On said truck, when you go to stop, the brakes grab a bit, then release , then the pedal goes to about 2 inches off the floor, then they grab and hold. Pumping does nothing. No abs light on the dash. Today we put the truck in 4high and while back up I had full brake pressure from the top. Also when you take off, either in the mornings or during the day, it has a slight vibration, kinda like a brake grabbing, then all is fine. The brake grabbing isn't there 100% of the time, I would say 95%.

Any ideas? I haven't changed the brake pads, rotors, or anything yet. Just didn't want to throw money at it and still not fix the problem.


Thanks

 

Well you can start by looking for leaks rust holes in the break lines
Then inspect the pads and rotors f and b make sure calapers arent sticking
That's where I would start process of alimentation
Keep us posted

How many miles on the truck?

 

truck has 171000 on it. Will check it out this weekend. Suppose to be dry, just chilly.

 

I've been having this exact problem in my 2000 F-150 4x4. 180k miles on it. It only does this at very low speeds, though. If I am stopping quickly, it brakes normally. If I stop gradually the pedal will get soft and drop a couple inches, and then firm back up. There is also a bit of a groaning noise. Were you able to figure out the problem? I figured it was an ABS sensor or something.

Let me know, please. Thanks!

 

I put new brakes and drums and rotors all the way around it. Fixed the problem.