Brake Problem on my Tow Rig

[Cisco Kid]

It a 1975 Ford f250 crew cab 4x4 highboy<O</O
The front has disk brakes <O</O
The calipers have dual pistons<O</O
We installed a new brake booster and master cylinder<O</O
After installation the brake paddle will go all the way down and you need to pump it like 4 times just to get any stopping<O</O
We adjusted the brake paddle and the inside of the booster ajustment screw then the front brakes lock up (both of them)<O</O
So we went back to original install and again same a 1st time need to pump brakes like 4 time just to get some type of stoppage.<O</O

 

[TREE68]

bleed the system again. or you have a vacuum leak.

 

[Cisco Kid]

bleed the system again. or you have a vacuum leak.

Done the bleed so many times that I can now do it in my sleep ;-)

we move the vacuum line to the back of the carb to be on it own, but will check on that again.

Do we just adjust the brake peddel a bit at a time ?

 

[XPirate]

Cisco, i had a 66 chevy truck witha similar problem.... part of the problem is your vacuum... either not getting enough or the actual brake booster could be malfunctioning... in my case it was the booster, bought a brand new booster and solved the problem.... hope that helps...

 

[XPirate]

Also, are you running a proportional valve... a lot of vehicles need one if you are running disk and drum...

 

[Cisco Kid]

Also, are you running a proportional valve... a lot of vehicles need one if you are running disk and drum...

Yes a new one too and new brake lines ;-)

 

[onerich]

Something from here might also read the comments , good luck.
[ame="http://www.youtube.com/watch?v=06uRlg-MQ2U"]http://www.youtube.com/watch?v=06uRlg-MQ2U[/ame]

 

[dkiewicz]

Done the bleed so many times that I can now do it in my sleep ;-)

we move the vacuum line to the back of the carb to be on it own, but will check on that again.

Do we just adjust the brake peddel a bit at a time ?

You probably don't have manifold vacuum from the back of the carb. I'm with Garrett, not enough vacuum come straight off the manifold with a 3/8 diameter line.

Dan ...

 

[tomcav]

you may have to run a elec vac pump , or convert it to a hydro-boost type

 

[dezerteryx]

might try pressure bleeding the system, if it was a vacum issue the pedal usually gets hard to push down not drop to the floor.

 

[Slacker]

Agreed on pressure bleeding, especially if you replaced the master cylinder.

 

[ageekwithajeep]

So did you try the blocking off?

How did you already tow your trailer? Did you just go with weak brakes?

 

[Cisco Kid]

Did not have time to check it out, will try all ;-)

Thanks ;-)