So, Im drivin my 91 XJ around town doin some drop offs and such, and it was warm today, about 90*. The Jeep seemed ok, ran a bit warm later on, but overall ok, however I soon found that my brake pedal began not wanting to push in and out smooth like it always does. And the front-left brake wasn't realesing the rotor, makin my XJ pull left and not want to roll. When I went to work, the weather cooled, and when I started it up to go, everything ran all nice and happy. Im thinkin a vacuum leak somewhere towards the driver side front calipher.. any ideas?

 

Pistons more than likely sticking...I would suggest replacing the calipers.

 

Pull the caliper off and look at the mounting bracket for the pads.....you will more than likely see a worn in notch and a bent brake pad because the pads get jammed in the notch. Also could be a bad brake hose, but since it was better later I tend to think it is in the mounting bracket and the brake pads are bent or worn on an angle.

 

So check the calipher, and if I see this wearing or bending, what should I replace? The brakes and caliphers? Would the newly arrived heat cause this or was it mere coincidence? Also, if it helps any, when I relase my brake pedal it squeeks, like its worn a little. I always thought the squeek was just a "WD-40" fix but just haven't gotten around to it.

 

Wd-40 won't do jack after the first 10seconds of driving.

Pull the calipers check for signs of damage or improper use like the other guy stated. Though I can already tell you you're already looking at replacing them more than likely. Very doubtful its your brake lines, its possible but not likely. If they're stretched or kinked it will make them not work and overwork another side, etc.

You'll notice it once you pull the wheel and brakes off. Not to mention it doesn't hurt to upgrade brakes...stock is crap.