Control arm relationship to alignment

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Hi, so I take my car to the Nissan dealer that sold it to me for all repairs and I get things repaired ASAP. Last week I was here getting four tires repaired and an alignment. After I left the shop I started to notice that my steering wheel would jerk in my hand while driving on the highway. I took it back to the dealer today (still here) to get them to fix what ever is happening. They said it is the right front control arm and that it has nothing to do with what they worked on last week. I do not know about cars but it seems like they are related.

Is it possible that last week's work brought out this issue? And how did they not notice this last week if it is such a large repair like they say?


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Friday, March 10th, 2017 AT 1:23 PM

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This is the classic example of why mechanics have such bad reputations. Car owners who admittedly know nothing about cars, and are not expected to, hold mechanics to much higher standards than they do doctors.

First you must understand that all tires have a rolling resistance that is trying to prevent the vehicle from moving forward. Next, all tires want to pull in the direction they are leaning in or out on top. Most manufacturers call for their front tires to lean out a little on top. On the alignment printout, that angle is "camber" and is the first one checked of the main three angles. Finally, a very obscure angle related to the designed-in suspension geometry, called "scrub radius", has been modified to eliminate the brake pull to one side that would result if half of the brake system failed. That angle is modified to prevent your loss of control if a sudden, unexpected leak were to occur. That is the technical part of the story.

The next part has to do with finding worn parts on your car. You seem to be under the impression we just stand underneath it and we identify those parts by staring at them. That would equate to your expecting your doctor finding you have cancer because you went in for a sprained ankle. There are dozens of things on any car that can prevent a wheel from being held in perfect alignment. Of those, only a few commonly cause problems, and even fewer cause handling symptoms. As a suspension and alignment specialist myself, we always inspect the parts that commonly wear out, before we start any alignment. To overlook a worn part can result in unsatisfactory handling and/or tire wear, and the need to do the job over for free.

How many times have you had to go back to your doctor multiple times before the cause of your symptoms were finally diagnosed? Did you call him incompetent because he did not perform the one decisive test the first time? Were you angry with him because he did not spend your money on every conceivable test for every possible illness, on your first visit? Why is your mechanic any different?

Before we spend your money on an alignment, we inspect the most common parts that can prevent us from performing a quality alignment. If a part is worn and will not allow us to align the car properly, it would be unconscionable to take your money for that job. The part(s) must be replaced first, then some customers accuse us of selling you parts that are not needed. Some people insist on us doing the alignment without replacing the worn parts. Fortunately the new-car dealer I worked for would always back me up if I refused to do the job, and sent you to a competitor down the road. We put ethics ahead of profits.

The next part of the story centers around the fact you have been taking your car to the same shop over and over, regardless if that is the dealer or an independent shop. They develop a history, just like your doctor does with you, and they know there is no need to inspect every part of your car on each visit. At your annual check-up, your doctor checks your blood pressure, and pokes around a little. He waits for you to have symptoms of something more serious before he lets you spend money for further testing. It is the same with your car. We have to charge you by the hour for inspecting things and looking for worn parts, and we are not going to waste your money on things that do not appear to be needed. With the way the insane engineers have added an unnecessary, complicated, unreliable computer to every possible system in today's cars, we have way more work than we an handle. We do not need to go looking for more. Instead, we wait for you to have symptoms that need a diagnosis. That is what you are observing today. Your doctor will have you spend money on preventative services and tests. When we do that, we're accused of selling unneeded parts and services, and you are angry.

This goes back to the rolling resistance of tires. In most cases a pair of tires will have equal rolling resistance. If it were unequal, the car would pull to one side when you let go of the steering wheel. The issue here though, is the personality of your new tires is different than that of the old ones. Handling, braking, and steering response will be different, even though you may not notice it. The front-end was also aligned. Previous to that, it is entirely possible a wheel was tipped or turned too far, and that resulted in a pull that put enough stress on a worn part to prevent it from causing symptoms. Now that the alignment is right, that wheel is free react more to the bumps in the road than to the alignment pull. You are dealing with two variables that were changed, tires and alignment, and either one can cause or hide the symptoms of a worn part. There are even some brands of tires that call for some alignment angles to be modified from what the car manufacturer specified, because they know that is what is needed to eliminate a common symptom.

The point of this story is your mechanic didn't see a need to spend your money on inspecting parts that were not causing a problem. You were not observing any symptoms, or at least you did not tell him about anything unusual. You are expected to come back when those new symptoms show up. That is when a more in-depth diagnosis is called for. Unlike with your doctor, the way any reputable shop would handle this is you are expected to pay for the additional parts and labor, (just like would have been included in the original charges), but the alignment would be done a second time at no charge. Try getting that service a second time for free from your doctor. The shop owner knows the mechanic did not do anything wrong, so he is going to be paid for his time to do the second alignment. You are not going to be charged for it. That is part of the cost of doing business.

What you have described happens every day at every repair shop. No mechanic, being a customer at a different shop, would raise a question as to the ethics or the competency of another mechanic, because they know how things like this are handled. You get a lot more for free from a car repair shop than you do from a doctor.

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Friday, March 10th, 2017 AT 3:31 PM

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