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Old 10-20-2008, 06:47 PM   #46
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Re: Wrong master cylinder - should I worry?

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Originally Posted by bobss396
I would (cringing..) take the master & power booster apart again (you are a pro at it by now) and adjust the rod out another 1/8" and see what happens.

You made good progress with the last adjustment, so I thing all you need is a little more to get full travel within the master. Make the adjustments gradually until it stops well enough to make you happy. 1/8" increments are safe and sane.

If you go too far, the brakes won't release once it is fully warmed up. But that will be a matter of backing off the rod a little.

Bob
'


NOOOOOOOOOOOOOOOO Bob! Say it ain't so! Yes, I am getting to be a pro - took me less than 30 minutes to get it out last time but still *can you hear the whine????* Yeah, my husband would have cringed to tell me that as well.

Ok, I'll try your advice and give it one more shot. So, if the push rod is not at its proper length, that would cause the fronts not to have enought pressure? Just want to double check before I do this... for what feels like the eleventymillionth time.
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Old 10-21-2008, 05:54 AM   #47
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Re: Wrong master cylinder - should I worry?

Oh yes, you have to do it. I believe that's your problem, if the rod isn't out far enough, you don't get the full travel within the master.

Can you accurately measure where you're at now with it? If I knew the thread size, I could tell you how many turns it would take to get you an 1/8" of travel. A good scale or better yet a caliper (not brake related) would work.

If it were my car, I'd go the 1/8" and slap it back together and see how it stopped, which should be on a dime. You're close so keep on keepin' on.

Bob
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Old 10-24-2008, 08:50 AM   #48
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Re: Wrong master cylinder - should I worry?

Well, guess what.

I am currently tieing the last loop on the noose that I plan to hang over the rafters in the garage. - just kidding... but I'm definitely frustrated.

The adjustment of the push rod did not change the status of the brakes. It changed the feel of the pedal when the car was off, but did not help the front brakes work any better.

I stayed up until 2am this morning going through the trouble of taking apart, cleaning/rebuilding the old/original master cylinder to put it in - just to see what it accomplished. Annnnnnndd nada - exactly the same with the old mc as it was with the new mc. And yes, I did a thorough bench bleed.

Here is what I have that keeps stumping me. The back brakes are good (if not too good) one side will lock up easily, but the fronts have very very weak power. There is some braking going on, but it is not enough to safely stop the car. When bleeding the front calipers, I get very good fluid movement. I can fill the bleeder container up in about 4 pushes of the pedal.

Is it possible that we got 2 bad calilpers? They were from the same place at the same time....

What about the brake booster? What are the signs of a bad one?

AAAAAAAAAAAAAAAAAAAAA!

Maybe I should just sell this one and go with the beautiful 68 Torino for sale here....
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Old 10-24-2008, 09:25 AM   #49
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Re: Wrong master cylinder - should I worry?

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Originally Posted by RaeRae1

Here is what I have that keeps stumping me. The back brakes are good (if not too good) one side will lock up easily, but the fronts have very very weak power. There is some braking going on, but it is not enough to safely stop the car. When bleeding the front calipers, I get very good fluid movement. I can fill the bleeder container up in about 4 pushes of the pedal.

Is it possible that we got 2 bad calilpers? They were from the same place at the same time....
Calipers go bad when they do not retract or they leak. Usually, a firm application is not a problem if the pressure is there.

Okay, remind me a bit, you have a disc brake master cylinder, where you have one large chamber hooked up to the calipers and one smaller one going to the drums on the rear, right?

You have an adjustable proportioning valve, right?

I assume you have tried adjusting the valve for maximum pressure to the front, right?

Okay, is the valve hooked up properly, so the inlets and outlets are not reversed?

Are you sure the front brake lines are good? A tiny kink in the line or a squashed section can produce this problem. If you are not sure, try reversing the outlets on the valve, so the rear brake outlet is not pushing on the fronts, etc and see if you still have the same problem. If yes, then there may be some kind of obstruction on your front line.
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Old 10-24-2008, 02:37 PM   #50
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Re: Wrong master cylinder - should I worry?

I agree that the calipers are good if they produce a steady stream when bled. A bad power booster would give you a rock hard pedal. If you want to disable it, unplug the hose from the engine, plug the open line on the manifold and try it. You should do this since it takes a few minutes and you need to understand how it works.

Maybe you need more adjustment on the rod until it does something. How much free play is there at the pedal?

