Need some advice guys... I have '40 Ford drums on my Model A and have had to pump the pedal a couple of times before I got a firm brake. I just changed one of the brake cylinders and the master cylinder (not power). I bleed all 4 brakes and worse than before. Can somebody please help me fiqure out how to get a firm brake pedal? Also, I have the in-line pressure parts for keeping residual pressure.... Thanks! Mark
One way to narrow it down to a specific wheel would be to use a vice-grip and (gently) pinch off the brake hose to each wheel one at a time. Then get in the car and hit the brakes. If the pedal is suddenly better the problem is in the wheel that you just took out of the equation. Another thought would be the MC push rod. Sometimes there are differences in master cylinders and they can require an adjustment of the rod length. Did you bench bleed the master before installing it? Sometimes if you don't do that it can take a LONG time to get all of the air out. Did you re-adjust your brakes after installing the wheel cylinder?
On some occasions I have had to bleed backwards...meaning starting with the closest wheel first, just to get some pressure from empty lines. Also, sometimes just lightly holding a finger over a bleeder while someone else pumps the pedal slowly will help.
A quick note on bleeeding brakes, and I always try to mention it when people are having problems with getting the air out of a system. DO NOT pump the brakes when bleeding. This can cause bubbles, and with the new dot 4 fluid this is particualy true. Just have one person open one bleeder, and when open push the pedal to the floor and hold until the bleeder closes the valve. Let the pedal up, tell them to open the bleeder and push the pedal down...repeat. No pump until you have done all 4. Maybe you know that, but its the best way IMO.
I like the one way bleeders. Their not expensive and your auto parts store probably has them in stock. Try um, you'll love um.
All great advice... didn't know that about pumping like a modern brake system. will try that. I am also not very knowledgable in adjusting the pads. Any advise on that? and should the pads be adjusted before the bleeding? Thanks guys!
Adjust your brakes til they're locked, then back off a couple turn until they lightly drag. Take it for a spin and see if your pedal firms up. If that's the case, tune your brakes a bit further by stopping from different speeds and in different scenarios like locking them up etc. Adjust til the car stops quickly, locks 'em up evenly (fronts should lock before rear), and the brakes don't pull either direction. Drums are fun!
Turn your adjusters out until you can get the wheels to spin equally (by hand, hard spin) about 1 1/2 spins before they stop. Takes some practice, but you"ll get it. You should adjust then bleed, but it doesnt make a lick except getting pedal to be in the right spot and it will feel more "right" when you adjust then bleed, since your pedal height will be right.
If you have 39-41 backing plates with the adjustable anchors at the very bottom it takes a very specfic adjustment procedure. This has been covered here many times, do a search. ALWAYS adjust brakes BEFORE trying to bleed !!
thanks again guys... I have the two bolts on the top around 2 & 10 o'clock. Another question... this has been the case since before I even changed the leaking master. I can push the pedal all the way down and nothing. I have to pump it quickly two and three times before I get a firm pedal. This is the case every time. I have never had a firm pedal unless I pump it. Makes for nerve racking rides in traffic. Is this air in the lines or a leak somewhere?
Since it did it before the new master, I think the guys are correct about the brake adjustment being way off. Adjust all 4 wheels and see how it is. And make sure the master pushrod has some freeplay before it hits the piston, but not a lot of play.
post your entire system- if you have residual valves when you dont need them you'll have problems- many masters have them incorporated. are you running stock parts in the stock location? floor mounted aftermarket mastercyl? -rick
69 Fury rum systems need residual checks ,does not matter where the MC is mounted! If they were not needed car makers would not have installed them in one place or the other in every drum system they made ! And have one in line and one in the master cylinder will not cause problems.
Old school : Adjust the brakes up till you have a light drag and see what you get. If you do not have anchor adjusters you have 42-48 style back plates. If you are not sure what you have please post a picture showing the lower part of the backing plate.
I take a small piece of clear aquarium tubing and put it over the bleed valve into a little catch cup, i have my expert brake bleeder (wife) do her thing, I can see exactly what is coming out and can see a clear flow with no bubbles this way.Is your master cylinder above or below your wheel cylinders? This can cause some troubles, air doesn't want to purge.
I had a similiar issue dog me before. Wound up being a small leak in the hard line (it was corroded where it ran through a frame rail). It was such a tiny leak that I never did find it while it was on the car. How I solved it was: all new wheel cyl, new mast cyl, new soft lines...only thing left was hard lines...started to do those 1 by 1, and lo a behold, once I the line that ran front to rear replaced I had perfect brakes. Wound up hooking the old line to a different chassis (just hooked it into the MC with the end plugged off) and put pedal pressure on it and saw a little drip come from it about midway. What a pain that was.
I may just be a chicken but I would next replace all of the brake hoses that I had pinched off to run the test. Charlie Stephens
Charlie : I'm with you on this ,ain't no way in hell I'm going to pinch off old hoses and then run them. NEW SOFT fuel or heater/radiator hoses Ok maybe . I would not even pinch a new brake hose. Where are the safety Nazi's when you need 'em.
Not to be insulting, but maybe you don't have the right residual pressure valve? If you've always had a problem with having to pump the brake pedal *to build pressure* before you had braking action, it seems like a possibility to me. Am I right in saying that all drum brake set ups need a 10 lb. valve? Ford brakes that old are all nonservo, huh? If my guess above is wrong you probably need to adjust 'em pronto. Well, good luck with your problem, and stay safe, man!
Any chance you are running DOT 5 Silicone brake fluid? Although I like the fluid you must take extreme care to avoid trapping small bubbles. Charlie Stephens
yeah i know drum systems need residual valves, but i've heard that two in line will cause problems-but i guess that would cause a pressure stack in the line, and might keep them from releasing, which is not his problem.
I have a brand new old style two chamber master mounted under the floor two 10lbs. residual checks inline new braided soft lines. I do not have any slop in the rod going into the master, I need to adjust this for sure, it is very tight. For photos of my brakes they can be seen, I think in my photo gallery of the '28 model A. o... Dot3 fluid Thanks guys....
No clearance in the pedal to MC pushrod can cause probs. Make sure the MC piston is touching the snapring holding it in ,then the push rod should have just a bit of free travel. Be sure you have a return spring on the pedal.
ok, backed off the master cylinder rod until there was some play. Re-adjusted the pads, bleed the brakes 5 times. I still have to pump the bitch up at least twice before I have a good firm brake pedal. Frustated....
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