I recently did the ABS (Bendex 9) conversion to the boost system. New master cylinder, new booster, new front brakes and calipers, new hubs, new proportion valve, new brake lines.
I bench blead everything, and blead everything a million times. I'm getting some pedal pressure when its not running and it goes straight to the floor with ease with vacuum pressure. I have next to zero brakes (although exciting at times), adds about 10 years to my life anytime I move it.
my question is this, if my rear drum brakes are shot, will that cause the pressure to act that way? I know its probably a dumb question, but I'm tires of throwing hundred dollar bills at this thing.

 

Sorry, I don't have an answer for you. But I remember reading on here something about needing to have the dealer 'flash' something or other when ABS is involved.

 

Which direction are the bleeders facing?

 

There is no ABS system left in it, I yanked all that crap out. Its a simple booster system out of a 97 grand cherokee now.
I just need to know if the rear drums are shot and lets say the shoes are gone and the self adjuster has nothing left to adjust, will that be cause for no pressure.

 

And by the bleeders, are you refering to the bleeders on the rear brakes?
those sit on top and face inwards.

 

The front.

Did you remove or replace the front calipers?

 

Sorry, I misread. I thot you went TO ABS brakes. My bad

"...lets say the shoes are gone and the self adjuster has nothing left to adjust, will that be cause for no pressure." I don't know that.. but it's certainly cause for new rear brakes!

 

Even if the rear brakes are shot, you should be able to get some sort of pedal as long as the hydraulics are sound. Is this a new master cylinder, or the one from the doner XJ? Make sure the bleeder on the front calipers are pointed up.

 

When you say, "new master cylinder", do you mean truly NEW or a rebuilt. If if was a rebuilt you could have gotten a bad one. Happens. I quit buying rebuilts. No joy!

 

The front calipers have been replaced new, the bleeder screws on the front calipers also face inwards. My front brakes will slightly lock up, and you can see the caliper flexing when applying the brakes. All the lines are getting fluid.
This is Master Cylinder number 2, the first was the OEM off the donor vehicle, the 2nd is a remanufactured. I guess both could be bad. I dont think either one was or is though. I do know for a fact that the rear brakes are shot. I do know that all the lines are gettin lots of fluid, nothing is collapsed(rubber lines), theres no air in the system. If the rear brakes arnt the culprit, then I can only surmise its got to have something to do with the booster, but it builds pressure it seems just fine, I wonder....does anyone know if the throw arm on the booster needs to be a certain length? maybe its getting too much or not enough throw.

 

"The front calipers have been replaced new, the bleeder screws on the front calipers also face inwards." I think what gee oh dee was asking was are the bleeders pointing UP.. Some calipers will fit left for right and vice versa, and the bleeders point down. Not good for bleeding. Not to imply that you made a noob mistake

 

Air in the system.

Did you bench bleed the M/C?

 

Sytem has been bench blead, proportion valve was blead, all the lines have had 200 gallons of fluid put thru them bleeding, Ive blead the system a million times. zero air. Ive replaced the master cylinder, even tho the original wasnt bad. Replaced the proportion valve, even tho that wasnt bad, theres no leaks, the booster is making all kinds of vacuum. Just no pedal. Has anyone else ever done the ABS to boost system mod on here? What can I possibly be missing?
Im down to rear brakes and the push rod to the booster. Was just hoping someone could enlighten me before I go spend more dead presidents.

 

I guess I'm confused as to what you're asking/saying. The bleeders on my front calipers are on the side of the caliper/horizontal with the opening facing inward > <. I assume you're talking about the bleeder screws.

 

I swapped a 97+ booster, m/c, and prop valve into my son's 91 Briarwood. Worked as soon as we bolted it and relocated the pin on the brake pedal.