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So here is MY brake story....scratching my head.


Bmartin

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Ok, I replaced the front wheel cylinders and shoes.  Performed a major adjustment with the AMMCO tool on all four wheels, and set the minor adjustment with a healthy amount of drag to be safe.  I also replaced all soft lines and one hard line that was twisted.  I bled the system for about an hour and did not see any more bubbles coming out.  Unfortunately, I still have a soft pedal. 

 

My next thought is the master cylinder.  Its only got about 300 miles on it.  Are there any misadjustments of the master that could cause a soft pedal?  I usually read about a blocked return port and how it causes the brakes to drag. 

 

I'll measure the pedal travel in the morning and may try locking down all four wheels with the minor adjusters as a test. 

 

Although the master is new, that's no guarantee its not bad.  May have to yank it for an inspection. 

 

 

EDIT:  Just went back and read thru the posts again.  I'm going to try and clear out the relief port on the master, see what that does.  Crossing my fingers.  I also have a friend who will lend me a power bleader.  I'll try that as well. 

Edited by Bmartin
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Sounds like you still have air in it.

 

Having replaced the hoses and at least one of the hard lines, it is possible that you have a joint that is leaking slightly. If you don't have a pressure bleeder you can make one from a garden sprayer and some readily available plumbing fittings and a spare master cylinder cap for really cheap. I spent less than $20 for mine. Anyway with a pressure bleeder with 15 or 20 psi on it providing pressure into the brake system closely examine all the hoses and tube, especially at all junctions for weeping.

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Hey Bmartin,

 

Like I said in a previous post, I replaced the front hard lines, and all the soft lines, rebuilt one front wheel cyl., and rebuilt the MC. I went round and round for 2 days bleeding the brakes. Then I cleaned out the relief port. Presto had hard pedal after 1 inch. Before that I had no pedal till 2 inches, then soft pedal for 5-7 inches, then hard pedal for the last inch to the floor.

 

 

Remember, a bullet may have your name on it, but a grenade is addressed "To whom it may concern".

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soth122003 - thanks again.  Your post is the one I reread.  I'll have to figure out how to pull the floor plan to do this, can't see a darn thing from the engine bay. 

 

I've also been thinking on this a little more.  I know that the previous mechanic adjusted the new master cylinder to get the brakes correct.  I know that pedal travel is partially set by the minor adjusters.  So when I messed with the minor adjusters, that changed pedal travel and may have misaligned the master cylinder with respect to the relief port. 

 

Now I need to do some research and find out the details of adjusting the push rod on the master.  Maybe I just go by free travel, I'm sure there are a bunch of threads on here. 

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Hey Bmartin,

 

 

Pulling the floor is easy. Adjust seat all the way back, pull carpet back up over the seat or remove, then remove the 10 or so bolts holding the floor pan down. Once this is done the MC and brake and clutch pedals come out as an assembly.

 

The adjustment rod on the MC only affects pedal free play. use a 9/16" and 5/8" open end wrench to loosen the jam nut then adjust the rod to set freeplay to about 1/2". This should be done last after the assembly is mounted back in place.

 

That being said, you might be able to clear the relief port using a acetlyne torch tip cleaner file, (I didn't have one so I used a bread twist tie) and a vacuum pump of some sort, without having to pull out the MC.  The relif port hole looks to be about .05 thousandths of an inch. I had to clear mine from the bore side of the MC, which meant I had to remove and disassemble it. use the twist tie to gently clear the port and use the pump to help remve any debris. If you can't clear it from the top thru the filler cap, you'll have to remove the MC. Heer is a picture of my floor pan and a diagram of the MC.

 

 

Remember, a bullet may have your name on it, but a grenade is addressed "To whom it may concern".

 

 

 

 

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Again, thanks for the help guys.  I have pulled the pan and taken the cover of the master to access the relief port.  I stuck a piece of welding wire in there, it went in and is hitting what feels to be something rubbery.  I assume this is the piston cup? 

 

I thought I read that, if adjusted properly, the wire would just go through and not hit anything.  If that is the case, do I adjust the minor adjusters at the wheel to try and solve that or adjust the piston rod?

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Again, thanks for the help guys.  I have pulled the pan and taken the cover of the master to access the relief port.  I stuck a piece of welding wire in there, it went in and is hitting what feels to be something rubbery.  I assume this is the piston cup? 

 

I thought I read that, if adjusted properly, the wire would just go through and not hit anything.  If that is the case, do I adjust the minor adjusters at the wheel to try and solve that or adjust the piston rod?

If you are hitting rubber then your master cylinder piston is not retracting all the way. Two causes I can think for this: 1) Cylinder is crudded up and the piston is not moving properly. Or most likely 2) your pedal to cylinder push rod is adjusted too long.

