Brakes just wont work tried everything

[pat1234]

I have an 89 cherokee. I have replace the pads, master cylinder,two front calibers , the rear self adjusters, and played arond with the adjustments on the master cylinder itself and still the brakes only come to a slow stop. The pedal goes all the way to the floor and stops very slow. I have also bled the brakes many times. any info that can possibly help me fix this problem would be greatly appreciated. I am out of solutions Thanx Pat

[Saudade]

Did you "bench bleed" the master cylinder? There should have been a instructions with the MC. If not, search the forum for bench bleed.

[Ray H]

Originally Posted by pat1234

I have an 89 cherokee. I have replace the pads, master cylinder,two front calibers , the rear self adjusters, and played arond with the adjustments on the master cylinder itself and still the brakes only come to a slow stop. The pedal goes all the way to the floor and stops very slow. I have also bled the brakes many times. any info that can possibly help me fix this problem would be greatly appreciated. I am out of solutions Thanx Pat

X2 on the bench bleed. There are lots of places in the master cylinder for air to hide. Theres a little thimble on the end of the piston that is notorious for holding an air pocket. I took mine apart and drilled little holes around that thimble to allow air to escape. Also, drive it for a few days then bleed, bleed, bleed it again.

[DonSor]

You said you had replaced the master cylinder. But a typical symptom of seals leaking in the master cylinder is the pedal going all the way to the floor when you push in the pedal slowly. But a fast or sudden braking will not.

[AlohaBra]

Originally Posted by pat1234

I have an 89 cherokee. I have replace the pads, master cylinder,two front calibers , the rear self adjusters, and played arond with the adjustments on the master cylinder itself and still the brakes only come to a slow stop. ****

On my 97 XJ both rear slave cylinders were frozen. Jack the Jeep up and run in 2WD. Apply the brakes and see if the rears are working. All cars will stop with mostly the front brakes so most people will not know if the rear set is actually working. I found out when my Jeep was on the dyno for the Smog Tests in Cali(fornia).

They make a vacuum pump that has a brake bleed adapter so you can "sucK" the air out from the cylinders and calipers.
You can also open the rear bleeder and pressurize the master cylinder end. The have professional units for this, but I have made one with a MC cap with a hole drilled on top and 2 small holes in the rubber dust seal and then blow lightly with a compressed air nozzle.

[flagship202]

Originally Posted by pat1234

I have an 89 cherokee. I have replace the pads, master cylinder,two front calibers , the rear self adjusters, and played arond with the adjustments on the master cylinder itself and still the brakes only come to a slow stop. The pedal goes all the way to the floor and stops very slow. I have also bled the brakes many times. any info that can possibly help me fix this problem would be greatly appreciated. I am out of solutions Thanx Pat

I had the same problem on my Comanche. Same as a Cherokee. I tried the bleeding and adjusting thing over and over with no results. Take a look at the calipers you just installed and see if the bleeder screws are at the top of the piston chamber. If they are on the bottom air will be trapped in the top of the piston chamber and will not bleed out. If this is the case the calipers must be switched to lthe other side or taken off turned upside down and then bled. Insert a piece of board between the outer caliper frame and the piston to keep it from being pushed out of the caliper. Hope this helps. flagship

[AlohaBra]

Bleed nipple must always be at the top to get the air out.