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By masterced - 11 Years Ago
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Hello all, its been a long time since I have been on this site but its good to be here again! Recently Ive been working on a '59 F-100 for a buddy of mine, and I am having such a hard time with the brake system I am almost at my wits end. I thought I would share the insanity with all of you and see what you thought...
It has the original style single reservoir master cylinder. When he first brought the truck over it was empty and looked like it had been that way for a number of years. I removed the MC, cleaned all the old gunky fluid out with clean brake fluid and parts cleaner, and bench bled it. Seemed to get all the air out just fine, I went until I saw no bubbles and my trusty wooden dowel became nearly impossible to push in.
I had a buddy come by to help me bleed the rest of the system. I cracked all the bleeders at each one of the wheel cylinders first to make sure that I wasnt going to snap any off after I called a friend over, of course closing them off again before we got to work.
I started at the right rear, got a few solid pumps of fluid, and then every pump after that had a very large amount of bubbles. We bled the right rear for about 20 pumps of the pedal, I refilled the reservoir before it emptied, and still was getting a LOT of air bubbles. No fluid was leaking from the lines. I just figured this system was a little bit harder to get the air out than most any other brake job Ive done, so we diligently kept on the bleeding process. But after about 40 more pumps, with still massive amounts of air bubbles coming from the back rear I was starting to get frustrated. I checked the fluid level in the MC and realized it was dangerously low, so I figured that we went too far, I had been introducing air back into the system, and that I should just stop while I was ahead and start on a new day.
Well today was the new day. I pulled out the MC again to bench bleed it again, in case I let the fluid level get too low. The dowel hardly moved, and no air bubbles came out so I guess it never went dry like I feared. Reinstalled the MC, started the bleeding process again at the right rear (with a different buddy, not that I was blaming my bad luck on the first guy- I guess the buck stops here right?) and it took probably 5 pumps or so and I got a solid shot of fluid, finally. Thinking bad thoughts about my first buddies capabilities, I moved onto the left rear. I had my partner do about 10 pumps of the pedal with nothing but massive air bubbles coming out of the left rear. Now there is a single line going to the rear that tees at the rear axle, so since I got a solid shot of fluid at the right rear, it should not have taken much to bleed the shorter line going to the left rear.
About this time I started to suspect that the MC actually was bad, and that somehow it was letting air into the system. I figured that since I used a wooden dowel for the bench bleed I was not getting enough of an advantage (even though a wooden dowel has been enough to bench bleed the other 13 or so other master cylinders I have bled in my short lifetime). But just to silence the voices, I left the MC in the truck this time, reinstalled the plug in the line, and had my buddy push down on the pedal very slowly while I looked in the reservoir. No bubbles, and with all his force on the pedal, it would hardly move. Again, verified that the MC was definitely bench bled, and was not introducing air to the system.
Well back to the left rear wheel cylinder. I have gone through over half a gallon of brake fluid, the MC has no trouble moving fluid through the system, but I am still getting massive amounts of air at the left rear. I know some systems like to hold onto air but this is getting absurd. How can there still be air bubbles coming out of the bleeder valve? Since I was just about to run out of brake fluid, and I was getting very frustrated by this point, I closed the valve, had my buddy push down to test the pedal thinking that maybe I was just having a bad dream and that I had magically bled the brakes even though all I could see was air bubbles. The pedal went straight to the floor, no pressure. Of course I opened the left rear bleeder while his foot was still on the floor, saw another squirt of mostly air bubbles, then closed the bleeder before I had him bring the pedal back up (heaven forbid I introduce air into the MC by having him do a test pump to test the pedal pressure)
So there you have it... How is this possible? Where the heck is air getting into the system if there arent any puddles of fluid on the shop floor? After over half a gallon of brake fluid run through the lines and still getting air bubbles I am at a total loss. Sorry to make such a long story out of my tribulations, but I wanted to make sure anyone reading this wasnt thinking 'oh great, another dummy who doesnt know how to bleed brakes' Who knows maybe you are thinking that, and if you are, please, enlighten me! Thanks all
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By The Master Cylinder - 11 Years Ago
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masterced (10/12/2013)
Sorry to make such a long story out of my tribulations, but I wanted to make sure anyone reading this wasnt thinking 'oh great, another dummy who doesnt know how to bleed brakes' Who knows maybe you are thinking that...
