No Brakes. HELP!

so heres the deal, ive got a 2000 cherokee. fullwidth 44 and 9" from a 76 ford f-150. i had a caliper sieze up on the front pass side. bought a new one, and replaced the old one with it (installed crush washers). bled the lines, all four corners, and nothing. so im thinking master cylinder... bought a new one today, put it on, bled the lines again, still nothing.

correct me if im wrong, but the booster doesnt have anything to do with if you have brakes or not? it simply runs a vaccum and makes the pedal easy to press down. if the booster goes bad, then the pedal is tough to push to the floor, but the jeep will still have brakes. correct?

the only other 2 things i can think of, is to adjust the drum brakes on the rear, or losen the jam nut on the rod in the booster, and move the rod out like .25" ...... im kinda outta options, and have a huge ride coming up saturday morning so im down to the wire. any help or suggestions would be greatly appreciated. thanks.

yeah the booster just amplifies the pedal pressure, and the brakes will still work without it. however the pedal doesn't get rock hard unless the booster loses all vacuum, usually a leak on the cabin side of the diaphragm will make the pedal feel like it has more slack in it since the booster is not engaging and pushing the rod for you

brakes are over rated....

thechief86 said:

brakes are over rated....

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haha thats what i keep hearing...

back to topic, its crunch time, down to one day before the ride. gah i hate cutting stuff this close

saybye said:

. . . so im thinking master cylinder... bought a new one today, put it on, bled the lines again, still nothing. . .

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Did you "bench bleed" the master before you put it in? I always bench bleed it before. Just to be "safe". Also, did you bleed them starting at the wheel furthest from the master?

New master must be bench bled until rock solid. It can be done with solid plugs in the outlet lines or looping hoses up to the top, usually a new master comes with one or the other. Did you do that?

There has to be freeplay between the booster's pushrod and the master at rest, or the compensating port will be blocked eliminating the fluid return to the m/c's piston.

Once those two items are there, and if your calipers aren't on the wrong sides, work it downstream if the pedal's still not there. Loosen fittings and catch the spray while someone else runs the pedal. At the outlet of the m/c, down at the prop valve and so on.

Booster test is pump several times with engine off to deplete vacuum, then hold while starting the engine. Pedal height should drop. But you'd have to have a pedal first- don't think that's the problem.

EazyXJWJ said:

Did you "bench bleed" the master before you put it in? I always bench bleed it before. Just to be "safe". Also, did you bleed them starting at the wheel furthest from the master?

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yes did both of these

JJacobs said:

New master must be bench bled until rock solid. It can be done with solid plugs in the outlet lines or looping hoses up to the top, usually a new master comes with one or the other. Did you do that?

There has to be freeplay between the booster's pushrod and the master at rest, or the compensating port will be blocked eliminating the fluid return to the m/c's piston.

Once those two items are there, and if your calipers aren't on the wrong sides, work it downstream if the pedal's still not there. Loosen fittings and catch the spray while someone else runs the pedal. At the outlet of the m/c, down at the prop valve and so on.

Booster test is pump several times with engine off to deplete vacuum, then hold while starting the engine. Pedal height should drop. But you'd have to have a pedal first- don't think that's the problem.

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yes i bench bled the mc.

so i shouldnt have to losen the jam nut on the pushrod in the booster and bring it out any?

calipers are on the right side; i only replaced one of them. what i dont get is why i had brakes when i parked it in the garage two weeks ago, i replace the caliper and mc, and now i cant get any brakes. we're gonna be working on it all day to try to figure out whats going on, if anyone else has anymore ideas post up! thanks guys

I don't know if you need to adjust the pushrod, do you have free play? Get out the calipers and check. Was the bench bleed done correctly? Have someone pump and hold the pedal, crack the fitting loose on the side of the master, does fluid spray out? I'm just repeating everything from my earlier post, it covers all the basics.

What kind of master cycl are you running?

I had to run a dodge 2500 master cycl to get good brakes with my hp44 ford 9. I also had to add some spacing to the master cycl ram to have the pedal feel proper.

i would check the rear brake adjustment.
also , are you getting a good pedal when you are bleeding the brakes or not? if you are getting good flow to all of the wheels , then something needs to be adjusted.

KSXJ said:

What kind of master cycl are you running?

I had to run a dodge 2500 master cycl to get good brakes with my hp44 ford 9. I also had to add some spacing to the master cycl ram to have the pedal feel proper.

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i am running the factory style master cylinder. it is a brand new one, not a reman'd one. what might the chances be that the brand new mc might be bad???

on that dodge 2500 mc you used, was it a direct bolt on? i might have to try that...

Haha, if you tried what I said you'd already know if the master was bad!