94 jeep grand cherokee laredo brake problem

If youve replaced all those parts start by checking everything is mounted correctly. If it is even a tiny amount out it will cause issues.
Next Re-Bleed the brake system starting with the caliper furthest away from the master cylinder and do the nearest one Last.

With any style of brake (drum or rotor), new shoes/pads will always be thicker than the ones you are replacing. You have to retract the brake cylinder pistons to get drums/calipers on. For drum brakes, squeeze the two shoes together at the brake cylinder. If there is no more play and it still won't go on, the shoes you are using are too thick - this can happen with certain aftermarket parts. Try the OEM shoes instead.

Once you have bled the air from the brake lines,clamp off the front brake hoses carefully.Does the pedal feel better now?
Then the pad /caliper fit is allowing too much play.Is the pedal the same?Then clamp the rear hose and try the pedal.Is it fine with the rear hose clamped?If so we now know the problem is at the rear brakes.One common low pedal rear brake cause is brake shoes that do not fit the drums.Remove the drums and look at the shoes,are they showing contact wear fully or just in the middle of the shoe?Remove a shoe and place it in the drum.Can you rock the shoe against the drum surface?Once drums have been resurfaced,the shoes will not fit fully against the drum allowing the shoe the flex when applying pressure to it and this can easily create a low soft brake pedal. Of course rear brake adjustment must be correct once brake shoe contact is correct.To correct brake shoe contact,have your shoes re arc-ed to fit resurfaced drums or install new drums.Don't overlook brake master cyl /brake pedal push rod adjustment too.

Either bleed all lines again or check master cylinder. Start with a slow thorough bleeding job making sure master is never low of fluid.

Did you clean the protective covering off the drums and rotors before installing ? Is it possible there is a film of oil on them ?

Time to redo the bleeding of the system again...starting with the master cylinder...you do not have to remove the master to re-bleed it. disconnect both brake lines from the master, and start again by pushing pedal to floor, and rebleed each line at the master...this is critical to work properly...you mentioned new master cylinder, if remanufactured I would return it. As noted above, after confirming the master is fully bled...rebleed each caliper beginning with the rear, farthest away from the master...you must have "air" in the brake lines. Hope this helps.

Sounds like the master cylinder is full of air.Somebody let it run dry when doing a pad change.(maybe)Did the calipers get rebuilt or were the pistons just pushed back in?
Brakes are a sealed unit.If there is no leaks,then you must start at the 1st point of operation.The master system.Hope this helps.

JEEP VECHICLES 2001 MODELS AND UP HAS TO BE BLED USING A DRB BLEED TOOL.YOU HAVE TOW VECHICLE IN.MOST TIME YOU CAN TRY MANUAL BLEEDING BUT BRAKES WILL BE SPONGY AND ABS LIGHTS WILL TURN ON.THE DEALERSHIP HAS TO BLEED IN ORDER TO GET GOOD SOLID BRAKES AGAIN.

1. Raise and support the vehicle safely using jackstands. Remove the wheel(s) on the side to be worked on.
   

NOTE: Removing a small amount of brake fluid from the master cylinder using a turkey baster

Fig. 4: Tighten the C-clamp until the piston reaches the bottom of its bore

Fig. 5: Remove the caliper mounting bolts

Fig. 6: Slide the caliper off the brake rotor

1. Drain a small amount of the brake fluid from the front reservoir using a suction gun or a turkey baster.
2. Place a C-clamp on the caliper so that the solid end contacts the back of the caliper and the screw end contacts the metal part of the outboard brake pad.
3. Tighten the clamp until the caliper moves far enough to force the piston to the bottom of the piston bore. This will back the brake pads off of the rotor surface to facilitate the removal and installation of the caliper assembly

Fig. 7: Support the caliper so that no tension is placed on the brake hose

Fig. 8: Hold the anti-rattle clip while removing the outboard pad (4)

Fig. 9: Removing the outboard brake pad

Fig. 10: Remove the inboard pad and anti-rattle clip

Fig. 11: Removing the inboard brake pad

Fig. 12: Removing the anti-rattle clip

1. Remove the C-clamp.
   

Do not push down on the brake pedal or the piston and brake pads will return to their original positions up against the rotor.

1. Remove the caliper mounting bolts. Tilt the top of the caliper outward and lift it off the rotor.
2. Hold the anti-rattle clip against the caliper anchor plate and remove the outboard brake pad.
3. Remove the inboard pad and the anti-rattle clip. Be sure that the support spring is removed with the inboard pad.

