An Owner's Guide to the 2008-2017 Audi S5 CV Axle Shaft
Hearing a clicking noise when you turn? Your S5's CV axle shaft might be the reason.
- A clicking sound when turning is the most common sign of a failing CV axle on your S5.
- Aftermarket axles are a cost-effective option, but OEM (GKN) axles offer the highest quality and durability.
- The large center axle bolt is a one-time-use stretch bolt and must be replaced and torqued correctly (147 ft-lbs + 180 degrees).
- Regularly inspect the rubber CV boots for tears to prevent grease loss and premature axle failure.
Is Your Audi S5 Making Strange Noises?
The CV axle is a strong part, but it doesn't last forever. The most common problem isn't the metal axle itself, but the rubber cover over the joints. This is called the CV boot. Over time, the boot can crack or tear. When this happens, the special grease inside leaks out, and dirt and water get in. This quickly ruins the joint, leading to failure.
Symptoms of a Failing CV Axle Shaft
If your S5 has a bad CV axle, it will give you clear warning signs. You should get it checked out if you notice any of these:
- Clicking or Popping Noise When Turning: This is the most common sign. You will hear a repeated clicking or popping sound that gets faster as you speed up during a turn. This almost always points to a worn outer CV joint.
- Grease on Your Wheels or Suspension: Look on the inside of your front wheels. If you see dark, thick grease splattered around, it's a sure sign of a torn CV boot.
- Vibrations While Driving: A worn-out CV axle can cause vibrations that you feel through the steering wheel, especially when you accelerate.
- A Loud Clunking Sound: If the joint is severely damaged, you might hear a loud clunk when you accelerate or decelerate. This is a serious sign that the axle is close to complete failure.
Known Issues for the Audi S5 (2008-2017)
While there are no direct recalls from the NHTSA for the CV axle shafts on this specific model range, Audi has issued Technical Service Bulletins (TSBs) for similar noises. TSB 2059129/4 notes that noises in tight turns on some models can be caused by the center differential and may be fixed with an oil change. TSB 2047920/10 points out that a bad wheel bearing can also make a humming or buzzing noise that might be confused with a CV axle problem. This shows how important it is to correctly diagnose the sound before buying parts.
Choosing the Right Aftermarket CV Axle
When your S5 needs a new CV axle, you have a few choices. You can buy an original part from Audi (OEM), or you can choose an aftermarket part. For a car like the 2008-2017 S5, an aftermarket axle can be a smart choice.
- OEM Axles: The original axles are typically made by GKN and are excellent quality. However, they are very expensive, sometimes costing over $1,500 for the part alone.
- Aftermarket Axles: These are much more affordable. Brands like Surtrak offer a budget-friendly alternative. The quality of aftermarket parts can vary. The most important things to look for are the quality of the CV boot material (neoprene is good) and the warranty offered. A lifetime warranty can provide peace of mind. While some cheap aftermarket axles have a reputation for failing early, many owners find them to be a good value for the money, especially on an older vehicle.
Pro Tip: The biggest weakness of a budget-friendly axle is often the rubber boot. No matter which brand you choose, inspect the boots during regular maintenance. Catching a small tear early and replacing just the boot can save you from having to buy a whole new axle.
Understanding Replacement Costs
The cost to replace a CV axle can change based on where you live and which parts you choose. Here is a general idea of what to expect.
| Part or Service | Estimated Cost (USD) |
|---|---|
| New Aftermarket CV Axle | $183 - $362 |
| New OEM CV Axle | $1,600 - $2,000+ |
| Shop Labor | $170 - $550 |
| Total Aftermarket Job (Est.) | $353 - $912 |
| Total OEM Job (Est.) | $1,770 - $2,550+ |
Frequently Asked Questions
Can I replace just the CV boot?
Yes. If the joint is not yet making noise or showing signs of damage, you can replace just the torn boot and repack it with fresh grease. This is a great way to keep your high-quality original Audi axle. However, if the joint is already clicking, the damage is done, and the entire axle shaft should be replaced.
Is the front CV axle the same for the driver and passenger side?
For the 2008-2017 Audi S5, the front left and front right CV axle shafts are often the same part number, making them interchangeable. However, you should always confirm the part number for your specific vehicle before ordering.
How difficult is it to replace an S5 CV axle?
For a DIY mechanic with the right tools, this is a medium-difficulty job. It requires a large breaker bar and a torque wrench capable of high torque settings for the main axle bolt. You will also need a special triple-square socket bit for the bolts that connect the axle to the transmission.
What happens if I don't replace a bad CV axle?
A clicking CV axle will get louder over time. Eventually, the joint can break apart completely. If this happens while driving, the car will lose power to that wheel and you will be stranded. It is a safety issue that should be addressed as soon as possible.
Technical Specifications
OEM Part Numbers: 8K0407271AJ 8K0407271AL
The front CV axle assembly for the B8/B8.5 platform S5 connects the front differential to the wheel hub. It uses a 10mm triple square bolt pattern for the inner flange and a large, single-use center axle bolt at the hub. The center bolt torque specification is critical: 200 Nm (147 ft-lbs) plus an additional 180-degree turn.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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