Well we already talked about potholes, so we might as well talk about suspension

We've all been there, a strange noise, a knock that you can't quite pin down so you take the car to the shop, spend three or four hundred dollars on engine work, you get the car back and that knock is still there. Obviously since the first shop didn't figure it out you take the car to a different shop and they fix the knocking not by replacing engine parts, but adding a couple of 20 dollar bushings to the sway bar instead. Needless to say you feel taken advantage of by the first shop, and you can't be blamed for feeling that way. But you have also learned an expensive lesson, suspension is important to your vehicle.

As you have seen me write before, vehicles, be it a Dodge Neon to a Cadillac Crossfire to a Lamborghini Murcielago, are engineered from the tires up. Each one has its own performance and manufacturing specifications and costs that are taken into consideration, but each one is a marvel in its own way. So lets get on our backs, crawl under the car and take a look at the suspension system.

Suspension systems consist of the following main components in some combination, shock absorbers, struts, springs, and torsion bars. The primary job of a suspension system is to help the wheels maintain maximum contact with the road to help the driver maintain control. So why do most cars have struts in front and shock absorbers in the rear? A strut allows for greater freedom for steering because of how it is connected to the vehicle by use of a ball-joint and a control arm. A shock absorber (or coil-over-shox) does not provide the same freedom in steering, but does provide greater directional stability. Keep in mind that struts and shock absorbers are not interchangable as terms or as components.

If you crawl under the rear bumper of the car and look up you'll see what is called a torsion bar (aka sway bar), the purpose of the bar is to help minimize “body roll”. Body roll is basic phsyics, as you drive your car, its weight gains momentum in a certain direction, the car wants to continue going in that direction when you make a turn, that is why it feels you are getting thrown in the opposite direction you are turning. What the sway bar does is help equalize traction, helping change momentum of the vehicle to the direction of the turn and minimizing that feeling.

But how do you pay attention to suspension?

Tires are like an X-ray for your car. They can help diagnose problems with suspension and steering. Uneven surface wear across the face of the tire can indicate weak ride control components. One sign is tire cupping as a result of improper tire balancing or improper damping force in the shock absorber. Also, tires may have inside or outside excessive edge wear from improper wheel alignment. This should prompt you to suspect things like worn tie rod ends, collapsed control arm bushings or maybe a bent strut or spindle. A bounce test can be used to visually demonstrate the lack of resistance in badly worn dampers. Push down on one corner of the vehicle and rock the suspension several times, then release it. Repeat the test at each corner of the vehicle. Good dampers should stop the motion within a bounce or two.

After seven to 10 years of service, many of these older systems start to develop leaks that allow air to escape from the system. The same thing can happen to plastic air lines. Wiring connectors, solenoids, compressors and height sensors are also vulnerable to corrosion and vibration, which, over time, may lead to failures that disrupt the normal operation of the air ride system. This isn't due to poor engineering, its just due to the natural stresses the system experiences even if you aren't driving the car hard.

If you need to have the suspension repaired and it is going to involve the replacement of any part that has bearing plates, unless the plates are in perfect shape, have them replaced. As the name implies, these plates bear the weight of the vehicle on the suspension system, so if they fail, you're going to have a low-rider, but not the way you want to make your car one.

So now that we have idea what the pieces of the suspension system are, it should be apparent that the main purpose is not for ride enjoyment, it is for ride safety. Now you're not among the 70 percent of people that think the primary role of suspension is for ride enjoyment.