How firm is your brake pedal ? dumb question time..

I just converted to "Scotties" disk brake system.  I'm using the 1972 B100 van master cylinder  cardone # 10-1572M which is for manual brakes with front disc.
Every check I do on the master cylinder comes out as good.  I've bubble bleed the brakes many times. Yet every time I have a soft spongy pedal. like there is air in the system. But I can not pump them up. The pedal feels like I have power brakes. I also installed all new hoses. Anybody got any ideas of what else I should look for. I was a mechanic at a Chrysler dealer for 20 years, so I've bleed brakes more times than I can remember. Not my first rodeo. but I'm stumped.

I wish I knew you were doing them !!!!
1st did you bench bleed the master cylinder ??? as per instructions??
did you preload the calipers ?? (fill them up with fluid before installing them) ??
the bleeders are not at 12 o'clock   That is where your air is at !!
remove the calipers bolts hang them from a coat hanger over night with the bleeders at 12 o'clock
leave the hoses connected. go to the hardware  store buy clear plastic hose that will fit over the bleeders .run the hose from the bleeders to a pop can or such , fill the mc and crack the bleeders. let it gravity bleed over night.   tomorrow hold the calipers in place with the bleeders still at 12oclock   have some one pump the brakes while you bleed them,  if you still have problems  

dix wrote: I wish I knew you were doing them !!!!
1st did you bench bleed the master cylinder ??? as per instructions??
did you preload the calipers ?? (fill them up with fluid before installing them) ??
the bleeders are not at 12 o'clock   That is where your air is at !!
remove the calipers bolts hang them from a coat hanger over night with the bleeders at 12 o'clock
leave the hoses connected. go to the hardware  store buy clear plastic hose that will fit over the bleeders .run the hose from the bleeders to a pop can or such , fill the mc and crack the bleeders. let it gravity bleed over night.   tomorrow hold the calipers in place with the bleeders still at 12oclock   have some one pump the brakes while you bleed them,  if you still have problems  call 412-997-7031( Dix )

I've bench bleed the MC everyway possible, and the MC is good. The caliper bleeders are at 12 Oclock, I've gravity bubble bleed the front and rear systems. The rear brake are adjusted up good with no excessive play.
Should not have to prefill the calipers. I've never done or heard of doing this.
Funny thing is, when bench bleeding the MC. I get great MC pressure and pedal feel. But once I connect the lines and bleed. I loose the firm feel. I've been doing this stuff since I was 15. And done it 20yrs to earn a living. and this ones got me stumped.
Like they say on the X files... the truth is out there

i didn't make norwalk last fall, i don't know what conversions  took place... ...send me a picture of the caliper,. not sure how to bench bleed and have any pedal  ??. every thing is easier to trouble shoot  with all the info ???


https://www.youtube.com/watch?v=kEPXgDGU6_0

?

take the line off the master cylinder for the front calipers and recirc it back to the reservoir as if you were bench bleeding it,,,,,leave it like that and go bleed the rear wheel cylinders like normal put the caliper line back on and see what the pedal does,,,,,try bleeding the front now or go recirc the rear line and then bleed the calipers,,,,,,,the deal is to get each line bled separately not making the master cylinder pump both lines at a time,,,,,one good line pressure can stop the pressure from building up in an air filled line,,,,so see if this helps,,,,,,,,,,

with every thing connected try using a stick of some sort to press and leave the brake pedal down 1/2 way or so, leave it there for a day or so, there is air in the system some where ,
it's just a matter of finding it, That is why i asked for a photo of the caliper. With the calipers installed on mine the bleeders are at about 11 o'clock, they must be at 12 o'clock
to remove any trapped air, you can remove the calipers from the rotors and hang them with a wire with the bleeders cracked and at 12 o'clock,
try tapping the rotor with a hammer , I'm telling you there is AIR in the system

here is a photo of mine  THE BLEEDER IS NOT AT 12 O'CLOCK this is where the air pocket is at.
sorry about the dirt ,
I drove it back from cleveland last sunday night After the big car /van show in the rain and snow

Okay, you do not have to pre-bleed a master cylinder to get good brakes, you don't have to fill a caliper before installing to get good brakes and neither of those will eliminate air in the lines any better than a few extra pumps, but they do make for a messy install.

So do you have air bubbles coming out of any of the calipers or wheel cylinders when bleeding, if you do then the MC is no good or you have a defective line/hose/caliper/cylinder, if no air bubbles then look at the possibility of the residual valve (in the MC) for the rear brakes may not be working, it keeps a wee bit of pressure on the rear brakes, does not matter how tight you crank the rear brake adjuster, that only adjust the bottom portion of the shoes, the tops move by the wheel cylinder, no residual pressure you have move those shoes to contact each time you press the pedal, makes for a squishy pedal. Solid MC pedal without lines attached does not mean the residual valve is working. You can install an inline valve just to verify or as a back up, having two does not hurt.

dix wrote:i didn't make norwalk last fall, i don't know what conversions  took place...   ...send me a picture of the caliper,. not sure how to bench bleed and have any pedal  ??. every thing is easier to trouble shoot  with all the info ???


https://www.youtube.com/watch?v=kEPXgDGU6_0

Dix you were holding out on me. I just called Gary Myitych. He told me that you were involve with his low pedal issue . When he was having the same type of problem that I'm having. His fix was to add a 2lb residual check valve in the front brake line . Putting it after the MC..before it goes into the Tee connector.
He also told me how to test my system. His test confirms that my rear brakes are Not the problem.
He was surprised that you did not think about all the problems that he had. Anyway I'm going to get the valve, and go from there.
Thank you for all your help. I will keep everyone posted how things go.

by the photo I would say that's the right side, correct ? to me the possibility of the calipers trappin air at the top is still there. I say slip the calipers off and block the piston and make the bleeder the highest point. just crack the bleeder open and see if bubbles come out before a steady drip of fluid. if you see even a few bubbles that could be enough times 2 sides. then one slow steady press of the pedal and close the bleeder before the pedal hits bottom. good luck. been at this wrenchin game since the 70's and mostly dodge dealers too......

that photo is from Dix's van, not mine. But very close to the same. Thanks.

yep that is the right side . and you are correct jkr that is where the air is getting traped

It's been awhile, But I installed a 2lb residual valve between the master cylinder and the front brake splitter Tee. This gave me a fair brake pedal feel. I drove the pickup with the residual valve install. The brakes were somewhat OK, but not good enough to make me happy.
Then the weather got bad.
So I re-bleed the system. Did not get any air. BUT then I re adjusted the rear brakes. That really helped the pedal feel.
Drove it again today, All in All at this point, I think everything will be fine. But until I get plates and insurance back on it. I will not be able to give it a real true test drive.