cj5 brake bleeding problems front disc

[johnnybravo5150]

so after going thru the front bearings and axle ujoints.... the problem is that i cant seem to bleed the front brakes. to get at the axle i had to remove the caliper but the bolt going thru the banjo fiting on the brake line is traping the bolt holding the caliper on so i had to remove it now i have air in the line. after working on the axle it is all back together i have bled and bled till im sick. my buddy that sold it to me a year ago tells me that he had to pay a shop to bled it before but they had to take the calipers off an turn them upside down or some thing of that sort but the catch 22 is i cant get the caliper off because one of the caliper bolts is trapt by the bolt thru the banjo fiting? any help is appreciated. i am a competent mecanic but im stumped

 

[jasonmark1993]

The bleeder is at the top right?

 

[bondo258]

i cant get the caliper off because one of the caliper bolts is trapt by the bolt thru the banjo fiting?

A 79 should only have one bolt securing the support key, which is in turn bolted to the Anchor plate. No bolt should go through the caliper at all, except the banjo. Sounds like somebody swapped in something else, at one point. Got a pic?

Are the bleeder screws trashed? Is the bleeder seat trashed?

Are you using a vacuum bleeder or "Suction pump" by chance? If so, some teflon tape on the outer few threads only will keep air from entering in through the threads, and getting sucked back out through the bleeder hole. This "no suction" condition is common with vacuum bleeders.

If you go this route, be careful go slow. You DO NOT want any bits to get inside the tapered seat area. Cut tape to width, if necessary.

The threads aren't designed to seal against hydraulic pressure, or incoming air from a vacuum source on the bleeder screw. The tape will not effect the bleeder screws operation at all.

The tapered seat is what seals the bleeder when tightened, Not the threads.

Many replacement bleeder screws and "speed bleeders" come with that painted on thread sealant for the same reason. That paint on plastic sealant would be ideal, if you can find some. I couldn't. I use tape instead. Maybe you could buy the replacement bleeders with the sealant already on them if teflon tape on your brakes sounds scary or unsafe to you.

And keeping with jasonmarks response and question. The bleeder is at the top or higher than the caliper piston, correct? If not, the left caliper and right caliper are on the wrong sides. Swap them around and use new sealing washers when doing so.

If the jeep was lifted, someone might have swapped caliper sides, instead of buying longer brake hoses. Plan ahead for this as well if the calipers seem to be on the wrong sides.

 

[johnnybravo5150]

yes

 

[johnnybravo5150]

the bolt going thru the banjo fiting is the bolt that is traping the caliper mounting bolt

 

[johnnybravo5150]

this is a two bolt caliper an the bottom bolt is the one that is trapped by the banjo bolt and yes the bleeder is at the top.

 

[jasonmark1993]

Are you just ending up with a soft pedal? Or are you actually seeing air come out the bleeder?

There are a handful of things that can give you a soft pedal feel, all related to the caliper moving during compression. I had a vehicle come in once that had brakes done somewhere else and they couldn't get a hard pedal. I eventually discovered that the new pads were sitting up on a little lip at the interior of the rotor; there was a little gap until you pressed the pedal which had to be taken up before the pedal got hard. Pulled the rotors and had to turn them all the way to the outer hub.

I'd have someone depress the pedal while you are watching and make sure you don't see any movement or deflection at the caliper/rotor.

Did you let all the fluid empty out of the MC maybe and you have a little air up there?

I've always gotten away with gravity bleeding and then one good pumped force bleed and thats it.

 

[johnnybravo5150]

well i bleed and still have no pressure. takes maybe 7 or 8 pumps to get hard peddle then... it looses it and must be pumped up again to get a hard peddle. ima try doing a gravity bleed first tonight

 

[jasonmark1993]

Thats without opening the bleeder?

Theres two reasons a pedal fades to the floor:

Leaks

Failed MC

It doesn't matter how much air you have in there, you can still pump it up and it'll get hard and stay hard.

If the pedal is fading and you have no leaks, better check the MC. Well, there isn't really a way to check it. Just gotta replace it at that point.

 

[johnnybravo5150]

ok well it all worked perfect till i opened the system and let air in while working on the axles. ima do a gravity bleed tonight then test an look for leaks. thanks guys

 

[jasonmark1993]

Can you shoot a picture of the caliper. I don't have discs on mine, but the other guy seemed very familiar with how it should be. Sounds like yours is a little different for some reason.

I don't really see how that could be effecting things but who knows.

Maybe try bleeding where you just open the bleeder, depress the pedal once, then close the bleeder. Might have some fluke bubble of air that doesn't want to come out.

Still not sure why the pedal won't stay pumped up though. Takes more pumps but air compresses too.

 

[johnnybravo5150]

it may take me a bit to figure out getting pics on here but again i gravity bled them then vacum bled no bubbles for two quarts of fluid and still no preassure and i cant find any leaks!

 

[jasonmark1993]

I don't get it.

Either the MC is bypassing or something is moving somewhere (like the rotor or caliper) causing you to have to move a lot of fluid.