Bad Motor Mounts
Motor mounts, or engine mounts, are the parts that keep your car's engine in place. If you've ever poked around under your hood, it might look like the engine is held in place simply by being wedged in there. In reality, it's secured to the car's chassis by motor mounts, which can vary in appearance based on the size, shape and strength needed for any given car.
Motor mounts are usually made of metal and rubber, and can be found nestled between the engine and the "frame" of the car. (The term "frame" is used loosely here, because the engine's specific location within the engine bay determines where it will bolt up, and that is a little different for every car.) In other words, the engine will always be bolted to structural components, though those components vary based on the vehicle's design.
The metal in the motor mount provides the structural integrity needed to hold everything in place, and rubber helps absorb the engine's vibrations. Of course, both of these materials wear out over time, and motor mounts need to be replaced periodically. When the motor mounts are worn, the metal is no longer providing a firm brace between the engine and the chassis, and the rubber is no longer absorbing all the vibrations. It's as likely a reason as any that you might suddenly or gradually notice shaking in your car's front end.
If you have a high-performance car or a car that has been modified, you might have high-performance motor mounts, which are made of a firmer material and don't absorb as much vibration. There's nothing wrong with firmer motor mounts, but some drivers find them annoying.
Bad motor mounts could be giving your vehicle the shakes, but what if those bad vibrations come on only when you apply the brakes? Find out on the next page.