What are trailing arms, exactly? Well if you're looking for a set for your car or truck, then you probably already know. But if not, then let's talk about what they are and what they do. First off, there are trailing arms and control arms, and although they may seem similar, they're not. Control arms typically are on the front of a vehicle, while trailing arms are on the back. Going one step further, they're designed to "control" the rear axle of the vehicle's suspension travel — so even though control arms may seem like the best term, it's not quite right. How do they control the axle? Well there are a few different methods, but typically there are anywhere from 2-6 links that stop the axle from moving both laterally in the chassis (side to side), as well as up and down. To complicate things further, some trailing arm setups allow the axle to rotate throughout its travel to keep the pinion angle correct, while others keep it static. All trailing arms have some kind of pivot, and at that point they usually have a bushing. If you're building an older car or truck, and if your rear suspension has never been rebuilt, then the bushings are probably trashed. That can cause all sorts of handling problems, making it very difficult to keep your vehicle under control, which is dangerous. So why would you want replacement trailing arms then? Sometimes the stock bushings are a pain to remove, so replacing the entire arm makes more sense. Also, newer arms are usually made with round tubing, which is typically stronger, too. Therefore, buying new arms is usually a cheaper and safer proposition than just swapping out bushings. It's ultimately your call of course, but knowing that you can improve the overall safety of your vehicle while simultaneously fixing any messed up parts? It's a win-win scenario.