Go over the things that Magic Rat suggests, although I doubt you have a brake line or hose issue since the calipers are getting lots of fluid. Unless you have a piece of crud that is in the line right off the master that feeds the fronts. This can be taken off and blown out with compressed air. Or just blow it out the old fashioned way (ptooey.. don't inhale), that way you'll be able to feel anything clogging it up.

I'm not a big advocate on adjustable proportioning valves for street use, which is either a crutch or monkey wrench in your case.

Now we go full circle to your original problem, maybe you have an incompatible master cylinder?

Bob
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Old 10-24-2008, 03:33 PM   #51
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Re: Wrong master cylinder - should I worry?

Thanks MagicRat and Bob,

Here is what I’ve been thinking today

MagicRat - Hmmm… so on the calipers – you say the calipers only have issues with retraction or leaking, but could I be maxing them out before they stop the car? If they are incorrect would it be possible that they have a caliper travel that isn’t enough…. Sorry – I know I seem to be grasping at straws but I’m just trying all avenues. I’m thinking about taking them off and pushing the pedal to see how much travel they have. Would this damage them?

Yes, I do have the disc front and drum rear master cylinder. I should take pictures of everything, just in case you guys with the sharp eyes can catch something I am missing. I will do this tonight and post up the pics of how everything looks, maybe that will help. It has the smaller reservoir for the rear (this is the second reservoir from the firewall) and a larger reservoir for the front brakes (the first reservoir toward the firewall, the first reservoir that the push rod hits basically). It matches the OEM exactly. In fact, what I did last night was I stayed up till 2am cleaning out the old MC really well, putting it back together and trying it out… just for giggles. No luck. Still the exact same pedal feel with the original MC that I get with the new MC - no firm grab on the front.

Yes, I have an adjustable proportioning valve, mostly got it as a diagnostic tool and to make sure our original wasn’t the problem. I have turned it so that the back brakes are completely off. This is how I am sure that the front brakes are the issue. When the rear brakes are turned on they get plenty of grab, when the backs are turned off, the fronts can barely hold the car in place. This also indicates that I do have it connected correctly to the rear brake lines (it is inline on the main rear tube).

I am not completely certain the front brake lines are good but I would say IMO they are fine. I get great fluid flow to the calipers and I can’t visually see any kinks or leaks. The front pads just aren’t giving good grab.

I’ve been thinking all day…. Could there be trapped air in the distribution block? Somewhere that would affect only the front lines? If I plug the main ports on the mc, the pedal gets very stiff. But the minute I attach the distribution block, spongy again. The pedal gets relatively stiff after bleeding but returns to spongy once the car is started and I get very little grab on the front. If there was an air trap issue, it seems like this would be how it would react, I would still get good fluid flow, but terrible pressure. If there is the possibility of a trapped air bubble in the distribution block, how would you guys suggest I get it out? Should I try attaching the vacuum bleeder directly to the dist block and “bleeding” it from there??? Sounds kinda crazy but at the same time… plausible.

To answer your question Bob – the pedal gets very stiff with the MC plugged, but there is still just a little bit of “free play” at the top of the pedal. It will travel maybe ¼” freely and then kind of “clunk” when I hit the resistance. I am pretty sure this free play is the push rod freely sliding and the clunk is when it hits the MC valve. However, there is still a ton of resistance travel to the floor, and again, I am moving fluid very easily and freely through the front calipers when I bleed them.

I am going to take off the old MC and put the new one back on again (the new one is so much prettier J), I will adjust the push rod out just a little more again just to be sure. Hey, I can now do this in about 30 minutes – HA!

Oh, and just an FYI - I don’t really care for the adjustable valve much either but it is a pretty valuable diagnostic tool at the moment. I plan on putting in the old one if/when I finally get this dang gremlin the hell out of my brakes!

This is a now a novel – page 4 now? – I think you guys should get a paycheck for this one, or at least a medal!

Thanks SOOOOOOO much!
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Old 10-25-2008, 09:18 PM   #52
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Re: Wrong master cylinder - should I worry?

Well, caliper travel is usually not an issue. The caliper pistons do 'retract' from the rotor, but only a miniscule amount, so small it can hardly be seen.
The total piston travel is less than 1/32 of an inch or so when you press on the brake.

The brake pads actually maintain full contact with the rotor, (they rub against the rotor) even with the pedal released. But they have no pressure so the wheels turn easily.

IMO do not apply the brakes with he calipers removed. The pistons will fly out of their bores and are a real pain to put back in.

The front line may still be blocked internally with rust, but may still look good. Also the flexible brake hoses can collapse internally, causing a blockage, but still look good.

Have you replaced the front pads and rotors? If no, have you removed and inspected them to make sure they are not covered in oil/grease/brake fluid?

