Most cars with full suspension systems will have axle bushes at the front and rear to control the ride quality of every journey. They come in a variety of materials, from nylon to polyurethane to aluminium, so their durability differs from product to product. However, due to the amount of pressure they withstand, no matter the material, they will always need replacing at some point. A typical sign that replacement axle bushes are needed is the sound of a certain clunking when you hit a bump in the road or take a corner that puts pressure on the suspension. It is perfectly normal for them to wear down, but it is important to replace them quickly before permanent damage occurs to the joints in your suspension system.