Unusual vibrations from your car’s rear wheels don’t necessarily indicate that the rear suspension is going to fall off. For all you know, it may just be an axle bumper that’s missing in action.

The bumper is a piece of rubber that “stops” the wheel axle from hitting the body panel as it bounces over the road. Through time, though, road salt, heat, and water can cause the bumper to suffer dry rot. Once the bumper hardens and starts falling apart, it’s only a matter of time before the axle smashes it into pieces.

That’s why you hear an annoying “thud” whenever you drive over bumps. Fortunately, the axle bumper is neither hard to locate nor is it hard to replace. It’s usually bolted on top of the wheel axle.