Brake Bleeding Issues

Just did a rear disc swap, replaced all soft lines and the rear axel hard lines. I also did a ZJ proportioning valve swap (spring, cap and the post inside swapped into my stock unit). I also took the Master Cylinder off but once I found that the replacement SSBC sent me didn't fit I went right back to my stock unit.

So...I bled the prop valve and it bled just fine, and then I made the rounds of the calipers. I have a nice firm pedal engine off, but under power I get nothing...to the floor...nada...no leaks anywhere I can see...I need help at this point...thanks guys.

ETA: just bled it all a second time, its better but still down to the floor, at least now it stops the rear wheels up on jack stands...

keep bleeding and dont run the master dry. getting all the air out may take awhile.

how are you bleeding them?

are you sure the calipers arnt upside down with the bleeder on the bottom?

ha, that would be funny...they are mounted with the parking brake attachment up with the bleeder screw approximately in the middle, probly not the best design but hey... not my fault...

I'm using the one person bleeder kits with the cups.

Unless the bleeder screw is at the top of the caliper, you'll have a very difficult time getting that air bubble out of there.

might be time to invest in a mityvac.

http://www.tooldiscounter.com/ItemDisplay.cfm?lookup=MIT6820&source=froogle&kw=MIT6820

The rear soft lines have their own bleeder screws above the caliper's bleeders, bled those out, helped some, but still not great...now I can't bleed the prop valve, it doesn't come out of the nipple, just drips out the bottom of the threads...

get a wind shield wiper bottle with the motor still attached. fit a length of tubing. lengthen the wires to reach the battery from the passenger rear wheel. put a switch on the wire close to the bottle. now attach the tubing to the passenger rear wheel. fill the bottle with brake fluid. open the bleeder, switch the pump on. then go to each one of the calipers and bleed till no more air comes out or the fluid is clear. i have used this system for sometime and brakes are shite hot. if you can find a small one way valve attach this to the tubing as the fluid might run back when you switch the pump off. you are basically reverse bleeding the system and works great to replace old fluid. i have taken an old brake fluid bottle, made a hole in the cap, slipped so tubing in to the bottom, slightly filled the bottle with fluid (no air return) to catch fluid when bleeding the other calipers. no mess!!

if you took off the master cylinder shouldn't you have bench bled it?

x2, i was about to say that

flyingbrick said:

if you took off the master cylinder shouldn't you have bench bled it?

Click to expand...

why would you need to do this. i have always just filled the reserve bottle, then loosened each brake line pipe connecting to the master cylinder at a time and bleeding it that way. it has worked perfectly well.

Bench bleeding is required if the MC doesn't set level in the truck. Generally, the MC is tilted upward from horizontal. Some times, it's possible to jack the rear up, to level the MC, but generally it should be removed and "bench" bled in a vice.
With the MC not level, air can collect at a point in the MC's cylinder that defies bleeding; the bubble sets above and forward of the discharge port.
Since you did remove the MC, it needs proper bleeding, as described above.

you can do it in the vehicle too, just most people do it out of the vehicle
there's plenty of links online on how to do it,

The only reason I see to bleed to old MC is if it ran dry when it was removed.:doh:

itbrokeagain said:

The only reason I see to bleed to old MC is if it ran dry when it was removed.:doh:

Click to expand...

Correct as far as I understand it. If the MC is removed and replaced with the hard lines left in place and the cap left on the bottle there should be no need to bleed it....although you may want to bleed at the proportioning valve.

I'm beginning to think this is a hardware issue associated with the MC, I'm having someone make me a hardline and modify the bracket for the prop valve for the larger MC so I can install it and see if that helps the issue since it is recomended with the kit.