brakes not working as expected....HELP

[Steve-W]

So when I bought my 1969 c10 it had drums in the front and drums in the back that were closed off by the PO. there was no brake booster. so only the front brakes were there to stop it, which is like trying to make an emergancy stop with a 1000 Feet oil tanker...

I bought a complete 73 crossmember including disk brakes. I also installed a new master brake cylinder with booster. put in a new brake balancer, one tha as I was told should be for a disk/drum setup, the rear brakes are all new and the system was bled to the point where my brake pedal is rock hard.

so far so good. last Friday I finally got to the point of the first test drive and boy, was it a major downer... the brakes are nearly as bad as before.

my conclusion and I'd love to hear your opinion:
1) the brake booster isn't working..but how do I test that, because we checked whether the vacuum is good and it is.
2)the brake balancer is somehow messing things up?
3) I got the plumbing on my master brake cylinder back to front, but I cannot imagin this having such an enormous impact seeing that surface times power is pressure and the two chamber don't have such a big difference.

am I overlooking something?

[andrewmp6]

How much vacuum are you pulling ?Most boosters take 18 or more anything under will not enough power to use the booster.The brake pedal when you use it does it feel normal or is soft or hard,Does it ever drop to the floor?

[Steve-W]

NO it doesn't drop to the floor and I just tested it by putting my foot on the brake while starting the engine and when it fires up the pedal drops about half an inch further down, so I guess the booster is working
it's a Delco Morane, no further specs on it, sales man said it was for trucks

[lolife99]

Which M/C did you buy?
(what application/year?)
I would have opted for a 71-72 application or a Wilwood aftermarket M/C.

[Steve-W]

well living in Europe limits the options for off the shelf units..and this one was off the shelf.
to be honoust, I didn't even look at brands..I just rang up the fellow and ask if he had one laying around for a truck.. this is what I got.

[oldman3]

Let us see a better pic, of what you are calling a "brake balancer". The way the lines are running does look right. What we call a combination valve would look like this. But I dont see a line going to the rear from your pic....Jim

[Steve-W]

You're right, this is an old picture. The brake line to the back is now connnectec to the top (seeing how I positioned the balancer..could that possible cause a problem?)
And do I have the plumbing correct? So most forward chamber of the mbc is for the front brakes and the chamber closest to the booster is for the rear brakes.

[oldman3]

Originally Posted by Steve-W

You're right, this is an old picture. The brake line to the back is now connnectec to the top (seeing how I positioned the balancer..could that possible cause a problem?)
And do I have the plumbing correct? So most forward chamber of the mbc is for the front brakes and the chamber closest to the booster is for the rear brakes.

Steve is you valve centered in your brake balancer (combination valve) so you have front and rear brakes. If this valve is not centered you would only have brakes working on half your system....Jim

[Steve-W]

Originally Posted by oldman3

Steve is you valve centered in your brake balancer (combination valve) so you have front and rear brakes. If this valve is not centered you would only have brakes working on half your system....Jim

If you mean whether I have both the front and back brake lines coming out of the balancer, yes. so from the master brake cylinder I have two brake lines, one front, one back and both go to the balancer.

unfortunatly I didn;t have any time to spend on the truck this evening, but perhaps tomorrow.

what would be a good root-cause approach? excluding the balancer and just hook up the brakes directly to the master cylinder?

[Steve-W]

As you can read in my build thread (link in my signature)
I changed my new MBC and Booster for an old one I had laying around, because it turned out that the new one is for a Nova or something simular small. (that takes care of one problem)
But it turned out the MBC of the other set was broken, because whatever I tried I couldn't get any brake pressure.

so now I mounted a factory referbished MBC..but again no pressure after breeding the brakes extensively.. assuming the MBC is not broken, the only other conclusion I can think of is air in the system...but where?? we pumped over half a gallon of brake fluid through the system...

could the brake distrubutor play havoc? I plan on bypassing it and see if that will give any result.

we took apart the broken MBC just to see what the inside is like and I have question, why do the two chambers have different springs? when I see this I wonder if a brake distributor is still necessary?