 

The wheel shoe settings do not affect this at all.

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I had to adjust the rod about an inch or so to get a good pedal, but at that point the brakes all locked on and would not release.  I assume that means I was blocking the inlet port from Soth's diagram.  I had to adjust it back out quite a bit to get the rear passenger drum to fully release, not sure if that means anything.  The others released earlier. 

 

Its looking like pulling the master is going to be required.  Anything else to try before that?

 

This real time feedback is extremely helpful!

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First things first before you pull the master cylinder: See if you can adjust the push rod so that there is 1" of pedal travel before you feel the push rod touch the cylinder in the master cylinder.

 

Once you have that, then the master cylinder is adjusted and you should be able to bleed the brakes properly. Once the system is properly bled then any excessive pedal travel will be in the brake shoe adjustment.

 

If you don't do this in the correct sequence you can easily end up chasing your tail.

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Most suggest on a total brake update to do new steel lines at the same time, up to you and your abilities or wallet!

 

I disagree. We all know how brake fluid sucks up moisture and creates rust. Here we are dealing with steel brake lines that are likely to be 70+ years old. You are sure to see surface rust on the outside of them,but what you can't see is the rust inside the lines. You have no idea how thick or thin the tubing wall is and it's one of those things where it is safe right up to the instant it's not,and at that very instant it can be fatal.

 

Replacing steel brake lines and rubber hoses with new ones on cars this old shouldn't even be optional and is the absolute worse place in any project to try to save money. It can not only cause you to end up looking for a whole new expensive front clip for your car,it can kill or cripple you as well as others. You can throw a blanket over a seat or paint your car with a brush to get by,but you can NOT cut corners on brakes,suspension,gas lines,or tires.

 

Besides,you can now go to the local NAPA store and buy brake lines that you can bend by hand without kinking,and it doesn't even cost very much. Why even consider taking the chance when you know it's something you are going to have to do anyhow?

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Ok, Adjusted the pedal to have 1" of travel, then rebled the brakes, did get a little more air out.  Then set the minor adjusters to full on to be safe and still no pedal.  Looked at all the connections and lines and no leaks that are obvious.  I assume its something in the master.  going to see if I can get the power bleeder today, may try that out first. 

 

Thanks again for all the help.

 

 

EDIT:  Question on master cylinders.  Assuming this one is bad, what is the best route to go?  For info, I still have the one that was taken out under the assumption it was bad(by mechanic, not me).  Not sure it is original.

 

Rebuild Existing or Old one:  I never liked rebuild kits for brake parts on modern cars.  Always had issues.  Is this different with older models?

 

Buy New:  That is what this one was, not impressed.  It seems all the new ones are cheap China crap, so that does not seem the best choice.

 

Resleeve my olde one: I have read of services that will sleeve the master and rebuild it.  Is it best to have the company sleeve and rebuild or just sleeve and I rebuild myself. 

 

Try and locate a NOS replacement:  seems difficult, but possible. 

 

Replace with Dual master from Butchs Cool Stuff knowing that someday I will go Disc:  Expensive, but will get spent eventually.  Does this work well with stock drums?

Edited by Bmartin
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Okay BMartin,

 

You said you still had the old MC. Have you taken it apart to look at it? If not do so. I'll post a diagram of the MC breakdown for you. The biggest failure of MC's is the cups. They either swell and will not move freely, or they scrape and tear over the corrosion in the bore and leak. When an MC is rebuilt, it is usally honed to clear the bore. You can take alot of material out and still not have to resleeve. I think you can go to about .05 thousandths and still have a usable bore. I honed mine for about 30 to 40 minutes. Still had some minor pitting at the end where the lines hook up, so it does not really affect the operation of the MC. Remember, when the MC is working right and the shoes are set at a slight drag, the MC pistion will only move about 1/16 to a 1/4 inch. (you can/t compress a fluid), and your pedal will travel about 1-2 inches.

 

That being said, the best way I found to do my brakes was to adjust the shoes to the drum first. Then bleed the system. That way you are not pumping your butt off to make up for the shoe to drum clearance. put the car on jacks and set each brake drum.

 

You said the rear brakes were slow to release. sounds like the soft line at the rear. The soft lines are the most expensive parts to replace, about 25 bucks apiece. the steel line you can buy already to go. Just bend to fit and connect them. A 60 inch line is about 5-6 bucks. They come in pre-made lengths. 8, 12, 30, and 60 inch lengths.