As for air in the lines.....if air were the culprit, you can temporarily overcome the air's spongy effect by stomping really hard on the brake pedal many times over and over again as quickly as possible. This will compress the air and give you a firm pedal, but it will go back to being soft for the next application. If much stomping makes no difference, air is not likely the culprit.
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Old 10-26-2008, 10:27 AM   #53
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Re: Wrong master cylinder - should I worry?

I still think you have rod length issues and the front brakes are not being fully applied. Your hydraulics are fine from what you are telling me. I think that this is down to a mechanical problem.

Bob
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Old 10-26-2008, 05:23 PM   #54
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Re: Wrong master cylinder - should I worry?

Quote:
Originally Posted by MagicRat
Well, caliper travel is usually not an issue. The caliper pistons do 'retract' from the rotor, but only a miniscule amount, so small it can hardly be seen.
The total piston travel is less than 1/32 of an inch or so when you press on the brake.

The brake pads actually maintain full contact with the rotor, (they rub against the rotor) even with the pedal released. But they have no pressure so the wheels turn easily.

IMO do not apply the brakes with he calipers removed. The pistons will fly out of their bores and are a real pain to put back in.
Ummm yeah, I thought of the piston flying across the garage as well. I agree - not a bright idea

Quote:
Originally Posted by MagicRat
The front line may still be blocked internally with rust, but may still look good. Also the flexible brake hoses can collapse internally, causing a blockage, but still look good.

Have you replaced the front pads and rotors? If no, have you removed and inspected them to make sure they are not covered in oil/grease/brake fluid?
With every line and part being new, I cant imagine they have any rust blockage. I also don't think there is any collapse because the only rubber liens are the ones going from the calipers to the SS lines in the wheel well.

We have brand new pads and we had the rotors turned. I have double checked for any fluid on the rotors, none that I can see. I have cleaned it again, just in case.

Quote:
Originally Posted by MagicRat
As for air in the lines.....if air were the culprit, you can temporarily overcome the air's spongy effect by stomping really hard on the brake pedal many times over and over again as quickly as possible. This will compress the air and give you a firm pedal, but it will go back to being soft for the next application. If much stomping makes no difference, air is not likely the culprit.
Hmmm. I may have to give that a try and see what it does.

Thanks!
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Old 10-26-2008, 05:26 PM   #55
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Re: Wrong master cylinder - should I worry?

Quote:
Originally Posted by bobss396
I still think you have rod length issues and the front brakes are not being fully applied. Your hydraulics are fine from what you are telling me. I think that this is down to a mechanical problem.

Bob
Ok bob. I'll go with your advice, you have been pretty on the mark so far. I plan on trading out the old MC for the new again anyway, so I will lengthen it yet more. I'm a little concerned about the "seizing" thing when they warm up... but I suppose we can cross that bridge if and when we come to it eh?

I'll let you all know. And I am going right now to take pics.

Thanks again.
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Your cheer-mobile needs a flat tire.
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Old 10-27-2008, 12:11 PM   #56
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Re: Wrong master cylinder - should I worry?

Thanks for the vote of confidence. I believe that you have got to force something to happen, even if you have to ultimately back it off a little bit. That's why you have to document what you're doing so you can UN DO it if you have to.

If your front brakes lock up from the rod being out too far, all you have to do is crack the bleeder on a caliper or master (if there is one) and they'll release.

Bob
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Old 10-27-2008, 12:25 PM   #57
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Re: Wrong master cylinder - should I worry?

Ok. Just a quick update. I tried what MagicRat suggested and pumped the brake hard in quick succession. No change. Never seemed to become stiff.

So, I removed the old MC, adjusted the push rod out an additional 1/4" or so.. (the visible threads now measure out just over 1"), put the new MC back on, re-attached all the lines, and I jacked her up in the front as high as I could go (sounds weird but if there is air, I am hoping this will cause it to congregate to one area and be easier to evacuate, just a sillyness perhaps, but figured it couldn't hurt). It is now sitting and waiting for me to bleed the system. I didn't do it last night because while working with the old MC I managed to break the check valve going to the booster... It basically just shattered . So, I am planning on getting a new one today, installing the check valve, and bleeding the crap out of them once again.

I will let ya'all know, hopefully tonight or tomorrow, what happens.

BTW - I did take pictures, but I figured they weren't worth posting because it is so hard to orient what lines are coming and going from where.

Oh and Bob - thanks for the info about cracking the bleeder - easy enough fix if they do happen to seize.
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Old 10-28-2008, 10:24 AM   #58
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Re: Wrong master cylinder - should I worry?

