qwestion i have a cj-7 8 years ago i put 1/2 ton chevy axles in brakes where ok somewhat now recently brakes got worse i changed out master went with a 78 chevy 1/2 ton master got a little better pedal but still doesnt stop that good,booster still is jeep nothing leaking a freind of mine has same issue and he just put a small blk chevy in his i also have a small block chevy 350 in mine and hes gone as far as changing everything and still hard pedal no brakes,mine soft pedal hardly any brakes,iv heard of people useing corvette masters?and others have done disc?any helpful hints for crappy brakes????  

the vast majority of the time its air in the system.  

old_schoolcj:
qwestion i have a cj-7 8 years ago i put 1/2 ton chevy axles in brakes where ok somewhat now recently brakes got worse i changed out master went with a 78 chevy 1/2 ton master got a little better pedal but still doesnt stop that good,booster still is jeep nothing leaking a freind of mine has same issue and he just put a small blk chevy in his i also have a small block chevy 350 in mine and hes gone as far as changing everything and still hard pedal no brakes,mine soft pedal hardly any brakes,iv heard of people useing corvette masters?and others have done disc?any helpful hints for crappy brakes????

Several things effect overall brake performance. Tires size, brake pad size, drum or rotor diameter, wheel cylinder or caliper bore diameter, master cylinder bore and the mechanical advantage/boost over master cylinder. There is nothing "magic" about a corvette master cylinder as it is the ratio of the master cylinder bore verse the caliper/wheel cylinder bores that determine the amount of force applied to brakes vs pedal effort. In your case there is a few things you can do here. First you can try a master cylinder with smaller bores as this will apply more force to brakes with same effort or you can use calipers or wheel cylinders with bigger bores. Either will work as long as you have enough pedal travel because it will travel a bit farther to displace needed fluid. If you have oversized tires I think I would start by pulling rear wheel cylinders and measuring their bores and increase bore size by 1/8 inch (.125) or a bit more. This is easy to do as you can good to a parts store that will work with you and just pull some wheel cylinders and measure them until you find what you are looking for. Try this first and then if rear tends to lock up before front when done then you need to increase bore in front brakes or decrease bore in part of master cylinder that feeds front brake. I hope I did not confuse you but it is quite fixable if you tinker with it some. BTW, if this does not cure it or you get brake fade you may need to install bigger brakes because big tire add more stress/strain for brakes to overcome but if these are 1/2 ton axles on a Jeep, I think the proper wheel cylinder/master cylinder combo should fix it.  

thanks i will try that this weekend ill let u know about performance of brakes  

hey thanks for the info corrected problem i went back to original master and i eliminated the porpotioning valve ran front resvoiur front brakes and back for rear brakes works great,but my rig is for rockcrawling only not street leagal,i did try it out on street back locks up first but for rockcrawling cant complain,thanks guys for all your info very apprecated