Brake problems

mmcj7

mmcj7

Well-Known Member
Joined
Aug 30, 2009
Location
yadkinville
My son is building his first cj using parts I've collected over the years. We have put some axles under it from a 1975 cj5. He used them for the 3.73 gears the front axle has drum brakes. Our problem is we can't get any pedal. After about 5 pumps it will build up to about half the height from the floor. We replaced all 4 wheel cyclinders and the rubber brake lines still no pedal. I had him change the master cyclinder and proportional valve from a jeep we were driving and still no pedal. I remember having this problem with a dodge dart in the 80's but that was the 80's :). I have already tried putting a hose in fluid and connecting to the bleeder screw and pumping fluid back but that didn't help. I was wondering if I need to get a master cyclinder and proportional valve for the 1975 cj5 but wasn't sure if that would make a difference. Any suggestions?
 
Should I also change the proportional valve or will the newer one work?
 
I read that the proportional valve has plunger that has to be pulled or pressed depending on the year model while bleeding the brakes? Is that true
 
I believe what your thinking is, the valve Can jump to 1 side or the other, if the system gets unbalanced, as if a line was to break. I've never had this happen, doing a bleed. Even if it did, you would have partial brake. Brakes either on front or back.
 
We did change all the rubber lines with braided steel lines. I was googlin for an answer an found that info.
 
Will that help get air out off the line? I was thinking a loose shoe would allow the wheel cylinder to open more and in turn push the air out.
 
No, but a loose shoe won't help either. Might hurt it. You're trying to clear the lines, but the cylinder opening will give fluid and air somewhere to hide instead of coming out. Also, you may never have a good pedal with poorly adjusted brakes.

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I have a '72 Commando with the sMe brake system you have. If you have bled the brakes and you can find no leaks, then like Mark said, adjust the shoes out until they just begin the drag.
 
Going to put some time into it today and I'm starting by adjusting the shoes until getting drag at the drum. Hopefully we will get it worked out. Thanks for the help.
 
Adjusted all 4 hubs to a light rub and bled. I have good pedal after 1 pump and a little pedal at the bottom of the 1st pump. I'm going to get a master cylinder for a 75 model and may replace all the shoes. PO said they had been replaced but seem a little thin to me. Thanks for the help.
 
I will say that when I did the brakes on that Courier, I replaced the shoes on all corners with remanned Raybestos shoes from RockAuto. First, the box looked like it was 25 years old. Second, the material looked thinner than the brake fluid soaked shoes I took off.
 
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