Fig. 13: Install the support spring onto the shoe of the inboard brake pad

Fig. 14: Installing the inboard pad

Fig. 15: Piston extension on new and worn brake pads

1. Use a piece of wire to support the caliper so that no tension is placed on the brake hose. Do not allow the caliper to hang by the brake hose.
   

To install:

1. Clean all the mounting holes and bushing grooves in the caliper ears. Clean the mounting bolts. Replace the bolts if they are corroded or if the threads are damaged. Wipe the inside of the caliper clean, including the exterior of the dust boot. Inspect the dust boot for cuts or cracks and for proper seating in the piston bore. If evidence of fluid leakage is noted, the caliper should be rebuilt.
   

Do not use abrasives on the bolts in order not to destroy their protective plating. You should not use compressed air to clean the inside of the caliper, as it may unseat the dust boot seal.

1. If not already in place, attach the support spring to the inboard brake pad.
2. Install the anti-rattle clip on the trailing end of the inboard pad's anchor plate. The split end of the clip must face away from the rotor.
3. Install the inboard pad in the caliper. The pad must lay flat against the piston.
4. Install the outboard pad in the caliper while holding the anti-rattle clip.
5. With the pads installed, position the caliper over the rotor.

Before securing the caliper, ensure the brake hose is not twisted, kinked or touching any chassis parts.

1. Lubricate the caliper pins and bushings with silicone grease. Line up the mounting holes in the caliper and the support bracket and insert the mounting bolts. Make sure that the bolts pass under the retaining ears on the inboard shoes. Push the bolts through until they engage the holes of the outboard pad and caliper ears. Thread the bolts into the support bracket and tighten them to 7-15 ft. lbs. (9-20 Nm).

CAUTION On models with manual/power brakes, pump the pedal until the caliper pistons and brake shoes are seated. On models with anti-lock brakes, turn the ignition ON and allow the booster pump to build pressure. Pump the brake pedal until the shoes are seated and the indicator lights turn off.

1. Fill the master cylinder with brake fluid and pump the brake pedal to seat the pads.
2. Install the wheel assembly and lower the vehicle. Check the level of the brake fluid in the master cylinder and fill as necessary.

Remember to rate this, good luck.

YOU NEED REMOVE A LITTLE BRAKE FLUID FROM MASTER CYLINDER.THEN YOU RAISE VECHICLE SAFELY.SUPPORT IT WITH JACK STAND.MAKE SURE VECHICLE IS ON LEVEL SOLID GROUND.REMOVE TIRE OR WHEEL.THEN YOU NEED A LARGE C - CLAMP.PLACE C - CLAMP OVER BRAKE CALIPER AND BRAKE SHOE BACKING.TIGHTEN C - CLAMP JUST ENOUGH PUSH CALIPER PISTON BACK IN CYLINDER BORE TO REMOVE CALIPERS FROM ROTORS.TO REMOVE BRAKE CALIPER YOU NEED 2 OPEN AND BOX END WRENCHES ONE TO HOLD CALIPER SLIDE PINS AND THE OTHER WRENCH FOR LOOSEN CALIPER BOLTS.THEN YOU REMOVE CALIPER AND REPLACE FRONT BRAKE SHOES.IF YOU NEED TO REMOVE BRAKE ROTORS JUST REMOVE THE BRAKE CALIPER CARRIER SUPPORT BOLTS THE REMOVE THE BRAKE CALIPER CARRIER SUPPORT THEN REMOVE ROTOR.YOU NEED TO REPLACE BOLTS WITH NEWS AND USE LOCK TIGHT.THEN YOU PUT IN NEW BRAKE PADS IN CALIPER PUT CALIPER BACK ON SUPPORT CARRIER.REPLACE WITH NEW BOLTS USE LOCK TIGHT THEN TORQUE BOLTS TO 26 FT LBS.MAKE SURE MASTER CYLINDER COVER IN PLACE.WHEN YOU FINISH REPLACING BOTH FRONT BRAKE PADS PUMP BRAKE PEDAL TO SEAT BRAKE SHOES AGAINST BRAKE ROTORS SO YOU WILL HAVE FIRM BRAKES WHEN YOU APPLY THEM. THEN CHECK YOUR BRAKE FLUID LEVEL IN MASTER CYLINDER MAKE SURE ITS NOT LOW. MAKE SURE YOU HAVE FIRM BRAKES BEFORE DRIVING.IF YOU HAVE ANY PROBLEMS CHANGING FRONT BRAKE PADS YOU CAN GO TO ANY AUTO PARTS STORE AND BUY A HAYNES REPAIR MANUAL.