acer99

My brakes have been really soft, and so I decided to bleed them. In the process, the passenger rear drum bleeder valve snapped off clean. Old and rusty.

I got ahold of some rear discs from a ZJ and mounted them on my 8.25. Unfortunately, no matter how much I bleed them, they are just as soft as before... like pedal to the floor soft.

I'm not finding any leaks around the calipers, proportioning valve, hoses or master cylinder. I don't see any more air in the lines when I bleed with a vacuum pump. I have no idea what else to try.

There is one thing that seems a bit odd. Sometimes when I push the pedal all the way to the floor I hear a slight popping sound coming from the engine area. I don't know of that's worth noting or not.

I'm pretty fed up with trying to figure this out. I don't feel safe driving with it like it is.

caged

for starters, did you put the calipers on the correct sides?
what did you do about the proportioning valve?

maybe your master is leaking into your booster?

maybe you should take it to a brake mechanic...

Willys55

or...All The Above

nickxj94

Still have the original brake lines?

freegdr

does brake pedal stay solid when pushed ?

ut-xj-frk

just replace the booster. those boosters suck. if you can..you should upgrade to the duel booster out of a newer jeep. but even then a new factory replacement would most likely fix your problem.

acer99

Brakes are all installed correct, and this was all happening before the disc swap, so something else is a problem. I haven't touched the proportioning valve.

The master leaking into booster... Hm. How would I go about checking into that? I'll google around, but I appreciate any pointers.

acer99

If pumped, yes. Otherwise, no.

acer99

I bought some front hoses for a '95 GMC 1500 for the extra length, but I haven't fit them yet. Rear hoses are original.

I haven't put a priority on swapping them (I definitely will today or tomorrow). I was thinking if they were collapsed or a problem, then they would either leak fluid near a crack, or not release fluid when bled.

mechanic6339

When you switch to disc brakes on a vehicle you should change allot of items. This is because drums take a different amount of fluid and pressure than disc. First is the proportioning valve. Since disc is stronger than drum the line pressures need to change for correct front to rear proportioning. Or you could just be over using the front or rear to much. This can also change with master cylinders. Disc normaly take a different amount of fluid so the master cylinder bore size can change. Also as noted above insure that calipers are placed with bleeders at the top, and use the same DOT brake fluid throught out. If you mix fluids it can screw allot of things up. If possible I would try to salvage the same proportioning valve, and master cylinder off of the vehicle that you got the rotors and calipers from. This is some food for thought. Reply back with what you find.

acer99

That's an idea. Do you know off hand which model/year will fit? Is it a lot in solution?

xjtimbo

I know you said this before but, I did a brake job on my jeep and have done it a few times so I feel I know what I'm doing. The last time I replaced the calipers in the front I must have had a brain fart and put them in upside down they fit perfect on ether side. They were doing what you're saying with no air coming out but as soon as I flipped them they bleed right away. If they are installed with the bleeder screw on top I will shut up now.

I was reading about this brake swap awhile back and the big question was the proportioning valve. What I came up with was I was not going to use the zj valve. Other than the bleeding issue how well did the swap go? Could you list all the parts you had to use from the zj. Thanks Jon.

nickxj94

93 to 98 zj with the v8 you have to trim the rod a little but its pretty much bolt on there are tons of Wright ups on the booster and MC swap. You may try getting some stainless brake hoses for front and rear did that on a buds cj7 with 4 wheel disc it help alot and his petal is not squishy anymore. Its my next upgrade since I just done the zj rear disc too my petal is squishy also unless I pump the brakes a few times but it stops better than it ever did with drums

freegdr

what years this ?

acer99

2000 XJ Sport