I don't have an answer where you are getting air from, only suggestions, and I don't know all the people on here personally, but after being on this site for awhile now I can almost certainly attest that there are not too many who would think bad of you for asking a question...
With that out of the way, the first thing that comes to mind is maybe a bleeder isn't closed all the way? Maybe some crud caught in it?
When bleeding brakes I like to run a tube from the bleeder to a FRESH jar of fluid so I can see bubbles as they come but also it will draw fluid back into the system not air.
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By charliemccraney - 11 Years Ago
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Since the mc was empty, I assume he didn't drive it over. All of the gunk that was in the master cylinder is also probably in the wheel cylinders. Those should probably be taken apart and cleaned or rebuilt or replaced.
Maybe a seal is letting air in but also keeping the fluid inside.
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By masterced - 11 Years Ago
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Ok, thanks for the fast responses guys!
MasterCylinder- first off, nice name- sounds like Im talking to the guru. When I run a tube into a fresh jar of fluid do I still need to open and close the bleeder with every down and up stroke of the pedal? Or can I just open the bleeder and slowly pump the pedal up and down? I have heard of this method before but always just stuck with what I know has worked in the past. Maybe its time to break out of my comfort zone and try something new... And actually if I could get away without opening and closing the bleeder it sounds like I could do a bleed job on my own. Now that would revolutionize my bleeding procedure! No more waiting for buddies, but also no one else to blame a botched bleeding job on haha. Wait, never mind, I forgot the buck stops here...
Charlie- No, he didnt drive it over. He flat towed it over, had his son keep it in gear and used the clutch as a brake. He said the bakes had "always been bad", but I dont think he is the first owner haha. I just translated that into 'the truck has been sitting since I broke a line or the master cylinder went bad.' I agree that the gunk from the MC found its way into the wheel cylinders, but I have certainly done some flushing of the system. I would have thought that the fluid would be leaking if it was letting air in, but who knows... There definitely isnt an air source inside the system, so it is getting in from somewhere.
I will pull out all the bleeders, take a look at them and inspect the bleeder holes for any gunk that is preventing them from being closed, and if that fails I will start looking into repairing/replacing the wheel cylinders. Ive been wanting to get one of those honing bits to be able to repair wheel cylinders for a while, so maybe now the time has come. I will keep you all updated on my progress and please dont be shy if you think up any other suggestions!
Thanks again
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By The Master Cylinder - 11 Years Ago
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masterced (10/12/2013)
MasterCylinder- first off, nice name- sounds like Im talking to the guru. When I run a tube into a fresh jar of fluid do I still need to open and close the bleeder with every down and up stroke of the pedal? Or can I just open the bleeder and slowly pump the pedal up and down? I have heard of this method before but always just stuck with what I know has worked in the past. Maybe its time to break out of my comfort zone and try something new... And actually if I could get away without opening and closing the bleeder it sounds like I could do a bleed job on my own. Now that would revolutionize my bleeding procedure! No more waiting for buddies, but also no one else to blame a botched bleeding job on haha. Wait, never mind, I forgot the buck stops here...
Yes leave them slightly open and pump slowly. Don't pump them up and then open the bleeder, you'll blow fluid out of the jar if there is air in there. And yes I have bled brakes by myself with this method but it is still a good idea to have a friend do the pumping so you can watch for bubbles and keep and eye on the M/C level. And you have the friend there in case it doesn't work and you need someone to blame... HA!
Oh and no guru here. The Master Cylinder is the nemesis of Felix the Cat...
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By oldcarmark - 11 Years Ago
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This is just my opinion but if this was my Truck I would be redoing the whole system with new Wheel Cylinders and Master.If this has been sitting for an extended period of time with no fluid in the Master there has been moisture in the system as brake fluid absorbs moisture.With a single Master Cylinder you cannot afford to have a failure in the system front or back.You need the Brake System to be in top dependable condition.Wheel cylinders and Master are not expensive to purchase new and I would also be replacing the flex hoses too.
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By dbird - 11 Years Ago
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I have to agree with oldcarmark, the parts you need are cheap, around $100 for all cylinders and hoses and you get an incredible amount of peace of mind, not to mention outright safety. That said, I've had good luck bleeding systems with a vacuum pump when I got bubbles forever using the conventional foot pump method.
