I have an 86 CJ7. I am having problems getting my brakes to work good. I have replaced rotors, drums, pads, rear brake cylinders, lines, master cylinder, and fluid. The jeep has power brakes but I still have to stand on the brakes to get the thing to stop. I don't like to drive it with the bigger tires because it is so hard to stop. I drove my cousins 79 cj with manual brakes and it works way better than mine. I was thinking about taking it in to a shop to see if they could pressure bleed it. Any help would be appreciated.
Thanks,
Bryan Rennick <img src="/forums/images/graemlins/confused.gif" alt="" /> <img src="/forums/images/graemlins/confused.gif" alt="" />

you could have several problems. check and see that your master cylinder is covered tight. i lost pressure through my cap at one time and it was like i had no fluid at all.

your drums have eccentrics (sp?) on the back to adjust the shoes closer to the drum. it is a long process requiring much patience to properly adjust them. jack and brace the rear of the jeep, block the front, and put the trans in neutral. loosen the lock nut with an open end wrench and turn the eccentric (needle nosed vice grips work good here) to the front of the jeep as far as you can. this should push the shoes into the drum. now have someone try to turn the tire you are working on while you loosen the eccentric. you want the brakes to feel like they are dragging a little. repeat the process for the other side and road test.

if it is still non functioning, i would find out if the master cylinder is moving enough fluid (weirder things have happened.) *then* i might take it to a shop, but only after i had done all i could...

What I would do is simple:

1. While the engine is running, place your ear next to the master cylinder and listen for a hiss. If there is a hiss, then pull the vacuum hose from the grommet and cover the end with your finger (or thumb) and check for a strong vacuum. If you have a strong vacuum and the hiss goes away, then your master cylinder has a vacuum leak which is usually in the diaphragm (the big round thing) and needs to be replaced.

2. If you don't hear a hiss and you pull the vacuum line away from the master cylinder, then see if there's a vacuum at the hose, again by placing your thumb over the end. If not, pull the hose and check if it's clogged or the one-way valve is installed wrong (that happened to me once). You might also check the vaccum input at the intake manifold to see if is clogged as well. The opening sometimes get fouled by oil and dirt.

If those fail, then open one of the pepcock valves at the brake cylinders and see if fluid comes out when you press on the brake. It should go to the floor easy, if not, then you may have a clogged master cylinder, although it's new.

As a note, even a weak vacuum will help you brake.

But I believe your problem sounds like you vacuum assist is shot. Especially if you have to stand on the brakes to get it to work. The master cylinder on vacuum assited brakes are smaller than manual brakes. That's why your friend's manual brakes are easier to use.

pablo

\I'LL SECOND THAT DOES SOUND LIKE VACUUM PROBLEM KEEP US POSTED AS TO YOUR FINDINGS

Dealing with a similar problem on my YJ; I have installed a new vacuum diaphragm can (it was leaking), and rerouted the vacuum hose from the valve cover to an electric vacuum pump. Braking my YJ w/ it's 37 x12.50's is now a lot easier, and I have the added advantage of having vacuum assisted braking even when the jeep engine stalls. It will be interesting to find out what was casing your hard braking condition; look forward to your post.