiling the cause? Guess it could be could try flushing/bleeding the brakes again to get it out. If it was 1 of the pedal rods too long guess as a test when it happens again loosen the master to see if that helps. If so then 1 of the rods is too long. If that does not help the try cracking the brake lines at the master to see if it will bleed of the psi. If that helps and the fluid has been flushed then I would say bad master. Dave ---- |
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TSM = Technical Service Manual
75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4805 |
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Here's my 2 cents - First off the system needs flushed of the contaminated fluid. Leaving that lid off is a HUGE no-no. It can be done after you troubleshoot this problem but it must be done.
To troubleshoot this properly, follow the steps I have below in that order so you can tell what's causing this. The first step to do is after the brakes are locked, loosen the nuts that hold the master to the booster and see if they release. If so your push rod is to long, or the pedal is sticking and not returning as it should. (could be the linkage as pitcrew suggested or a bad booster will do this) If the brakes are still on, do as Dave suggested and loosen the lines at the master and see if they back off. If they do, replace the master and flush the system. If none of the above works, crack the bleeder at each wheel, one at a time, and see if that backs that particular brake off. If it does, then the hose is bad. Replace ALL the hoses (and the master too IMO) and flush the system out as it's contaminated. Good luck and hope you find it! I'm curious to hear what you find. |
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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johne
AMC Apprentice Joined: Aug/04/2012 Location: UK Status: Offline Points: 145 |
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I had a F**D with this problem once - wound up changing the booster.
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67 Rebel SST convertible (parts car) RHD
68 Rebel SST convertible RHD 56 Chevy 210 (Long term project) |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19612 |
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It could be the booster or the master cylinder. A bad booster can apply brakes by itself, though that's not the usual failure mode. There are valves in the booster that can fail though, and it can happen. Since everything have been rebuilt or replaced to the wheels, and all four are locking, it has to be something that affects all four wheels. Only three things can do that -- the booster, master cylinder, or brake switch junction block. On the 70 you should have the same junction block with brake failure switch as a drum brake car and a proportioning valve in the rear. I've never known the block to fail in such a manner as you describe. It's almost impossible -- it usually sticks to one side so you have no front or rear brakes, but always have brakes on one end. It may be possible that it's partially blocked and is affected by heat, but I'd think you'd have marginal braking when it does work if that was the case. If you have a later model combination valve it can fail. Those have the two lines from the MC to the block then three lines to the brakes (one to each front wheel, one to the back). It may be possible for that one to get enough trash in it that it could lock all four brakes, but again, it's very rare and I've never heard of it happening -- usually just one end or the other fails. Therefore, I'd concentrate on the booster and MC. If the MC is a few years old replace it first as it's the cheapest of the two. If that doesn't help look for a new or good used booster.
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Frank Swygert
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4805 |
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So did you try any of things listed? What's the outcome?
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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AmeriMan
AMC Addicted Joined: Jul/30/2008 Location: Joliet, IL Status: Offline Points: 556 |
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BTW it's "brakes" not "breaks". Grammar police. I'll shut up now. ;)
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larue390@comcast.net
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greasygt III
AMC Addicted Joined: May/27/2014 Location: Florida Status: Offline Points: 676 |
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I didn't notice any mention of which type fluid you used. Did you by chance use a synthetic or silicone fluid? I hear it will do some nasty stuff to the seals if you previously had conventional fluid in the system. Just a thought.
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83 Spirit GT
79 Ranchero GT 460 |
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