Don
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By Talkwrench - 11 Years Ago
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Sounds like you may have a crack in a line, however that should be obvious. There is one other thing that comes to mind . DO NOT bench bleed single circuit M/cyls ! Best way to damage the seals.
Also make sure you are not pushing the pedal all the way to the floor when installed, only half way . Put a piece of wood or brick under it if you have to. when its working correctly the fluid will just about squirt out the filler cap opening when you pressing the pedal. messy!
As Mark said you should go over the whole system if its that old that includes the lines / hard lines.. Its really not that expensive to do the whole lot and for piece of mind its best.
Get a new M/C and get some speed bleeders, its so easy if you need to get started..
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By paul2748 - 11 Years Ago
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Something that was only mentioned briefly - check the flex line from the body/frame to the rear end. Replace it since you got a lot of crap in the system. At least remove it and make sure it is not full of gunk. I would remove the line that goes to each rear cylinder and clean it out with brake cleaner.
Sometime these flex hoses have internal damage that you can't see. my advice is to replace it. The front ones too.
Something else you may want to do as a test. Disconnect the lines at the wheel cylinders and then apply pressure to the pedal.. If you get a good stream then the wheel cylinders are probably to blame. replace them.
If there is a brake line connection between the master and the rear, open it up and check for flow. Often there is a connection somewhere on the frame running back.
Never heard of just pushing the pedal down part way. Always replace the cap before bleeding, this stops it from squirting.
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By The Master Cylinder - 11 Years Ago
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I agree with the others, you should really go thru the brake system before you go any farther trying to bleed the brakes. Maybe even upgrade to a duel M/C while your at it if your current M/C needs replacement. Minimal work and cost but makes for a much safer system.
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By charliemccraney - 11 Years Ago
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A dual master cylinder by itself does nothing for safety. A pressure differential valve is needed for the safety aspect and that is in a combo valve. Without that, a failure will result in a pedal that goes to the floor and braking ability that is not even remotely safe.
For now, solve the problem and think about upgrades later.
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By ian57tbird - 11 Years Ago
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I agree with the others, replace the wheel cylinders. I wouldn't bother rebuilding then as new ones are so cheep. Easy to tell if they are leaking, just peel back the rubber cups and you will soon see if they are wet in there.
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By The Master Cylinder - 11 Years Ago
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charliemccraney (10/13/2013)
A dual master cylinder by itself does nothing for safety. A pressure differential valve is needed for the safety aspect and that is in a combo valve. Without that, a failure will result in a pedal that goes to the floor and braking ability that is not even remotely safe.
I don't agree with that. It is two separate systems. A pressure differential valve only alerts you if there is a problem.
charliemccraney (10/13/2013)
For now, solve the problem and think about upgrades later.
My point was if he has to replace the M/C he may as well upgrade it now.
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By Bob's 55 - 11 Years Ago
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charliemccraney (10/13/2013)
A dual master cylinder by itself does nothing for safety. A pressure differential valve is needed for the safety aspect and that is in a combo valve. Without that, a failure will result in a pedal that goes to the floor and braking ability that is not even remotely safe.
For now, solve the problem and think about upgrades later.
That's not correct, the pedal will not go all the way to the floor although it will be lower than normal. You will still have half your brakes. The two systems are in no way connected (fluid wise) to each other.
The only way it could happen the way you describe is if you lost fluid in one system AND the seal between the two pistons failed.
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By masterced - 11 Years Ago
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Well I pulled out the two rear bleeder valves and didnt notice anything out of the ordinary. One of them seemed to have a bit more of a point than the other one, but both seemed to have a solid wear pattern around the point that seals them closed, so I dont think they are the culprits. I also looked into the wheel cylinders where the bleeders go in with my little mirror and couldnt see any noticeable crud that would be preventing them from closing.
I went ahead and pulled all the drums off and noticed a slight discoloration on some of the rubber boots, like they were wet at some point, but didnt see any drips on the wheel cylinders or traces of fluid on the backing plates. One of the front drums however had a nice rust pattern on the inside braking surface which looks exactly like something a leaky wheel cylinder would have left behind.
I found that the metal line leading from the master cylinder to the 4-way block on the frame (not sure the correct term for a fitting that has a place for 4 brake lines to thread into) had about a 6 inch piece of rubber hose incorporated into the design. Not sure why this would be. If the master cylinder is bolted to the firewall, and the 4-way block is attached to the frame, I dont see any reason to have flexible hose between the two. I already removed it and replaced it with a metal line.
