How to Replace a Car Axle
Your constant velocity axle, or CV axle, takes the power from your transmission or differential and transmits it to the wheels. Older rear-wheel drive cars had solid drive axles that integrated the differential and the axle, resulting in a simple drive system but less than ideal suspension setups. Modern vehicles mostly use independent suspensions, so the drive axles need to be able to flex when the wheels move up and down, independently from the differential or transmission.
This is where the constant velocity axle comes in. It contains a universal joint at the end of the axle that can move on three axis while it is spinning, allowing the wheels to move freely while still putting power down to the road from the transmission.
The downside of CV axles is that they are slightly more complicated than the old style, but the upside is that replacing an axle on one wheel is possible.
The Symptoms of a bad car axle
Your CV axle has an inboard joint on the transmission side of the axle, as well as an outboard universal joint on the wheel side of the axle. Both of these joints are protected by a rubber cover called a CV boot. Your CV boots look like a black rubber cone-shaped accordion and will have metal retaining clips or bands on either end to keep them place.
The CV boot is filled with grease to lubricate the moving CV joint and protect it from corrosion. If a CV boot cracks or splits, the grease can come out and foreign particles can make their way into the boot, resulting in damage to the CV joint. That’s when you’ll begin to hear the tell-tale signs of a bad car axle.
If the inboard joint is beginning to wear out, you will feel a vibration and hear noise during straight-line acceleration.
If the outer CV joint is wearing out, you’ll notice popping and clicking noises when you turn sharper corners.
Checking for a bad CV boot is as simple as doing a visual inspection of the boot. Take the tire off and use your fingers to check for cracks or leaking grease on the boot. If it feels soft and pliable, with no cracks or grease leaks, your symptoms are probably coming from a different issue. It is possible for a CV joint to fail with a good CV boot, but usually, the two go hand in hand.
If the unthinkable happens and one of the CV joints breaks, you will lose all power on that side of the vehicle and you could severely damage your transmission.
The Tools Needs to Replace a CV Axle
Most of the tools needed to tackle this job will be in the average home mechanic’s toolbox, but there are a few special tools that you’ll need to complete the task.
- Floor Jack and Jack Stands. You will need to elevate the car to take the wheel off and work on the CV axle. Always use jack stands for safety.
- Ratchet and Socket Set. If you want to do any work on your car, invest in a ratchet and socket set as well as sets of wrenches, screwdrivers, and pliers.
- Torque Wrench. All the suspension components you remove, as well as the CV axle, will require the nuts to be torqued to specifications in your repair manual. These are available through the AutoZone Loan-a-Tool program, but you might consider buying one if you intend to work on your car regularly.
- Needle Nose Pliers. One type of plier worth mentioning on its own is the needle nose, because you’ll need a set to remove cotter pins from a few of the nuts in this repair.
- Hammer. A hammer will be needed with the pickle fork and when separating the spindle from the wheel hub.
- Pickle Fork or Ball Joint Separator. A pickle fork is also known as a tie rod end separator and that’s exactly what it does. This tool is the safest and easiest way to remove tie rod ends without damaging the existing parts. A ball joint separator does the same for ball joints. Check AutoZone’s Loan-a-Tool program for these.
- Axle or Spindle Nut Socket. You’ll need this extra-large socket to take the nut off your axle on the outside of the wheel hub. These are available through AutoZone’s Loan-a-Tool program, if you would prefer not to purchase one outright.
- Breaker Bar. This is a long-handled bar with a socket fitting on the end for your spindle nut. You’ll need it to break the nut free, since it’ll be solidly torqued to the spindle.
- Repair Manual. A good repair manual for your vehicle can save you a lot of time and frustration.
Steps to Replace the CV Axle
This is a job most home mechanics could do in an afternoon, so read on for the basics of how to replace a CV axle.
Block the wheels to prepare for jacking up the vehicle.
Use your floor jack to elevate the vehicle and immediately secure the vehicle with jack stands.
Remove the lug nuts and take off the wheel.
Identify the spindle at the center of the wheel hub, remove the cotter pin with pliers and take off the nut retainer, before removing the axle nut. You can insert a screwdriver through the caliper into the brake rotor to keep it from rotating while you loosen the axle nut. Use the breaker bar and axle nut socket to remove the axle nut.
Check to see that there is no pressure on the suspension from the struts or springs before taking off any of the tie rod ends or ball joints. If there is downward pressure from springs, you could seriously injure yourself when releasing suspension components.
Detach the tie rod end and ball joints from the wheel carrier.
Thread the axle nut back onto the axle so that it is flush with the end of the axle, so that you can use your hammer to release the axle from the center of the wheel hub.
Remove the nuts or bolts from the transmission side of the CV axle and then pull the CV axle out carefully.
Replace the axle using the reverse steps and be sure to torque all nuts and bolts to manufacturer specifications.
Only remove one CV axle at a time, to avoid moving gears around inside the transmission and causing damage to the internals.
When it’s time to replace your CV axle, come to AutoZone for all your parts and tools, as well as expert advice on many common car care jobs. If you determine the job is too big to tackle, check out our list of Preferred Shops in your area to help you complete the job.