1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

front brakes locked up

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Old 09-25-07, 12:15 AM
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whaa

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front brakes locked up

ok so i had just rebuilt my master brake cyl and new ss brake lines all around. so the other day i was drivin back from the bank and i noticed my car had lost all power, finally figured out it was my brakes. stopped the car and smoke stared pouring out of my wheels.

so front brakes have the fluid going into them but the fluid is being caught there after a few pumps. it does not take much of any of the pedal to be pushed down for the brakes to work


so my question is could my check valve be in backwards or is it more of the passage ways being blocked in the master???!
Old 09-25-07, 12:21 AM
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What check valve are you refering to, the proportioning valve? That won't cause the fronts to stick/sieze. Sounds to me that with the new master, the calipers are getting better pressure than before and pushing the pistons in them to a point that they are sticking. If so, replace them.
Old 09-25-07, 12:26 AM
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its the same master just rebuilt. and its not so much a just a sticking as it is brake fluid not wanting to go back into the system.
Old 09-25-07, 12:26 AM
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if i open up the bleed valve the caliper works without a problem.
Old 09-25-07, 02:45 AM
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Either you made an error rebuilding the master, or the calipers are sticking.
Old 09-25-07, 07:47 AM
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sounds like the calipers are sticking...

take them and compress the piston back in and clean up the sliders and lubricate them well.

also inspect the piston, before compressing it, and make sure it's not all rusty
Old 09-25-07, 10:10 AM
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whaa

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looks like im gonna have fun today on my day off
Old 09-25-07, 10:32 AM
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It's also possible the master cylinder isn't fully retracting. If it's not pulling all the way back, it will block the compensating ports & you'll get behavior like this. Check the clearance into the master cylinder and the pushrod depth. Or, just retract the pushrod a turn or two & see if it clears up.

-=Russ=-
Old 09-25-07, 12:41 PM
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would brake pedal adjustment cause this as well. even when the brakes wouldnt stick brakes would start to engage with less than a two inch travel?
Old 09-25-07, 02:28 PM
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2" of pedal travel is too much for the brakes to engage. Specs are 0.28-0.35" for free travel. Download the FSM, brakes are in section 11. In the trouble shooting section it lists 10 causes for brakes not releasing.
Old 09-25-07, 03:40 PM
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whaa

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where would i find the fsm?
Old 09-25-07, 03:43 PM
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nvm found it
Old 09-25-07, 04:38 PM
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master is pulled. i can see where the piston is blocking the larger of the two holes on top where the res sits. closer to the firewall. would this be the problem?
Old 09-25-07, 04:39 PM
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its not blocking fully just partial
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