Im gonna go ahead and buy 4 wheel cylinders, and although I dont see any outside damage to the rubber lines, they do look old enough that they could be replaced, so I will add them to the list as well. When I tried to separate the two front flex hoses from the metal lines at the frame, both metal lines wanted to shear off, so I will be replacing some of the metal lines too. I will make sure to keep you all updated on the repairs. Assuming I can get the parts in the next few days I should have them installed by Wednesday night. Thanks for all the suggestions and we will soon have an answer!
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By charliemccraney - 11 Years Ago
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Bob's 55 (10/13/2013)
That's not correct, the pedal will not go all the way to the floor although it will be lower than normal. You will still have half your brakes. The two systems are in no way connected (fluid wise) to each other.
The only way it could happen the way you describe is if you lost fluid in one system AND the seal between the two pistons failed.
Well, this is my first hand experience, so it is correct. The pedal did, in fact, go to the floor and the truck kept a rollin' after a leak developed at a poor flare in the rear brake circuit. I, too, thought it was suppose to be safer. It is not. Fortunately, my experience took place in my driveway.
That experience made me research the brakes more, because the dual master cylinder by itself was no more safe.
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By Talkwrench - 11 Years Ago
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Charlie thats why I didnt go ahead and put a dual circuit on my 35 P/up. I could not find anywhere someone who sold a nice bolt on system that worked. Most Duals are 1" Not 1 1/6" as per the original. I kept reading guys saying "yeah it works but the pedal is closer to the floor" that got me thinking , well if it fails the pedal needs to go further to hit the second curcuit, if the pedal is already closer to floor well you just gonna hit the floor and get nothing!
I just bought a new orginal USA made M/Cyl and some speed bleeders and its as it should be. Now if only my new lining would turn up .. MACS !!!!
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By Bob's 55 - 11 Years Ago
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Charlie I don't want to argue with you because obviously it was your "first hand experience" so all I'm saying is you should have had front brakes even with the loss of your rear brakes. My feelings are either your other brakes were out of adjustment or something else was wrong. Maybe the seal between the reservoirs was NFG. The M/C should have provided brakes on the front brakes.
The pressure differential valve would not have any bearing on it in any event. As someone already mentioned all it does is tell you there is a problem. The Front and Rear Systems are NOT tied together.
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By paul2748 - 11 Years Ago
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One of the problems with a dual master cylinder on early cars is that the amount of travel may not be sufficient to engage the safety feature. This has been a problem when the TBirders started to do conversions. The answer, so I have read, was to relocate the pushrod so there was a bit more travel.
More to home, I have dual master cylinder on two of my cars, a 48 Ford Conv and a 54 victoria.
I experienced fluid loss on both cars. The 48 had an aftermarket kit from a well known brake house and the 54 I did a Granada conversion. Both had combo valves and were set up correctly.
The leak on both cars resulted in complete brake failure. I surmise that the pedal travel situation found in the TBirds was the problem.
Be aware that your conversions may have the same situation.
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By charliemccraney - 11 Years Ago
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This just goes to show how much misinformation is out there. Everything I read about the differential valve indicated that it not only activated the switch, but also cut off flow through the failed circuit to prevent further fluid loss.
If Paul has experienced the same sort of failure with the valve, in two instances, then that must not be true. I had not yet heard about the pedal travel issue. That one should be pretty easy to determine if specs for the dual master cylinder which is being used can be found. Just compare the spec to the linear travel of your pushrod and adjust as necessary.
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By snowcone - 11 Years Ago
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I would also assume that if you had half of a dual system fail and the normal pedal travel was not sufficient to activate the remaining brakes, then a couple of good pumps under panic should have been enough to get them working.
Also I bit the bullet recently and bought an air operated vacuum bleeder of Fleabay for around $30 and bleed a completely dry system with new lines and wheel cylinders on my own in around 10 minutes.
I would go back to the old up, down, up, down, routine after using this.
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By ian57tbird - 11 Years Ago
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The rubber hose mentioned might be to allow for any movement so you may need to put a coil in the steel line you have go down to the brass block on the chassis. Some of guys on this sight who are familiar with your type of car might be able to give you some better insight. I'm only guessing.
