Ford products get inspected much more closely than other brands because they have a big problem with steering and suspension parts separating leading to loss of control and crashes. In this case, the alignment mechanic overlooked something, and it could be serious. Some things that cause intermittent pulls are relatively difficult to see unless we know specifically to check them. In particular, control arm bushings have been causing more problems than in the past on all brands of cars and trucks.
The mechanic should have noticed the problem on the test drive after the alignment was completed.
Another thing I've run into is projectors shifting on the wheels after they were set up and calibrated. That can result in a poor alignment. In the '70s and '80s, Ford trucks and vans had terrible front tire wear and there was little that could be done to correct it, but now that is not such a problem. For that reason, a bad alignment will show up as unacceptable tire wear within a few thousand miles. You can also observe if the steering wheel shifts position when the truck changes the direction it's pulling. Normally one shifted projector will result in an off-center steering wheel, and that is totally unacceptable. If both shift, or they weren't calibrated properly, "total toe" can be off. That has to do with the way the two front wheels are steering and is the last thing that is adjusted during the alignment. If both wheels are steering away from the center of the truck, it will follow the tire with the most weight on it, and that changes as you hit bumps and go across intersections. That makes for a very miserable vehicle to drive.
Regardless of the cause, the first place to go is to the mechanic who did the alignment. If repairs were done first by a different mechanic, the alignment specialist may have not bothered to perform a thorough inspection. The people who did work for you deserve the chance to inspect their work and correct any mistakes they made.
Monday, March 2nd, 2015 AT 6:09 PM