I always use used parts on my vehicles but I would never do that with steering and suspension parts on a Ford product. The half shaft is not a problem or a high-failure item, but Ford has WAY more trouble with steering and suspension parts separating leading to loss of control and crashes than all other manufactures combined. Those systems should be inspected at a tire and alignment shop at least once a year and whenever you hear a clunk, squeak, or rattle. You may have a lower ball joint now that has more miles than the one you removed. If there is any play between the ball and socket it will allow the alignment to change between braking, coasting, and cruising. Worn control arm bushings can cause what you're describing too.
You also have to look at the tires if they aren't the same. The rolling resistance can be different even with the same brand and model if they were built at different times or at different plants. If shifting wheel alignment has been ruled out you can identify a tire pull on a front-wheel-drive car pretty easily on a test drive. The car will pull one way under acceleration and the other way during braking. If you switch the tires side-to-side it will usually pull the other way but sometimes the car will go straight under all conditions.
Another clue to watch for is steering wheel position. If it's a tire pull the steering wheel will turn when you accelerate and you WILL have to pull it back to center to keep the car going straight. With a loose part allowing the alignment to change, a wheel is going to turn, the car will follow it, and you will have to turn the steering wheel the other way to counteract that pull.
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Friday, April 5th, 2013 AT 10:49 PM