Unfortunately you fell for the same trick Ford has been pulling on unsuspecting buyers since the mid '80s with the Escort / Tempo "killer cars". On those the front tires were tipped out REAL much on top and the rears were tipped in like on your car. The front ones lasted about 15,000 miles and there was nothing we could do about it. There was no way to adjust that alignment angle called "camber". The aftermarket parts industry came up with a wedge and smaller diameter bolt that could be installed on the rear suspension to try to straighten up those tires, and that worked real well, but you couldn't get those parts from Ford. The thinking was, I believe, with this terrible alignment, the car road very smoothly on the edges of the tires compared to similar-size cars from Chrysler and GM, so people bought a lot of them. Later they found out the salesmen didn't bother to tell them about the horrendous tire wear.
A typical camber setting for most cars is around 0.25 to 0.75 degrees. (0.00 degrees is perfectly straight up and down, and at 90.0 degrees, the wheel would be laying on its side). At 1.00 degree we would start to get nervous about tire wear. The Escort called around 2.50 degrees on the left and slightly less on the right. That was enough to easily see when standing beside the car, and it goes against all of the alignment specialists' training and experience.
The Ford engineers also found out they could leave four key grease fittings off. At a nickel each, 20 cents per car translated into a huge savings in their cost to manufacturer them, but the failure rate of the Escort outer tie rod end was so bad, we couldn't keep them in stock at the mass merchandiser I worked for. Every Wednesday we got in a half dozen tie rod ends for GM cars, a half dozen for Chryslers and imports, and 40 for the Escort / Tempo. By Saturday we were sold out of the Escort parts and had to order them from local parts stores.
From a marketing standpoint, the Ford engineers are geniuses because they produce cars that ride very nicely AND they sell a real lot of replacement parts, but from the consumers' standpoint, the value was questionable because the cost of ownership was so high. That business mentality still exists and is what helps to keep them profitable. In the case of your car, as with the early Escorts, the aftermarket industry has come to the rescue with "problem-solver" kits.
First of all, you should be aware it is very unlikely you have a defective or worn control arm. They're actually pretty beefy compared to what's used on larger cars. If one were to bend, that wheel would typically tip out on top, not in like they all do. That would also just affect one wheel, not both. The reason for replacing them is because the aftermarket industry incorporated a camber adjustment into some of their designs that the Ford engineers didn't bother to do. There are also upper strut mounting plates built with an offset for the front. With the Escorts the front tires tipped out so much on top that everyone could see that when they followed those cars on the highway, but there was no adjustment possible. Your car uses the same design but some improvement in tire wear is possible with those offset plates.
Understand too that providing your own parts is like bringing your own food to a restaurant and asking them to cook it for you. If you don't like the quality of the meal, you have no recourse. Independent shops usually buy their parts from the local auto parts stores, just like you can, but then they mark them up, just like any other store. That profit helps pay for the person who went to get them, the person who made the phone call to order them, and most importantly, all the costs associated with replacing them again if one is defective. In this case the car will have to be aligned when any steering or suspension parts are replaced. We get defective parts probably one out of one or two dozen times. That means reordering another one, arguing on your behalf why the first one was no good, installing it on your car for the second time, and realigning it again, all at no additional cost to you. When you provide the parts, you will only get a warranty on the labor in case the mechanic does something incorrectly. If, for example, the rubber bushing becomes sloppy in one end of the control arm, and the arm has to be replaced, nothing was the mechanic's fault so you can be expected to be charged for the parts and labor a second time. There went your savings.
Incorrect parts are often ordered too, AND, it is not uncommon to order a part for the left side and get one for the right side. That means shipping the first one back and paying for shipping the correct part a second time. That happens to us real often because to the person picking the parts off the shelf, lefts and rights look the same.
Rock Auto is a very well-respected internet parts supplier. If you still want to order your own parts, consider installing them yourself, then have your mechanic perform the alignment. Be aware any part with a rubber bushing must be tightened while the car is sitting at normal ride height on the ground, not with the suspension hanging down. If you tighten the bushings while the car is jacked up, that's where they'll be clamped, and they'll be in a permanent twist when the car is on the ground. That will lead to very early bushing failure and the incorrect assumption the part was defective.
If you look at the Rock Auto web site, they will show the problem-solver parts you can pick from and they often list how much camber correction can be obtained. When you can see a tire leaning, you typically need 2.00 or more degrees, but it is not necessary to have the wheel perfectly straight up and down. Some negative camber, (leaning in on top) on the rear is normal and acceptable. This is where your alignment specialist's experience is valuable. He will know what he wants each wheel to be set at for best possible tire wear.
Saturday, October 5th, 2013 AT 12:43 PM