I have posted several brake questions on here as I have tried basically everything. I have '42-'48 ford juice brakes, new shoes, wheel cylinders, lines, and MC. I have added residual valves in both the front and rear system (dual master) 10lb as recommended, and in the right direction. I have bled them literally 20 times. I even bought a vacuum brake bleeder and ran a liter of fluid through them just tonight. I CANNOT GET A SOLID PEDAL ON THE FIRST PUSH...I get a firm pedal on second push and every push after, the pedal stays firm and does not fade. If I take my foot off for 5-10 seconds, and depress the pedal again, it goes down past half way. It stays firm at that position (doesnt go to floor) but isnt a full pedal. Full pedal comes on second push. I have asked just about everyone I know and had a few buddies look at them with me, we are all scratching our heads. Here are things we have considered as issues: 1. The lines have a high point trapping air 2. Maybe brakes need adjusted (they are all set to drag and spin less than one rotation. 3.Maybe shoes need bevelled 4. Bad Master Cylinder (It has been been bench bled, and upon capping both outlets, it won't budge a centimeter, so seems good to me) 5. Bad wheel cylinders (can they suck air even though they arent leaking?) 6. Master cylinder has a larger reservoir in front and smaller in back. (I have 1 1/8" bore in back, and 1 1/4" in front wheel cylinders (I do have 1 3/8" to try if that could be it) 7. push rod, it can be adjusted, but it goes all of the way in and all of the way out when I press pedal, so I am not losing any distance there 8. Residual valves are about 14" from MC, not 4" but should still hold the pressure in the system forward of that, I dont visually see fluid flowing back into MC The only abnormal piece in the whole system, is a 1" aluminum spacer that sets the MC back allowing some more pedal room in the cab. Could this be an issue. The pushrod has plenty of adjustment to make up for it, and as I said above does its full travel in and out. Anyway, I am out of ideas and basically throw my hands up at this point. Anyone have an idea whats next or what else to try?
Let me ask you, why do you have residual valves in the system ? Is the MC way below the wheel cylinders ? I am running basically the same setup as you on my 27 and have never had a residual valve in it, and my MC is under the floor. I don't like residual valves, we had them on my Sons T bucket and ended up gutting them so they are straight pipes now and it works better. Just a thought. Don
The MC is a universal Speedway MC/Pedal Setup, has a 1" bore, it does not have internal residual valves in it, so I added a 10lb PSI one in both front and back system about 15" away from MC, not much room around the MC to be closer, but could be if I knew that was the issue, more I read, it doesnt seem to be an issue. I am ready to try a new MC, but it seems to check out, by bloxking off the outlets and it being totally firm, is that a good indication my MC is fine?
On discs, the 2lbs ones are only needed if the MC is below the calipers to prevent bleedback. Ive seen cars with this issue and you have to tap the pedal to get them to touch, then hit again to get them to apply if its not there. Fluid levels its self. On drum brakes, 10 pounds are needed as the shoe springs can push the wheel cyilinders too far into the cups ad blow out. Most early MCs have internal ones, so you dont need them inline. You may not have had an issue yet, but the potential is there, and brakes are somethig I dont like leaving up to "odds" of it going wrong.
I tried a 1" bore m/c with early ford brakes. Had the same issue you're having. I changed to a 1 1/6" and liked it. I believe a stock early ford m/c is 1 1/8, those brakes require lots of volume.
If its truly a master made for drums, it would have the res valves in it already, and dont need the inlines. I always check before I use a master, rather than rely on what a counter jockey says.
Sounds to me like you have a high point and aren't getting a fast enough flow while bleeding to force the air bubble far enough past the high spot so that it can't flow back before the next stroke. Pressure bleeding with a steady flow will keep the bubbles moving until they get pushed out through the bleeder. If you have to bleed by pumping the pedal, install a union at the highest point, bleed the system normally and when you get to the point you are at now, (almost bled) crack the union and give one push, close the union and you should have a good pedal.
So you guys think get a different MC? I have been told 67 mustang, but these guys at speedway say thats what MC it is.
I used a compressor and a vacuum bleeder tonight for an hour round the car 4 times, no bubbles, unless I just need to keep going...
Don I read on here all the time about all the brake problems lots of guys have. I'm always amazed at all the conjecture about solutions. Lots of bad info passed around as solutions! I'm one of the "sinners" that uses single m/c's, I use them on every combination ! ( I hate duals for my own reasons ) I have three different m/c's that I use; 1 1/6", 1", & 7/8". With these three I've been able to make most any set up work very well. These m/c's have internal residual valves, some times I will remove the valve, depending on the application. With my own car that has early ford brakes I used a 1 1/6" single m/c with internal residual valve, works great ! ( gee . . . that's kinda' like Henry did it ! )
Pete, I'm running a single MC on my 27 too (66 Chevy pickup brake/clutch MC) and it has been flawless for the 25 years I have had the car. I've also used mid 60's Mustang dual MC without residual valves too on other cars with good luck. Don
Can you go too big of a bore? Since 1" sounds like it isnt cutting it, wonder how big I can actually go. The Mustang ones people have used are 1" bore, so thats odd those work if my 1" isn't. Anyone want to buy a nice sedan (that kind of stops kidding. Oh well, figure it out eventually
I used to run single MCs on cars too. I once had the flex line going to the rear come apart on the road as I was coming up on traffic. I now only run duals. You may NEVER have an issue not running any res valves on drums, BUT, I know guys that use low grade bolts on suspension and never had an issue either
Check fittings at master. I found one of mine sucking air last weekend during bench bleed without a hint of a leak anywhere.
Too big of a bore will make the pedal hard to push, too small will not push far enough. The cylinders need to match, bigger slave cylinders need bigger master cylinders to keep the same ratio. The original 40 brakes used 1 1/16, that's what matches the slave cylinders. Many cars in the 60's used more than one brake cylinder size, manual/power, different drum sizes, etc. The master cylinder you have is for disk drum, drum/drum should hake similar size reservoirs, just like disk/disk.
I have two cars with early Ford brakes, using a 1" dual (drum/drum) master and they work/stop just fine. Too big of a master will give you a hard pedal and not stop the car (not enough pressure to the wheel cylinder). Too small, and the pedal will hit the floor from too much travel (not moving enough fluid). Not sure if your using all new parts, but there are a lot of mis-boxed, or just plain crap products being sold these days, just because something is new out of the box, doesn't mean it's good. Those residual valves may not be working. A drum/drum Mustang master cylinder will have a built in residual valve, might be worth a try.
Most drum-drum master cylinder would have both reserviors the same size while disc/drum has a larger reservior for the disc calipers since they have a much larger piston. The drum/drum would also have residual valves built in. I think you have a disc brake MC. Your wheel cylinders are also very large for the MC bore. Going larger on the front cylinders will make the problems you are having worse. A typical small car like an early Mustang would have 1 1/8" cylinders on the front and the rear would be smaller than 1", either 13/16" or 7/8". You are not pushing near enough fluid for the diameter wheel cylinders you are using. See if you can move the 1 1/8" cylinders to the front and get some smaller ones for the rear. That will go a long way toward fixing the problem. If you still can't get a good pedal, you will need to change the MC, too.
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