What is a Drive Axle?
A drive axle is an axle in a vehicle which is powered by an engine. People most commonly think of cars when they think about drive axles, with some cars having the front axle driven by the engine, while others have their rear axles driven by the engine. In all wheel drive cars, the engine supplies power to both axles and all four wheels. This axle is a critical part of the systems which allow a vehicle to move down the road.
The drive axle is also a fairly complex piece of equipment. First, energy must be transferred vertically from the engine, and the drive axle must respond to input from the steering wheel as well. The car is also geared to use energy as efficiently as possible. As a result, several interconnecting systems interface with the drive axle to power it, control its movement, and increase efficiency.
While people may think of an axle as a solid object, the drive axle is actually split. This is because both of the driving wheels do not necessarily turn at the same speed at all times, making it necessary to add some equipment which will allow for movement at different speeds. Whenever someone turns a corner with a car, for example, the inside wheel slows down, because it has less ground to cover, while the outside wheel speeds up, allowing the car to corner smoothly.
It is a good idea to regularly inspect the drive axle and its components, such as the constant velocity (CV) joints. Mechanics often give the axle a quick look during oil changes and routine maintenance to identify any obvious problems, and they will alert drivers to any issues identified during maintenance appointments. A mechanic can also provide advice about how serious a problem is, ranging from a recommendation to address it immediately to a recommendation to keep an eye on it.
Drive axles are used in a wide range of other vehicles, with the power of the engine turning the axle to generate movement. People who are interested in the engineering behind such systems can find kits which allow people to play with various motorized components and axles to see how changes to a system impact the way in which it moves. Such kits can also be an excellent way to introduce young people to engineering topics, and to get younger people interested in the sciences.
I once had a car axle break on me while I was driving. I used to drive an old Audi 80 FWD when I was in High school. I was driving down a mountain notch near a ski resort, coming back from a day of mountain biking. I came around a sharp corner, and my front passenger drive axle broke, turning the tire sideways. By the time the vehicle came to a stop, I had damaged a brand new tire, twisted the tie rod, and snapped the spindle off the lower control arm.
The repairs ended up costing me quite a bit of money, and about a week without a car. I would have paid $2000 for repairs from my local dealer, but I was able to replace all of the parts, as well as install a new CV on the driver’s side for about half that. Lesson learned…pay attention to the funny noises my car makes.
@ Amphibious54- Wheel and axle problems are the most common problems with vehicles, especially when you live in places where you have extreme weather conditions or dirt roads. You can perform some physical checks to determine if you have a bad constant velocity (CV) joint.
The first check is to inspect the tire for cupping, or uneven wear. This can be a sign that there is too much play in the CV joint.
The second check you can perform requires looking underneath your vehicle. If you notice that the rubber boots around your CV joints are torn or missing, you will likely need to replace the entire half-shaft. If the tear is small, check the grease. If the grease is gritty, this means that there is debris inside of the joint, which will probably require the joint be replaced rather than the boot replaced.
Finally, jack up the wheel in question and give it a good wiggle. If you notice that there is excessive play in the wheel, it could very well mean that your CV joints are bad, although this can be a sign of other problems too.
@amphibious54- You can check your drive shaft in a few different ways. Noise is the most obvious way to tell if you have a CV joint that needs replacing. If you hear a clicking when you are cornering, especially in reverse, you have a bad outer CV joint. If you are hearing a noise that is more like a grinding or humming, it is likely the wheel bearings (although it can be the brakes or another component). Shudders and vibrations on acceleration can also be indicators of bad CV joints, although these symptoms are more likely with the inner plunge joints rather than the outer joints.
As for the cost of fixing the CV joints, it really depends on the model car, and the labor rates in your area. Replacing CV joints is a relatively easy job, so expect to pay a much higher premium at a dealership. Honestly, I would have the repair done at a trustworthy local mechanic. Typically, you can expect to spend anywhere from $75-250 for the parts, and around two to three hours of labor costs per axle. Good luck!
How can I tell if my CV shafts need to be replaced? What happens when a CV shaft breaks? Are they expensive to repair should they break? I have been hearing a funny noise coming from the front end of my vehicle for the past month now, and a friend said it might be a CV joint problem. Are there any mechanics or gear heads on here that can help me out? My spouse told me that she gets great responses from the wisegeek community.
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