Fix It

Torsion bars are long metal springs that are used in low-cost car suspension. As more load is placed on a torsion bar, the more the bar twists. The amount of the twist will differ depending on the material used in the bar. Torsion bar suspension is used because it is cheap and durable, but it can still go bad. Most often torsion bars are damaged through impacts on the undercarriage or through rust.

Instructions

1

Shine a flashlight into the wheel well of the car or truck. The torsion bar will be sticking out from the cars frame perpendicularly. Depending on the car, the other end of the torsion bar will be bolted to a control arm or the steering knuckle itself. Look for any cracks in the torsion bar. If there are any cracks in the bar, then it is only a matter of time before it cracks in half.

2

Feel along the torsion bar for rust. Rust patches will feel gritty like a scab. If rust is present, then the torsion bar must be replaced. Also feel the bolts that secure each end for rust. If the bolts are rusted, then it is guaranteed that the rust has spread to the torsion bar bolt holes. Make sure to repeat this process in each wheel well.

3

Turn the car of truck on and take it for a test drive. If one corner seems to sag excessively, then that torsion bar has gone bad. Any metal object can succumb to metal fatigue over time, especially if under constant, heavy loads. Pay special attention when driving over speed bumps. If you hear a bang, then the torsion bar has grown too soft and allowed some suspension parts to come into contact. Any worn out torsion bar must be replaced.

A catalytic converter is an exhaust emissions device that is part of a vehicles exhaust system. In charge of lowering the exhaust emissions that exit a vehicles tail pipe, a catalytic converter can negatively impact vehicle performance if it goes bad or stops working properly. What follows is a brief list of the most common signs of a bad catalytic converter.

Reduced Exhaust Flow

A major sign of a plugged up and/or bad catalytic converter is reduced exhaust flow measured at the vehicle tail pipe. Engine exhaust must travel through a catalytic converter before exiting the tail pipe; a bad catalytic converter can block and/or impede exhaust flow.

Reduced Engine Power

If a bad catalytic converter seriously impedes the flow of a vehicles engine exhaust flow, reduced engine horsepower can occur. This is due to the increase in engine exhaust back pressure that results whenever engine exhaust flow is impeded and/or reduced.

Reduced Exhaust Pipe Temperature

It is common for a bad and/or plugged catalytic converter to cause abnormally low exhaust pipe temperatures on the backside of a catalytic converter. As engine exhaust exits an engine and travels down the exhaust system and through the catalytic converter, the exiting exhaust flow can be restricted enough to cause significantly reduced exhaust pipe temperatures between the catalytic converter and the tail pipe.

Increased Hydrocarbon Emissions

Catalytic converters work by reducing the levels of hydrocarbon emissions exiting a vehicles tail pipe. A bad catalytic converter can lose its emissions-lowering capabilities and cause an increase in exhaust hydrocarbon emissions, a condition that is normally picked up when a vehicle is undergoing a routine smog inspection.

Reduced Fuel Economy

Any obstruction and/or abnormality in a vehicles exhaust system has the potential to reduce vehicle gas mileage by creating exhaust back pressure within a vehicles engine. A bad catalytic converter can cause a reduction in vehicle fuel economy if it restricts the flow of engine exhaust to the point of causing a marked increase in engine exhaust back pressure.

For most people, a "bad" brake rotor is one with a few scratches and grooves in the surface that cut into the pad, or one thats wavy and warped. But theres a lot more going on with your brake rotors than you might see on the surface -- and even thats bad enough as it is.

What is a "Bad" Rotor?

A lot of things can go wrong with a brake rotor. Most obvious are mechanical faults like grooves in the rotor caused by harder particulates in the pad material, cracks in the rotor and waviness or warping in the rotor surface. A front brake rotor must regularly absorb about 30 to 35 percent of all of the energy that goes into moving your car, which creates a lot of heat. Heat, among other things, causes the rotors metal to expand; when the metal cools and contracts, certain zones in the metal will cool faster than others. The uneven cooling pull those zones in different directions, causing the rotor surface to warp and become wavy. Extreme heating can also affect the metals crystalline structure, causing even bigger long-term problems.

Grooved Rotors

All brake rotors that arent brand-new exhibit a certain amount of grooving on the rotor surface. When the grooves are microscopically small, the peaks between the grooves will cut into the brake pad material. Simultaneously, the harder particles in the pad will resist this cutting and abrade the sides of those grooves. Eventually, the grooves will get large enough to be visible and cut large, matching grooves in the pad. So, its not a matter of if the grooved rotor will cut into your pad -- and vice versa -- but rather how far and how much the pads will deepen those grooves. If the rotors dont exhibit grooves deep or sharp enough to catch a fingernail, then you can replace the pads without machine-work or replacement. You can put new pads on a deeply-grooved rotor, but bear in mind that a) it will take some time for the pads to "bed in" and conform to the grooves in the rotor, b) while bedding in, the pads will rapidly accelerate groove widening and c) grooves create weak points in the rotor, increasing the odds that it will crack or shatter.

Warping

A warped rotor could easily eat your new pads alive, and may damage other, more expensive parts in the brake system. This is particularly true for some cars with antilock braking systems. An ABS system works by boosting or dropping brake pressure to each wheel. If the crests of the waves in your rotor are further apart than the pad is long, then the entire pad will drop in between the waves. When the crests come along, theyll shove backward on the pad, creating tiny fluid pressure fluctuations in the brake lines. These oscillations can damage the antilock brake pressure modulator, which costs far more to replace than itll cost you to have the rotors machined flat. So, if your rotors are warped, new rotors are advisable, particularly since new rotors arent usually much more expensive than machining. And, after machining, youll wind up with thinner rotors that are more prone to overheating and structural failure.

Material Changes

This little-known, but endemic, problem has both plagued and bewildered brake mechanics for a century or more. Long ago, mechanics noticed that, after the rotors for warpage or overheating, cars would often roll back into the shop when the rotors re-warped a few months later. And the re-warping problem has existed as alternately a puzzle or a myth -- depending upon who you asked -- since then. But, fairly recently, engineers have discovered that, following an episode of extreme overheating, the areas of the rotor that got the hottest would change in crystalline structure from the normal ferrite structure to the far harder cementite. Cementite, also known as iron carbide, is much like a ceramic and has far different properties in terms of hardness, abrasiveness and thermal conductivity. Think of chunks of oak floating in frozen ice cream, and youve got the right idea. Once these cementite spots form and penetrate the rotor surface to more than a few nanometers, the rotor is shot and will quickly self-destruct.