The Audi S4 axle assembly is a sub-system of your car's suspension system. The S4 axle assembly consists of an axle shaft with a CV (constant velocity) joint at either end, each protected by a specialized gasket called a CV boot. Your Audi S4 axle assembly may also include a U-joint.

The S4 axle assembly serves to transfer rotational force to your wheels from your transmission. To accomplish a seamless transfer, the CV joints of your Audi S4 axle assembly are heavily lubricated and carefully packed inside the CV boots. Your S4 axle assembly's CV joints contain many moving parts that are under constant pressure while your vehicle is in motion, and they will quickly become damaged if there is a breach in the CV boot.

Hard bounces and jolts during driving can also bend or snap the axle shaft. If your car is making grinding noises, especially when you turn, this may indicate trouble with your Audi S4 axle assembly. It goes without saying that a bent or broken axle shaft must be replaced. If the problem with your S4 axle assembly originates at the CV joint, you may be able to flush and repack the joints and replace a damaged CV boot. However, the process of repairing a CV boot or CV joint is messy and time-consuming, and will fail as often as it succeeds. You are usually better off replacing your entire Audi S4 axle assembly. When you purchase a new S4 axle assembly from our online catalogue, you are ensured of freshly sealed CV joints and durable CV boots that will withstand cracking and tearing for a long time to come.