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Discussion Starter #1
I installed a new Master Cylinder/Booster/P-valve set up from CPP on my 67. I also replaced the wheel cylinders at the rear wheels and all the lines from front to back to include the rubber line at the differential. The front has had a recent disk brake conversion (done by previous owner). I made all the hard lines myself and made them in several sections so I could install them in the stock locations without taking the car apart. So unlike a stock setup, there are more unions in the lines than normal.

When I started I bench bled the MC then proceded to bleed the lines. But I never could get all the air out of the back lines. (I tried normal bleeding, vacuum bleeding and I installed speed bleeders) I worked on this over several weekends and finally found a leaky wheel cylinder (fluid leaking past the cup and piston into the dust seal) so I replaced it again. Now I have the same problem... I bleed and bleed and bleed but there seems to be a never ending supply of air bubbles. I have checked all of the unions many times and I don't see any signs of leaking fluid.

I did notice the wheel cylinders were at a slight angle when mounted to the backplates. I figured air could hide at the high end so at one point I did unbolt them and shake them around while bleeding (used a c-clamp to keep the pistons from popping out). Basically the same thing suggested for calipers if your bleed screw is not at the very top.

I am using valvoline synthetic fluid if it makes any difference.

The front calipers seem to be free of any air, but the pedal is very spongy. The car will stop if you don't expect it to happen real fast.

What I want to do now, and I'm looking for suggestions, is to start breaking the system into sections to see if I can get the air out and determine the source of the problem. Who has an idea for bleeding lines without a bleed valve. Or maybe something I could make to add a bleed valve to the end of a hardline. Any suggestions will help...I would like to get the troubleshooting over with as quickly as possible because my wife is complaining that her jeans are starting to get tight in the thigh area on her right leg!:eek:
 

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make sure the car is level, some guys like to clamp off the brake hoses to isolate but i'm not really a fan of that. new hoses, why clamp 'em and possibly damage them? old hoses? why clamp them and possibly break off interior walls of hose and have debris in the lines? no, i'm not a fan of vise-gripping the hoses...

if you don't mind making a little bit of a mess... you can get tube plugs and remove the lines at the PV... install tube plugs and block off ports. now those lines are removed and you've isolated the master & valve... step on the brakes... are they firm? if so you know up top is good. now unplug the rear or front line and leave the other plugged. rebleed just the one system (they are completely separate systems) make sure that all bleeders are pointing up. once bled, test it... is it firm? OK so now unplug the other system and rebleed that one...

might have air trapped in PV. if i recall some of the bracket assys are on an angle so air can get trapped inside the PV...


hope i helped...
 

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I almost went crazy when I was bleeding my brakes after the car was done. I did everything you did! Found out there was a leek in the rear lines at the hose that goes from the body to the rear diff. Got rid of the leak and had brakes.
 

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If the flex hoses arent that old on the front, using "Line Clamps" and not "Vise Grips" will aid in isolating the problem.The hoses will be resilient enough. Clamping off the lines will can sometimes provide one with enough pressure to purge that air out. I have to agree, air in the PV can really mess things up.
Wish I could be there to help:(

Good luck
 

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If the flex hoses arent that old on the front, using "Line Clamps" and not "Vise Grips" will aid in isolating the problem.The hoses will be resilient enough. Clamping off the lines will can sometimes provide one with enough pressure to purge that air out. I have to agree, air in the PV can really mess things up.
Wish I could be there to help:(

Good luck

YES, there is a BIG difference between using the "proper tool" and something that one "thinks" will work. ;)
 

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Discussion Starter #6
I am ruling out the front brakes...I didn't mess with them, they seem to be air free, and they were working before. I haven't considered the PV...and I did bench bleed the MC seperate from the PV. Maybe I should bleed them as a unit and eliminate the rear brakes and lines altogether to see where that gets me. I will try it tonight and report back tomorrow.
 

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Which hole in the pedal did you mount the push rod to? The '64 I just picked up had power booster and front discs installed before I got it but I noticed the pedal really didn't feel all the firm and when down a ways before engaging. Looking at it this weekend I found it was in the upper hole on the pedal which is for non power brakes. I moved it to the lower hole and now I have a firm pedal, doesn't go as far down and REALLY stops now.

Might be something to check.
 

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Discussion Starter #8
I am pretty sure I put it in the upper hole...because the angle looked correct. I think for my set up, the lower hole would cause the pushrod to bind at the end of travel. And I dont think either hole would cause air to remain in the lines. Or would it?????
 

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I know the angle looks correct in the top hole but that is for manual brake only. Power brakes must use the bottom hole or the leverage ratio is completely wrong and the pedal feel and travel will never be correct.

This weekend before I moved my rod to the lower hole, I could not lock up the brakes and it took a lot of effort to even hold the car still. Moving it down and I can lock up the brakes, use less effort to hold the car still and feels like power brakes should.

What you might be feeling is the brake feeling like they have air because you are not getting enough travel in the pedal to engage the rears correctly.

If you still think you have air in the rear, you haven't bled them enough (I use a vacuum style bleeder) or you have some type of leak. BTW, I tried Speed Bleeders before and had back luck with them sucking air back in. Even with vacuum bleeding, I might still see some air bubbles as it's pulling the air past the bleeder valve threads.

