CV Axle
Many cars, especially those designed for rough terrain and four-wheel driving, use a CV axle for one or both of the axles in the car. This kind of an axle helps minimize friction and allows the drive shaft to keep a constant speed, even when bent or moved to odd angles. These sorts of axles are also known as Constant-velocity joints or Homokinetic joints. Some cars will have only two of these while others will have as many as ten CV axles on half axles and driveshafts. Having many CV axles allows for a smoother ride as well as more efficient motion. Since less friction is created when using a CV axle, less energy is required overall to keep the car in motion. The CV axle does not create huge increases in fuel efficiency, but when coupled with other fuel-efficient designs they can help to create a car that is overall more fuel-efficient.
The main place where CV axles can be used is in the drive axle. A CV drive axle is common in front-wheel drive cars. It is also known as a CV axle shaft. The front drive axle connects the transmission of the car to both of its front wheels. Because front-wheel drive can expose the car to various dips and bumps in terrain and because the car needs to maintain constant low level of friction in its front wheels to stay in motion the CV joint is ideal for the front axles. The CV joint allows the front axles to experience large bumps and rocky terrain without suddenly adding a lot of friction to the motion of the axle which would cause the car to slow down quickly. Sudden high levels of friction that slow the axle of a car can be damaging both to the car and to its passengers, depending on the severity of the sudden stop that is incurred with high levels of friction. Also, if the joint is not a CV joint and it is suddenly subjected to large amount of friction this will add extra weight or pressure to the axle and could cause it to become damaged or broken. This can be very dangerous as a damaged axle is not always obvious right away, and a broken axle can cause deadly accidents.
Some possible CV axle problems can be that the CV joint itself can become damaged or broken. Most commonly, a damaged CV joint can be recognized if there is a clicking noise that can be heard when making turns. This method is only useful for recognizing problems in the front axle of the car. If CV joints are used in the back axle or elsewhere, they would need to be tested separately. The CV axle is protected by a CV boot which generally keeps the axle from any harm. The main purpose of the boot is to prevent debris from getting into the joint and wearing it down prematurely. There are many more moving parts in a CV joint than in other simple joints. The way it works is that it has several rolling balls that move at different rates depending on the pressure being exerted on the joint. The pressure exerted can be be stronger or softer and can come from any direction on a CV joint. Because it uses small rolling balls to evenly distribute the pressure, CV joints are the best joint available today for a smooth and dependable ride. If any debris enters the CV boot and begins to wear down, block, or otherwise affect the motion of the small balls this will destroy or damage the boot and it will need to be repaired or replaced.
If a CV axle boot is damaged, the rest of the CV joint is likely to be soon damaged or broken. It is important to notice if a CV joint is malfunctioning as a broken or malfunctioning axle can cause a deadly car accident. CV boots, though durable, can sometimes become cracked or chipped, allowing debris to enter the joint. This in turn creates abnormal wear and tear to the joint which can prematurely make it unusable. When the CV boot is in good condition, however, CV joints are quite durable and function for very long periods of time with little or no maintenance. CV joints on front axles will need to be checked or maintained more often than those in rear axles, and if the car in question is used for very rough terrain on a regular basis it would be wise to check the CV joints often.
Once damaged, CV axle replacement cost can vary wildly. Depending on the type of car and the location of the CV joint, it can be more or less expensive. Much of this cost is based on the cost of labor, however. CV boot replacement alone is generally about $200 to $400, depending on the make and model of the car. However, many mechanics will insist on replacing the entire axle. This is because once the boot is damaged the joint may be damaged as well and most mechanics will not want to be held responsible for any damage to the joint. While this is much more expensive, many companies will offer warranties for replacing a CV axle, allowing them to be replaced with minimum out-of-pocket money.