Cj5 brake question

svsteve · Feb 23, 2008

I have a 71 cj5 with a dana 27 front axle it has disk brakes on it and I dont think they came factory...

my brakes work great as long as I pump them once each time I use them
the master cylinder that is in it is newer or at least looks new
it has brand new calipers new pads and the rotors were cut

the rear brakes appear to be working and moving fine but the shoes are worn down

my question is what do you think is causing me to need to pump my brakes in order to get them to work... proportioning valve? is there a different one I need to put in because of the disk brakes in the front? I bought the jeep mostly done and it only need a few finishing things to be ready I have wheeled it as is ,but I would like them to work properly the first time I hit them

thanks Steve
any input is greatly appreciated

leadfoot067 · Feb 23, 2008

well if ya have to pump them that means theres air in the system....rear shoes being worn will cause a low pedal...my suggestion would be replace rear shoes and properly adjust them,then bleed the system and see what happens then...if its a prop valve issue then it will have too much or not enough pressure to one end if its the wrong valve...if the valve is stuck to one side one end will lack pressure and the brakelight will be on(if there is one)..

svsteve · Feb 23, 2008

I assume your talking about a in dash brake light... there isnt one I will try putting new shoes on it and bleeding the system again it does slow down the first time you hit the pedal just not very fast thats why i thought prop valve

anyway thank you

pokey · Feb 23, 2008

if it still has the stock master cyl. then your not getting enough fluid to the front brakes. take the top off of the master and look. The side feeding the front should be at least twice the size of the back since the discs use a lot more fluid then do drums. Post a pic if you can.

svsteve · Feb 24, 2008

the side feeding the front is really small probably half the size of the rear

could I use a master cylinder from a later/newer year cj, one that came factory with disk brakes?

leadfoot067 · Feb 24, 2008

so the lines could be on the wrong way........im sure you could use a later master...i think pokey would know for sure on interchangeability....

pokey · Feb 24, 2008

The most common one to use is from a 1978 cj with disc brakes.(non power) I was able to use the stock porp. valve on my 74 when I put the discs on mine.