I pull the vacuum, break the valve open and watch what the MC is doing. When I get a even, steady drop in fluid, I'll close the valve and then shut off the vacuum. I do that all the way around twice on a new system and then pump the pedal hard (engine off on PB setup) and then push as hard as I can and hold it for 30 seconds. If no bleed down of the pedal and no leaks, I am usually good to go.

I am still thinking your first problem is the pedal ratio.
 

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Discussion Starter #10
I played with it again last night. Capped off the rear lines but left an 8" line off the back of the PV. Before I capped it off I put a clear tube and ran it back to the resivor. Pumped that until the air was out of it. Bled the 8" line by slightly opening the cap while the wife pushed the brake pedal.

At this point the pedal was firmer than it has been but not firm enough. So I started bleeding the front passenger caliper and got a seemingly never ending stream of fine bubbles. Probably ran half a quart of fluid before I was convinced I wasn't getting any more air out. At this point I lost my brake actuator (wife) so i had to quit. Never got to bleed the driver side but I checked the pedal one last time and it was firm but I could force it to the floor if I pushed hard enough. This morning I checked it again and it was mushy.

To recap I have the front brakes connected that worked before and I have done nothing to any of the lines. I have an 8" line off the PV that is capped.

I guess tonight I will move the rod to the lower hole and see if that helps.
 

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Brake actuator

Yeah, mine left in the middle of the job too. Funny how that works. Bleeding the air out takes a lot of patience.
Keep after it.
 

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Discussion Starter #12
I tried moving the actuator rod to the lower hole and it won't reach. The rod won't angle down far enough without using a little force to get the bolt in the hole. I did manage to force it down and get the bolt in but the angle was so steep the pedal wouldn't move. I re-read the instructions and I noticed they talked about an upper and lower hole being 1" apart. My holes are 2" inches apart (save the crude comments). The kit also came with installation instructions for 55-57 chevys. Those instructions said drill a hole 1" lower than the original. I guess I'll make a call to CPP and see what they say, and I will probably be drillin a hole tonight!:mad:

 

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That lower hole is for power brakes when you use an angle bracket on the booster. Your lack of brakes has nothing to do with what hole the rod is in. You have it on the right hole.

If you are getting air in the system, after you bled it all out, you either have a flare leaking, your crush washers are bad, or something else.

T,
 

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Discussion Starter #14
I just got off the phone with CPP...they confirmed the top hole is the correct one. Just like Tom said if you have the booster mounted at an angle, the lower hole would be correct.

So Im back to troubleshooting for now. More capping off of lines and brake pumping. I suppose i will have to take the wife out to dinner or something to get her to pump brakes for me again!:D
 

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I always use a pressure bleeder after I do a complete brake install. it will find all the weak spots in the system.
 

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Use silicone grease around the bleeder screws...keeps the air out and will not contaminate the system
 

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I recently made all new brake lines for my nova. When I first bled it initially it had a decent pedal that had some sponginess in it. When I would hit the line-lock the pedal would become firm meaning that something in the front brakes was making the pedal spongy... It turned out that there was an air leak in one of the fittings. I tightened up the fitting and my friend inspected all of the fittings on my car for leaks as I pressed the pedal. Once we where sure that there was no leaks we re-bled the brakes and now the pedal is firm

sometimes it doesn't take much to make a brake pedal spongy.
 

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Discussion Starter #18
I have tried the grease trick...and speed bleeders have coated threads to stop air leaks. Tonight it will be back to bleeding the fronts with the back capped off. I kinda got side tracked yesterday on the "which hole on the brake pedal is right" thing.

I'm considering the pressure bleeder approach also, I'll see how it goes tonight.
 

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Discussion Starter #19
Dallas Cowboy Cheerleaders

This thread doesn't have enough pictures in it...so here is a picture I snapped at the Dallas/New Orleans game last month.

Something to look at until my next update on the brake problem.:D

 

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Well, regardless of whether the linkage is in the right hole or CPP saying it's "correct", the fact remains that anyone using the upper hole for a power brake setup, is using the wrong one. Just because an aftermarket company says something is correct versus how GM designed it, doesn't mean they are correct.

The holes are specific for pedal ratios. The top hole will not move the pushrod as far with the same pedal movement as if the rod is in the lower hole. This in turns make you have to push the pedal futher with a booster than if you are using a manual master cylinder. This is also why the bore sizes on the MC are different between power and manual.

The aftermarket makes it easier with straight brackets to have clearance for the engine, hood, inner fenders, etc. but that doesn't mean it's the right way it should be done.

With the rod being in the top hole, you might not be getting enough pedal travel to push out all the air. Even if the pedal hits the floor, you'r getting less movement of the rod than if the lower hole is used.

I understand the rod being hard to get into the lower one and the angle is way off. Mine is doing that too but my pedal moves. Since the brackets are really the source of the wrong angle, I have seen done in many kits for other applications, where a very thick piece of flat bar with two holes is place onto the booster rod and bolted to it. Then the clevies is bolted into the other hole and allow it to line up with the lower hole in the pedal. Basically making an offset rod. This allows everything to be in line and in the correct holes.

I might do that this weekend...
 
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