This is something we can't answer directly for a number of reasons. You're right, the ball joints should have been caught during the inspection, but we can't be in too big a hurry to blame the mechanic.
The first problem is we don't know what you mean by "the wheel fell off". Do you mean the wheel broke around the center of the hub and went sailing off into the ditch? A broken ball joint will let the tire move rearward and hit the back of the fender / wheel opening, and either the bottom will squirt out or the top will fall over and lean way out on top. Improperly tightening the lug nuts can lead to the studs snapping off, and the wheel / tire, again, running off into the ditch.
The next problem is historically, Ford has had way more trouble with steering and suspension parts separating, leading to loss of control and crashes, than all other manufacturers combined. That goes back to the mid '70s when a bean counter figured out they could leave off four grease fittings, at a cost of a nickel a piece, and save four million nickels for every million cars they built. Some Ford models in the '80s even had the nickname, "killer cars" for the extremely high failure rate of their ball joints and tie rod ends. Outer tie rod ends on the Ford-built Escorts rarely lasted more than 15,000 miles. Those would send you into the ditch or into oncoming traffic.
The next problem has to do with how Ford's ball joints act when they have developed excessive wear. Normally we raise and solidly support a vehicle in such a way that it removes compression and tension forces on the suspension parts so it allows any wear to be able to be observed when we pry on them. Slop between a ball and its socket is pretty easy to spot, except on most Ford parts. Since they don't have grease fittings and are not filled with grease, they fill up with road dirt and rust. That eliminates most of the slop we're used to seeing, and even when we're aware of that, and work extra hard to find those worn parts, they are still real easy to miss.
To add to the frustration, we are constantly aware of our reputation for trying to sell you parts and services you don't need. Truth is, we have so much work now with all the highly-unreliable technology, we don't need to manufacture more work, but a few bad apples still gives us that reputation. If we go by past experience and tell you new ball joints are needed, then you get a second opinion that says there is no wear evident in them and replacement is not necessary, who is right and who is wrong? If you believe the person who said the ball joints are okay, then one separates a week later, who is to blame? Is it you for not listening to the person who you think was trying to sell you unneeded parts, or the second mechanic who failed to find the worn parts?
Related to that, there was a well-publicized story about an early '80s Thunderbird that was inspected, then had four new tires installed for an upcoming cross-country trip. Everything was found to be fine by two very experienced suspension specialists. Well, a lower ball joint broke 700 miles later while driving through the mountains in Tennessee. Not one single part could be identified as worn or defective, so what should the mechanics have done differently?
For future reference, be aware any time you hear a clunk or rattle, a part is worn or loose, and while a lot of those causes are not safety-related, you don't want to risk your life by not knowing what is wrong. When you hear those noises on other car brands, have the vehicle inspected as soon as possible. When it's a Ford product, and more-so with their front-wheel-drive cars, I'd be nervous about driving it a few miles to the shop. Normally we get plenty of warning, often weeks or months, to have a worn part replaced. But with Ford owners, we commonly hear them tell us they never heard any warning clunks or other noises leading up to the loss of control.
The first thing you need to do is describe the exact type of failure. If possible, multiple photos will help. About half of the time we can figure out the cause of the failure, what led up to it, and sometimes potential clues or observations that could have helped make you aware of that impending doom.
The next thing you must be aware of is tie rod ends never cause shaking in the steering wheel. Vibrations and shaking, whether felt in the steering wheel, seat, or brake pedal, have to be caused by something that is rotating. That means tires, wheels, brake rotors, and drive shafts. As proof of that, those vibrations only occur when the car is moving. Worn tie rod ends, ball joints, control arm bushings, and to a lesser extent, struts, can allow that shaking to be worse or more noticeable, but they do not cause it. Those parts are only responsible for holding other parts in place.
Finally, if a ball joint did indeed separate, it needed to be replaced during the original service you took the car in for, so you can be expected to have to pay for it now. No one's actions or inactions caused that wear leading up to the failure. Reputable shop owners are going to want to help you, but as I pointed out, it can be difficult to place blame for overlooking the worn part. In this regard, mechanics are held to much higher standards than are doctors. If a doctor misses a diagnosis, you run to the next one, and the next one, and each one sends you a bill. If a mechanic misses something, the first thing we think of is "lawsuit" or "incompetence". People in no other profession are held to higher standards than are mechanics. In spite of that, at most shops, they will offer some combination of reduced labor charge to replace the broken part, reduced cost of the part, cover part of additional repairs needed due to the part failure, or some other concession or good will gesture. If the work is done by the same shop that did the alignment, almost all of them will do the next alignment at no charge.
If there was some other type of failure involving the wheel, let me know what that is, and I'll address those issues.
Friday, December 20th, 2019 AT 5:01 PM