Stop thinking that you have air in the system! You could if you have a remaining yet to be detected leak, but since you're getting solid brake fluid out of the calipers, you don't have any air in the lines. Those Fords were very user friendly for bleeding and I have rebuilt hundreds of those calipers and have never ever had a air entrapment issue with one.

I think you're on the right track with bring the rod out gradually. I'm just curious what got you to this point in the first place. Any Ford (or any other brand of car) that I've replaced a master and or power booster on has been totally "plug and play". I've had to do some fine tuning to get free play at master cylinders once in a while, but that resulted in a bound up system, the opposite of what you have there.

Bob
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Old 10-28-2008, 12:58 PM   #59
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Re: Wrong master cylinder - should I worry?

Quote:
Originally Posted by bobss396
Stop thinking that you have air in the system! You could if you have a remaining yet to be detected leak, but since you're getting solid brake fluid out of the calipers, you don't have any air in the lines. Those Fords were very user friendly for bleeding and I have rebuilt hundreds of those calipers and have never ever had a air entrapment issue with one.

I think you're on the right track with bring the rod out gradually. I'm just curious what got you to this point in the first place. Any Ford (or any other brand of car) that I've replaced a master and or power booster on has been totally "plug and play". I've had to do some fine tuning to get free play at master cylinders once in a while, but that resulted in a bound up system, the opposite of what you have there.

Bob
Thanks Bob, I actually don’t think it is air that is causing the problem. I am just bleeding the brakes this much now because I keep introducing air into it every time I remove the MC. I can’t get the push rod out unless I undo the lines, hence allowing air, so I just bleed the system each time.

The push rod is maxed out. It cannot go any further.

Here is what I observed last night. The pedal is stiff. It has very little play (there is no longer any top pedal play, like there was before the rod adjustments). When I apply the brakes with the back brakes turned off it literally feels like the power assist is just not working, stiff pedal and all. If you stand on the pedal with a lot of force, you can get the fronts to grab. It is the oddest thing. If I turn the back brakes on, the right rear will lock before any of the others and the car tries to stop with only that one brake.

I know what you mean about being curious what got us to this point. We have ALWAYS done our own brake systems, and never EVER have we had this kind of difficulty. I think one of the things we are fighting here is that we replaced an entire system rather than just a part at a time. It could have started as several issues and we are just narrowing it down.

I go back to the possibility of the booster being a culprit, but it doesn’t figure right – if the booster were loosing vacuum: A – it would effect the entire system, not just the front calipers; B – there should be some external hissing or indication of vacuum loss; C – It held enough vacuum to hold tightly onto the push rod after sitting for a good 2 hours, and it made one heck of a ‘woosh’ of air when I removed the check valve to release the pressure.

Soooooo…. Another school of thought is the distribution block, but again, it doesn’t figure right – if it were not working correctly A – the brake light “switch” probably wouldn’t be functioning properly; B – I get plenty of fluid flow to each caliper.

The boggling thing is the back drums are working well. They will lock up before I get the fronts to fully engage (if I have the back brakes turned on). I have one that grabs (the right rear) before any others but I am pretty sure that is either a tiny bit of contamination or it just needs some more fine tuning adjustment.

I sound like a broken record and I am sure this is getting tiring for others as well as myself. I may just put her away for a while and come back to it. I’m fried at this point. I know it has to be something I am just missing…. But I can’t imagine what that could be at this point. I was pretty sure I had covered all the bases.

Only other thought is that they gave me the wrong calipers….. but I dunno – the sure matched up visually to the old ones and the pads fit exactly.
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Quote:
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Old 10-29-2008, 07:31 AM   #60
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Re: Wrong master cylinder - should I worry?

You must have an incompatible piece of hardware somewhere. The calipers are fine if they match up, they only have one moving part and that year Cougar really had no other option for calipers, so if they fit, they're right.

So, between your power booster, master cylinder and proportioning valve, something is "not exactly". I always had my power boosters and masters rebuilt so I always got "mine" back. I had my '68 Mustang with the Kelsey Hayes disc brake set up done that way.

The bitchy thing about Cougars and other Mercury products is that if you don't get the EXACT match up with parts, you'll have headaches like yours. Often enough, parts were specific for ONE year only and that's it.

Do you still have your old power booster and master? If so, shell out a few $$ and get them rebuilt. If not, try to get some NOS parts that still have the Ford/Mercury part numbers on them. You may even find them aftermarket if you hit upon the right source. Is there a club in your area that might be able to help?

I'm also not sold that you have the correct proportioning valve. This alone would be the basis of your woes.

Bob
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