New Brake Bleeding

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prostreet68

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I did a search and then went thru all the threads on bleeding brake issues and I have yet to find any answers to my problem.
All the lines have been replaced along with the 74 Valiant front disks and 1 ton wheel cylinders on the Dana 60 rearend. I did bench bleed the mc before bolting it in. I have used a MityVac that a friend of mine said was in good working order. Since I have never used one before now I took his word for it. I am getting fluid in the catch bottle when I bleed all corners but the pedal still goes to the floor.
I have even tried having my wife pump the pedal while I bleed the brakes the old school way but still nothing. I do get a good stream of fluid but pedal still doesnt stiffen up.
I have checked all the fittings, hoses and connections and I cant find any leaks..

What do you think?

Thank you
Rick
 
Are the one ton wheel cylinders using all the fluid capicity of the master cylinder because of their large bore? You master cylinder may not be able to push enough brake fluid to operate the larger id ehrrl cylinders. The bore on one ton master cylinders is larger to match the other larger cylinders.
 
Oklacarcollecto said:
Is the one ton wheel cylinders using all the fluid capicity of the master cylinder because of their large bore? You master cylinder may not be able to push enough brake fluid to operate the larger id ehrrl cylinders. The bore on one ton master cylinders is larger to match the other larger cylinders.
Click to expand...

That right there is the answer.

That being said, I've also seen MANY bad master cylinders (new), right out of the box. On my Dodge D50 I must have tried 4 or 5 master cylinders in a row (new) and each one the pedal would travel to the floor.

My front brakes barely worked, if at all. And the rear brakes were only slightly better. Tried gravity bleeding, vacuum bleeding, etc. Finally I swapped the Master Cylinder off of a Parts Truck (the used m/c was about 2 years old, from Napa) and within a couple minutes I had a full brake pedal.

Sent the new one back to Advance and got my money back. Ironically enough, every time I've seen a defective Master Cylinder or Clutch Cylinder, they had been purchased at Advance or Autozone :wack:
 
The mc is out of a b body or something like that came with a Hemi. It has a 1 1/4" bore and I bought it from Napa. Yes it is a drum rear with the disk front...non power.
 
You're gonna need huge legs to push a brake pedal using a mc with that big of a bore. In the case of master cylinder bores, bigger is not better!
As for bleeding, easiest way I've found is just use gravity. With the car level, set up your catch-can and crack the bleeder open. check the mc fluid level every ten minutes or so while you work on other things. after an hour or so, close it up and move on to the next wheel. Works great!
 
You can easily eliminate some things. Go down to the store and buy 4 inverted flare unions the correct size to fit your brake tubes AT the cylinders. For the disks, you'll have to get them to fit where the hoses disconnect. Then buy 4 inverted flare plugs to fit the unions

Unhook all your cylinders/ calipers and install the unions/ plugs. Rebleed system. IF you have ANY pedal at all, "final bleed" using the manual pump pedal method. BE SURE you tighten the plug EACH TIME and BEFORE your partner releases the pedal. Best way, after you seem to be getting "all fluid" is to ANTICIPATE the pedal coming down, and tighten the plug then. Yup. It'll be messy. Last time I did this was 20 some years ago. I took two of the plugs to make bleeding easier, and filed a notch down the length of the threads to allow fluid to escape. Don't damage the flare seat on the bottom.

(Another way if you can find them is to buy a "bleeder assembly" One place to get them is somewhere that sells parts for high pressure oil burners, as in oil furnace. The Oil burners uses a bleeder with 1/8 pipe thread. You could get on/ two of those and with a "1/2 union" ---1/2 inverted flare and 1/2 pipe thread, this would adapt the oil burner bleeders to your brake tubes.

When you get this all bleed you should have a VERY high and hard pedal. Because disk calipers don't "return" much fluid, IE they don't move back very far, hook up just one caliper, bleed it, and check for pedal, do the other caliper. If OK so far, tighten the rear shoe adjusters until you can NOT turn the wheels, and bleed just one rear, if OK, do the other. IF you still have good pedal (IE the rears are bled) back off your adjustment until there is still some drag on the brakes. Jab the pedal periodically as you adjust them to "reseat" the shoes, and "tune in" the adjustment.

I agree, huge diameter rear cylinders =more rear shoe pressure = less pedal pressure = less shoe movement = more use of fluid and =less pedal height.

I had a HECK of a time finding a decent photo of these, here

http://www.behrents.com/mm5/merchan...ode=OLBrakes-CaliperAcc-BleedScrews/TubeAssem

OL235-2305-L.jpg
 
You need to get a mid 70’s “A” Body manual disk/drum brake, “NEW” not rebuilt, master cylinder. Also you need to down-size that one ton monster wheel cylinder and break assembly to an “A” Body size brake drum & 7/8” dia. cylinder. Too large a rear wheel cylinder and too much drum will cause early rear wheel lock up under moderate to heavy braking in an “A” Body.

Think about it, your car fully loaded would be about 4500 lbs., a ton truck would be well over 6000 lbs., and possibly have duel wheels with a lot of rotating mass. Over kill for an “A” Body.

You need to adapt 10 inch brakes to your axel
 
I use a clear bottle and a short piece of vacuum hose. I pour an olive jar half full of brake fluid and put the hose on the bleeder and submerge the other end in the jar. Break the bleeder and you can pump the brakes till the cows come as long as the master cylinder doesn't go dry. Bubbles go out on pedal downstroke and fluid is sucked in on return stroke. No way to suck air. With the clear bottle you can observe if line pumps pressure as you will see the fluid swirl. You can also see when all air is eliminated. Then close bleeder and move to next one. If you observe all corners pumping fluid you know the m/c isn't up to the task. If you can't eliminate bubbles you can narrow it down to which corner. If fluid doesn't swirl the m/c is bad. I wond do it any other way. With a long enough vacuum line you can do it by yourself.
 
prostreet68 said:
The mc is out of a b body or something like that came with a Hemi. It has a 1 1/4" bore and I bought it from Napa. Yes it is a drum rear with the disk front...non power.
Click to expand...

It is bore and travel length of your master cylinder and push rod that has to work uniformly. Master cylinders used with disc/drum combination brake systems will use a large reservoir for the disc brake portion of the system and a small reservoir for the drum brake portion. I have a feeling your master cylinder isn't capable of putting enough brake fluid to the extra large one ton wheel cylinders.

I went though this while taking a hydro-boost system off a Chevrolet one ton. To ever get a brake pedal I had to use a master cylinder off a one ton van in the end. We tried several with the same bore but the piston in the master cylinder had to be able to put the correct amount of brake fluid to each wheel to ever get a pedal. We had no problem getting enough brake fluid to each wheel for bleeding but never enough to build a pedal without pumping until we found that one master cylinder.
 
500stroker said:
No way to suck air. .
Click to expand...

This method is fine for the "first round" BUT THE BLEEDERS can suck air, right up past the threads.

The best final method at least to "CHECK" on the final bleed is and always has been either a pressure bleeder on the master, or the old manual pedal method.
 
Sounds strange about the 1 ton wheel cylinders needing to have the mc matched because I know tons of Dodge 2500 guys using the same thing. I never did upgrade my mc which is smaller than the monster mc that I have on my car now. I have never had an issue with mc issues using the 1 ton cylinders on my 2500.
There is no way that this mc is too small to feed this brake system.
 
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