alrighty guys i need some wisdom. 91 cherokee, had the horrid ABS system in it that completely stopped working. I swapped over a booster and master from a 93 parts jeep that still had plenty of brake pressure. I also bought new rear wheel cylinders for the rear and new shoes, front calipers seem to be functioning just fine. pedal goes to the floor and has very little pressure, any clues as to the problem? When buying new wheel cylinders they wanted to know if it was non ABS, are they actually any different from each other,and does the same go for the calipers?? Thanks in advanced.

 

in every car i ever had ,pedal to the floor meant no back brakes. front were fine but didnt work till back were fixed, leaking or air in system.
fixed back,good solid pedal and front work fine. had others tell me the same thing.
my 98 has abs light on ,no abs . brakes work normal.
i drove my 00 home with "no"brakes till i replaced a rotted back line. filled it up by filling the master and letting it drain thru the new line. tightened it. solid brakes 8 months later, no bleeding,i always break off the bleeders!! just telling it as is.

 

pull the fuse to the abs and see if it makes a difference if it don't you have other issues

 

the whole abs system has been removed, nothing about it is in play. Kind of leaning towards nujeepguys response. after thinking on it i remember i drained that master dry in the process of transporting it, never bench bled it. and judging by the upward angle it sits in the jeep i bet there's a pretty substantial bubble up in the front of it thats not able to be evacuated. Seem plausible?

 

Yes. Very. A master cylinder must be bench bled before use if run dry. The parts store should have a kit with threaded fittings and some clear tubing for bleeding master cylinders.

 

actually after fixing back, a front line opened. i cut it and spliced it with coupler. then filled master and let fluid find its way,pumping gently till all tubing was filled, tightened all fittings, no bleeding.
solid pedal ever since.
have not bench bled in ?40 yrs!.
i think ive worked on brakes on every vehicle ive 0wned, over 30. just remembered one i wish i never saw!

 

welp, pulled the master off and bench bled it. Got a few tiny bubbles but nothing huge and the master will build plenty of pressure with the lines blocked off, but no change after putting it back on the jeep. went around the corners twice and bled them, no more air bubbles are coming out... still no pedal. -_-

 

Check all your flex lines as one or more may be swelling when the brakes are applied.

Max

 

Just checked Rockauto and there was no mention of ABS or non ABS calipers, but i do see ABS and non ABS wheel cylinders. Never messed with this myself so i have no idea how significant this is, but this is what they show.

Wheel cylinders:
ABS w/ 9" drum = 3/4" bore
non ABS w/ 9" drum = 13/16" bore
10" drum = 7/8" bore

Agreed. If the old fluid was dark, they should be replaced anyway as it has been contaminated with dirt, rust and moisture.

 

visually the flex lines look fine, no cracks or wet spots. Any test i could preform?

 

yes easiest way is to go around the jeep and clamp off the soft line at each wheel to see if you can narrow down where the problem is coming from .


Clamp the rears then hit the brakes, that would eliminate the problem being in the front if you have good pedal. Then it would mean you either have a problem in the rear soft line or the rear wheel cyl....

 

will give that a go, i can hear the rear shoes moving, so the the cylinders are doing something.

 

there is allot of info on the web to do it very methodically, just don't have time to type I out, but you have to narrow down where the problem is...


you have to rule out the master and booster too.... allot of ways to test the master, plug the ports and push the brakes....


test the booster, shut off the jeep make sure it is holding vacuum, and that the one way check valve from the intake is operating correctly.

 

i plugged the ports on the master today when i bench bled it, got hard as a rock. booster seems to holding a vacuum as well judging by the sudden rush of air when i pull the valve off. will have to do some more reading. This is on a jeep i got when i was 16, been sitting almost 2 years now and this is the only thing keeping me from driving it. might end up taking it some where if i cant figure this out soon.

 

put in another prop valve today and re bled four times. no change. Crimped of rear brake lines, no change. I have no clue what else to do at this point. guess im going to have to take it some where.