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By The Master Cylinder - 11 Years Ago
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paul2748 (10/14/2013)
I surmise that the pedal travel situation found in the TBirds was the problem.
Now there is something to be aware of using parts not originally designed for your particular car. I seem to remember checking mine but it was so long ago that I don't recall so I think I will check it.
Paul, how did you lose fluid? was it a burst line or bad flare like Charlie had? Always looking for things to check...
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By paul2748 - 11 Years Ago
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In the 54 it was a pinched line in the right front. Still don't know how it happened. Checked everything out, turned the wheel to the extremes both ways an still can't see how it might have happened. That line (a braided stainless covered one) has been on the car for 7 years or more and has quite a few trips under it.
The other car was even odder.
The Master Cylinder (10/14/2013)
paul2748 (10/14/2013)
I surmise that the pedal travel situation found in the TBirds was the problem.
Now there is something to be aware of using parts not originally designed for your particular car. I seem to remember checking mine but it was so long ago that I don't recall so I think I will check it. Paul, how did you lose fluid? was it a burst line or bad flare like Charlie had? Always looking for things to check...
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By ejstith - 11 Years Ago
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It has always been my understanding if one had drum brakes all around there was no proportion valve. The big reservoir went to the front brakes (only) and the smaller one went to the rear brakes (only). If a rear line went bad I fail to see why the front brakes wouldn't still work.....
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By Talkwrench - 11 Years Ago
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That's true no proportioning valve, the different wheel cyl sizes sort that out. However there are many different styles of M/C you cant use a Disc / disc On a Drum setup. they have some sort of residual valve inside and probably bore size . The lines "generally" go front / front but not always..!
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By masterced - 11 Years Ago
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Sorry for the extreme delay, I replaced all rubber hoses, wheel cylinders, and re-bled the system. The old rubber lines looked bad from the outside so it was a good thing to do regardless. The only thing out of the ordinary that I noticed was that the front left rubber hose that threads directly into the back of the wheel cylinder was without a copper washer. The front right still had one, and both new hoses came with replacement washers.
I got solid shots of fluid using my traditional method of bleeding (having a partner bring pedal to floor with bleeder open, closing valve before letting pedal go up) and everything seemed to be going fine until the last wheel cylinder (front left). Then before I could get a solid shot, with pedal halfway to floor I started getting extreme amounts of bubbles again. Not only that, when I closed the valve and had my partner bring the pedal back up we could hear what sounded like bubbling inside the master cylinder. There was also a few drops of brake fluid on the cab floor, another telltale sign that the MC was the culprit.
Being very fed up with the project and suspecting that I should just replace the master cylinder, I set the job aside, ordered a new master cylinder, and wasnt able to get back to the project til now. Interestingly in the two weeks or so since it has been sitting it has not lost any more fluid. The pedal is strong, and I am able to push on the pedal with all my strength without seeing any more fluid loss from inside the MC, or drips on the cab floor.
In the directions of the new MC, it says when bench bleeding make sure not to push the dowel or pushrod in more than one inch or it will give the appearance of the MC leaking. I thought that was very interesting information. Anyways, I know that you all would suggest to just put in the new MC but since I have a firm pedal with little travel and no fluid loss, Im going to drive the truck around my country roads slowly for a few days to see how it reacts. I will keep the truck in gear and turn off the key in case of a complete brake failure. I just want to see if I lose any more fluid or get a spongy pedal before I put in the new $110 MC (that includes the $16 core and unfairly large shipping costs).
Just wanted to update you all on my progress even though it took so long, and say thanks for all the advice on the subject. As soon as I see any more drops of fluid in the cab, or lose pressure at the pedal I will be putting that new MC on. And if not I will save it for one of the other old Fords in my yard without brakes...
-----Ive edited the post 3 times and still cant figure out how to only underline the word SLOWLY - Im not mentally challenged, just too computer illiterate I guess... Anyways, Im sure you all are smart enough to figure out what I was trying to do, and no more fancy typing tricks for me from now on haha
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By The Master Cylinder - 11 Years Ago
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Masterced, Undo the all the underlining, then select just the "SLOWLY" and select the 'U'. You have to finish all your typing THEN go back and underline. Hassle but that's the only way I have found to do it on this site. Same for 'B'old, 'I'talics, Font Color, etc.
Good luck with your brakes.
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