hello this is my first post about this truck. im in a hurry my daughter is about to go out of town for the holidays and i need to fix her truck. its a 2007 f150 v6. has 55,000 miles. just got her new tires for Christmas. the truck has doing this for awhile. when you use the breaks the pedal pulsates and the truck jerks back and forth. feels like bent rotor or something. been doing it about a year keeps getting worse. last year i had the rotors turned and put new pads on got a little better. but not for long continued to get worse again. so i just just bought new rotors and pads and still sucks. i thought it could be a bent rim so i just rotated the tires and still no better.
where should i go from here? calipers? something in the front end loose?
thanks for any input guys

 

put new calipers on today still no change.
anything you guys? im stuck.
thanks,
hunter

 

Front or rear? I've heard of a parking brake problem that gives this effect. If its in the front end the steering wheel will move with the pulsations. If in the back, the whole truck will shake but the steering wheel will not 'pull' with each pulse. Most of the time changing out the rotors takes care of it, which is why you're not getting many responses on this. I would start pulling wheels and turning the rotors to see if you can detect run-out (side to side oscillation of the rotor). Watch the gap at the outboard pad and see if it closes and opens as you turn the rotor. This would indicate a bad rotor OR possibly something abnormal about the rotor mounting surface, like a high place in the steel, either on the back side of the rotor or on the hub. Look at every wheel stud to see if there's anything at the base of it that won't let the rotor hit the hub.
Are you using an impact wrench to tighten the lugs? You may be over-tightening them which has been known to distort rotors. You need to set them with a torque wrench in the proper sequence.
Just throwing stuff out there - I saw this when you first posted but still have no real answer. Its too bad you're having this problem because the 2007 has some terrific brakes when everything is right.
ETA: Thought of another possibility - check the front wheel bearings for excessive play.

 

Worn or loose outer tie rod ends may contribute to this as well under braking

 

Well guys I finally pin pointed the problem. Thanks for pointing me in the right doe toons guys. I believe it was the rear rotors one may have been cracked weren't perfectly round either. Replaced the pads and rotors and are riding smooth now. Thanks for the help guys. Happy holidays.