This is because there is likely a problem with your front brake rotors. On the 240 you will need to replace the pads and rotors, and have the wheel bearing hub assemblies checked to make sure they are OK before installing new pads and rotors.
Here is some more info about brake vibrations:
...or these vehicles but that I "should stay close to home." It is absolutely not a wiring issue. What should I do? The car is running fine - new rattling sound to left of steering wheel, like plastic is loose...