our 99 has a horrible thump up front, feels like is right under the floorboards. it does this when we take off or when we have been driving for a while. don't matter if the rig is cold or warm. i first suspected a caliper hanging up. i changed the driver side and it still thumps. maybe i should change the passenger side. i've been told my rotors could be out of whack but like i say this problem happens if the brakes are cold or warm. i will say that the noise will go away at normal driving speeds but seems to be more noticable at low speeds. i had a worn idler arm and i replaced it. didn't change anything. i visually checked u-joints, ball joints, everything i could see in the front suspspension. i have jacked all 4 tires off the ground and started the vehicle and put it in gear. didn't notice the problem while in the air. i've checked for wheel bearings as well. I recently drove in 4 wheel drive and i could hear a slight sqeak and a continuous thump and the rig wanted to pull all over the place. when i let my hands of the wheel it wants to pull to the right. it never has acted like this before in 4 wheel drive. one final note sometimes when we are going uphill and punch the throttle it really wants to pull to the right. maybe it is the caliper on the passenger side. i would like some suggestions before i buy another $100 caliper. thanks

 

Been noticing a lot of hung calipers on Expeditions recently at shop, but have also noticed that the bracket that suspends brake hose will collapse fluid flow and hang calipers. Take a pair of channel locks and try to relieve the hoses first. Have you checked the front sway bar links to make sure 1 isn't broken? sometimes they will break and you can't see them right away.

 

i don't think i've looked at sway bar links closely. i'll check them and the brake hose. thanks