Strange brake problem

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dodgefreak73

dodgefreak73

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Help!!!! :banghead:I don't know if this topic has been touched on before but I need to know that I'm not going crazy. First off my car is a '73 Dart with a 318ci and power disc brakes everything is factory nothing converted or modified. The problem I'm having is the front brakes are not releasing right away, this doesn't happen every time and seems to be worse when turning. This problem has always been there since I got the car 4 yrs ago but has gotten worse. It has always had very touchy brakes (over assisted) and will plant you against the windshield if you hit them too quick. I had it out for a run the other day and it was the worst it's been yet. I was slowing for a turn let off the brakes and started to turn the corner and the car kept slowing down, this was not a stop and turn it was a rolling turn the car almost came to a stop before it let go. What I've done to attempt to rectify this problem so far is new master cylinder, both calipers and both flex hoses so far nothing has changed. I don't want the car to sit all summer but I will not drive it any more the way it is as I'm afraid of getting rear ended as the brake lights go out but the car keeps slowing. Sorry for the long post but I wanted to get as much info in as possible. Can anyone shed some light on this? Thanks in advance.
dodgefreak73:banghead:
 
There is an adjustable rod between booster and the master cylinder, try backing it off a little, it may be keeping pressure on the mater cylinder.
 
JLP said:
Could be a bad booster.
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I can't really see that as the problem is only on the front. When this happens it does the nose dive which leads me to believe it is front only. I could be wrong about the booster idea but I know the rear brakes are not affected by this problem.
 
When did you change out the master cylinder? Did it act any differently after you made that change? Was it new or a rebuilt?
Does the car continue to slow down even if you give it some gas?
C
 
clhyer said:
When did you change out the master cylinder? Did it act any differently after you made that change? Was it new or a rebuilt?
Does the car continue to slow down even if you give it some gas?
C
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I put the master on last fall just before I put it up for the winter, it was a reman unit. It did not change the braking problem as I had this problem before changing the master. If you get back on the gas lightly within about 10-15 seconds after releasing the brakes yes it does continue to slow down. This does not happen on every application and if you come to a complete stop and then take off it won't do it. It does seem to be worse when turning especially to the left (don't ask me what left turns have to do with it), this is whats confusing
 
OwdKasd said:
My bet is bad rubber hoses at the Calipers.
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This is kinda what I was leaning toward but they have already been changed. I guess maybe I got some bad ones though, and that would explain why it seems worse when turning. I'll have to get another pair of flex hoses and try that, they should last more than a year but who knows with the crap they are making these days
 
green1 said:
If your pistons are black, they are bakolite. They swell up. Get alum from local.
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This would be a good place to look, the pistons may be pushing out and not returning when you take your foot off the pedal.
 
Sound like a proportionary valve to me, he has changed all that stuff and it is still doing it, pretty sure thats the issue, it's the only thing he hasn't changed.
 
412 Stroker said:
Sound like a proportionary valve to me, he has changed all that stuff and it is still doing it, pretty sure thats the issue, it's the only thing he hasn't changed.
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I was wondering about this valve but I don't an extra one to try and haven't been able to find one around here.:glasses7:
 
dodgefreak73 said:
I was wondering about this valve but I don't an extra one to try and haven't been able to find one around here.:glasses7:
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Do some research, I believe there is a way to "reset" them, I have read such things but don't remember the process. Maybe someone here knows.
 
My Brother in law had this problem with a full size Buick years ago If my memory is correct a brake booster was causing his to act like that.

Brian
 
Personally I am thinking your prop valve which I am sure is original is either plugged, rusty, who knows, but that has to be your issue, and if it is the booster why only the front brakes?? I had my passanger side rear brake stick then not then stick, turns out I at one point had water in my system and the rear brake cylinder had rust in the bore and that was making it stick, drove me nuts trying to figure what it was so I share your pain, hope you get it figured out.
 
412 Stroker said:
Personally I am thinking your prop valve which I am sure is original is either plugged, rusty, who knows, but that has to be your issue, and if it is the booster why only the front brakes?? I had my passanger side rear brake stick then not then stick, turns out I at one point had water in my system and the rear brake cylinder had rust in the bore and that was making it stick, drove me nuts trying to figure what it was so I share your pain, hope you get it figured out.
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Well I guess I'll be getting a prop valve and hope for the best. It does make sense and yes it is the original valve. Thx:pl:
 
when you are turning and it is still braking if you turn your wheel the other way will the brake release? Reason I ask when I turn to right all the way while braking mine will not release until I turn back a little
 
red67gts said:
when you are turning and it is still braking if you turn your wheel the other way will the brake release? Reason I ask when I turn to right all the way while braking mine will not release until I turn back a little
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I've not actually tried or really paid attention to that, but when it does it I'm not turned full lock
 
I have everything brand new and took wheels off and turned wheels lock to lock and clearanced everywhere it may be binding. I finally gave up and when I notice it I just turned back a little. Mine only does it turning to right into my driveway coming from opposite direction which is a hard turn.
 
So let me rethink a little here, does it seem BOTH front brakes are sticking or only one, if it is only one then red67gts might have something, are all the rubber brake hose hold downs still on and where they should be?? could be a pinched brake line when you corner, if your missing the hose clamp hold downs. red67gts has a good point thats free put it on some stands and turn the wheels max both ways and look for the hos binding, my money is still on the prop valve though.
 
412 Stroker said:
So let me rethink a little here, does it seem BOTH front brakes are sticking or only one, if it is only one then red67gts might have something, are all the rubber brake hose hold downs still on and where they should be?? could be a pinched brake line when you corner, if your missing the hose clamp hold downs. red67gts has a good point thats free put it on some stands and turn the wheels max both ways and look for the hos binding, my money is still on the prop valve though.
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When this happens it is both sides like I've said it seem intermittent as one time it'll do it the next time it won't even under the same circumstances. The hoses are routed properly with all the right clips etc. I do agree with you about the prop valve, though for the price of flex hoses I think I'll throw another pair on first just to eliminate those for sure. The front brakes do seem to grab very quick when applying the pedal (almost like the pressure isn't equal), the rears are working but maybe not fully. I think you might be onto something though with the valve:sign7:. thx
 
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