Brake Problems Driving Me Nuts

I have just finished my project Jeep, 1969 CJ5A(It's been three years) and I cannot get my brakes to lock up. I replaced the front axle with a D30 with disk brakes, CJ7 Master Cylinder and Brake Booster, and CJ hanging pedals, also have the original rear drum brakes on the D44. I ran all new brake lines and put new wheel cylinders in the rear brakes. If I bleed them again, I am going to buy stock in Brake Fluid!!! What could be my problem? Also, I can't seem to find anyone who has a new brake hardware kit for the old drum brakes.

Thanks

Meterman

I will try to post some pictures soon!!!

 

Is the pedal soft? Are the backs grabbing, but not the fronts?

 

There is a little bit of pressure at the pedal. The back and the front both react the same way. When I press on the pedal, the brakes will barely apply any pressure. If I pump on the brakes there will be just a little more pressure. I can still freely spin the wheel with just a little bit of drag.

Thanks

 

Are the master and booster new? Rebuilt? Take offs? Could master and or booster be bad. Incorrect pedal ratio could be a problem. AM

 

Ok First I just completed almost the same conversion on my 72 had lots of issues similar to what you have had. 1. Did you gravity bleed the fronts with the calipers off of the mounts and the bleeder screw pointing up? As a test pinch off the flex line to the passenger side caliper and hit the pedal you will most likey have more pedal still spongy but harder feel that would confirm the air issue because there will be much less air to compress. The way they mount to the axle there is a huge air bubble in the caliper that cannot escape in the mounted position even if you power bleed the system. 2. Are you using a Prop valve in the system? You need one now with the disc setup. 3. If you replaced the lines did you use the same size that was on the master of the donor jeep you need the same volume to the prop valve as was on that vech.

 

The master is new, but the booster is from a donor. I will try to extend the pushrod a little bit. I never new I had to gravity bleed the calipers, that would explain why the front discs don't grab. I did not check on the size of the original brake lines, I just replaced all of the brake lines with what was used for the rear brakes. I also do not have a porportioning valve, is there a particular one that I will need to get? Should I just get one from a 77-78 CJ with the same 6 bolt caliper bracket that I have?

Thanks for all of the help, when I get time this afternoon I'll tell a great story about the Jeep. It involves my welding job of the brake pedal. I should have taken others advice and had it done professionally.

 

A prop valve from one of those should work. I didn't know about the air pocket and the gravity bleeding either until I had the same issues you are having. With the line size issue It would only be a problem if you are using a smaller line to the prop valve then was originally there because there could be volume issues out to the wheels which could effect the amount of pedal required to get goos brakes. Hope this helps. You will love the way the disc setup works just don't put yourself through the windshield.

 

That's the booster/MC/Prop I used for my swap out Lynn. I just had the issues with the air trapped in the calipers and also a flaky wheel bearing. But your right it was very easy just needs a couple of holes drilled in the firewall and connects right up.