rusty front brakes

I was driving into work this AM, and while rolling up to a stoplight, the front brakes seemed to grab a bit in certain spots. I think "OK, it rained last night, was kinda humid....maybe a little surface rust. It should clear up." However, the problem just got worse.

I usually apply gentle pressure to the brakes....and roll slowly up to my stops. Today, when I do this, suddenly the Jeep will lurch forward as the brakes grab (several times they grabbed hard enough to lock a front wheel). Then, after a second or so, it brakes normally....then grabs again for another second.

Here's the things that are really baffling me. I put 75-100 miles on this Jeep every day, so it's not been sitting around for 6 months. Why do the brakes act like the rotors are rusting?? Also....the problem got worse the more I drove. It happened once, gently, as I was leaving the addition...by the time I pulled into the office parking lot (40+ miles later), I was fighting to keep the wheels from locking up.

Any ideas would be great....it kinda feels like the front axle is gonna get pulled out from under me!

Calipers, check your pads, if they are worn you might need new pads. If the calipers are old they may be hitting rust and corrosion in their bores and sticking.

I forgot to mention that. I've got good pads/rotors on there, just replaced front brake lines (the flexible portion) about 2 months ago. While I had all that apart, I also replaced bleeder screws, and cleaned up the calipers a bit. However, I do need to get in and replace the wheel cylinders in the rear...that would allow me to adjust those brakes

Rusty rotors work really well . I sand my rotors every time I do a brake service. At a 45% angle one direction and then reverse it and a 45% cut in the other direction. This leaves an X pattern of sanding scratches. This helps reduce the grooves that get cut into a disc over the years.
You may have some rust buildup in the pad face, that will likely eventually rub off. Or you can lightly sand the pad face also. a good thing to do with brand new pads anyway. Some pads are softer than others and tend to pick up more embedded junk.
Sticky caliper pistons is also a possibility, but more likely to happen on one side or the other. Torn dust boots on the caliper piston is sure to cause problems sooner or later, the bores get full of rust and junk.
If any kind of water is mixed in with the brake fluid it can work it's way down to the calipers and may boil and make steam. I've seen brakes lock down completely doing this. Opened the bleeder valve and steam and brake fluid came out like a fountain.
Sometimes the grooves worn in the rotor and the ridges worn on the pads, don't line up exactly anymore. Water in some pads makes them swell. Rubbing makes heat, heat causes more swelling, chain reaction.
Just a few possibilities.
It may also be something not letting the calipers release correctly, something making them hold some pressure instead of going completely limp and retracting a millimeter. If the pads are retracting properly, you can often wiggle them a little when they are cold, maybe 0.015 thousandths of play or so. Though they do sometimes touch the rotor very lightly when they are retracted (pressure released).

Thanks for the suggestions, let's keep them coming =P

Something else to add to the mix. Over the course of 2-3 months, I lost 90% of the fluid in rear portion of the master cylinder, and maybe 45% of the fluid in the front portion. I'm attributing that to a small seep somewhere, I think its somewhere on the left side (wet spot on the inside of the wheel), so I'll tear into that tonight as well.

However, there are no wet spots on the backing plates of the rear. Is it possible that the wheel cylinders are leaking onto the brake shoes?? If so, would this make them squeak when engaged/released at slow speeds (i.e. backing into a parking space)

Brake fluid on the shoes or pads will make them swell and get soft (sometimes, sometimes the brake fluid bakes on there and makes a kind of glaze). They grab, squeal and often lock up, it seems to get worse when they are fluid soaked and wet. They also pick up a lot of brake powder, dust and junk.
Hanging the front calipers by the brake lines can kink them and may even separate the layers. The inside layer is thin and can act like a check valve. The outside layer cracks easy.
Never leave the cap off of the brake fluid bottle, brake fluid sucks up moisture from the atmosphere like a sponge. If your constantly having to add fluid, you may be also pouring moisture in there. One thing I don't buy in bulk is brake fluid, I buy a whole bunch of small containers.

Question time!!

Tore into the brake system today, just on the front axle. Found absolutely nothing wrong, good rotors, 40% life on the pads, etc....Put it all together and took it out for a test drive. Still had the problem....Grrrrrr!

When I was pulling back into my driveway, the puppy ran out in front of the Jeep. I jumped on that brake pedal, and sure enough....laid a stripe of rubber.........from the Left Rear!


Any idea what could be causing this?? It's obviously after 10PM (damn city noise ordinaces....), and I didn't get a chance to pull that wheel off. I wonder if I'm going to find broken springs, cracked/snapped shoes, etc....Oh, the suspense is killing me!! lol

mine did the same thing especially when brakeing into a right turn like a street or driveway wheel cyl were leaking replaced and that was it pay attention to the parking brake setup its tricky to reinstall if you didnt pay attention upon removal or you just end up doing the back and forth thing from one side to the other to look at how its installed