vintagephilg

...........Yes. The Rear brake pads are adjusted properlly, and work great. And the front calipers are new, and installed properlly.....I was bleeding the brakes the traditional way withy 2 people, one in the car/jeep pumping the brakes, the other person under the car "craking the bleeder.....and bleeding the brakes. I think it might have something to do with the differential block/proportioning valve (under the Master Cylinder) or just not being able to get the air out?? I've never seen annything like this........

BLKXJ 96

Are the calapers on the correct sides? the bleeder screws need to be at the top of the calaper. I have put the calapers on incorrectly before and all the air will not bleed out of the system.

tcountry

Try bleeding it at the porportioning valve, may be that will get all the air out of it

bigbadxj

Check everything again then go get one of those one person bleeder pumps. That way there is no doubt on the bleeding problem. If it is a leaking connection,bad line, or the Proportioning valve you will not be able to get all the air out. But the Proportioningvalve hardly ever goes bad all it does is keep the pressure balanced when you have front disc's and rear drum's. Proportioning valve's usually go out When a premature rear wheel slide is obtained on brake application, it could be an indication that the fluid pressure to the rear brakes is above the reduction ratio for the rear line pressure and that a malfunction has occurred within the proportioning valve unit which should be tested.To test the proportioning valve, proceed as follows: During testing, leave front brake lines connected to the valve. (1) Install one gauge and “T” of set C-4007A between brake line from master cylinder secondary port and brake valve assembly (Fig. 2).
(2) Install the second gauge of set C-4007A to the rear brake outlet port between valve assembly and the rear brake line. (An adapter tube, made up locally of a 9/16 x 18 tube nut, short piece of brake tube and 3/8 x 24 tube nut will be required to connect the hose to the valve). Bleed the rear brake system.
(3) Have a helper exert pressure on the brake pedal (holding pressure) to get a reading on the valve inlet gauge and check the reading on the outlet gauge. If the inlet and outlet pressures do not agree with the values on the following chart, replace the valve.
(4) Valve assemblies for all models are shipped in the front failed position to improve bleeding. When installing a new valve, bleed the rear brakes first

Split Point (PSI)/Slope Inlet Pressure From Master Cylinder Outlet Pressure To Rear Brakes
220/.43 1000 500-600
300/.27 1000 430-550

caged

you may need to replace the master/booster.
i went through the same thing, and just upgraded to a 99 brake booster/master, and now i have killer brakes. i can lock up my 36's, no problem.

BlueXJ

Mighty vac is what you need.
http://www.mityvac.com/

PNWJeep

Oh man those mighty vacs are worth every penny.

I know it sounds repeated but rebleed, I did a clutch master cylinder that wouldn't even start giving us air until we pumped the clutch close to, no joke, 200 times. The air was getting caught somewhere and we had to just keep at it.

If you can get a fluid extractor you will save yourself time, alot of time.

Good luck, let us know.

James

TheatreJunkie

I'm having what sounds like the same issue. When I bled the brakes with the collection bottle I could get it clear with no bubbles coming out, but with the one person bleeder pump I'm getting a lot of bubbles. I definitely have a hole in the system somewhere, I'm just trying to track it down now.

XJ-92

You can get the mighty vac from harbor freight for half the price of everywhere else. And yes its the same packaging and labels as every auto parts store.

Parsnip

Does the jeep have abs?

Razzle308

Sorry for draggin up old postYou got any specs on doing that swap?? Sounds like what i need to do.
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caged

oh man, it was so long ago.
but if i remember, i just went to a junkyard and pulled everything off a 99ish year xj. i did however have to have a new line flared to go from the master to the proportioning valve. i did have to divorce the prop valve from the master so it would go in the same spot as the stock 90 location. got a new line flared up at a brake/muffler shop. didn't cost much. i could have done it myself, but it needed a double flare on one end, and a bubble flare on the other. i reused one line however.
but as for the brake pedal rod coming from the booster, i just had to ream out the hole and grind the end flat for the brake switch. the rod was a bit longer than the stock 90, but i quickly got used to it. there is another year booster that you can use that has the same length, but i do not remember exactly what year. 96 maybe. dunno. someone may chime in with that correct info.

best brake upgrade i've ever done. like night and day. cheers.

Camaroboi13

To specify, it was 95-96 for the exact fit. The rods are longer but there is a spacer that goes between the booster and firewall to keep your pedal height where it needs to be. If you find any other year at a junk yard, you can go to any grocery store, buy a thin plastic cutting board, and use a jig saw/dremel to make your own spacer. But if you can find a master cylinder/brake booster combo from one of those years, it's a direct bolt on. As stated above you will have to work with the prop valve lines as far as getting them to fit. The valve itself is in a different position so you'll have to toy with it. Also, not sure on what year it was, but the washer fluid bottle may or may not be in the way. Going single diaphram to dual diaphram takes up a little more space in the engine bay so you may have to move some things around. Personally, I could care less about a washer bottle as mine is a dedicated trail rig and the more mud on her the better.

https://www.cherokeeforum.com/f67/br...pgrade-194211/

XJlimitedx99

To reiterate the point about the brake line fittings between the master cylinder and the proportioning valve (because I just went through this):

There are two lines (front circuit and rear circuit). Both 3/16" diameter brake line.

-Front circuit (rear of MC) is a M10x1.0 fitting with a bubble flare (ISO flare) at the master cylinder and a 1/2-20 fitting with a double flare at the proportioning valve.

-Rear circuit (front of MC) is a M12x1.0 fitting with a bubble flare (ISO flare) at the master cylinder and a 7/16-24 fitting with a double flare at the proportioning valve.

To accomplish this I purchased some double flare to bubble flare adapters at the MC side and reused the old fittings at the proportioning valve side.