 

Next, have you replaced all the soft lines? one for each front wheel and one for the back wheels. (Usually on the left side at the front of the rear axle). Have you checked all your fittings and wheel cylinder for leaks?  how about the steel lines? If your good to go there, then it is probably your MC. A thing to note, back in the day they made these parts for the cars to be repaired or rebuilt. Thats why all the parts are bulletproof.

 

Now what I would do is look at the old MC first. If the bore looks decent, get a cylinder hone from Autozone for about $18.00 and hone the hell out of the bore. Make sure to use brake fluid as the lube oil for the hone. You can  do this while your waiting for an MC rebuild kit, about $15 bucks with s&h from Rockauto, to arrive in the mail.  When your rebuild the MC, your primary cup should set between the suppy port and the relief/bypass port. Also make sure your ports are clear after honing.

 

Now if you had all the parts on hand it should only take about 2 hours to do this. My problem was waiting for parts and my job so it ran about 2 weeks till I was finished. My total cost of brake rebuild was about $125.00. One MC rebuild kit, 3 soft lines, one cylinder hone and the steel line for the front brakes.(the back lines were still good).

 

I hope this helps. I think your mechanic might be one of those replace instead of rebuild kinda guys. Like I said those MC's were bullet proof and you can rebuild them indefinitley.  Here is the breakdown of a typical MC.

 

 

Remember, a bullet may have your name on it, but a grenade is addressed "To whom it may concern".

 

 

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Thanks again Soth.  All soft lines have been replaced.  I have not been able to find any leaks yet.  I picked up a couple of plugs and caps so I can isolate front and rear for troubleshooting.  I bench bled the old master, and want to swap it in just to see if it behaves the same.  You are probably right in that I should have pulled it apart and inspected it first.  I'll get back to it again this week and see what happens. 

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I made a simple homemade dual master cylinder mount that allows you to mount a very inexpensive ford non power, drum drum, master cylinder right in front on the brake pedal and right underneath the steering column. I can shoot you an email with some pics if interested. Just in case you are not finding success with a single port master cylinder. I'm sorry to hear all the troubles you are going through .

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Good call with the plugs. I did that to, just forgot to mention about them. Aside from isolating the front and back brakes with them, you can also isolate the MC. that's what I did after the rebuild to make sure it worked right.

 

 

Remember, a bullet may have your name on it, but a grenade is addressed "To whom it may concern".

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Well, I disassembled the master tonight.  When I took it apart there were all the parts plus a seal that was all the way inside the master.  Its not on the diagram in the book.  It seems like it was all the way in front of the valve assembly.  I was emptying the rest of the fluid out after diassembly and it fell out.  Problem is, it has a lip on it and I don't know which way the lip goes - toward the piston rod or the outlet.  Its a new master, as in not original.  Wondering if anyone has taken apart a similar one and can comment on the orientation of the seal.  My guess is it goes towards the outlet. 

 

Otherwise I can find nothing wrong with the master.  The relief port was clear, there was a little bit of gunk inside on the valve, looked like lint.  Otherwise pretty clean.  I can not see anything that would make it not work.

 

I tried to plug the front hard lines at the brake switch but the lines are not budging and even with a 7/16" flare nut wrench, they are starting to strip.  So its leave them or replace the entire hard line.  I'm going to clean everything up and reassemble next.  I have a rebuild kit coming for my other master.  I bench bled it and its now leaking from the rear seal, so its shot. 

 

I still have not found the source of the original problem. 

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Hey B,

 

Sounds like that is the valve seat seal. Did it have a 1/2" hole in the middle of it? If it fell out, that's what it probably was. As far as the lip on it, it might have been worn into it from the spring tension. If there was no hole, then someone screwed up when they put it together. The sequence from where the brake lines come into the MC to the Adjustment rod should be, End cap, End cap seal, Valve seat, Valve, Spring, Primary cup, Piston, Secondary cup (installed on piston), and the Piston stop assembly. Or as I like to call it the other end. Put the MC together like that and temp install it in the car. Use the caps to plug the lines at the MC and plugs at the MC. Press the brake by hand and you'll know if the MC is good or not.

 

As far as the other one leaking from the rear seal, If it is the end cap seal, try flipping the seal around.

 

Most of what I am basing this off of is the way my MC is built and the Motors Manual I am using. Could you post a pic of your MC, so I can make sure I am not giving you bad or confusing info.

 

 

 

Remember, a bullet may have your name on it, but a grenade is addressed "To whom it may concern".

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Looks like a standard set of MC guts, except for that big silver washer. Try putting it back together without that and see if that fixes the clearance problem.  When assembled correctly the primary cup should set between the suppy port and the relief port.

 

 

 

Remember, a bullet may have your name on it, but a grenade is addressed "To whom it may concern".

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