Mopar Big Brake Kit Problems

I recently installed the Mopar big brake kit on my 2009 JKU-R, and have had nothing but problems ever since... I bench-bled the master cylinder until there were no more air bubbles coming through the lines (pretty standard stuff), and replaced the booster, master, front rotors, and calipers without much issue. The problems came when it was time to bleed the brakes and actually put them into service. When I bleed the rear brakes, the pedal stops solid about 1/2 way down - it will NOT go all the way to the floor? When bleeding the fronts, however, the pedal goes all the way to the floor as you would expect. The real problem is, the brake pedal feel is now terrible and it takes about 2/3 of the pedal travel before anything happens at all? And worse yet, often times while sitting there with light pedal pressure applied, say at a stop light or something, the pedal will actually drop away from my foot and I have no brakes at all until I pump the pedal???? Just looking for ideas on things to check, tests to run, etc? Oh, and I've got a buddy that has the Chrysler scan tool to perform the ABS system bleeding, and we did that as well with NO change :icon_crazy: Thanks in advance for any help.

i think you have to have the scanner hooked up and in the abs section and activate for bleeding with ABS brakes on these while you are bleeding. I haven't done it but i'm sure is heard that somewhere.

also ,were you wearing safety glasses? that might be the issue.

You set the booster pushrod to the right length? That may not explain the pedal stopping half way for the rear but it would explain the symptom in the front. Do you know if this system has a proportioning valve? And you're 100% sure the steel lines were screwed back into the correct ports on the MC?

WJCO said:

You set the booster pushrod to the right length? That may not explain the pedal stopping half way for the rear but it would explain the symptom in the front. Do you know if this system has a proportioning valve? And you're 100% sure the steel lines were screwed back into the correct ports on the MC?

Click to expand...

I did not manipulate the pushrod length... the kit instructions did not make any mention of doing so? Honestly never thought about it...

There was not a new prop valve with the kit, but I'm *ass*umming there is one somewhere in the factory system? It was not mentioned in the kit instructions or otherwise manipulated in any way, however.

Yes, steel lines are in the correct ports, as they are different thread sizes and only fit one port or the other.