Front brakes binding - Team Camaro Tech
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post #1 of 13 (permalink) Old Feb 11th, 02, 03:10 AM Thread Starter
 
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I have 1980 camaro suspension and brakes on my Hot Rod. I have replaces all the brake pads and disks, the booster, the master cylinder and the equalizer valve. My front brakes bind a little, like if in neutral, it will not roll. I have tried to put a spacer between the master cylinder and booster. There is no pressure from the pedal. I really wonder if the front wheel pressure from the equlalizer valve can be adjusted?? Any suggestions would be appreciated.

thanx

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post #2 of 13 (permalink) Old Feb 11th, 02, 04:20 AM
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David Pozzi
 
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I had a friend with a street rod that had that problem.
Try opening a bleeder screw on one front caliper for about 20 seconds. Then try rolling the car without pressing on the brake pedal.

If it frees up, you have a residual pressure valve in the line to the front brakes somewhere. This will hold about 10 psi in the brake line and is usually only used on drum systems.
Check it out and come back here and post what happened, we'll go from there.
David

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post #3 of 13 (permalink) Old Feb 11th, 02, 05:28 AM Thread Starter
 
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Thanks...I will try tonight and inform ya. I was thinking that maybe the heat from the brakes created a problem. But, if there is a residual pressure as you say, I hope this is adjustable.

rob

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post #4 of 13 (permalink) Old Feb 11th, 02, 10:06 AM Thread Starter
 
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OK. I jacked up the rod, tried to rotate the wheels and they were very tight. I opened the front right bleeder and expected a gush of fluid, but not. After a few minutes, I tightened it and the wheel turned easily. Next, I touched the brake without it running. The wheel was a little stiffer. Then I started it and tapped the brakes, the stiffness increased. It now turns with a little effort and you can feel the dragging very much. What do you think?



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post #5 of 13 (permalink) Old Feb 11th, 02, 11:35 AM
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Did you install new front brake hoses when you did the installation of the brakes?

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post #6 of 13 (permalink) Old Feb 11th, 02, 12:12 PM Thread Starter
 
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No, same hoses...why?

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post #7 of 13 (permalink) Old Feb 12th, 02, 09:18 AM
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I think you may have a residual pressure valve in the system.
What is the master cyl from?
If it is a drum brake master cyl, it may have a residual pressure valve in the outlet port behind the brass seat in the front brake line port.
The residual pressure valve is a small rubber piece the size of a pencil eraser.
If your master cyl is a dfferent type like an old single piston below the floor master cyl.
The residual pressure valve is inside the MC bore at the end of it.
David

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post #8 of 13 (permalink) Old Feb 12th, 02, 11:30 AM Thread Starter
 
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David,
I usually ask for a 1979 - 81 brake parts and get the right?? thing. First, The booster is 10" dia. and came from NAPA #5471119, it has a fixed length about 1.6". The master cylinder (Autozone#M1521)is a 3 3/8 bolt spacing by 7 1/2" long, square courners, front reservoir large, back small. Autozone said it was for 79 Camaro power brakes. I don't see anything other than the tube connections front and back. It has a single wire to seal the cap. The 'Combination valve' was from GM #25509418 valve 4.690 and looks exactly like the one pictured in http://www.mpbrakes.com/mp21.htm. I can send a picture of my arrangement. I guess my question is the combi valve maybe not for disc/drum. I am certain I connected everything right. You say something about a residual pressure valve, can I see this from the outside assembly??

Thanks...rob

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post #9 of 13 (permalink) Old Feb 12th, 02, 01:32 PM
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I can only guess that if opening the bleeder helps reduce drag that something is keeping pressure in the front brake lines.

The only things I can think of that would do that are the RPV in the front line, or something is not allowing the master cyl piston to return fully, preventing proper venting of front brake line pressure.

Try loosening the front brake line at the master cyl and see if the wheel turns easier.
If it does, the master cyl either has a residual pressure valve in it, or is not retracting the piston fully.
None of those square type disc brake master cyls should come with a residual pressure valve in them, so it might be something else.

Also check the that the caliper is able to move with out binding.
David

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[This message has been edited by davidpozzi (edited 02-13-2002).]
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post #10 of 13 (permalink) Old Feb 12th, 02, 01:39 PM
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How old are the flex hoses? When they deteriorate, they do so from the inside (they delaminate and expand internally and you can't see it from the outside); they restrict the flow of fluid, and will maintain pressure at the caliper. If they've been around for a while, replace them - they don't cost much. The only other logical explanation (other than corroded, sticky caliper pistons) is that you have a drum brake master cylinder with 10 psi residual pressure valves (disc master cylinders have them too, but they're only 2-3 psi).

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post #11 of 13 (permalink) Old Feb 13th, 02, 07:57 AM Thread Starter
 
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Thanks for the opinions. I will of course need to take the front brakes apart this weekend and inspect the hoses and calipers and pistons. I will inform ya of the findings. By the way, this am I called the auto parts and re-confirmed the parts were for a 79 Camaro. Rob

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post #12 of 13 (permalink) Old Feb 16th, 02, 12:11 PM Thread Starter
 
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Dear David & John,
Many thanks for the information. First I opened the line after the equalizer valve and did not see any positive pressure. So, I tried to compress the calipers with a clamp. It was very difficult. While doing this, it seemed the piston was rusty and then I realized when I put in new brakes, the thicker pads forced this rusty caliper piston back and it only took a short time to start binding. I removed the calipers and exchanged them for remanufactured ones (only 9.99 each) and replaced them. By the way, the hoses were in very good condition and I used long pipe cleaners to wipe the internal hoses and was sure they were sound. So, I drove aroung and after jacked up the rod and the wheels turned freely about 1 1/2 turns. Great...Thanks again.

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post #13 of 13 (permalink) Old Feb 16th, 02, 06:08 PM
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That caliper must have been pretty bad!
Glad you got it fixed.
David

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67 RS 327 Origonal owner. 69 Camaro Vintage Racer, 65 Lola T-70 Chev SB Can-Am Vintage Racer
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