There are all kinds of different designs, and Ford has a real bad history of poor designs with a very short life expectancy. The 1980's Escorts and Tempos, for example, were referred to as "killer" cars for their outer tie rod ends that would separate, often in as little as 15,000 miles, leading to loss of control and crashes. At the mass merchandiser where I used to work, we got in forty of them every Wednesday. That was all the corporate office would allow. By Saturday they were all sold, and we had to order more from local auto parts stores. In contrast, each week were restocked a dozen tie rod ends for GM cars, a few for Chrysler products, one or two for imports, and dozens more for all the other Ford products.
The Taurus was the first domestic car to use their "rubber-bonded-socket" ball joints and outer tie rod ends. They dropped the ball into the socket, then poured in molten rubber, and expected the part to last with all the twisting motions it goes through. The aftermarket industry had to come to the rescue and produce improved replacements with grease fittings. All the Ford front-wheel-drive cars had no provision for correcting an alignment pull. The "fix" in the field, was if the car always pulled to the right, you broke the tapered connections of the outer tie rod ends' studs, turned the steering wheel to the left, then re-tightened the studs in that orientation. When you put the steering wheel straight, those tie rod ends were in a permanent twist that tried to make the steering turn left. That was equivalent to using a rubber bungee strap between the body and steering linkage. Of course with the constant tension on the tie rod ends, that rubber "glue" let go in short order, but at least it solved the customer's complaint of pulling for a little while.
This sad story could go on for hours, but the bottom line is your mechanic is correct in not aligning your car with worn parts, if he has your best interest at heart. Ford is also famous for leaving off one of the three main alignment adjustments on many of their cars, as I just mentioned. That is "camber". If you look at your wheel from in front of the car, camber is how much it leans in or out on top. Most cars are set with the top leaning out just a little, (positive camber), and specs for that is given down to the hundredth of a degree. Older mechanical equipment could measure accurately only to the tenth of a degree, and that was good enough for older rear-wheel-drive cars. Lightweight, and other front-wheel-drive cars need to have camber set to within a few hundredths of a degree to each other to prevent pulling to one side when you let go of the steering wheel on a straight road. Only an alignment computer is accurate enough to measure such tiny adjustments.
Once camber is set, it is up to the ball joints and control arm bushings to hold the wheel there. A worn and sloppy ball joint can allow camber to change as much as a full degree or more long before it is worn enough to fall apart. What good is it for the manufacturer to specify a camber setting that will provide the best tire wear, with a tolerance of up to 0.10 degrees, when a worn ball joint can allow ten times as much movement? If the parts won't hold the wheel in position, the mechanic knows he is wasting your money if he tries to align the car, and even if you have a lifetime agreement, he is wasting his time that could be used to get another customer's problem taken care of. There is no point in tying your shoe laces if they are not in the shoes. There is no value in doing an alignment if there is no hope the wheels will stay there.
For reference, 0.00 degrees camber means the wheel is standing perfectly straight up and down. 90.00 degrees would mean the wheel is laying flat on its side, on the ground. Most cars call for a setting of as much as 0.50 degrees. The engineers pulled a fast one on Escort owners. Their camber was factory-set at over 2.50 degrees, and there was no way to correct it. You could easily see the tires tipped way out on top, and of course, they wore out in less than 15,000 miles. The purpose of that horrible design was to make the little cars ride much smoother than similar cars from other manufacturers, so they sold a pile of them. No one knew they would have to keep on buying tires. The rear tires were tipped in almost as much, but those could be corrected with aftermarket wedge kits.
As far as which design your car uses, we just have to look when it is a model we do not work on very often or do not have memorized. You can also look on a web site for an auto parts store. I use the Rock Auto site every day for reference. You have the most common design, and you will see there is a lip on the bottom. That means you have to press it out in the direction of pushing on the stud. Friction holds it in. Only a very few models, mostly imports, use an additional wire ring or a snap ring around the body to hold it in. That is just a little extra insurance to keep it from working loose. If yours slides in with little effort, you need to add a couple of wire-feed welder spots to hold it tight. We do that in places where it's easy to grind them off next time. The intent is to prevent the housing from moving around and grinding the hole in the control arm bigger. That would also let the joint wobble around and change camber.
When you tighten the "castle" nut on the stud, always use a click-type torque wrench to set the tightness, then tighten it just enough more so the cotter pin will go through. Never loosen the nut to get the cotter pin hole lined up. Use that torque wrench on the lug nuts too. Those studs and nuts are easily damaged when they are over-tightened, but that damage does not show up until the next time they are removed.
Monday, February 20th, 2017 AT 4:50 PM