Brake help

I've been trying to fix my brakes for about a month now. I had a 3/4 ton D44 front and D60 rear w/ a dodge MC and it worked great, then I swapped back to stock axles ('99 xj w/ 96 D30 and 8.25).

The problem is that whenever I start the engine and press the pedal it goes to the floor, and it barely stops. If I slam on the brakes on my snow covered driveway the fronts will lock, but the rears wont.

It has a new booster, new master cylinder (2nd one I've tried). New lines to the prop. valve, new prop. valve, new lines to the front hoses, new front hoses, new calipers. I've tried two different rear brake hoses, has new lines on the rear axle, new wheel cylinders, hardware kit, and shoes.

The rotors and pads haven't been changed, but the pads have alot of material, and the rotors are still within spec. The drums in the rear were turned, and are at the min. thickness. The shoes are adjusted out, and the rod in the booster is adjusted right.

I have no leaks anywhere, and it has been bleed both normally and gravity bled. I've also brought it to 3 different places and they cannot figure it out either.

I am at a loss as to what the problem could be, my next step is to replace the hard line from the prop. valve to the rear hose.

I'm open to suggestions, and could use some help. I need to get this fixed ASAP.

Try bleeding them again? Sounds liek theres air in the line somewhere... But you can also try adjusting the rears by hand. They have a built-in auto adjuster that often gets rusty/dirty and stuck and won't tighten on the pads as they wear down. Just pop off the rubber plug on the drums and you'll see a little gear in there. Grab an old flatblade screwdriver and try spinning the gear either up or down. It should go easier one way then the other (if it even goes both ways... it should really only spin one way). Now you want to make sure you're not adjusting them too much, or they'll always be on, and too little will have your fronts locking up and your rears never locking.

They have been bleed over and over again, no air in the system that I can see. The rears have been adjusted properly.

I thought I'd put up some more info. Today I took out the prop. valve. And blocked off the front port of the M/C (essentially feeds the rear brakes). Then took the back port and plumbed it to a tee, and connected both front hardlines to the tee. So I'm only doing front brakes.

I still have the same issues. Which tells me the problem is in the front somewhere.

If I block off both ports to the m/c I cannot push the pedal at all, which (from what I'm told) means that the M/C should be good.

I've rechecked the pads, smoothed the portion of the brake brackets where the pads slide on and greased them.

My next step is to remove and replace both NEW front hoses w/ the braided hoses I had used w/ my old axles.

After that I'm stumped.

Did you try hooking it up the other way so that the MC powers only the rears?

It does sound like the MC is good

Doubtful that the front hoses will cure your problem, if they were that bad you would see them bulging.

When you slam on the brakes, the fronts lock and rears don't sounds like a problem with the rears. Also, the rears have the greatest affect on your pedal travel. When I had to replace a line on my rear axle it took forever for it to get the air out. I ended up using a trick that I used on Cessnas which is to hook up a mighty-vac backwards (turn it into a mighty-pump) and pump the fluid back up to the MC. It is very hard to force air down to the wheel cyl., might as well help it up to the MC.

Good luck

Well, to update, It did feel a little better after I switched hoses and it felt better, but not great.

Then I hooked up the rears directly to the front port of the M/C. No prop. valve at all. I bled it, and gravity bled it, and it didn't feel that great to me.

Then I got pissed and put the wheels back on so I could get it out of my garage. When I went to pull it out it felt ok. I went out in the driveway and slammed on the brakes and got the wheels to lock. I'm going to drive it when I get a chance and see how it does.

If it's ok, I'm going to put in an adj. prop. valve I have lying around to dial in the rears better.

I'm at the point to where I hate this jeep.

Rust Heap said:

Doubtful that the front hoses will cure your problem, if they were that bad you would see them bulging.

When you slam on the brakes, the fronts lock and rears don't sounds like a problem with the rears.

Click to expand...

X2 I'd hook it up the opposite of what you had and see what you find out. IF you can lock the fronts, they're probably not too bad, but if the rears never lock I'd start looking there.

98hd said:

Then I hooked up the rears directly to the front port of the M/C. No prop. valve at all. I bled it, and gravity bled it, and it didn't feel that great to me.

Click to expand...

Many many problems with soft pedals have been fixed by double-checking the rear brake adjustment. I know you said they are properly adjusted, but are you sure they are right? You should turn the adjusters with a screwdriver until they are completely locked up, and you can't turn the adjuster any tighter. That helps to get the brake shoes "seated" in their new position. Then back off the adjusters until you can turn the wheel. Then pump the brake pedal a few times, pull and release the parking brake a few times, and you'll probably have some more slack that you can take out.

ok, so I'm at home bored because its too cold to work in the garage.

There is another post about long pedal travel from a couple days ago. Long story short, check the front wheel bearings. Theoretically a bad bearing can cause the rotor to move enough to push the caliper in far enough to affect pedal travel. Seems like a longshot but not improbable.

Yes, I'm absolutely sure the rears are adjusted properly.

I took it out and drove it with the prop. valve out and the brakes feel like normal. The only problem is that there isn't a prop. valve and the rears lock up first.

Hopefully, it will work again once I get the prop. valve back in.

The only question now is do I put back the OEM valve, or an Adj. valve. I have both here, and I'm thinking the adj. valve would be the best. BTW: I'm getting this fixed so I can sell the jeep, so the OEM one would be better.