Brakes!!!

I do not get why uyou replaced the calipers, rotors, and lines? My first thought like others here is brake booster and like others why have you or a shop been replacing the master three times that makes no sense and why are you or they replacing the master and not the booster? Reading through all the post I think it has something to do with the ABS, if it is not a booster, I know he said he had the dealer flash it but...

 

Another that believes the booster and probably the ABS has nothing to do with this problem. If the booster is leaking, you should have an extremely stiff pedal from the get-go that doesn't change when pressing on the pedal. Like Rick, I think the problem is with the master cylinder bleeding and that is something you can easily do yourself on a JK with the cylinder still mounted. You just need two "U" tubes from the cylinder ports back to the reservoir and then pump the dickens out of it until there are no bubbles in the output. BTDT after MOPAR's stellar designed lift kit completely removed about 6" of the right rear steel brake line the first time it got twisted up good.

 

Concur with the above…and speaking as a “u-tube certified mechanic” I suspect incomplete/ improper bench bleeding of the MC and ABS system

 

The stuff being said here about the booster is true in most cases but not all. I purchased my XJ 3 months ago and the booster is leaking under the dash I know it is the booster because when I step on the brake the sound changes but my brakes work fine the pedal is not stiff nothing out of the ordinary, the point is not everything does the same thing each time.

 

Unless someone has come up with something I don't know about, booster systems are in no way connected hydraulically to the brake circuit, be it vacuum, electric, or hydroboost. The brakes should still function even if the boost system has failed-IF the basic brake system is functional. That does not appear to be the case in this thread.

 

Your post makes no sense, seems to me you are assuming things not said