Drive Axles Repair
Regular axle inspection is paramount to avoiding more costly repairs down the road. Having one of All Auto’s professional mechanics inspect your drive axles regularly will help you avoid the headache of repairing more than just the axle.
There are many parts to the drive axle assembly. If any of these parts fail, you can incur costly replacement service. Below is a list of the parts of the axle assembly. If you think you may have an issue, have All Auto inspect your vehicle immediately.
What Is a Drive Axle?
The drive axle is specifically an axle that is driven by the engine. Split with differential and universal joints into two half axles, the drive axle connects to each wheel by way of a constant velocity joint, or CV-joint, to give the wheel assembly free movement when making turns and the up and down motion of the suspension.
• Differential half shafts – Rear Wheel Drive Vehicles
Half shafts, otherwise known as axle shafts, are fitted in rear-wheel-drive cars only. They give relatively little trouble during normal motoring, although they are highly stressed components.
When a half shaft fails, the rear wheels cannot be driven.
The main symptoms of a worn half shaft are a knock or clunk when accelerating or decelerating. The cause is wear and excessive play between the shaft and differential splines. If you feel like you may have a worn half shaft, have our experts at All Auto diagnose the issue. It requires special tools to check wear on these parts. If there is oil leakage, it may be caused by oil-seal failure. In this case the half shaft must be removed and the seal replaced.
• CV Joints – Front Wheel Drive/All-Wheel Drive Vehicles
All front-wheel drive cars have Constant Velocity joints or CV joints on both ends of the drive shafts (axle shafts).
The inner CV joints connect the drive shafts to the transmission, while the outer joint connects the drive shafts to the wheels. CV joints can also be found of many rear wheel drive and all wheel drive vehicles as well.
What does it do?
The CV joints are needed to transfer the torque from the transmission to the drive wheels at a constant speed, while accommodating the up-and-down motion of the suspension. In front-wheel drive cars, CV joints deliver the torque to the front wheels during turns.
Where is it located?
The CV joints are located under the vehicle, connecting the wheel to the transmission. Although every car is a little different, this is one part that is pretty much the same in every vehicle.
CV-joint problems
Unless there is damage to the boot, the CV-joint typically does not need to be replaced. Many times you can see an intact CV-Joint on a car with 200,000 miles and still have the original part. Most damage to CV-Joints occurs when a vehicle is subject to rough roads, impact with debris, or off-road driving. When the boot gets cracked or damaged, the grease inside will ooze out which will cause the CV-joint to wear down faster and eventually fail due to lack of lubrication and corrosion. Usually outer CV-joint boots break first, as they have to endure more movement than the inner ones.
Grease coming out of a small crack or tear is the early sign of the CV joint boot failing. If the damage is bigger, you might see dark grease splattered on the inside of the wheel rim and around the area inside of the drive wheel. If you continue to drive on a worn out CV-Joint, the joint will eventually fail and the car will be non-drivable. Although a worn CV-Joint can last for a little while, it is best advised to replace it as soon as possible. How can you tell if your CV-Joint is failing or damaged without getting under your vehicle? The most common symptom of a badly-worn outer CV joint is a clicking or popping noise when turning. Usually the noise gets louder when accelerating in turns. One of the symptoms of a failed inner CV-joint is shudder or side-to-side shakes during acceleration. Another indicator of a worn-out inner CV joint may also cause clunking when shifting from “Drive” to “Reverse”.
Fix or Replace?
Although it is a little bit cheaper to just fix the boot on a CV-Joint, the added cost to replace the whole joint and axel may not cost much more than just the boot itself because of the labor time involved. At All Auto, we recommend that you just replace the whole unit. This will ensure that all the parts are working and there isn’t anything that is missed when just repairing the boot.
Bearings
A wheel bearing is a set of steel balls held together by a metal ring called a race. They help wheels spin fast with as little friction as possible. On a car, a wheel bearing rides on a metal axle shaft and fits tightly inside the hub. When the bearings start to wear, a low hum can be heard from the wheel hub with the failing bearing. Over time, this sound will become louder as the bearing continues to break down. This is usually due to loss of lubrication in which case the bearing will need to be repacked or if there is excessive wear, replaced.
What are some common symptoms associated with drive axle assembly issues?
• Loud clicking noise when turning. This is usually due to a failing CV axle shaft assembly. CV axles will become loose and make the clicking sound when they are excessively worn.
• Vibration is felt in the steering wheel when driving. This vibration can be caused from a bent drive axle which can be a dangerous situation. If the drive axle is bent, the stress from repeated rotation can cause the shaft to break, wear down on other parts, or even destroy your differential.
• Excess movement of the drive axle up and down. There should not be any excess movement of the drive axle if the vehicle is jacked up and supported. If there is more than ½ inch, the drive axle is too worn and needs replacement.
• Knock or clunk when accelerating or decelerating.
• Oil leakage anywhere on the ends of the drive shafts.
• Grease is visible from cracks or tears on the CV boot.
• Loud hum coming from the wheel hub.
As you can see, there are many parts to the drive assembly. Although problems are rare, they can occur at any time during the life of your vehicle. If you notice any of the symptoms above, bring your car in to All Auto and have one of our master technicians evaluate the situation. With drive axle repair, it is labor intensive, but we can usually get the work done in less than most franchise dealership service centers.
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