cj breaks driving me crazy. need help.

randy2117 · Nov 14, 2012

Ok I have a 79 cj 5 when I got it the booster was not hooked up. It had a vacuum leak so I got a new one then a another new one. Had a lot of trouble with it sticking I would suck the break paddle to the floor, so I got that fixed but then it started sticking again, then I unhook the boost it would work good but no booster. Now I put Chevy axles under my jeep and the breaks are sticking again. They don't stick right a way it starts sticking after driving a bit. Could it b getting to much vacuum??? I'm lost, I need help thinks...

superj · Nov 14, 2012

Do you have that little check valve on the line from t he engine to the booster?

The pedal slowly gets pulled down as you drive or it just fails to return up?

randy2117 · Nov 14, 2012

I did put a new check valve on it its the one that comes off the booster. It acted like it was working fine on the way to work but on the way home the brakes was sticking and hot when I got home. And it acts like they don't all the way release after braking. I would bet that if I unhook the booster they won't stick. But I would like to have power brakes.

PoliceMonkey161 · Nov 14, 2012

Food for thought.....Are you certain that you have the master cylinder designed for power brakes? Manual brakes will have a loop end connecting the cylinder piston rod to the pedal, power brakes are more of a fork (V) type connection to the pedal. SuperJ may be reffering to the check valve that would be installed in the brake line where it threads into the master cylinder? If your Jeep was converted from front drums to discs, there would be a check valve in the front brake line that needs to be removed. I can't imagine this being the case as you would have severe brake wear.

randy2117 · Nov 14, 2012

I don't know about that. but I was talking with a guy and he had me recheck the rod between the master cylinder and brake booster I shortened the rod the most I could and it seems to be working better now but I haven't had the time for a long drive yet. So well see.

randy2117 · Apr 12, 2014

Up date my brake nightmare..brake booster was making my brakes stick so I got a new booster it seemed to be working then I found my new proportioning valve Was leaking So I got a new one and when I went to bleed out the brakes I wasn't getting good brake fluid Out at the wheels. So I got a new master cylinder and now I'm getting good brake fluid Out at each wheel but my brakes are still soft and my back brakes like to lock up first now. I have bleed out the brakes a lot looking for air but it looks good I see no air in it. And I can find no leaks. I was thinking could my proportioning valve be bad??? Or is it not set right and I need to set it some how?? Please looking for help

superj · Apr 12, 2014

We are having soft pedal issues on my buddies cj7 now that we put a brand new master cylinder on, today. His locks the backs and the fronts don't grab well also. I think for our problem, we have an air bubble so he is going to drive it around for a few days to push the trapped air to wheels so we can bleed it out.

Are your shoes and pads good?

We thought his proportioning valve was bad at first, too. Then we discovered at almost every threaded joint in the brake system, there was a very very small leak so we had to tighten every single connection. but, it caused lots of air to get in and its going to take time to get it all out. Make sure you have nothing like we had

Tison78_CJ5 · Apr 13, 2014

I just fought my 78 CJ on the sticking problem.
It turned out to be air in the lines. I bled them 3 times before it cleared out.
I found the master cylinders are not the same. Make sure the piston is not being pushed when not pressing the peddle. I had to shim my master cylinder 1/8" out, to keep the pressure bled off when not in use.

randy2117 · Apr 13, 2014

I was thinking it could be the new proportioning valve the place that makes it has this on the site. I'll try to up load it. But when I read there tech info it sounds like it's my proportioning valve. That's bad but its the 2 nd new one I have had on there???? The valve is mbm pv 2.
If the pic don't show up goto "mbm" site and look under tech.

randy2117 · Apr 13, 2014

The more I look into it I'm thinking I have a bad proportioning valve from mbm I found some at summit but do I get a new brass pv2 from a different co. With 9 good reviews, or go with a adjustable one from summit or the ssbc has one but they look the same??? Ok thinks

69jeepcj · Apr 14, 2014

In post #4, I think PoliceMonkey is on the right track. If you converted from front drums to disks there is a valve or spring in the master that needs to come out. I have not done this myself but have read several write ups about it. You can go to JPmagazine,s wedsite and search drums to disks and find the info.

randy2117 · Apr 14, 2014

My jeep came with disc brakes in the front. I had great brakes once but they would stick some times making a long story short I slow start replacing everything then one day I found out is was my new booster making the brakes stick so replaced that then the master started acting up replaced That then my proportioning valve started leaking which was new so replaced that again and it started leaking again and in the middle of all this crazyNess my brake bleed out good can find air in the lines or leaks but the brakes are soft and the rears lock up. I talk to a guy at in line tubes and said the proportioning valve needs to be set using the brake warning light. I'll try and up load the pics for this.

randy2117 · Apr 14, 2014

So I guess I'll try to bleed out using the brake warning light. If that does work I'm thinking about running the fronts straight to the master and using a adjustable proportioning valve on the backs only.

69jeepcj · Apr 15, 2014

let us know how it go,s.

randy2117 · Apr 16, 2014

It may not look pretty but it works. And me and my jeep

hoobness · Apr 20, 2014

Yikes! Dude I'd clean that up. You could catch that on something and lose brakes.

richgilbert81 · Apr 27, 2014

I had all sorts of brake issues on my 87 yj when I first purchased 9 yrs back. I did a ton of research on the issues and they were similar to what u are having. What I found out was that it was the booster, and the valve. So I found a write up on line that had directions to take the entire set up out of a older f150. The entire package of booster, master cylinder, and the valve. Had to pick up some adapters to connect my brake lines to all the new components. And then also modify the little push rod a little bit. I run large mt tires and have stock axles still. Stops on a dime now and locks all four brakes up if I have to slam on them even with all the heavier mods my jeep has and the big ass tires. Good luck.

randy2117 · May 11, 2014

I found that hang up it was the booster not pushing the pin in at the master far enough. I have to make the adjustments on the brake petal rod that goes through the firewall to make it longer to push the master cylinder further. And I did have the booster adjustable pin at the master. Brakes are good and strong now thanks for your help. Here are some up dated pics.