brake problem


Active member
Have 94 yj 6cyl manual transmission. I replaced the front calipers and roters since the passenger side caliper went bad on me, I replaced both front brakes.
Replacing the calipers I just unhooked the brake line and sit it aside installed the componets, hooked the brake lines back up and and bled the front brakes.
Was unable to get pedal pressure, a little but not much. So I decided to bleed all the brakes starting with the rear passenger, next rear driver, next front passenger, then front driver side.
The best result as far as pedal pressure was after pumping them I could get half a brake pedal. But upon releasing the pressure and waiting about 20 seconds and stepping on the brake pedal it would go all the way to the floor. Able to pump them back up and same result. Then I pumped them back up with the engine off,got half a pedal, started the jeep pedal went to the floor upon starting.
Two people seem to think that the diaphram in the brake assist may have ruptured. But I thought it odd cause the brakes had pressure before I did this operation, so the diaphram was good at the point of time parking it and changing the calipers.
The proportion valve which set underneath the master cylinder has a rubber boot on the end of it. From doing a little research last night on this site I figured that may be the problem. So I pulled the rubber boot off expecting to see a pin or something to push or pull, But ahhh I pushed and pulled on the thing and nothing happened. So I is a little confused .


Are the calipers, pads and rotors stock or performance?
Did you or could you verify the front brake calipers have seated the pads against the rotors?
Also verify you didn't accidentally put a kink in a line or twisted the rubber length and kinked it?
Have you changed all the fluid? Not a bad idea. Brake fluid absorbs water and needs to be changed. Never use an old already opened bottle.
When you bleed it is the liquid clear or foamy?
Don't bleed with the engine running.

When I bleed brakes I run a tight cleat tube over the bleeder into a mason jar with fluid (jic a foot slips). I watch the fluid for clarity.

It is possible when bleeding the diaphragm ruptured. First verify you have no leaks at any wheel or along the lines. If the diaphragm ruptured there likely will be fluid between the master cylinder and the booster. You will have to loosen the nuts and pry Sparta to verify.
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I had the calipers on the wrong wheel, switched them around. Every thing is groovy .:verry-happy:
So you had the bleeders pointed down?

Well glad you figured it out.

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It's always a good idea to do one side at a time. That way if you forget or have any questions on how it goes together you can reference the other side.
Yup bleeders down. I usually take pics as I am taking anything apart, how could I possibly screw up a simple brake job,lol.