Projects 1963LeSabre Brake Issues

im keeping the drum/drum system for now! as its a budget build and my first ever build lol

i drove it for 2-3 months with no issues and now the booster went bad

replaced shoes all around , got my self this new dual master cylinder and booster and filter checked it to match my vehicle

https://ebayvehicle.com/app/31PS

bled the entire brake system about 2 times lol

i tried to connect everything like the original system

so i blocked the two left sides with plugs and connected the one brake line onto the new master and connected my original sensor

my vehicle has one brake line connected to the master and goes down connected to a Tee line

and well i thought i was good but im still getting spongy brakes ! pedal feels nice and firm as it should but as soon as i turn the engine on it goes completely flat!

not sure if i forgot to add something ? not sure if that proportion valve i believe it’s called was supposed to go on ? really lost lol

 

Your link doesn’t work as you expected, well not for me anyways.
Why the new MC if the booster went bad?

 

came all together as one is all

 

Are the brake shoes adjusted properly? When you bleed again does any air come out? How are you bleeding them?

 

So you connected your single line system to a dual master, using only one port? Did I understand this correctly? Can you post a photo of what you have?

 

^^^^^ This is how I’m seeing it as well.

We need actual photo’s from you, not a link from where you bought your supplies from to get a better understanding.

 

Pictures... we like pictures...

 

Yes we do.

 

So you didn't like the responses you got so you posted the same question again?

 

naaa lol new to this page was trying to figure out where and how to post lol

 

Kinda at the top right of your thread, click on “watch thread” set it up to notify you-how you want.
Then click on the notification and it brings back to the first unseen reply.
Easiest way to find a thread you started.

 

See under your poll vote thing?

 

yes shoes are adjusted and no air comes out when bleeding . bleeding w car off, pump 5 time and hold the pedal down while i bleed each side

 

thanks for that boss!

 

yes this is exactly what i think i did as well lol

 

I’ll say very little but I have to ask. How did you bleed the rear circuit???

 

that one line that’s connected from master cylinder goes down to Tee line i’ll go take a pic right now

 

Does that mean you don’t have a separate front and rear circuit?

 

I understand what you’ve done. What I’m asking is, is there zero air left at the rear circuit of the master cylinder?

 

That ain’t going to work there sparky. Split the front and rear brakes and get a chevelle proportioning valve and plumb it correctly. Or better yet find one from a GM B body 67 and up and use that.

 

In theory it can. But never engineered to be used that way. Also if op got into an accident where braking would become an investigating issue. Well, op would be SOL.

 

I believe the second unused chamber of the M/C is the problem. I think both chambers need to have bled pressure.
You are so close, eliminate the tee, and connect front and rear lines to the M/C.

 

If they are both bled then it should work but at this point may as well split them

 

okay will do !! i will need to add 2 10Lb residual valves to each line correct? one for front and rear?

 

I'm not big on proportional valves myself. On something like this car, I would go distribution block.

It is a lot less complicated. I have CPP one in my car. Summit sells a similar one for a little less. It takes a hydraulic brake light switch.

 

As SS327 and bobss396 have pointed out, you need a distribution block. Proportioning & residual valves are for cars with under floor master cyl. Distribution blocks have 2 inlets to accommodate the 2 coming out of the m/c and 2 outlets to feed front and rear. Lose the light switch, both m/c outlets have to go somewhere.
There's 6 inches of snow on it but I can take a pic of the 64 Wildcat I changed to a 2 compartment m/c

 

Nope this is completely wrong, wether or not a brake system needs proportioning or residual valves is not dependent on master cylinder location.

 

57 Fargo I’ve been watching brake threads for a while. I plan on replacing the single pot MC on my early Dart with a dual reservoir. One question I’m still unsure on is when do need a residual valve. I understand the proportional valve - I think - my understanding is that with a proportional valve you can dial in front to rear bias.
Thank you
Dan

 

Residual valves main purpose was to prevent air entrance into the wheel cylinders upon brake release. So any drum brakes should use 10# residual valves unless the wheel cylinders have cup expanders. Now if the master cylinder happens to be below the wheel cylinders or calipers then they can be used to prevent brake fluid from running back to the master.

If you search a thread I did for tech week a few years ago it’s explained in there. I believe it was 57 Fargos brakes 101. Some thing like that!